In vivo apparent digestibility and in vitro solubilization—the influence of pig live weight and diet

Abstract

The in vivo ileal and faecal apparent digestibility (AD) of a barley-soya-bean meal based pig feed was determined, employing five cannulated pigs, at five discrete instances from about 19 to 62 kg live weight. As the pigs gained 1 kg live weight, the ileal AD of crude protein (N × 6.25), non-starch polysaccharide (NSP) residues and mixed-linked β-glucans were found ( P < 0.05) to increase 0.12 units, 0.11 units and 0.36 units, respectively, and the faecal AD of dry matter, ash, crude protein, crude fat and NSP residues to increase 0.10 units, 0.47 units, 0.09 units, 0.23 units and 0.22 units, respectively. The in vitro dry matter solubilization (DMS) of a test feed was studied employing duodenal, ileal and faecal inocula from the pigs involved in the in vivo study at the same instances, and further when the pigs weighed about 120 kg. Donor pig live weight accounted for 19%, 30% and 42% of the variation in in vitro DMS with duodenal, ileal and faecal inoculum, respectively. The influence of donor pig diet was studied, employing the pig feed (as above) alone and substituted with 15% of either purified potato fibre or wheat fibre. Donor pig diet accounted for 52%, 66% and 49% of the variation ( P < 0.001) in in vitro DMS with duodenal, ileal and faecal inoculum, respectively. Results indicate that, within the range studied, pigs could be used irrespective of live weight as donors of in vitro inocula and that donor pig diets need to be standardized and standard feed samples included in in vitro studies.