National Academies Press: OpenBook

Fat Content and Composition of Animal Products: Proceedings of a Symposium (1976)

Chapter:Status Report on the Alteration of Fatty Acid and Sterol Composition in Lipids in Meat, Milk, and Eggs

« Previous: Market Implications of Changing Fat Content of Milk and Dairy Products
Suggested Citation:"Status Report on the Alteration of Fatty Acid and Sterol Composition in Lipids in Meat, Milk, and Eggs." National Research Council. 1976. Fat Content and Composition of Animal Products: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/22.
×
Page200
Suggested Citation:"Status Report on the Alteration of Fatty Acid and Sterol Composition in Lipids in Meat, Milk, and Eggs." National Research Council. 1976. Fat Content and Composition of Animal Products: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/22.
×
Page201
Suggested Citation:"Status Report on the Alteration of Fatty Acid and Sterol Composition in Lipids in Meat, Milk, and Eggs." National Research Council. 1976. Fat Content and Composition of Animal Products: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/22.
×
Page202
Suggested Citation:"Status Report on the Alteration of Fatty Acid and Sterol Composition in Lipids in Meat, Milk, and Eggs." National Research Council. 1976. Fat Content and Composition of Animal Products: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/22.
×
Page203
Suggested Citation:"Status Report on the Alteration of Fatty Acid and Sterol Composition in Lipids in Meat, Milk, and Eggs." National Research Council. 1976. Fat Content and Composition of Animal Products: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/22.
×
Page204
Suggested Citation:"Status Report on the Alteration of Fatty Acid and Sterol Composition in Lipids in Meat, Milk, and Eggs." National Research Council. 1976. Fat Content and Composition of Animal Products: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/22.
×
Page205
Suggested Citation:"Status Report on the Alteration of Fatty Acid and Sterol Composition in Lipids in Meat, Milk, and Eggs." National Research Council. 1976. Fat Content and Composition of Animal Products: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/22.
×
Page206
Suggested Citation:"Status Report on the Alteration of Fatty Acid and Sterol Composition in Lipids in Meat, Milk, and Eggs." National Research Council. 1976. Fat Content and Composition of Animal Products: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/22.
×
Page207
Suggested Citation:"Status Report on the Alteration of Fatty Acid and Sterol Composition in Lipids in Meat, Milk, and Eggs." National Research Council. 1976. Fat Content and Composition of Animal Products: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/22.
×
Page208
Suggested Citation:"Status Report on the Alteration of Fatty Acid and Sterol Composition in Lipids in Meat, Milk, and Eggs." National Research Council. 1976. Fat Content and Composition of Animal Products: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/22.
×
Page209
Suggested Citation:"Status Report on the Alteration of Fatty Acid and Sterol Composition in Lipids in Meat, Milk, and Eggs." National Research Council. 1976. Fat Content and Composition of Animal Products: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/22.
×
Page210
Suggested Citation:"Status Report on the Alteration of Fatty Acid and Sterol Composition in Lipids in Meat, Milk, and Eggs." National Research Council. 1976. Fat Content and Composition of Animal Products: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/22.
×
Page211
Suggested Citation:"Status Report on the Alteration of Fatty Acid and Sterol Composition in Lipids in Meat, Milk, and Eggs." National Research Council. 1976. Fat Content and Composition of Animal Products: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/22.
×
Page212
Suggested Citation:"Status Report on the Alteration of Fatty Acid and Sterol Composition in Lipids in Meat, Milk, and Eggs." National Research Council. 1976. Fat Content and Composition of Animal Products: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/22.
×
Page213
Suggested Citation:"Status Report on the Alteration of Fatty Acid and Sterol Composition in Lipids in Meat, Milk, and Eggs." National Research Council. 1976. Fat Content and Composition of Animal Products: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/22.
×
Page214
Suggested Citation:"Status Report on the Alteration of Fatty Acid and Sterol Composition in Lipids in Meat, Milk, and Eggs." National Research Council. 1976. Fat Content and Composition of Animal Products: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/22.
×
Page215
Suggested Citation:"Status Report on the Alteration of Fatty Acid and Sterol Composition in Lipids in Meat, Milk, and Eggs." National Research Council. 1976. Fat Content and Composition of Animal Products: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/22.
×
Page216
Suggested Citation:"Status Report on the Alteration of Fatty Acid and Sterol Composition in Lipids in Meat, Milk, and Eggs." National Research Council. 1976. Fat Content and Composition of Animal Products: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/22.
×
Page217
Suggested Citation:"Status Report on the Alteration of Fatty Acid and Sterol Composition in Lipids in Meat, Milk, and Eggs." National Research Council. 1976. Fat Content and Composition of Animal Products: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/22.
×
Page218
Suggested Citation:"Status Report on the Alteration of Fatty Acid and Sterol Composition in Lipids in Meat, Milk, and Eggs." National Research Council. 1976. Fat Content and Composition of Animal Products: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/22.
×
Page219
Suggested Citation:"Status Report on the Alteration of Fatty Acid and Sterol Composition in Lipids in Meat, Milk, and Eggs." National Research Council. 1976. Fat Content and Composition of Animal Products: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/22.
×
Page220
Suggested Citation:"Status Report on the Alteration of Fatty Acid and Sterol Composition in Lipids in Meat, Milk, and Eggs." National Research Council. 1976. Fat Content and Composition of Animal Products: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/22.
×
Page221
Suggested Citation:"Status Report on the Alteration of Fatty Acid and Sterol Composition in Lipids in Meat, Milk, and Eggs." National Research Council. 1976. Fat Content and Composition of Animal Products: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/22.
×
Page222
Suggested Citation:"Status Report on the Alteration of Fatty Acid and Sterol Composition in Lipids in Meat, Milk, and Eggs." National Research Council. 1976. Fat Content and Composition of Animal Products: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/22.
×
Page223
Suggested Citation:"Status Report on the Alteration of Fatty Acid and Sterol Composition in Lipids in Meat, Milk, and Eggs." National Research Council. 1976. Fat Content and Composition of Animal Products: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/22.
×
Page224
Suggested Citation:"Status Report on the Alteration of Fatty Acid and Sterol Composition in Lipids in Meat, Milk, and Eggs." National Research Council. 1976. Fat Content and Composition of Animal Products: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/22.
×
Page225
Suggested Citation:"Status Report on the Alteration of Fatty Acid and Sterol Composition in Lipids in Meat, Milk, and Eggs." National Research Council. 1976. Fat Content and Composition of Animal Products: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/22.
×
Page226
Suggested Citation:"Status Report on the Alteration of Fatty Acid and Sterol Composition in Lipids in Meat, Milk, and Eggs." National Research Council. 1976. Fat Content and Composition of Animal Products: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/22.
×
Page227
Suggested Citation:"Status Report on the Alteration of Fatty Acid and Sterol Composition in Lipids in Meat, Milk, and Eggs." National Research Council. 1976. Fat Content and Composition of Animal Products: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/22.
×
Page228
Suggested Citation:"Status Report on the Alteration of Fatty Acid and Sterol Composition in Lipids in Meat, Milk, and Eggs." National Research Council. 1976. Fat Content and Composition of Animal Products: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/22.
×
Page229
Suggested Citation:"Status Report on the Alteration of Fatty Acid and Sterol Composition in Lipids in Meat, Milk, and Eggs." National Research Council. 1976. Fat Content and Composition of Animal Products: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/22.
×
Page230
Suggested Citation:"Status Report on the Alteration of Fatty Acid and Sterol Composition in Lipids in Meat, Milk, and Eggs." National Research Council. 1976. Fat Content and Composition of Animal Products: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/22.
×
Page231
Suggested Citation:"Status Report on the Alteration of Fatty Acid and Sterol Composition in Lipids in Meat, Milk, and Eggs." National Research Council. 1976. Fat Content and Composition of Animal Products: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/22.
×
Page232
Suggested Citation:"Status Report on the Alteration of Fatty Acid and Sterol Composition in Lipids in Meat, Milk, and Eggs." National Research Council. 1976. Fat Content and Composition of Animal Products: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/22.
×
Page233
Suggested Citation:"Status Report on the Alteration of Fatty Acid and Sterol Composition in Lipids in Meat, Milk, and Eggs." National Research Council. 1976. Fat Content and Composition of Animal Products: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/22.
×
Page234
Suggested Citation:"Status Report on the Alteration of Fatty Acid and Sterol Composition in Lipids in Meat, Milk, and Eggs." National Research Council. 1976. Fat Content and Composition of Animal Products: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/22.
×
Page235
Suggested Citation:"Status Report on the Alteration of Fatty Acid and Sterol Composition in Lipids in Meat, Milk, and Eggs." National Research Council. 1976. Fat Content and Composition of Animal Products: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/22.
×
Page236
Suggested Citation:"Status Report on the Alteration of Fatty Acid and Sterol Composition in Lipids in Meat, Milk, and Eggs." National Research Council. 1976. Fat Content and Composition of Animal Products: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/22.
×
Page237

Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

JOEL BITMAN Status Report on the Alteration of Fatly Acid and Stero! Composition in Lipids in Meat, Milk' and Eggs Demonstration of the high positive correlation between saturated fat intake and heart disease (Figure 1) and between blood cholesterol levels and heart disease (Figure 2) has made the American consumer wary of the fat in meat, milk, and eggs. The percentage of fat con- tributed by these food groups over a 20-year period is shown in Table 1 (Economic Research Service, 1965; Agricultural Statistics, 1969~. A 50% decline in butter consumption and 20% decline in egg consump- tion were especially meaningful trends. The American consumer has maintained a high consumption of beef, but that portion that is fat is an unwanted obesity-inducing nutrient. Thus, in 1973 approximately 2.5 billion pounds of excess fat, valued at 1.15 billion dollars, were trimmed from beef carcasses (Hendricks, 19741. The animal scientist, reluctantly and belatedly, has finally recognized and accepted this message from the marketplace. Within the last few years, research has been directed towards altering animal fats to make them more acceptable to the consumer, i.e., to in- crease the polyunsaturated fats in meat and milk and to lower the cholesterol in eggs. The task that faces the scientist who wants to change the lipid composition of the ruminant is considerably more difficult than it is to change the body fat composition of the nonruminant. In mono- gastric animals, such as man, pig, and chicken, body fat can be changed readily by changing the composition of the diet. Many experiments 200

Alteration of Fatty Acid and Sterol Composition in Lipids 201 40 20 20 10 _ CHD DEATH RATE PER 1000 n n n n ~ CALORIES FROM SATURATED FATS ~n 11 GR JAP NETH FIN YUGO IT US FIGURE 1 Coronary heart disease deaths and percentage of total calories provided by saturated fats in the diet of men from seven countries (Keys, 1970). have demonstrated that if higher levels of dietary polyunsaturated fats are fed to pigs and chickens, these polyunsaturated dietary lipids will be absorbed and incorporated into body fat. In ruminants, however, if increased amounts of polyunsaturated fats are fed, they are utilized by microorganisms in the rumen or metabolized by these organisms to form saturated and mono-unsaturated fatty acids; as a result, the meat and milk fat do not show any increase in polyunsaturated fat. The data in Table 2 demonstrate that although the normal plant diet of the ruminant is primarily polyunsaturated, both meat and milk fat normally TABLE 1 Contribution of Fat from Various Food Groups a Percentage of Fat Contributed by 1947-19491968 Change (% ) - Meat, including fish 33.5%35.2% +S Milk and dairy products, including butter 21.6%17.1% -20 Eggs 4.3 %3.4% -20 Total 59.4%55.7% -6 a Data from ERS, 1965; and Agricultural Statistics, 1969.

