|Campbell Roger G, - BUNGE MEATS, LTD|
|Ballard Malcolm, - HEARTLAND LYSINE|
Submitted to: Journal of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 6, 1995
Publication Date: N/A
Interpretive Summary: This study was designed to determine whether administration of porcine somatotropin (pST, the growth regulatory pituitary hormone) alters the distribution and overall metabolism of protein and individual amino acids (AA) growing pigs. Barrows were fed a diet similar in AA composition to what is currently considered optimal for pig growth. Pigs were fed on a restriction scale so that average feed intake was identical for control and pST-treated pigs. Under these conditions, it appears that achievement of enhanced protein deposition by pST, does not require additional dietary protein input. These data suggest that pST administration is associated with higher concentrations of individual AA in carcass, head and skin, but not in viscera. However, when the concentration of each AA was expressed on a per unit protein basis the AA profiles of control and pST-treated pigs were quite similar. Administration of pST markedly enhanced rates of deposition of AA into body proteins of all tissues, but the relative distribution of each AA appears to be similar in control and pST-treated pigs. This indicates that synthesis rates of proteins can be influenced by pST, but balance of AA remains largely unaffected. It also appears that currently recommended pattern of dietary AA for growth is also sufficient to sustain enhanced growth associated with pST treatment.
Technical Abstract: This experiment was conducted to establish the influence of porcine somatotropin (pST) on tissue distribution and deposition rates of amino acids (AA) in pigs. Barrows were treated daily with buffer or pST (0.1mg/kg) when they weighed between 30 and 64 kg (n = 8 pigs/ group). The diet was designed to meet muscle AA profile with respect to lysine as the first limiting AA growth. Tissue levels of 18 AA were determined. The concentrations (mg/g dry wt) of all AA were greater in carcass, skin, head and empty body of pST-treated pigs; AA concentration in viscera was not influenced by pST. However, when the concentration of each AA was expressed on a per unit protein basis the AA profiles of control and pST-treated pigs were quite similar. Average deposition rate of each AA was increased approximately 67% by pST. When deposition of each AA was calculated in relation to lysine, the pattern of AA utilization for growth was similar for control and pST-treated pigs; exceptions were arginine, glycine and tryptophan. The ratio of indispensable to dispensable AA was also similar for control and pST-treated pigs. These data indicate that synthesis rate of individual proteins can be influenced by pST, but the balance of AA remains largely unaffected suggesting that the changes in protein metabolism elicited by pST are consistent with normal growth processes.