Metabolic Modifiers Effects on the Nutrient Requirements of Food-Producing Animals (1994) / Chapter Skim
Currently Skimming:
5. Effect of Metabolic Modifiers on Nutrient Requirements of Growing Swine
5. Effect of Metabolic Modifiers on Nutrient Requirements of Growing Swine
Pages 38-51
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 38... ...
Second, an increase in the rate of protein deposition requires increased daily amino acid! intake, and an increase in the proportion of total body protein requires an increase in total amino acid intake.
|
From page 39... ...
The interrelationship between protein and energy intake and protein deposition has been studied in several species, but data are most extensive for growing swine (Black et al., 1986; Campbell, 1987; Dunkin, 1987~. One must assume that metabolic modifiers likewise operate within this framework, until data on biological mechanisms suggest otherwise.
|
From page 40... ...
Any metabolic modifier that enhances protein deposition without altering the efficiency of protein digestion and/or partitioning of amino acids to protein deposition could do so only if there were a concurrent increase in dietary protein intake. The relationship between energy intake and protein deposition must be precisely defined for both nontreated pigs and pigs treated with metabolic mollifiers in order to differentiate between the animal's tissue requirement for protein EMU, M2)
|
From page 41... ...
Conversely, with ad libitum energy intake, the tissue requirement for amino acids is independent of energy intake so that the relevant expression of dietary needs is grams per day of a particular amino acid. EFFECT OF METABOLIC MODIFIERS ON NUTRIENT REQUIREMENTS Consideration of how nutrient requirements are altered by metabolic modifiers and other new technologies requires a systematic approach to quantitatively define how each of the components of nutrient use is affected.
|
From page 42... ...
Digestion The tissue requirement for amino acid deposition is a function of both the need for deposition in tissues and for maintenance. The dietary requirement, however, is a function of the extent to which dietary protein is digested and amino acids absorbed as well as the efficiency with which absorbed amino acids are used for protein deposition.
|
From page 43... ...
Values on the order of 0.80 to 0.94 have been achieved in growing pigs given semipurified diets and fed to optimum rates of growth (Moughan and Smith, 1984; Wang and Fuller, 1989; Chung and Baker, 19921. Although there is no satisfactory explanation for this inefficiency, involvement of amino acids as substrates for processes other than protein deposition accounts for only a small proportion of this inefficiency.
|
From page 44... ...
In each study, protein accretion was determined by the comparative slaughter technique in control and pSTtreated pigs and regressed on dietary protein intake. These data enable determination of the tissue requirement for and efficiency of amino acid deposition as protein so that improvements in protein deposition can be quantitatively related to required dietary inputs.
|
From page 45... ...
Based on these results, the dietary protein (amino acids) requirement for pST-treated pigs during the finishing phase of growth would increase in direct proportion to the increase in protein accretion rate (Figure 5-61.
|
From page 46... ...
et al., 19901. Each con(lucted experiments with female and castrate male pigs in which successive increments of either dietary protein or lysine (diets exceeded anticipated requirement for other amino acids)
|
From page 47... ...
The regression coefficient for the linear component of the protein deposition-energy intake relationship of pST-treatecI males and females was also similar to that reported for younger pigs by Campbell and Taverner (19881. Accordingly, the dietary amino acid requirements of pST-treated pigs in the finishing phase might logically be expected to approximate those of pigs weighing 15 to 20 kg.
|
From page 48... ...
The need for a more complete description of experimental conditions with information appropriate for a more dynamic approach is apparent and should be incorporated into the design of future experiments. Ultimately, estimates for nutrient requirements must be related to the expected energy intake to ensure that the requirements for amino acids are met.
|
From page 49... ...
This appears to be a common feature for this class of metabolic modifiers and results in a greater proportion of lysine cleposition relative to other amino acids. Thus, lysine would appear to be first limiting and, as such, should be the focus of initial efforts in the evaluation of amino acid requirements.
|
From page 50... ...
Therefore, the efficiency of protein utilization was not altered as observed in studies with pST with an increase in protein deposition requiring a proportional increase in dietary protein (amino acids)
|
From page 51... ...
This review emphasizes the need for systematic research and gives precedence to studies clesigned to address the causes of low and variable efficiency of amino acid use. This is the single most important factor affecting estimates of the growing pig's requirements for dietary protein (amino acids)
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.