202 o o to Cal LL JOEL BITMAN 200 50 00 50 FIRST MAJOR CORONARY EVENT _ MEN 40-59 ~ :,n,n,n,J,Q,: 175 200 225 250 275 300 SERUM CHOLESTEROL mg 96 FIGURE 2 Relationship between serum cholesterol level and incidence rate of the first major coronary event (Intersociety Commission for Heart Disease Re- sources, 1970). contain only 2%-4% polyunsaturated fat (Hilditch and Williams, 1964; Bitman et al., 1974b). Recently, a process was developed that represents a breakthrough in the attempt to increase the polyunsaturated, fatty-acid content of TABLE 2 Fatty Acid Composition of Pasture Grass and Bovine Milk and Meat Fat a Weight in Lipid ( % ) Fatty Acid Grass Milk Meat Myristic 14 01 12 3 Palmitic 16:011 31 26 Stearic 18:02 11 14 Oleic 18:15 24 47 Linoleic 18:212 3 3 Linolenic 18:362 1 1 Others 7b 18c 64 a SOURCE: grass (Hilditch and Williams, 1964); mild and meat fat (Bitmap e' al., 1974a). b Primarily 12:0 and 16: 1. c 4:0-12:0 comprise, 11%; 14:! and 16:1, 4%; minor acids, 3%. Primarily 16:1.

Alteration of Fatty Acid and Sterol Composition in Lipids 203 ruminant meat and milk. T. W. Scott and his colleagues in Australia (Scott et al., 1970) coated polyunsaturated oils with a protein and then protected these particles from microbial attack in the rumen by treat- ment with formaldehyde. The coated oils passed through the rumen (pH 6-7) and into the abomasum and omasum (ply 2-3), where the more acid conditions hydrolyzed the protein-formaldehyde coat, re- leasing the intact dietary polyunsaturated oil, which could then be ab- sorbed and incorporated into body and milk lipid. The process had earlier been utilized by Ferguson et al. (1967) to increase wool growth of sheep by protecting dietary casein from microbial degradation in the rumen. This innovative technique has been the subject of intensive research within the last 4 years and has, for the first time, provided a range of new polyunsaturated ruminant foods. An attempt has been made in this review to summarize research di- rected towards altering the fatty-acid and sterol composition of meat, milk, and eggs. The typical fatty-acid composition of the foods of animal origin is shown in Table 3. This is the base upon which the experimental alterations have been made. It can be seen that ruminant fat contains more saturated fatty acids and less polyunsaturated fatty acids than do swine and poultry fat. Of the three major dietary components fats, pro- teins, and carbohydrates most attention has been given to the effects of feeding fats upon the fatty-acid and cholesterol composition of the animal. The tables are intended to group typical experimental findings and are not necessarily comprehensive and complete. TABLE 3 Typical Fatty-Acid Composition (Weight Percent) of Fat from Different Animal Sources a Ruminant Nonruminant Fatty Acid Milk Beef Pork Poultry Eggs Saturated Lower C`-C1. 11 Myristic 14:0 12 3 1 1 1 Palmitic 16:0 31 26 25 25 23 Stearic 18:0 11 14 14 4 4 Unsaturated Palmitoleic 16:1 4 3 3 7 5 Oleic 18:1 24 47 47 43 47 Linoleic 18:2 3 3 8 18 16 Linolenic 18 :3 1 1 - 2 Others 3 3 2 2 2 a Data from Hilditch and Williams ( 1964) and Bitman et al. (1974a).

204 A SYNOPSIS OF ALTERATIONS IN THE LIPID COMPOSITION OF SWINE JOEL BITMAN A summary of the changes brought about in fatty-acid composition by experimental dietary alterations in swine is presented in Table 4. The data clearly demonstrate the ready capacity of the pig to store fat of the type present in its diet. A wide variety of plant and fish oils, con- taining large quantities of polyunsaturated fatty acids, were fed to pigs; and the polyunsaturated fats were promptly absorbed and incorporated into their body fat. Most of these studies were conducted with growing pigs (8-28 weeks); end the depot fat alterations, although rapid, re- quired several months to achieve equilibrium. Experiments during the twenties and thirties, in which polyunsaturated fats were added to the diet, produced a soft or oily pork, characterized by a high linoleic ( 18: 2) and a low palm~tic ( 16: 0) and low stearic ( 18: 0) content.* Consumer acceptability was poor. While Table 4 may appear to indicate that alterations in the fatty-acid composition of swine have been well explored, I would suggest that this table, based upon approximately twenty reports, instead shows that fat ~ The first number refers to the length of the carbon chain in the fatty acid; the second, to the number of double bonds in the chain. TABLE 4 Fatty Acid Changes in Pig Fat a Diet 18:2 18:1 18:0 16:0 16:1 20-22 References Plant Lipids Corn, corn oil + 67, 68, 69, 71, 82, 123 Soybeans, soybean oil + - - - 16, 68, 69 Peanuts + - - - 68, 69 Cottonseed oil + - + - 70 Fish Lipids Menhaden oil Whale oil Cod liver oil-lard Animal Lipids Tallow Cholesterol VFA High carbohydrate Vitamin D Copper 17, 18 83 + + 84 O O O O + + + O + - O 123 113 14 66 113 2, 30, 142, 212 a CODE: ~ = increase,-= decrease, and 0 = no change.

Alteration of Fatty Acid and Sterol Composition in Lipids 205 modification research in pigs is relatively limited when compared to the number of studies on the role of fat in cardiovascular disease, where literature references run into the hundreds. The advent of modern gas-liquid chromatography has made investigation in this area much more practicable. Thus, the mechanism for control of fat composition in swine would seem to be susceptible to more exact elucidation. There are some additional, scattered literature references that indicate that several other factors affect fatty-acid composition (sex, age, breed, starvation, temperature), but this limited information was not included. A SYNOPSIS OF ALTERATIONS IN THE LIPID COMPOSITION OF POULTRY DEPOT AND EGG LIPIDS Summaries of the changes that can be effected in fatty-acid composition of poultry depot fat and egg lipids are presented in Tables 5 and 6. Several major features are apparent: 1. Alterations in egg lipids are complete within 16 days, while depot fat changes are much slower, requiring several months to reach an equilibrium. This difference reflects ovum maturation time in the egg-laying cycle and a relatively rapid transfer of blood lipids to a small fat compartment (egg lipids) in contrast to a much slower balance between blood lipids and a large lipid compartment (depot fat). 2. The chicken stores fat of the type present in its diet: dietary saturated or unsaturated fat causes the deposition of lipids of that re- spective type in the depot fat. 3. Dietary unsaturated fats pass readily into egg lipids, thus ingestion of a wide variety of unsaturated plant oils results in the appearance of the characteristic unsaturated fatty acids in the egg. Dietary saturated fats, however, have relatively little influence upon the composition of egg lipids. 4. An approximate inverse relationship exists between linoleic acid and oleic acids in egg and tissue lipids in response to dietary unsaturated fat ingestion. Particularly because of the marked resistance to change of the saturated fatty acids in egg lipids, most compositional changes in response to dietary fats occur in the relative proportions of 18:2 and 18:1. To the extent that generalizations between species are valid in these two monogastric animals, the chicken and the pig, it is apparent that the body fat of swine and poultry will reflect either greater saturation or unsaturation, depending upon the composition of the diet. Egg lipid composition, however, can be altered readily only in the direction of more unsaturated lipids.

206 to Go ~o o _ ~ Go ~o ++ + 4 - Ct 4 - o _~ o U. Cd v . ~ C) ¢ Ct + 1 + + GO C~ .. oo _ .. oo .. oo 1 1 1 1 o ·. oo .. o .. o .. ~ + o .. ~ + _ o .o,~ -~ o ° ~ ~°o fi ~ o _t oo ~ ~ ~ ~ o o oo oo t_ ~ ~ 1 ++++++o 1 1 1 1 1 1 1 1 . - o o _ o o ~ + + + os 11 o Ct Ct a~ 11 - U' .= 11 + . . o . - o o O ~ :' O ~ ° ~O _ ~ E ~

207 P~ . . ~o . . oo _4 . . oo o · - oo _~ Ct ~ .. to _, :^ o 5- .. o .= o Cq ~ C o V .. ~_, ·C) 4-^ ° ~ ~a, ~ ~ E ~ E ~ ~ E o o o d ++ - ~i ~ ~ 0 X ~ ~ o o oo ~oo C~ ~ ~ _, o ~ ~ o ~ o oo ~ ~ oo ~ oo ~ 0N ~ ~ ~ ~ r~ _( ++ + + o +++++ ++ ++ - ~o o ~X _4 ~ _, o oo + 1 +1 1 1 1 1 1 1 + o 1 1 1 o 1 1 1 + 1 1 1 + o 1 1 o + o o ._ o ~ .- _ ~ o o o ~ ~o o3 o~ ~o ~: 'e s o 11 o - u, 'e 11 1 . - o o ~ 3 ~ ~ ~ - a, Cd C, .= 11 .. o 3 o

208 SYNOPSIS OF ALTERATIONS IN EGG CHOLESTEROL CONTENT JOEL BITMAN Table 7 presents a summary of factors that can alter egg cholesterol content. Such limited studies as have been carried out on age and season as factors influencing egg cholesterol have not been included. A large number of studies dealing with changes in serum cholesterol and liver cholesterol in poultry, but which do not contain data on egg cholesterol, are not discussed in this review. Cholesterol, like the other lipids in eggs, can be altered by dietary means. Studies with labeled acetate (Kritchevsky and Kirk, 1951, Kritchevsky et al., 1951), cholesterol (Andrews et al., 1965, 1968; Connor e! al., 1965), and triglycerides (Budowski et al., 1961) and the experiments with cholesterol inhibitors in which desmosterol builds up in the egg (Burgess et al., 1962) have demonstrated that changes in egg cholesterol occur within hours of treatment. The time course of egg cholesterol changes thus appears to agree well with the time course of changes in egg fatty-acid composition (Reiser, l951b). Data from studies with dietary lipids disclose a large number of un- certainties. Thus, there is no agreement on whether or not corn oil, safflower oil, linseed oil, soybean oil, or coconut oil will increase egg cholesterol. Use of almost every oil at the same level by different workers has yielded different results. At the present time there is no good explanation for these serious discrepancies in research results by reputable, competent scientists. The inclusion of cholesterol in the diet of the hen promptly causes increased amounts of cholesterol in the egg. Addition of fat to the diet along with the cholesterol rather uniformly produces a doubling in egg cholesterol, probably by increasing the absorption of dietary cholesterol in the gut. Agents that influence (a) the intestinal absorption or (b) the enterohepatic circulation of cholesterol alter egg cholesterol. Thus, surface-active agents such as Tween or lecithin improve cholesterol adsorbability and increase egg cholesterol. Conversely, the plant sterol, ,3-sitosterol, promotes the fecal excretion of cholesterol and conse- quently decreases egg cholesterol. Sitosterol quantitatively replaces cholesterol in the egg. Two published reports, which disagree, are inadequate to determine whether dietary fiber reduces or increases egg cholesterol. The few studies with vitamins do not demonstrate striking or consistent effects. D-thyroxine was found to increase egg cholesterol, apparently by stimu lating cholesterol turnover and excretion via the egg.

Alteration of Fatty Acid and Sterol Composition in Lipids TABLE 7 Effect of Dietary Agents on Egg Cholesterola 209 Group Agent Effect References Oils Corn Safflower Linseed + o 39 32,63,80,122,143, 158, 220 7, 80, 209, 219, 220 220,222 80, 219 222 Soybean + 80, 209 0 7,51 Coconut + 7, 220 0 32 Cottonseed 0 167 Lard 0 32,63 Tallow 0 39, 51, 63, 80, 122, 158, 220 Rapeseed 0 122 Sterols Cholesterol + 32, 52, 53, 60, 64, 90, 102, 135, 182, 220, 226 0 121, 136 Sitosterol - 36 0 220 Protein 0 39, 63, 143, 158 Surface Active Tween 0 220 Lecithin 0 220 Cholestyramine 0 111, 134 Tween-cholesterol + 220 Lecithin-cholesterol + 220 Fiber Cellulose + 135 Cellulose - 216 Pectin - 216 Vitamins Niacin 0 220 Vitamin C 0 155 Vitamin A + 182 0 60, 220 Drugs Clofibrate 0 220 MER-29 - 25 Azasterols - 184 Diethyl-aminoethyl diphenyl valerate - 146 Probucol - 146, 147 Hormones D-thyroxine + 220 a CODE: + = increase,-= decrease, and 0 = no change.

