Comparative Amino Acid Digestibilities in Growing Pigs and Sows

240 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1998.Experiments were conducted to investigate the extent to which gestating and lactating sows are able to digest amino acids. A procedure for surgically inserting a T-cannula in the distal ileum of gestating sows was developed, and ileal fluid was successfully collected from sows in gestation as well as in lactation. It was shown that apparent ileal amino acid digestibility coefficients (AIDs) of six commonly used feed ingredients were higher for lactating sows than for growing pigs. Gestating sows had AIDs that were intermediate between growing pigs and lactating sows. By correcting AIDs for the non-specific endogenous losses of amino acids estimated after feeding a nitrogen-free diet, standardized ileal amino acid digestibility coefficients (SIDs) were calculated. There were no differences (P $>$.05) between lactating sows and growing pigs in SIDs, but gestating sows limited to a ration of 2 kg/d had higher (P $<$.05) SIDs than growing pigs and lactating sows for three of the six feed ingredients. It also was shown that growing pigs, and lactating and gestating sows given free access to feed have similar losses of endogenous protein. However, gestating sows restricted in their feed allowance to 2 kg/d, had endogenous losses that were higher (P $<$.05) than for any of the other groups. In further experiments with growing pigs, it was shown that endogenous losses were constant for pigs heavier than 60 kg BW; however, elevated losses and changed amino acid composition of endogenous protein was observed for 35-kg pigs compared to heavier pigs. We concluded that neither the physiological status of the animal nor the BW affects amino acid digestibilities in pigs heavier than 60 kg BW. However, the level of feed intake is of importance for accurate estimation of endogenous losses and in turn, the AIDs. Because lactating sows usually have a higher daily feed intake than growing pigs, they also have lower endogenous losses and higher AIDs. Therefore, values for amino acid digestibilities obtained with growing pigs cannot be used to accurately estimate amino acid digestibilities for lactating sows.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD