THE EFFECT OF FORMIC-ACID AND BUFFERING CAPACITY ON THE ILEAL DIGESTIBILITIES OF AMINO-ACIDS AND BACTERIAL-POPULATIONS AND METABOLITES IN THE SMALL-INTESTINE OF WEANLING PIGS FED SEMIPURIFIED FISH-MEAL DIETS

An experiment was carried out to examine the effects of supplementatio n of formic acid to semipurified diets containing fish meal for weanli ng pigs with low and high buffering capacity on nutrient digestion and bacterial populations and metabolites in the small intestine. Twelve barrows, weaned at 21 d, were fitted with a simple T-cannula at the di stal ileum. The BW of the pigs at weaning and at the conclusion of the experiment were 7.8 and 13.8 kg, respectively. The pigs were fed four corn starch-based fish meal diets according to a two-period change-ov er design. The diets were formulated to contain 18% CP. For two of the diets, referred to as NCaP, fish meal was the calcium and phosphorus source. For the remaining two diets, referred to as HCaP, the levels o f calcium and phosphorus were doubled (compared with the NCaP diets) b y the addition of calcium carbonate and dicalcium phosphate. The diets were supplemented with (+NCaP and +HCaP) or without (-NCaP and -HCaP) 1% (wt/wt) formic acid. The buffering capacity of the HCaP diets incr eased (P < 0.05) when the levels of calcium and phosphorus were double d. The pH of the diets were: 6.25, 4.46, 6.13 and 4.59 for the -NCaP, +NCaP, -HCaP and +HCaP diets, respectively. Supplementation of formic acid to diets with low and high buffering capacity did not affect (P > 0.05) the apparent ileal digestibilities of AA. The pH, ammonia and V FA concentrations, bacterial populations in ileal digesta and the inci dence of diarrhea were also not affected (P > 0.05). Therefore, the su pplementation of 1% (wt/wt) formic acid to corn starch-based fish meal diets with low and high buffering capacity for weanling pigs (7.8-13. 8 kg) does not affect nutrient digestibilities and bacterial populatio ns in the small intestine.