210 JOEL BITMAN Drugs that inhibit the biosynthesis of cholesterol at the reductive step in the pathway from desmosterol to cholesterol have been successful in lowering egg cholesterol, but there is an accompanying quantitative replacement of cholesterol by desmosterol. This alteration raises several questions: 1. Are eggs containing large quantities of desmosterol satisfactory as human foods? 2. What level of cholesterol is necessary in the developing ovum to permit satisfactory egg production? 3. What levels of desmosterol can the chicken successfully cope with? What are the long-range physiological consequences for the hen of in- creased levels of desmosterol? A number of studies have demonstrated that egg cholesterol concen- tration varies genetically. Eggs from broiler-breeder strains contained more cholesterol than did those from commercial layer strains (Edwards et al., 1960; Miller and Denton, 1962; Harris and Wilcox, 1963a; Col- lins et al., 1968; Turk and Barnett, 1971; Marks and Washburn, 1973; Cunningham et al., 1974; Washburn and Nix, 1974~. Whether these differences are large enough to be nutritionally and physiologically meaningful to humans has not yet been determined. Many of the substances that have been used in attempts to alter egg cholesterol are agents that reduce serum cholesterol in other species. Review of the serum cholesterol changes of the studies summarized in Table 7 indicated that there was no simple direct relationship between plasma and egg cholesterol concentration. Thus, both D-thyroxine and ,3-sitosterol lowered blood cholesterol; thyroxine increased egg cho- lesterol, while sitosterol lowered it. Cholestyramine caused a very large decrease in serum cholesterol but had no effect upon egg cholesterol. Feeding dietary oils or oils with cholesterol raised serum cholesterol and also raised egg cholesterol. A diagrammatic representation of major cholesterol compartments of the laying hen is shown in Figure 3. The lack of consistent results and the lack of understanding of cholesterol relationships in the laying hen suggest that the time has arrived for complete metabolic balance studies in egg cholesterol reduction research. Although studies of this type would be expensive, the many studies listed in Table 7 attest to the large amount of money already expended on this problem. Measure- ment of cholesterol levels in the diet, plasma, fat, liver, body, egg, and excrete; the use of labeled cholesterol; and gas chromatography to identify egg sterols could bring order to the cholesterol picture order

Alteration of Fatty Acid and Sterol Composition in Lipids 211 ,~. LIVER ~ ~ ~ ~ ~MACERATE ~ H MG ~ M VA DIETARY ENTEROHEPATIC / CHOLESTEROL ~ - 1 | CIRCULATION I N TESTIN A L ~ | I I ~DIETARY SYNTHETIC ( ~ 1 ~CHOLESTEROL // ~I PLASMA Is - CHOLESTEROL ( ~I CHOLESTEROL I ~ ~ \O FECES CHOLESTEROL FIGURE 3 Cholesterol pathways in the laying hen. - OVIDUCT =2 CHOLESTEROL first, of course, and then, it is to be hoped, an elucidation of the laws governing overall cholesterol metabolism in the chicken. Finally, control or the possibility of alteration might be feasible if greater understanding were attained. A SYNOPSIS OF ALTERATIONS IN THE FATTY ACID COMPOSITION OF MILK. INFLUENCE OF UNPROTECTED DIETARY SUPPLEMENTS Table 8 summarizes data on the alterations in milk fatty-acid composi- tion that can be effected by unprotected dietary materials. The results of most studies were in agreement, and the table represents an accounting of experiments in which minor differences were resolved or ignored to permit grouping and to develop a typical pattern. Fatty acids not mentioned in the synopsis are either not altered or not described in the investigation. Exact details, of course, can only be acquired by con- sulting the original literature. The effects of season, temperature, fasting, stage of lactation, and genetics upon the fatty-acid composition of milk are not described.

212 - Ct ·_4 o o ._ A_ ·_1 U) o o V · C) ¢ Ct o A_ Ct ._ o C) .. . Do ¢ Em Cal . . x . . x _1 . . Go o .. Go _I .. AD o .. _ o .. . . _ lo . . lo . . rot lo . . o .. o .. o o .. X o lo . . 4- C) .Q {~^ _1 C~] V) c ~0\ Go o ~ _. ~ ~ ~ ~ ~ _ _ ^ ox o ^ ^ ~ ~ ~ o _ ~ ~ of ~ ~X ~ Cal or or ~ u) cr o~ ~ o^o^ ~ ~ ~ o~ ~ ~ ~ ~ ~ ~ ~ ~ o ~ ~ ~X _ ~ ~ ~ ~ ~ ~ ~ ~ V~ + + + + +++ + ++ + ++++++ ++ + o + + 0 1 ++ + + + 1 °+ 1 1 1 ++ + ++ + ++ + + 1 + 1 °+ 1 1 1 ++ 0 ++ 1 1 1 1 1 1 1 1 1 ° 1 1+° 1 1 + 1 o 1 o + 1 1 1 1 1 1 1 1 1 ++ 1 1 1 1 +° 1 ++ 1 1 1 1 1 1 1 1++1 1 1 1 11 1 1 1 1 1 1 1 1 +° 1 + 1 1 1 1 1 ° 1 1 1 1 1 1 ° 1 1 1 1 11 1 11 1 1 1 ° 1 1 1 _ 0 ._ ~ =~ ~ e ~ ~ D~ O e c ~E ~= ~ ~ ~ _ ~ ~ ~ o ~ E

213 cr. ~ ~ oo C~ ~ ~ ~ ~ ~ ~ ~ ~ ~oo X oo ox 0 o~ 0 ax ~ o~ 0 0 0 0 0 0 0 0 0 o~ ~\0 0\ C ~C~ _~ ~ _4 ~ ~ ~ ~ C ~ ~ ~ ~ ~ ~ ~4 + +++ o o o ~_. _~ o C~ ~ . oo + ++ ~ _I + 1 1 1 +++ + ++ + ++ 1 °° 11 1 1 1 11 + 1 1 1 +++ + ++ + oo1 1 1 1 1 1 1 1+ 1 1 + + 11 1 +°°1 ++ 1 ++ 1 ++° 1 + 1 1 1 1 1 °° ++1 ++ ++1 11 1 o 0 +++ + ++ 1 +++ ++ o 1 + + 1 + ox + ++ 1 + + ++ 1 + C, 11 o Ct U) CS o ++ 1 +1 11 1 0 3 O D~ ~ ~ ~ ~ O ~ D ~ ~ ~ ~ ~ ~ O 5- '~ ~ ~ ~ ~' ~ e ~ ~ ~ ~o ~ ~ ~ ~ ~ E~ E~ ~ ~ ~ E~ E~ ~ ~ ~ m ~ V ~ ~ ~ CQ V U' ·S~ ~ ~ ~ ~ 0

214 JOEL BITMAN The bacteria in the rumen stand as a buffer between the diet and the metabolic pool that gives rise to milk and meat lipids. Thus, a wide variety of dietary materials can be ingested; but the bacteria modify these substances, breaking them down and utilizing them as nutrients for their own metabolism and growth. This buffering capacity of the rumen microorganisms thereby produces a rather uniform precursor pool for lipid synthesis. Consequently, milk retains a fairly constant composition in the face of great variations in the nature of the diet. The data of Table 8 illustrate the following facts: 1. Plant oils high in 18:2 increase milk fat 18:2 only slightly; 18:1, however, increases markedly, indicating that the microorganisms readily hydrogenate one of the double bonds. 2. The relatively large increase in 18:2 when these same oils are infused intravenously or intra-abomasally demonstrates that if the ruminal microorganisms are avoided, and the unsaturated acids enter the circulation, they are readily transferred into the milk. 3. Feeding pure fatty acids of 12-16 carbon atoms in length did not provide any evidence of chain elongation, since there were no increases in Cue acids in milk. 4. Short-chain-length triglycerides, administered intravenously, did not appear in milk fat to as great an extent as did intermediate and long- chain triglycerides, suggesting a rapid metabolism of the short-chain acids. There was evidence of chain elongation of the short-chain triglycerides. 5. Changing the physical form of the diet (fineness of grind, pellet- ing, heating) results in an increased transfer of unsaturated lipids into milk, perhaps because of more rapid passage through the digestive tract and lessened ruminal hydrogenation. A SYNOPSIS OF ALTERATIONS IN THE FATTY ACID COMPOSITION OF MILK. INFLUENCE OF PROTECTED LIPIDS. A summary of the alterations that occur in milk fatty acids as a result of feeding protected lipid-containing materials is presented in Table 9. The relatively large number of studies attests to the great interest that this process has stimulated since it was reported 4 years ago (Scott et al., 19701. It is clear that protection of the dietary unsaturated lipids enables them to survive passage through the rumen without undergoing hy- drogenation and that milk with increased amounts of polyunsaturated fatty acids can be produced. The levels of linoleic acid in milk fat

215 E~ . . oo . . oo . . ~o o . ~ oo o .. o .. o .. o .. _I o .. o .. _. o . . o o . . 4 ._ oo X ~ ~ ~ ~o o ~ ~ ~_4 -~ 5~ Ch~ =\ oo w) t_ o o ~ o C ~oo ooo ~o 00 00 C ~ ~ ~ '} _1 ~C'` ~_' ~ + + + + + + + + o + + ++ o 1 + ++ o 1 + + 1 1 1°++ 1 1 1 1 1 1 + 1 1 1 1 1 1 1 +°+ + + + 1 1 1 1 1 + 1 ~ ~ a ~&5 =0 ~ ~ ~0 0 0 ~ ° ° ~C ~ ~ ~ a 9 i~ == -~ o ~2 3 ° 11 o C~ U) Ct 4) C) G) 11 cn Ct Ca> .s 11 + . . o

216 JOEL BITMAN equals or exceeds that which can be attained by intravenous or intra- abomasal infusion. A large number of oils have been encapsulated, and the results are rather consistent in demonstrating transfer of the main lipid components of the encapsulated fat into milk. Search for more economical lipid-feed supplements to replace ex- pensive, pure vegetable oils, encapsulated with such expensive purified proteins as casein, has led to the development of a number of seed, bean, or full-fat flour supplements. In these preparations the native protein of the plant material is used to encapsulate the lipid, eliminating the use of casein. The manufacturing technology has also been simplified, and it has been possible to dry the preparations quickly without the use of expensive spray-drying equipment. The efficiency of the transfer of dietary lipids into milk may be a critical factor in the ultimate success of these protected feed supple- ments. A difference between 20% and 40% transfer obviously would make a twofold difference in cost of the supplement. Variability has been noted in those studies in which efficiency data were supplied (Table 101. It is not known whether any of the variability in efficiency of transfer of linoleic acid is associated with the variability in transfer of fat into milk in different breeds, 3%-4% in Holsteins vs. 6%-8~o in Jerseys. A SYNOPSIS OF DAIRY PRODUCTS CONTAINING INCREASED POLYUNSATURATED FATTY ACIDS A wide variety of dairy products have been prepared from milk contain- ing increased amounts of linoleic acid. These products reflect the milk from which they are made in composition and, generally, are char- acterized by large increases in 18:2, increases in 18:1 and 18:0, and decreases in saturated C~-16 fatty acids. A listing of products that have been made is given in Table 11. Research on the commercial development of polyunsaturated dairy products has proceeded intensively in Australia. The altered chemical and physical properties of the products, oxidative stability, and flavor are subjects not within the scope of this review and will not be discussed. A SYNOPSIS OF ALTERATIONS IN FATTY-ACID CONTENT OF RUMINANT MEAT. INFLUENCE OF UNPROTECTED DIETARY LIPIDS. Ruminant depot fats contain very small proportions of polyunsaturated fatty acids and very small amounts of fatty acids below C14 (Table 2).

