|Campbell roger g,|
|Ballard m r m,|
Submitted to: Proceedings of the Maryland Nutrition Conference
Publication Type: Proceedings
Publication Acceptance Date: 3/25/1994
Publication Date: N/A
Citation: Interpretive Summary: These studies were designed to determine whether pST alters the distribution and overall metabolism of protein, collagen and individual amino acids of growing pigs. Pigs were fed a diet similar in amino acid composition to what is currently considered optimal for pig growth. In these studies, pigs were fed on a restriction scale based on body weight 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. Moreover, at currently recommended dietary protein and amino acid levels, non-collagen muscle proteins are maximally enchanced by pST treatment. Present data also suggest that pST administration is associated with higher concentrations of individual amino acids in carcass, head and skin, and enhanced rates of deposition into body proteins of all tissues. Although pST administration has dramatic effects on collagen distribution and on the synthesis and deposition of all proteins, the relative distribution of each amino acid appears to be similar in control and pST-treated pigs. Moreover, while protein synthesis and degradation are enhanced by pST, the apparent utilization of dietary amino acids is also increased.
Technical Abstract: Treatment of pigs with porcine somatotropin (pST) increases growth rate and protein deposition. The objective of this study was to determine whether collagen and the pattern of tissue amino acid (AA) deposition is altered by pST treatment. Eight castrated pigs were treated with pST and a second group was treated with buffer between 30 and 64 kg. At slaughter, head, viscera, carcass and skin were separated, ground and dried. Collagen was estimated by colorimetric determination of hydroxyproline. Samples were also hydrolyzed and AA were quantified by HPLC. The concentration of all 18 AA (g/kg dry weight) was significantly increased in carcass, skin, head and empty body of pST-treated pigs; viscera AA concentration was not altered. However, the concentration of AA relative to total protein was similar for control and pST-treated pigs. The deposition rate (g/d) of all AA was increased on average 67% with pST treatment. When expressed relative to lysine, the accretion rate of individual AA was similar for control and pST-treated pigs. Collagen deposition was higher in skin, viscera and head of pST-treated pigs, compared to controls. In contrast non-collagen proteins were enhanced in muscle and bone portion of the carcass. Although pST is associated with enhanced protein turnover in different tissues, it appears that the AA profile of body protein is not altered.