Standardized ileal protein and amino acid digestibility by growing pigs and sows

Experiments were conducted to determine the effect of the physiological con dition of swine on standardized ileal digestibility coefficients (SID). The apparent ileal digestibility coefficients were determined for crude protei n and amino acids in six feed ingredients (corn, barley, wheat, soybean mea l, canola meal, and meat and bone meal) in growing pigs and in gestating an d lactating sows. Growing pigs and lactating sows were given free access to their diets, whereas gestating sows were allowed to consume only 2 kg of f eed daily. The nonspecific (basal) endogenous losses of protein and amino a cids were determined under similar feeding regimens after feeding a protein -free diet. The SID for crude protein and amino acids were calculated by co rrecting the apparent ileal digestibility coefficients for the nonspecific endogenous losses of protein and amino acids. With a few exceptions, there were no differences (P > 0.05) in the SID for crude protein and amino acids between growing pigs and lactating sows. Overall, gestating sows had highe r (P < 0.05) SID for crude protein and all amino acids, except for tryptoph an and aspartate, compared with growing pigs. Likewise, the SID of most ami no acids obtained by gestating sows were higher (P < 0.05) than those obtai ned by lactating sows. Interactions (P < 0.05) between animals and diets we re observed for gestating sows compared with growing pigs as well as gestat ing sows compared with lactating sows. As a consequence, it is not possible to extrapolate data from one feed ingredient to another. On most occasions , the lowest SID among the indispensable amino acids was calculated for thr eonine, valine, and lysine. It is concluded that gestating sows fed 2 kg of feed per day have higher standardized digestibility coefficients than do g rowing pigs and lactating sows given free access to their diets. This diffe rence may be due to differences in daily feed intake rather than to the phy siological status of the animals.