217 U. 50 m - .~ o _. ~4 ._ ._ ¢ ._ o ._ Ct ._ o U. Ct 50 o c) ._ Lo To m Ed ~ ·. X Ct En U. Ct < O -~ ~ =~ 8 A> - - ~Cd C. ~ a ~=~` ~ ~q ~A, ~ ~ q) q) ~ =0 an a ~ ~ a an ~ ~m 3 ~ > ~ ~C C ~ ~ V ~ ~ ~ ~ O OGo o ~ Go ~Go Cal Cry ~Do O Cal 3~m ~ ~a, 1 3 ~ 1 e Y ~ y =- ~ ~ -c 3 ~ ~ .~- ~ ~ _ ~ ~ _ ~ ~ _ ~ ~ ~ ~ ~ ~ _

218 JOEL BITMAN TABLE 11 Synopsis of Dairy Products Containing Increased Amounts of Linoleic Acid Product % 18:2 References Butter Cheddar cheese Processed Cheddar cheese 3-33 2-32 Cheedam, Gouda,13rie, 25 Camembert, cream cheeses Yogurt, sour cream Margarine Milk 18-20 5-35 Buchanan et al., 1970; Buchanan and Rogers, 1973; Harrap, 1973; Kieseker et al., 1974; Murphy et al., 1974; Wood et al., 1974; Bitman et al., 1975. Wang et al., 1973; Czulak et al., 1974a; Czulak et al., 1974b; Kieseker et al., 1974; Hodges et al., 1975. Czulak et al., 1974a; Czulak et al., 1974b; Hodges et al., 1975. Herbert and Kearney, 1975. Johnson et al., 1974; Edmondson et al., 1974; Johnson, 1974; Johnson and Tracey, 1974; Sidhu et al., 1974; Stark and Urbach, 1974. In contrast to milk, which has about 20%-25~o of C4-C~4 fatty acids, meat has about 90% of its fatty acids present as palmitic, oleic, and stearic. The results of the studies summarized in Table 12 make it abundantly clear that this ruminant adipose tissue composition is re- markably unresponsive to dietary influences. The rumen and its microbes modify the dietary components to present a rather constant precursor pool to the circulation and to the tissues. Also, body depot fat represents a relatively large compartment that changes only slowly. The very small differences, of a few percent or no change at all, in fatty-acid components when large amounts of lipids are fed suggest that there is very little hope of making significant changes in saturation or unsaturation of ruminant fats by dietary means. Although changes in fatty-acid composition induced by breed, age, sex, season, and growth are not described, these factors also exert influences of about the same order of magnitude. These studies have been needed, and the develop- ment of gas chromatography has stimulated an explosion in lipid re- search because of the relative ease with which fatty acids can be determined. It does not appear to be profitable, however, to pursue this type of meat research further, since there is now adequate proof that ruminant adipose tissues are essentially insensitive to changes in the fatty-acid composition of the diet. Slight differences, even those few that are statistically significant, are only minor perturbations on a background

Alteration of Fatty Acid and Sterol Composition in Lipids 219 of 90% palmitic, oleic, and stearic acids. While of interest scientifically, they are undoubtedly without physiological or nutritional significance for the consumer. A SYNOPSIS OF ALTERATIONS IN THE FATTY-ACID COMPOSITION OF RUMINANT MEAT. INFLUENCE OF PROTECTED LIPIDS. The studies reviewed in Table 13 indicate that feeding protected lipids will readily increase the polyunsaturation of the depot lipids in cattle and sheep. When 400-500-lb steers are fed protected lipids they rapidly take up the dietary linoleic acid such that tissue 18:2 levels approach a maximum at about 8 weeks. When heavier steers were fed, only small increases in 18:2 were noted, suggesting a slower turnover and deposi- tion of lipid in these animals as compared to the more rapidly growing younger animals. The protected lipids brought about similar increases in depot fat 18:2 in calves, yielding a polyveal, and in lambs, where the deposition of dietary 18:2 appears to be particularly rapid. In contrast to the re- sults with older steers, older sheep responded to dietary 18:2 with a rapid deposition in depot fat. The two cheaper seed supplements that have been developed, sun- flower seed-1 Onto casein-formaldehyde and sunflower seed-soybean (70:301-formaldehyde, were found to be very effective in producing polyunsaturated beef, lamb, and mutton. THE EFFECT OF PROTECTED FEEDS UPON CHOLESTEROL CONTENT OF MEAT, MILK,AND DAIRY PRODUCTS We have previously demonstrated that very large increases in plasma cholesterol occur, from a level of 140 mg % to 380 mg %, when pro- tected lipids are fed to lactating cows (Bitmap et al., 19731. We had also earlier reported that there appears to be a rigid blood-milk barrier, since there was no increase in milk cholesterol in spite of these large amounts of circulating cholesterol. If the high blood cholesterol accompanying protected lipid feeding caused deposition of cholesterol in the tissues, this could negate or counteract possible advantages due to higher polyunsaturated fatty-acid content. We have examined a number of food samples in our laboratory and compare these to other reported values in Table 14. The data show that the cholesterol content of these polyunsaturated foods was not greater than in conventional products.

220 Cd ._ o o . - ._ o o V ._ ¢ Ct o V, Ct ·_4 o C) _ i_ En U) t? a~ a l .. oo .. oo ·. oo o · oo . ~ ~o o · .. _4 o · o .. o .. o _I a, ._ oo ~ ~ ~o oo ~ ~oo ~_ tn ~ c ~ ~o ~ ~ ~ ~ ~ ~ ~ r~ oo tn ~ ~ ~ ~ ~ ~ ~ ~ e~ + ++ o 0 + 1 o + o +o 0 1 o o o + + 1°+ 1 1 1 oo 1 1 + o 0 1 1 oo 1 + 1 1 ° ° o o ++ + a~ c~ t4 Ce ~ C,} ~ o _ ~ O D- ~ D O ~ ~ ° c ~ o ~ C C ° E -~ C E c

221 as to I_ o ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~cr. ~ cry _4 ~ ~ _4 ~ ~ t_~ t_ I_ _ _4 ~ to 1 o +o o +++ + 1 + +o 0 0 1 1 o 0 0 +0 + + 1 o 1 °° ° 1too + o o o 1 1 1 1+ o ++ + + + ._ o .= Ca,,, _4 a' ~,` O O ~<, 3 :> ', ~ -o E E ,- c E 8 · o ~, a 5 r,-~¢E~= ~-~i en - R4 A> 00 A: Ct S C) 11 o US Ct CO C~ C, 111 CO Ct . 11 . . o

222 JOEL BITMAN TABLE 13 Effect of Protected Dietary Lipids on Fatty-Acid Compo- sition of Ruminant Meat a Diet 14:0 14:1 16:0 16:1 18:0 18:1 18:2 References Beef Safflower oil- casein-F Sunflower seed- soybean-F Veal Safflower oil- casein-F Lamb Safflower oil- casein-F Sunflower seed- casein-F Sunflower seed- soybean-F Mutton Safflower oil- casein-F Sunflower seed + + 42, 56,76, 128, 151 92, 98 + + 72,116, 228 _ _ + 43 + 81, 106 - + 98,218 ~+ 179 casein-F 81,92 a CODE: + = increase,-= decrease, 0 = no change, and F = fo~,~aldehyde. S U M MARY Times change, tastes change, and foods change. The chicken we have every Sunday is different from those our mothers enjoyed 30 years ago and different from the chickens our grandmothers ate 60 years ago. The rapidly growing chicken of today, fed on fish meal and animal tallow, undoubtedly tastes different from a 1930 bird. The polyunsaturated soft pork that received much attention 40 years ago may be more acceptable today, with modern refrigeration and a palate trained by the U.S. food industry. In plant research, a firmer tomato is developed with a harder skin for machine harvesting; sunflowers are developed with higher oil seed content, and fruits and vegetables are designed to be larger or smaller, or sweeter or drier, often with great success. Johnson has referred to this as "biomanipulation," and the introduction of techniques to change foods of animal origin is a step in the right direction (Johnson 1974~. I have attempted to outline the past as a step towards filling in the

Alteration of Fatty Acid and Sterol Composition in Lipids 223 TABLE 14 Cholesterol Content of Conventional and Polyunsaturated Meat, Milk, and Dairy Products a Polyun No. Sample Saturated saturated References 1 Subjects fed beef, dripping, 535 536 Nestel et al., cheese, butter, milk, cream 1973 2 As above+ice cream+ 493 520 Nestel et al., lamb 1974 3 Milk 14 14 Bitman et al., 1973 4 Ground beef 94 85 Weyant, Wrenn, Chuck 55 37 Bitman, unpub Round 40 49 fished Tail fat extracted lipid 161 154 5 Veal 74 80 Wrenn et al., 1973b 6 Omental or rib fat 185 360 (NS) Dinius et al., 1974a 7 Kidney fat 137 209 (<.05) Dinius et al., 1974b 8 Milk 13 12 Hodges et al., 1975 Butter 207 160 Hodges et al., 1975 Ground beef 75 74 Hodges et al., 1975 Other beef 48 57 Hodges et al., 1975 Lamb 68 69 Hodges et al., 1975 a Units are mg/100 ml or mg/100 g, except for 1 and 2, which are mg/day intake. future. I have summarized those researches that indicate which foods of animal origin can be altered in fatty-acid composition and have de- scrib~d the limits of these alterations. Additional research is needed to elucidate the mechanism of control of egg cholesterol. This is an exciting and important area, and it seems worthwhile to continue to search for methods to alter the composition of eggs for the benefit of the consumer. It should be recognized that the use of protected fat feeding to produce polyunsaturated meat and milk is a specialized technique and probably cannot supply polyunsaturated food for a large segment of the population. It can serve a specialized need for persons who must reduce their intake of saturated fats for medical reasons.

224 JOEL BITMAN In Australia, the feed supplement is approved for sale to farmers. A commercial dairy plant pays a premium to the farmers producing the milk. A wide range of polyunsaturated foods will soon be sold through two heart clinics. In New Zealand, four clinics are planning to provide these new foods for people with greater coronary heart disease risk. Distribution is being made in this way, because there is not enough food of this type to meet demand in the open marketplace. The ability to change foods, and to improve them, is one of the ob- jectives of the agricultural sciences. These new developments offer great promise in their ability to bring about lipid changes, but they also raise new problems. These problems extend over a wide range of science, from manufacturing technology to the biosynthesis of milk fats. Re- search directed towards providing foods with altered fat content and composition is an opportunity to serve the health needs of the nation. The importance of this type of research rests upon the health problem that stimulated it. Coronary heart disease is the leading cause of death in the United States; the best medical and nutritional advice recom- mends reduction in saturated fats in foods, as well as an overall reduc- tion in the total amount of fat. There is not a great likelihood that the preparation of an encapsu- lated supplement for feeding to a dairy cow to produce polyunsaturated milk can compete economically with direct homogenization of poly- unsaturated oils into skim milk. Direct synthetic preparation of poly- unsaturated cheese and meat is riot presently feasible, however, and the encapsulation process offers promise, therefore, for preparation of these foods. While the ultimate commercial future of these products cannot be assessed, this method provides a possible means whereby traditional foods can be produced, consumed, and enjoyed by the public without jeopardy to their health. R E F E R E N C E S Agricultural Statistics. 1969. U.S. Department of Agriculture, Washington, D.C. 2. Amer, M. A., and J. I. Elliot. 1973. Influence of supplemental dietary cop- per and vitamin E on the oxidative stability of porcine depot fat. I. Anim. Sci. 37:87. 3. Andrews, J. W., Jr., R. K. Wagstaff, and H. M. Edwards, Jr. 1965. An iso- topic steady state study of cholesterol in the laying hen. Poult. Sci. 44: 1348. 4. Andrews, J. W., Jr., R. K. Wagstaff, and H. M. Edwards, Jr. 1968. Choles- terol metabolism in the laying fowl. Am. J. Physiol. 214:1078. Askew, E. W., J. D. Benson, J. W. Thomas, and R. S. Emery. 1971. Metabolism of fatty acids by mammary glands of cows fed normal, re

