Digestion in the pig between 7 and 35 d of age

Abstract

1. In two separate experiments, forty-two pigs weaned at 4–5 d of age were given diets containing milk or soya-bean protein and slaughtered at 7, 28 or 35 d of age.2. The amino acid composition of the empty body of the pigs did not vary with age or sources of protein fed.3. The nitrogen and amino acid contents of the empty body gain were calculated between 7 and 28, and 7 and 35 d of age. The retention of absorbed N was greater in pigs given a soya-bean meal (SBM) diet than in pigs given milk or isolated soya-bean protein (ISP) diets.4. The retention of total absorbed N was greater in pigs given a pelleted milk diet (0.72) than in pigs given a liquid milk diet (0.58).5. Methionine and threonine appeared to be the first two limiting amino acids, as indicated by their high incorporation into the empty body, for pigs given soya-bean proteins in Expt 3, while methionine and lysine were the first two limiting amino acids for pigs given ISP in Expt 4.6. The addition of methionine to diets in Expt 3 reduced the retention of absorbed methionine in the empty body by 43–76%. Lysine supplementation did not alter the retention of the absorbed lysine.7. Retention of arginine, proline and glycine in the body was greater than the apparent absorption of each of these amino acids.