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 cu rrently unknown because of difficulties associated with collecting an adequ ate quantity of milk, and also problems in cannulating suckling pigs. A tot al of 14 kg of sow's milk was collected, two soluble indigestible markers ( Co-EDTA and YbCl3) 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. Anothe r four cannulated pigs were offered a similar amount of a 20% DM liquid die t 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 1 0 hourly meals from 0700 to 1700. Following 2 d of adaptation, ileal digest a 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 digest ibilities ranged from 84% (cystine and threonine) to 100% (methionine, hist idine, and glutamic acid); the average for all amino acids was 92 +/- 4%. B ased 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, a nd threonine) were less (P < 0.05) digestible than amino acids predominatin g in casein proteins (i.e., glutamic acid, proline, and methionine). When t rue ileal digestible amino acid concentrations in sow's milk were expressed as ratios to digestible lysine, it appeared that threonine, tryptophan; an d 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 ac ids had true ileal digestibility values significantly less than 100%.