Alteration of Fatty Acid and Sterol Composition in Lipids 225 stricted roughage, or magnesium oxide supplemented rations. J. Dairy Sci. 54:854. 6. Astrup, PI. N., J. J. Nedkvitne, T. Skjevdal, E. Bakk, P. Lindstad, and W. Eckhardt. 1972. A method to increase linoleic acid content in meat and milk is to coat the fat given to the ruminants. Nor. Landbruk 90:24. 7. Bartov, I., S. Bornstein, and P. Budowski. 1971. Variability of cholesterol concentration in plasma and egg yolks of hens and evaluation of the effect of some dietary oils. Poult. Sci. 50: 1357. 8. Beitz, D. C., and C. L. Davis. 1964. Relationship of certain milk fat de- pressing diets to changes in the proportions of the volatile fatty acids pro- duced in the rumen. J. Dairy Sci. 47:1213. 9. Bickerstaffe, R., and E. F. Annison. 1971. The effects of duodenal infusions of sunflower oil on the yield and fatty acid composition of milk fat in the cow. Proc. Nutr. Soc. 30:28A. 10. Bitman, J., L. P. Dryden, H. K. Goering, T. R. Wrenn, R. A. Yoncoskie, and L. F. Edmondson. 1973. Efficiency of transfer of polyunsaturated fats into milk. J. Am. Oil Chem. Soc. 50:93. 11. Bitman, J., T. R. Wrenn, L. P. Dryden, L. F. Edmondson, F. W. Douglas, Jr., G. C. Mustakas, E. C. Baker, and W. J. Wolf. 1974a. Effects of feeding formaldehyde treated soybean preparations upon milk fat polyunsaturated fatty acids. J. Am. Oil Chem. Soc. 51 :288A. 12. Bitman, J., T. R. Wrenn, L. P. Dryden, L. F. Edmondson, and R. A. Yon- coskie. 1974b. Pages 57-69 in J. E. Vandagaer, ed. Microencapsulation: Processes and Applications. Plenum Publishing Corp., New York. 13. Bitman, J., J. R. Weyant, and T. R. Wrenn. 1975. Plasma vitamin E, choles- terol and lipids during atherogenesis in rabbits. Fed. Proc. 34:892. 14. Bowland, J. P., B. A. Young, and L. P. Milligan. 1971. InDuence of dietary volatile fatty acid mixtures on performance and on fat composition of growing pigs. Can. J. Anim. Sci. 51 :89. 15. Bratton, R. W., W. F. Epple, J. W. Wilbur, and J. H. Hilton. 1938. A study of some of the physico-chemical effects of soybeans on the fat in cows milk. J. Dairy Sci. 21:109. 16. Brooks, C. C. 1967. Effect of sex, soybean oil, bagasse and molasses on carcass composition and composition of muscle and fat tissue in swine. J. Anim. Sci. 26:504. 17. Brown, J. B. 1931. The nature of the highly unsaturated fatty acids stored in the lard from pigs fed menhaden oil. J. Biol. Chem. 90: 133. 18. Brown, J. B., and E. M. Deck. 1930. Occurrence of arachidonic acid in lard. J. Am. Chem. Soc. 52:1135. 19. Brown, W. H., J. W. Stull, and G. H. Stott. 1962. Fatty acid composition of milk. I. Effect of roughage and dietary fat. J. Dairy Sci. 45:191. 20. Brumby, P. E., J. E. Storry, and J. D. Sutton. 1972. Metabolism of cod-liver oil in relation to milk fat secretion. J. Dairy Res. 39:167. 21. Buchanan, R. A., A. J. Lawrence, and G. Loftus Hills. 1970. The properties of butter made from polyunsaturated milk fat. XVIII. Int. Dairy Congr., Sydney, IE: 511. 22. Buchanan, R. A., and W. P. Rogers. 1973. Manufacture of butter high in linoleic acid. Aust. J. Dairy Technol. 28: 175. 23. Bucholtz, H. F., C. L. Davis, D. L. Palmquist, and K. A. Kendall. 1969.

226 JOEL BITMAN Study of the low-fat milk phenomenon in cows grazing pearl millet pas- tures. J. Dairy Sci. 52: 1388. 24. Budowski, P., N. R. Bottino, and R. Reiser. 1961. Lipid transport in the lay- ing hen and the incubating egg. Arch. Biochem. Biophys. 93 :483. 25. Burgess, T. L., C. L. Burgess, and J. D. Wilson. 1962. Effect of MER-29 on egg production in the chicken. Proc. Soc. Exp. Biol. Med. 109:218. 26. Cabezas, M. T., J. F. Hentges, Jr., J. E. Moore, and J. A. Olson. 1965. Effect of diet on fatty acid composition of body fat in steers. J. Anim. Sci. 24:57. 27. Chalupa, W., G. D. O'Dell, A. J. Kutches, and R. Lavker. 1970. Supple- mental corn silage or baled hay for correction of milk fat depressions pro- duced by feeding pellets as the sole forage. J. Dairy Sci. 53:208. 28. Chandler, N. J., I. B. Robinson, I. C. Ripper, and P. Fowler. 1973. The effect of feeding formaldehyde treated sunflower seed supplement on the yield and composition of milk fat. Aust. J. Dairy Tech. 28: 179. 29. Choudhury, B. R., and R. Reiser. 1959. Interconversions of polyunsaturated fatty acids by the laying hen. J. Nutr. 68:457. 30. Christie, W. W., and J. H. Moore. 1969. The effect of dietary copper on the structure and physical properties of adipose tissue triglycerides in pigs. Lipids 4:345. 31. Chu, T. K., and F. A. Kummerow. 1950. The deposition of linolenic acid in chickens fed linseed oil. Poult. Sci. 29:846. 32. Chung, R. A., J. C. Rogler, and W. J. Stadelman. 1965. The effect of dietary cholesterol and different dietary fats on cholesterol content and lipid composition of egg yolk and various body tissues. Poult. Sci. 44:221. 33. Chung, R. A., E. Y. Davis, R. A. Munday, Y. C. Tsao, and A. Moore. 1967a. Effect of cholesterol with different dietary fats on the fatty acid composi- tion of egg yolk and various body tissues. Poult. Sci. 46: 133. 34. Chung, R. A., Y. C. Lien, and R. A. Munday. 1967b. Fatty acid composition of turkey meat as affected by dietary fat, cholesterol, and diethylstilbestrol. J.FoodSci.32:169. 35. Church, D. C., A. T. Ralston, and W. H. Kennick. 1967. Effect of diet or diethylstilbestrol on fatty acid composition of bovine tissues. J. Anim. Sci. 26:1296. 36. Clarenburg, R., I. A. Kim Chung, and L. M. Wakefield. 1971. Reducing the egg cholesterol level by including emulsified sitosterol in standard chicken diet. J. Nutr. 101 :289. 37. Clemens, E., W. Woods, and V. Arthaud. 1974. The effect of feeding un- saturated fats as influenced by gelatinized corn and by the presence or absence of rumen protozoa. II. Carcass lipid composition. J. Anim. Sci. 38:640. 38. Collins, W. M., A. C. Kahn III, A. E. Teeri, N. P. Zervas, and R. F. Constantino. 1968. The effect of sex-linked barring and rate of feathering genes, and of stock, upon egg yolk cholesterol. Poult. Sci. 47: 1518. 39. Combs, G. F., and Helbacka, N. V. 1960. Studies with laying hens. 1. Effect of dietary fat, protein levels and other variables in practical rations. Poult. Sci. 39:271. 40. Connor, W. E., J. W. Osborne, and W. L. Marion. 1965. Incorporation of plasma cholesterol-4-1`C into egg yolk cholesterol. Proc. Soc. Exp. Biol. Med. 118:710. 41. Cook, L. J., T. W. Scott, and Y. S. Pan. 1972a. Formaldehyde-treated

Alteration of Fatty Acid and Sterol Composition in Lipids 227 casein-sa~ower oil supplement for dairy cows. II. Effect on the fatty-acid composition of plasma and milk lipids. J. Dairy Res. 39:211. 42. Cook, L. J., T. W. Scott, G. J. Faichney, and H. Lloyd Davies. 1972b. Fatty acid interrelationships in plasma, liver, muscle, and adipose tissues of cattle fed safflower oil protected from ruminal hydrogenation. Lipids 72:83. 43. Cook, L. J., T. W. Scott, K. A. Ferguson, and I. W. McDonald. 1970. Pro- duction of polyunsaturated ruminant body fats. Nature 228: 178. 44. Coppock, J. B. M. 1962. Some aspects of the influence of diet and husbandry on the nutritional value of the hen's egg. Chem. Ind., May, p. 886. 45. Couch, J. R., B. M. Cornett, T. M. Ferguson, and C. R. Creger. 1970. Effect of dietary fat on the fatty acid composition of turkey egg yolks. Nutr. Rep. Int. 1:83. 46. Crouse, J. D., J. D. Kemp, J. D. Fox, D. G. Ely, and W. G. Moody. 1972. Effect of castration, testosterone and slaughter weight on fatty acid content of ovine adipose tissue. J. Anim. Sci. 34:384. 47. Cruickshank, E. M. 1934. CXXXVI. Studies in fat metabolism in the fowl. I. The composition of the egg fat and depot fat of the fowl as affected by the ingestion of large amounts of different fats. Biochem. J. 28:965. 48. Cunningham, D. L., W. F. Kruger, R. C. Fanguy, and J. W. Bradley. 1974. Preliminary results of bidirectional selection for yolk cholesterol level in laying hens. Poult. Sci. 53:384. 49. Czulak, J., L. A. Hammond, and J. F. Horwood. 1974a. Cheese and cultured dairy products from milk with high linoleic acid content. I. Manufacture and physical and flavor characteristics. Aust. J. Dairy Technol. 29:124. 50. Czulak, J., L. A. Hammond, and J. F. Horwood. 1974b. Cheese and cultured dairy products from milk with high linoleic acid content. II. Effect of added lipase on the flavor of the cheese. Aust. J. Dairy Technol. 29: 128. 51. Daghir, N. J., W. W. Marion, and S. L. Balloun. 1960. Influence of dietary fat and choline on serum and egg yolk cholesterol in the laying chicken. Poult. Sci. 39:1459. 52. Dam, H. 1928. Die Synthese und Resorption des Cholesterins beluchet durch Versuch an Huhnereiern. Biochem. Z. 194:188. 53. Dam, H. 1929. Cholesterinstoffwechsel in Huhnereiern und Huhnehen. Bio- chem Z. 215:475. 54. Devier, C. V., and W. H. Pfander. 1974. Source and level of dietary fat on fatty acid and cholesterol in lambs. J. Anim. Sci. 38:669. 55. Dinius, D. A., R. R. Oltjen, and L. D. Satter. 1974a. Influence of abomasally administered safflower oil on fat composition and organoleptic evaluation of bovine tissue. J. Anim. Sci. 38:887. 56. Dinius, D. A., R. R. Oltjen, C. K. Lyon, G. O. Kohler, and H. G. Walker, Jr. 1974b. Utilization of a formaldehyde treated casein-safflower oil com- plex by growing and finishing steers. J. Anim. Sci. 39: 124. 57. Dryden, F. D., and J. A. Marchello. 1973. Influence of dietary fats upon carcass lipid composition in the bovine. J. Anim. Sci. 37:33. 58. Dryden, F. D., J. A. Marchello, W. C. Figroid, and W. H. Hale. 1973. Composition changes in bovine subcutaneous lipid as influenced by dietary fat.J.Anim.Sci.36:19. 59. Dryden, L. P., J. Bitman, T. R. Wrenn, J. R. Weyant, R. W. Miller, and L.

