True ileal digestibility of amino acids in sow's milk for 17-day-old pigs.

The digestibility of amino acids in sow's milk consumed by young pigs is currently unknown because of difficulties associated with collecting an adequate quantity of milk, and also problems in cannulating suckling pigs. A total of 14 kg of sow's milk was collected, two soluble indigestible markers (Co-EDTA and YbC13) were added, and the milk was fed to four pigs at 17 d of age that were fitted with a simple T-cannula at the terminal ileum. Another four cannulated pigs were offered a similar amount of a 20% DM liquid diet based on enzymatically hydrolyzed casein and lactose to assess endogenous amino acid losses. All pigs were fed about 875 g of each diet per day in 10 hourly meals from 0700 to 1700. Following 2 d of adaptation, ileal digesta were collected from 0800 to 1800 for 2 d. Diets and digesta were analyzed for amino acids using appropriate hydrolysis and preoxidation procedures. Average nitrogen true digestibility was 88%, whereas amino acid true digestibilities ranged from 84% (cystine and threonine) to 100% (methionine, histidine, and glutamic acid); the average for all amino acids was 92 +/- 4%. Based on average values, true digestibility of essential amino acids was not different from that of nonessential amino acids (P > 0.10). In whole milk, amino acids found in abundance in whey proteins (i.e., cystine, glycine, and threonine) were less (P < 0.05) digestible than amino acids predominating in casein proteins (i.e., glutamic acid, proline, and methionine). When true ileal digestible amino acid concentrations in sow's milk were expressed as ratios to digestible lysine, it appeared that threonine, tryptophan, and arginine were lower than what might be considered optimal. In conclusion, amino acids in sow's milk were highly digestible, but most of the amino acids had true ileal digestibility values significantly less than 100%.