228 JOEL BITMAN F. Edmondson. 1974. Effect of Triundecanoin upon lipid metabolism in the cow. J. Am. Oil Chem. Soc. 51:302. 60. Dua, P. N., B. C. Dilworth, E. J. Day, and J. E. Hill. 1967. Effect of dietary vitamin A and cholesterol on cholesterol and carotenoid content of plasma and egg yolk. Poult. Sci. 46:530. 61. Edmondson, L. F., R. A. Yoncoskie, N. H. Rainey, F. W. Douglas, Jr., and J. Bitman. 1974. Feeding encapsulated oils to increase the polyunsatura- tion in milk and meat fats. J. Am. Oil Chem. Soc. 51 :72. 62. Edwards, H. M., Jr., J. C. Driggers, R. Dean, and J. L. Carmon. 1960. Studies on the cholesterol content of eggs from various breeds and/or strains of chickens. Poult. Sci. 39:487. 63. Edwards, H. M., Jr., J. E. Marion, and J. C. Driggers. 1962. Serum and egg cholesterol levels in mature hens as influenced by dietary protein and fat changes. Poult. Sci. 41 :713. 64. Edwards, H. M., Jr., and V. Jones. 1964. Effect of dietary cholesterol on serum and egg cholesterol levels over a period of time. Poult. Sci. 43 :877. 65. Edwards, R. L., S. B. Tove, T. N. Blumer, and E. R. Barrick. 1961. Effects of added dietary fat on fatty acid composition and carcass characteristics of fattening steers. J. Anim. Sci. 20:712. 66. Ellis, N. R. 1933. Changes in quantity and composition of fat in hogs fed a peanut ration followed by a corn ration. USDA Tech. Bull. 368. 67. Ellis, N. R., and O. G. Hankins. 1925. Formation of fat in the pig on a ration moderately low in fat. J. Biol. Chem. 66: 101. 68. Ellis, N. R., and PI. S. Isbell. 1926a. Soft pork studies. II. The influence of the character of the ration upon the composition of the body fat of hogs. J. Biol. Chem. 69:219. 69. Ellis, N. R., and H. S. Isbell. 1926b. The effect of food fat upon body fats, as shown by the separation of the individual fatty acids of the body fat. J. Biol. Chem. 69:239. 70. Ellis, N. R., C. S. Rothwell, and W. O. Pool, Jr. 1931. The effect of ingested cottonseed oil on the composition of body fat. J. Biol. Chem. 92:385. 71. Ellis, N. R., and J. H. Zeller. 1930. The influence of a ration low in fat upon the composition of the body fat of hogs. J. Biol. Chem. 89: 185. 72. Ellis, R., W. I. Kimoto, J. Bitman, and L. F. Edmondson. 1974. Effect of induced high linoleic acid and tocopherol content on the oxidative stability of rendered veal fat. J. Am. Oil Chem. Soc. 51 :4. 73. Economic Research Service. 1965. U.S. Food Consumption Stat. Bull. No. 364. U.S. Department of Agriculture, Washington, D.C. 74. Erwin, E. S., W. Sterner, and G. J. Marco. 1963. Effect of type of oil and site of administration on the fate of fatty acids in sheep. J. Am. Oil Chem. Soc. 40:344. 75. Evans, R. J., S. L. Bandemer, and J. A. Davidson. 1960. Fatty acid distribu- tion in lipids from eggs produced by hens fed cottonseed oil and cotton- seed fatty acid fractions. Poult. Sci. 39: 1199. 76. Faichney, G. J., PI. Lloyd Davies, T. W. Scott, and L. J. Cook. 1972. The incorporation of linoleic acid into the tissues of growing steers offered a dietary supplement of formaldehyde-treated casein-safflower oil. Aust. J. Biol. Sci. 25:205. 77. Feigenbaum, A. S., and H. Fisher. 1959. The influence of dietary fat on the

Alteration of Fatty Acid and Sterol Composition in Lipids 229 incorporation of fatty acids into body and egg fat of the hen. Arch. Biochem. Biophys. 79:302. 78. Feeley, R. M., P. E. Criner, and B. K. Watt. 1972. Cholesterol content of foods. J. Am. Dietet. Assoc. 61 :134. 79. Ferguson, K. A., J. A. Hemsley, and P. J. Reis. 1967. Nutrition and wool growth. The effect of protecting dietary protein from microbial degrada- tion in the rumen. Aust. J. Sci. 30:215. 80. Fisher, H., and G. A. Leveille. 1957. Observations on the cholesterol, linoleic and linolenic acid content of eggs as influenced by dietary fats. J. Nutr. 63:119. 81. Ford, A. L., P. V. Harris, J. J. Macfarlane, R. J. Park, and W. R. Shorthose. 1974. Effeet of protected lipid supplement on organoleptie and other prop- erties of ovine muscle. Meat Research Report No. 2, CSIRO. Queensland, Australia. 82. Garton, G. A. 1969. Lipid metabolism of farm animals. In D. Cuthbertson, ed. Nutrition of Animals of Agricultural Importance. Part I. The Science of Nutrition of Farm Livestock. Pergamon Press, New York. 83. Garton, G. A., T. P. Hilditch, and M. L. Meara. 1952. The composition of the depot fats of a pig fed on a diet rich in whale oil. Biochem. J. 50:517. 84. Garton, G. A., and W. R. H. Duncan. 1954. Dietary fat and body fat: the composition of the back fat of pigs fed on a diet rich in cod-liver oil and lard. Bioehem. J. 57:120. 85. Goering, H. K., T. R. Wrenn, J. Bitman, L. P. Dryden, C. H. Gordon, and F. W. Douglas, Jr. 1973. Formaldehyde-easein protected by soy oil and cottonseed oil fed to lactating cows. J. Anim. Sei. 37:343. 86. Gooden, J. M., and A. K. Laseelles. 1973. Effeet of feeding protected lipid on the uptake of precursors of milk fat by the bovine mammary gland. Aust. J. Biol. Sei. 26:1201. 87. Guenter, W., D. B. Bragg, and P. A. Kondra. 1971. Effeet of dietary linoleie acid on fatty acid composition of egg yolk, liver, and adipose tissue. Poult. Sci. 50:845. 88. Harrap, B. S. 1973. Recent developments in the production of dairy products with increased levels of polyunsaturation. Aust. J. Dairy Technol. 28:101. 89. Harris, P. C., and F. H. Wilcox. 1963a. Studies on egg yolk cholesterol. 1. Genetic variation and some phenotypic correlations in a random bred population. Poult. Sci. 42:178. 90. Harris, P. C., and F. H. Wilcox. 1963b. Studies on egg yolk cholesterol. 3. Effect of dietary cholesterol. Poult. Sci. 42: 186. 91. Hendricks, H. 1974. The Drovers Journal, June 27, p. 10. 92. Herbert, L. S., and K. J. Kearney. 1975. The production of polyunsaturated tallows and their utilization in margarine manufacture. J. Food Technol. (In press). 93. Hilditch, T. P., and H. Jasperson. 1943. The influence of dietary fat of vary- ing unsaturation on the component acids of cow milk fats. Biochem. J. 37:238. 94. Hilditch, T. P., and J. J. Sleightholme. 1930. Variations in the component fatty acids of butter due to changes in seasonal and fasting conditions. Biochem. J. 24: 1098.

230 JOEL BITMAN 95. Hilditch, T. P., and H. M. Thompson. 1936. XCVI. The effect of certain ingested fatty oils upon the composition of cow milk fat. Biochem. J. 30:677. 96. Hilditch, T. P., and P. N. Williams. 1964. The Chemical Constitution of Natural Fat, 4th ed. John Wiley and Sons, Inc., New York. 97. Hill, E. G. 1966. Effects of methionine, menhaden oil, and ethoxyquin on serum cholesterol of chicks. J. Nutr. 89: 143. 98. Hodges, R. E., A. F. Salel, W. L. Dunkley, R. Zelis, P. F. McDonagh, C. Clifford, R. K. Hobbs, L. M. Smith, A. Fan, D. T. Mason, and C. Lykke. 1975. Plasma lipid changes in young adult couples consuming polyunsat- urated meats and dairy products. Am. J. Clin. Nutr. 28:1126. 99. Hoflund, S., J. Holmberg, and G. Sellmann. 1955. Investigation of fat diges- tion and fat metabolism in ruminants. I. Feeding unsaturated fats to dairy cows; fat digestion in rumen. Cornell Vet. 45:254. 100. Horlick, L., and J. B. O'Neil. 1958. The modification of egg-yolk fats by sunflower-seed oil and the effect of such yolk fats on blood-cholesterol levels. Lancet ii: 243. 101. Horlick, L., and J. B. O'Neil. 1960. Effect of modified egg-yolk fats on blood cholesterol levels. Lancet i: 438. 102. Hulett, B. J., R. E. Davies, and J. R. Couch. 1964. Changes observed in egg yolk cholesterol, serum cholesterol, and serum glutamic oxalacetic transaminase by feeding cholesterol and vegetable oil to mature hens. Poult. Sci. 43:1075. 103. Hutjens, M. F., and L. H. Schultz. 1971a. Addition of soybeans or methio- nine analog to high-concentrate rations for dairy cows. J. Dairy Sci. 54:1637. 104. Hutjens, M. F., and L. H. Schultz. 1971b. Effect of feeding soybeans or formaldehyde-treated soybeans on lipid metabolism in ruminants. J. Dairy Sci. 54: 1876. 105. Intersociety Commission for Heart Disease Resources. 1970. Circulation 42 (December). 106. Jagusch, T., and D. G. Clarke. 1975. The production of lamb with poly- unsaturated depot fats (from feeding a dietary supplement of formalde- hyde-treated ground sunflower seed). N.Z. J. Agric. Res. 18:9. 107. Johnson, A. R. 1974. Biomanipulation of ruminant fats. Implications for the food industry. Food Manuf. 49: 19. 108. Johnson, A. R., and M. V. Tracey. 1974. Polyunsaturated ruminant food products: a completely new range of foods derived from a more efficient animal. IV. Int. Congr. Food Sci. Technol. Madrid, Sept. 22-27, 1974. 109. Johnson, A. R., M. A. Brown, B. ter Huurne, and G. S. Sidhu. 1974. The role of copper and other factors in the autoxidation of milk high in linoleic acid. Page 171 in Third International Symposium on Metal Catalyzed Lipid Oxidation, Pari.s, September 1973. 110. Johnson, R. R., and K. E. McClure. 1972. High fat rations for ruminants. I. The addition of saturated and unsaturated fats to high roughage and high concentrate rations. J. Anim. Sci. 34:501. 111. Jones, D. 1969. Variations in the cholesterol content of egg yolk. Nature 221:780. 112. Jorgensen, N. A., L. H. Schultz, and G. R. Barr. 1965. Factors influencing milk fat depression on rations high in concentrates. J. Dairy Sci. 48:1031.

Alteration of Fatty Acid and Sterol Composition in Lipids 231 113. Jurgens, M. H., and E. R. Peo, Jr. 1970. Influence of dietary supplements of cholesterol and vitamin D on certain components of the blood and body of growing-finishing swine. J. Anim. Sci. 30:894. 114. Keys, A., ed. 1970. Coronary Heart Disease in Seven Countries. American Heart Association, New York. 115. Kieseker, F. G., L. A. Hammond, and J. G. Zadow. 1974. Commercial scale manufacture of dairy products from milk containing high levels of linoleic acid. Aust. J. Dairy Technol. 29:51. 116. Kimoto, W. I., R. Ellis, A. E. Wasserman, R. Oltjen, and T. R. Wrenn. 1974. Fatty acid composition of muscle phospholipids from calves, and growing and mature steers fed protected safflower oil. J. Food Sci. 39:997. 117. King, R. L., and R. W. Hemken. 1962. Composition of milk produced on pelleted hay and heated corn. J. Dairy Sci. 45:1336. 118. Kritchevsky, D., C. R. Grau, B. M. Talbert, and B. J. Kneuckel. 1951. Distribution of radioactivity in the egg after feeding sodium acetate-l-Cl4. Proc. Soc. Exp. Biol. Med. 76:741. 119. Kritchevsky, D., and M. Kirk. 1951. Radioactive eggs. II. Distribution of radioactivity in the yolk. Proc. Soc. Exp. Biol. Med. 78 :200. 120. Kunsman, J., and M. Keeney. 1963. Effect of hay and grain rations on the fatty acid composition of milk fat. J. Dairy Sci. 46:605. 121. Kurnick, A. A., J. B. Sutton, M. W. Pasvogel, and A. R. Kemmerer. 1958. Effect of betaine, choline, and methionine on the concentration of serum, tissue, and egg yolk cholesterol. Poult. Sci. 37: 1218. 122. Lall, S. P., and S. J. Slinger. 1973. Nutritional evaluation of rapeseed oils and rapeseed soapstocks for laying hens. Poult. Sci. 52: 1729. 123. Leat, W. M. F., A. Cuthbertson, A. N. Howard, and G. A. Gresham. 1964. Studies on pigs reared on semi-synthetic diets containing no fat, beef tal- low, and maize oil: composition of carcass and fatty acid composition of various depot fats. J. Agric. Sci. 63 :311. 124. Machlin, L. J., and R. S. Gordon. 1961. Effect of dietary fatty acids and cholesterol on growth and fatty acid composition of the chicken. J. Nutr. 75:157. 125. Machlin, L. J., R. S. Gordon, J. Marr, and C. W. Pope. 1962. Effect of dietary fat on the fatty acid composition of eggs and tissues of the hen. Poult. Sci. 41:1340. 126. Macleod, G. K., and N. M. Macleod. 1971. Influence of body condition at parturition and full-fat soybean-corn feeding on lactation performance. J. Dairy Sci. 54:806. 127. Macleod, G. K., A. S. Wood, and Y. T. Yao. 1972. InDuence of dietary fat on rumen fatty acids, plasma lipid, and milk fat composition in the cow. J. Dairy Sci. 55 :446. 128. Marchello, J. A., F. D. Dryden, W. H. Hale, and L. L. Cuitun. 1973. Effect of protected dietary lipids on bovine carcass lipid composition. J. Anim. Sci. 37:266. 129. Marion, J. E. 1965. Effect of age and dietary fat on the lipids of chicken muscle. J. Nutr. 85:38. 130. Marion, J. E., and J. G. Woodroof. 1963. The fatty acid composition of breast, thigh, and skin tissues of chicken broilers as influenced by dietary fats. Poult. Sci. 42:1202.

232 JOEL BITMAN 131. Marks, H. L., and K. W. Washburn. 1973. Selection for yolk cholesterol using a modified extraction procedure. Poult. Sci. 52:2056. 132. Mattos, W., and D. L. Palmquist. 1973. Performance of cows fed protected polyunsaturated fat. J. Dairy Sci. 56:650. 133. Mattos, W., and D. L. Palmquist. 1974. Increased polyunsaturated fatty acid yields in milk of cows fed protected fat. J. Dairy Sci. 57:1050. 134. McGinnis, C. H., Jr., and R. K. Ringer. 1963. The effect of a quaternary ammonium anion exchange resin on plasma and egg yolk cholesterol in the laying hen. Poult. Sci. 42:394. 135. Menge, H., L. H. Littlefield, L. T. Frobish, and B. T. Weinland. 1974. The effect of cellulose and cholesterol on blood and yolk lipids and repro- ductive efficiency of the hen. J. Nutr. 104: 1554. 136. Miller, E. C., and C. A. Denton. 1962. Serum and egg yolk cholesterol of hens fed dried egg yolk. Poult. Sci. 41:335. 137. Miller, D., E. H. Gruger, Jr., K. C. Leong, and G. M. Knobl, Jr. 1967. Dietary effect of menhaden oil ethyl esters on the fatty acid pattern of broiler muscle lipids. Poult. Sci. 46:438. 138. Miller, G. J., T. R. Varnell, and R. W. Rice. 1967. Fatty acid compositions of certain ovine tissues as affected by maintenance level rations of roughage and concentrate. J. Anim. Sci. 26:41. 139. Miller, L. G., and D. A. Cramer. 1969. Metabolism of naturally occurring and 14C-labeled triglycerides in the sheep. J. Anim. Sci. 29:738. 140. Mohammed, K., W. H. Brown, P. W. Riley, and J. W. Stull. 1964. Effect of feeding coconut oil meal on milk production and composition. J. Dairy Sci. 47:1208. 141. Moody, E. G. 1971. Performance and milk and blood lipids of milk fat- depressed cows fed tallow and sucroglyceride. J. Dairy Sci. 54: 1817. 142. Moore, J. H., W. W. Christie, R. Braude, and K. G. Mitchell. 1969. The effect of dietary copper on the fatty acid composition and physical prop- erties of pig adipose tissues. Br. J. Nutr. 23 :281. 143. Morris, W. C., and S. W. Hinners. 1968. Alterations in the cholesterol levels of blood, liver, and egg yolk lipids as affected by different dietary regimes. Poult. Sci. 47:1699. 144. Murphy, M. F., W. L. Dunkley, and F. W. Wood. 1974. Melting character- istics of milk fat, butter, and margarine with varied linoleic acid. J. Dairy Sci. 57:585. 145. Murty, N. L., and R. Reiser. 1961. Influence of graded levels of dietary linoleic and linolenic acids on the fatty acid composition of hens' eggs. J. Nutr. 75:287. 146. Naber, E. C. 1974. The cholesterol problem? the egg and lipid metabolism in the laying hen. Poult. Sci. 53:1959. 147. Naber, E. C., J. F. Elliott, and T. L. Smith. 1974. Effect of Probucol on reproductive performance and liver lipid metabolism in the laying hen. Poult. Sci. 53:1960. 148. Nestel, P. J., N. Havenstein, H. M. Whyte, T. W. Scott, and L. J. Cook. 1973. Lowering of plasma cholesterol and enhanced sterol excretion with the consumption of polyunsaturated ruminant fats. N. Engl. J. Med. 288: 379. 149. Nestel, P. J., N. Havenstein, Y. Homma. T. W. Scott, and L. J. Cook. 1975.

Alteration of Fatty Acid and Sterol Composition in Lipids 233 Increased sterol excretion with polyunsaturated fat, high cholesterol diets. Metabolism 24: 189. 150. Neudoerffer, T. S., D. R. McLaughlin, and F. D. Homey. 1972. Protection of fatty acids against ruminal digestion by formaldehyde treatment of full-fat soybean meal. Proc. Univ. Guelph Nutr. Conf., Guelph, Ontario. 151. Newbold, R. P., R. K. Tume, and D. J. Horgan. 1973. Effect of feeding a protected safflower oil supplement on the composition and properties of the sarcoplasmic reticulum and on post-mortem changes in bovine skeletal muscle. J. Food Sci. 38:821. 152. Nicholson, J. W. G., and J. D. Sutton. 1971. Some effects of unsaturated oils given to dairy cows with rations of different roughage content. J. Dairy Res. 38 :363. 153. Noble, R. C., W. W. Christie, and J. H. Moore. 1971. Diet and the lipid composition of adipose tissue in the young lamb. J. Sci. Food Agric. 22:616. 154. Noble, R. C., W. Steele, and J. H. Moore. 1969. The effects of dietary palmitic and stearic acids on milk fat composition in the cow. J. Dairy Res. 36:375. 155. Nockels, C. F. 1973. The influence of feeding ascorbic acid and sulfate on egg production and on cholesterol content of certain tissues of the hen. Poult. Sci. 52:373. 156. Ogilvie, B. M., G. L. McClymont, and F. B. Shorland. 1961. Effect of duodenal administrations of highly unsaturated fatty acids on composition of ruminant depot fat. Nature 190:725. 157. Opstvedt, J., and M. Ronning. 1967. Effect upon lipid metabolism of feeding alfalfa hay or concentrate ad libitum as the sole feed for milking cows. J. Dairy Sci. 50: 345. 158. Palafox, A. L. 1968. Effect of age, energy source and concentration on yolk lipids and cholesterol. Poult. Sci. 47:1705. 159. Palmquist, D. L., and H. R. Conrad. 1971. High levels of raw soybeans for dairy cows. J. Anim. Sci. 33 :295. 160. Palmquist, D. L., L. M. Smith, and M. Ronning. 1964. Effect of time of feed- ing concentrates and ground, pelleted alfalfa hay on milk fat percentage and fatty acid composition. J. Dairy Sci. 47:516. 161. Pankey, R. D., and W. J. Stadelman. 1969. Effect of dietary fats on some chemical and functional properties of eggs. J. Food Sci. 34:312. 162. Parry, R. M., Jr., J. Sampugna, and R. G. Jensen. 1964. Effect of feeding saBlower oil on the fatty acid composition of milk. J. Dairy Sci. 47:37. 163. Pennington, J. A., and C. L. Davis. 1974. Effects of intraruminal and intra- abomasal additions of cod-liver oil on milk and fat production. J. Dairy Sci. 57:602. 164. Perry, F. G., and G. K. Macleod. 1968. Effects of feeding raw soybeans on rumen metabolism and milk composition of dairy cows. J. Dairy Sci. 51:1233. 165. Plowman, R. D., J. Bitman, C. H. Gordon, L. P. Dryden, H. K. Goering, T. R. Wrenn, L. F. Edmondson, R. A. Yoncoskie, and F. W. Douglas, Jr. 1972. Milk fat with increased polyunsaturated fatty acids. J. Dairy Sci. 55:204. 166. Qureshi, S. R., D. E. Waldern, T. H. glosser, and R. W. Wallenius. 1972. Effects of diet on proportions of blood plasma lipids and milk lipids of

234 J OE L B I T MAN the lactating cow and their long-chain fatty acid composition. J. Dairy Sci. 55:93. 167. Reiser, R. 1950a. Fatty acid changes in egg yolk of hens on a fat-free and a cottonseed oil ration. J. Nutr. 40:429. 168. Reiser, R. 1950b. The metabolism of polyunsaturated fatty acids in growing chicks. J. Nutr. 42: 325. 169. Reiser, R. 1951a. The biochemical conversions of conjugated dienoic and trienoic fatty acids. Arch. Biochem. Biophys. 32: 113. 170. Reiser, R. l951b. The syntheses and interconversions of polyunsaturated fatty acids by the laying hen. J. Nutr. 44: 159. 171. Rhodes, D. N. 1958. Phospholipids. 5. The effect of cod-liver oil in the diet on the composition of hen's egg phospholipids. Biochem. J. 68:380. 172. Rindsig, R. B., and L. H. Schultz. 1974a. Effect of amount and frequency of feeding safflower oil on related milk, blood and rumen components. J. Dairy Sci. 57:1037. 173. Rindsig, R. B., and L. H. Schultz. 1974b. Effect of feeding lauric acid to lactating cows on milk composition, rumen fermentation, and blood lipids. J. Dairy Sci. 57: 1414. 174. Roberts, W. K., and J. A. McKirdy. 1964. Weight gains, carcass fat char- acteristics and ration digestibility in steers as affected by dietary rapeseed oil, sunflower seed oil and animal tallow. J. Anim. Sci. 23 :682. 175. Rumsey, T. S., R. R. Olden, K. P. Bovard, and B. M. Priode. 1972. In- fluence of widely diverse finishing regimes and breeding on depot fat composition in beef cattle. J. Anim. Sci. 35: 1069. 176. Scott, T. W., P. J. Bready, A. J. Royal, and L. J. Cook. 1972. Oil seed sup- plements for the production of polyunsaturated ruminant milk fat. Search 3:170. 177. Scott, T. W., and L. J. Cook. 1973. Dietary modifications of ruminant milk and meat fats. Pages 48-64 in The Coronary Heart Disease and Dietary Fat Controversy. Editorial Services, Wellington, New Zealand. 178. Scott, T. W., L. J. Cook, K. A. Ferguson, I. W. McDonald, R. A. Buchanan, and G. Loftus Hills. 1970. Production of polyunsaturated milk fat in domestic ruminants. Aust. J. Sci. 32:291. 179. Scott, T. W., L. J. Cook, and S. C. Mills. 1971. Protection of dietary poly- unsaturated fatty acids against microbial hydrogenation in ruminants. I. Am. Oil Chem. Soc. 48:358. 180. Sell, J. L., and G. C. Hodgson. 1962. Comparative value of dietary rapeseed oil, sunDower seed oil, soybean oil, and animal tallow for chickens. J. Nutr.76:113. 181. Shaw, J. C., and W. L. Ensor. 1959. Effect of feeding cod-liver oil and un- saturated fatty acids on rumen volatile fatty acids and milk fat content. J. Dairy Sci. 42: 1238. 182. Shrewsbury, G. C., G. A. Donovan, D. C. Foss, and D. E. Keyser. 1967. Relationship of dietary vitamin A and cholesterol to the concentration of these compounds in egg yolk, plasma and liver of the laying hen. Poult. Sci. 46:1319. 183. Sidhu, G. S., M. A. Brown, and A. R. Johnson. 1975. Autoxidation in milk rich in linoleic acid. 1. An objective method for measuring autoxidation and evaluating anti-oxidants. I. Dairy Res. 42: 185.

Alteration of Fatty Acid and Sterol Composition in Lipids 235 184. Singh, R. A., J. F. Weiss, and E. C. Naber. 1972. Effect of azasterols on sterol metabolism in the laying hen. Poult. Sci. 51 :449. 185. Skelley, G. C., W. C. Sanford, and R. L. Edwards. 1973. Bovine fat compo- sition and its relation to animal diet and carcass characteristics. J. Anim. Sci. 36:576. 186. Skellon, J. H., and D. A. Windsor. 1962. The fatty acid composition of egg yolk lipids in relation to dietary fats. J. Sci. Food Agric. 13:300. 187. Stark, W., and G. Urbach. 1974. The level of saturated and unsaturated y-dodecalactones in the butter fat from cows on various rations. Chem. Ind. (Land.), p. 413. 188. Steele, W., and J. H. Moore. 1968a. The effects of dietary tallow and cotton- seed oil on milk fat secretion in the cow. J. Dairy Res. 35:223. 189. Steele, W., and J. H. Moore. 1968b. Further studies on the effects of dietary cottonseed oil on milk-fat secretion in the cow. J. Dairy Res. 35:343. 190. Steele, W., and J. H. Moore. 1968c. The effects of mono-unsaturated and saturated fatty acids in the diet on milk-fat secretion in the cow. J. Dairy Res. 35:353. 191. Steele, W., and J. H. Moore. 1968d. The effects of a series of saturated fatty acids in the diet on milk-fat secretion in the cow. J. Dairy Res. 35:361. 192. Steele, W., R. C. Noble, and J. H. Moore. 1971. The effects of dietary soy- bean oil on milk-fat composition in the cow. J. Dairy Res. 38:49. 193. Stewart, P. S., and D. M. Irvine. 1970. Composition of bovine milk as affected by intravenous infusion of sunflower oil. Fixation of milk fat for electron microscopy. J. Dairy Sci. 53 :279. 194. Stokes, G. B., and D. M. Walker. 1970. The nutritive value of fat in the diet of the milk-fed lamb. 2. The effect of different dietary fats on the compo- sition of the body fats. Br. J. Nutr. 24:435. 195. Storry, J. E., and P. E. Brumby. 1970. The effect of polyunsaturated fatty acids on milk fat secretion. Proc. 10th Int. Meet. Soc. Fats Res. Chicago 231. 196. Storry, J. E., and J. A. F. Rook. 1964. Plasma triglycerides and milk-fat syn- thesis. Biochem. J. 91 :27c. 197. Storry, J. E., and J. A. F. Rook. 1965a. The effects of a diet low in hay and high in flaked maize on milk-fat secretion and on the concentration of cer tain constituents in the blood plasma of the cow. Br. J. Nutr. 19: 101. 198. Storry, J. E., and J. A. F. Rook. 1965b. Effect in the cow of intraruminal infusions of volatile fatty acids and of lactic acid on the secretion of the component fatty acids of the milk fat and on the composition of blood. Biochem. J. 96:210. 199. Storry, J. E., and J. A. F. Rook. 1965c. Effects of intravenous infusions of acetate, §-hydroxybutyrate, triglyceride and other metabolites on the com- position of the milk fat and blood in cows. Biochem. J. 97:879. 200. Storry, J. E., and J. A. F. Rook. 1966. The relationship in the cow between milk-fat secretion and ruminal volatile fatty acids. Br. J. Nutr. 20:217. 201. Storry, J. E., A. J. Hall, and V. W. Johnson. 1971. The effects of increasing amounts of dietary coconut oil on milk-fat secretion in the cow. J. Dairy Res. 38:73. 202. Storry, J. E., A. J. Hall, and V. W. Johnson. 1973. The effects of increasing amounts of dietary tallow on milk-fat secretion in the cow. J. Dairy Res. 40:293.

236 JOEL BITMAN 203. Storry, J. E., J. A. F. Rook, and A. J. Hall. 1967. The effect of the amount and type of dietary fat on milk fat secretion in the cow. Br. J. Nutr. 21:425. 204. Storry, J. E., B. Tuckley, and A. J. Hall. 1969a. The effects of intravenous infusions of triglycerides on the secretion of milk fat in the cow. Br. J. Nutr. 23:157. 205. Storry, J. E., P. E. Brumby, A. J. Hall, and V. W. Johnson. 1974a. Response of the lactating cow to different methods of incorporating casein and coconut oil in the diet. J. Dairy Sci. 57:61. 206. Storry, J. E., P. E. Brumby, A. J. Hall, and V. W. Johnson. 1974b. Responses in rumen fermentation and milk-fat secretion in cows receiving low- rollghage diets supplemented with protected tallow. J. Dairy Res. 41:165. 207. Storry, J. E., P. E. Brumby, A. J. Hall, and B. Tuckley. 1974c. Effects of free and protected forms of cod-liver oil on milk fat secretion in the dairy cow. J. Dairy Sci. 57:1046. 208. Storry, J. E., A. J. Hall, B. Tuckley, and D. Millard. 1969b. The effects of intravenous infusions of cod-liver and soya-bean oils on the secretion of milk fat in the cow. Br. J. Nutr. 23: 173. 209. Summers, J. D., S. J. Slinger, and W. J. Anderson. 1966. The effect of feed- ing various fats and fat by-products on the fatty acid and cholesterol com- position of eggs. Br. Poult. Sci. 7: 127. 210. Tanaka, K. 1970a. The effect of the type of dietary fat on milk fat secretion in the cow. Jap. I. Zootech. Sac. 41 :254. 211. Tanaka, K. 1970b. The effect of increasing amounts of dietary cod oil on milk fat secretion in cows. Jap. J. Zootech. Sci. 41 :453. 212. Thompson, E. PI., C. E. Allen, and R. J. Meade. 1973. Influence of copper on the stearic acid desaturation and fatty acid composition in the pig. J. Anim. Sci. 36:868. 213. Tove, S. B., and G. Matrone. 1962. Effect of purified diets on the fatty acid composition of sheep tallow. J. Nutr. 76:271. 214. Tove, S. B., and R. D. Mochrie. 1963. Effect of dietary and injected fat on the fatty acid composition of bovine depot fat and milk fat. J. Dairy Sci. 46:686. 215. Turk, D. E., and B. D. Barnett. 1971. Cholesterol content of market eggs. Poult. Sci. 50:1303. 216. Turk, D. E., and B. D. Barnett. 1972. Diet and egg cholesterol content. Poult. Sci. 51:1881. 217. Washburn, K. W., and D. F. Nix. 1974. Genetic basis of yolk cholesterol content. Poult. Sci. 53: 109. 218. Weir, W. C., Y. Yang, and W. L. Dunkley. 1974. Changes in linoleic acid content of lamb fat by feeding protected lipids. Fed. Proc. 33 :707. 219. Weiss, J. F., E. C. Naber, and R. M. Johnson. 1964. Effect of dietary fat and other factors on egg yolk cholesterol. 1. The "cholesterol" content of egg yolk as influenced by dietary unsaturated fat and the method of determination. Arch. Biochem. Biophys. 105:521. 220. Weiss, J. F., R. M. Johnson, and E. C. Naber. 1967. Effect of some dietary factors and drugs on cholesterol concentration in the egg and plasma of the hen. J. Nutr. 91:119. 221. Weyant, J. R., J. Bitman, D. L. Wood, and T. R. Wrenn. 1974. Polyun

Alteration of Fatty Acid and Sterol Composition in Lipids 237 saturated milk fat in cows fed protected sunflower-soybean supplement. J. Dairy Sci. 57:607. 222. Wheeler, P., D. W. Peterson, and G. D. Michaels. 1959. Fatty acid distribu- tion in egg yolk as influenced by type and level of dietary fat. J. Nutr. 69:253. 223. Williams, N. K., C. Y. Cannon, and D. Espe. 1939. Two methods of feeding soybean fat to cows and their effects on milk and butterfat production and on the nature of the butterfat. J. Dairy Sci. 22:442. 224. Wong, N. P., H. E. Walter, J. H. Vestal, D. E. Lacroix, and J. A. Alford. 1973. Cheddar cheese with increased polyunsaturated fatty acids. J. Dairy Sci. 56:1271. 225. Wood, F. W., M. F. Murphy, and W. L. Dunkley. 1974. Influence of elevated polyunsaturated fatty acids on processing and physical properties of butter. J. Dairy Sci. 57:585. 226. Wood, J. D., J. Biely, and J. E. Topliff. 1961. The effect of diet, age, and sex on cholesterol metabolism in White Leghorn chickens. Can. J. Bio- chem. Physiol. 39:1705. 227. Wrenn, T. R., J. R. Weyant, L. P. Dryden, and J. Bitman. 1973a. Influence of feeding fats, with and without protection from ruminal hydrogenation, on blood and milk lipids of cows. J. Dairy Sci. 56:650. 228. Wrenn, T. R., J. R. Weyant, C. H. Gordon, H. K. Goering, L. P. Dryden, J. Bitman, L. F. Edmondson, and R. L. King. 1973b. Growth, plasma lipids and fatty acid composition of veal calves fed polyunsaturated fats. J. Anim. Sci. 37:1419.

Next: Commentary: Gilbert A. Leville »
Fat Content and Composition of Animal Products: Proceedings of a Symposium Get This Book
×
Buy Paperback | $66.00
MyNAP members save 10% online.
Login or Register to save!
Download Free PDF
  1. ×

    Welcome to OpenBook!

    You're looking at OpenBook, NAP.edu's online reading room since 1999. Based on feedback from you, our users, we've made some improvements that make it easier than ever to read thousands of publications on our website.

    Do you want to take a quick tour of the OpenBook's features?

    No Thanks Take a Tour »
  2. ×

    Show this book's table of contents, where you can jump to any chapter by name.

    « Back Next »
  3. ×

    ...or use these buttons to go back to the previous chapter or skip to the next one.

    « Back Next »
  4. ×

    Jump up to the previous page or down to the next one. Also, you can type in a page number and press Enter to go directly to that page in the book.

    « Back Next »
  5. ×

    To search the entire text of this book, type in your search term here and press Enter.

    « Back Next »
  6. ×

    Share a link to this book page on your preferred social network or via email.

    « Back Next »
  7. ×

    View our suggested citation for this chapter.

    « Back Next »
  8. ×

    Ready to take your reading offline? Click here to buy this book in print or download it as a free PDF, if available.

    « Back Next »
Stay Connected!