Efficacy of supplemental 1 alpha-hydroxycholecalciferol and microbial phytase for young pigs fed phosphorus- or amino acid-deficient corn-soybean meal diets.

Young pigs (5 wk of age and 8 kg) were used to test the efficacy of 1 alpha-hydroxycholecalciferol (1 alpha-OH D3) and microbial phytase for improving the utilization of phytate phosphorus (P) and amino acids present in corn-soybean meal (SBM) diets. Phytase supplementation (1,200 units/kg) to a vitamin D3-adequate, P-deficient corn-SBM diet elicited a marked response (P < .05) in weight gain and ash content of fibula, scapula, and metatarsal bones, but dietary addition of 1 alpha-OH D3 (20 micrograms/kg) was without effect. A P- and vitamin D3-adequate, amino acid-deficient corn-SBM diet (15.5% CP) also was supplemented with 1,200 units/kg of phytase to evaluate the efficacy of phytase in improving amino acid utilization. Pigs gained faster (P < .05) and more efficiently (P < .05) when this diet was supplemented with limiting amino acids, and phytase addition also increased (P < .05) weight gain, regardless of whether the diet was deficient or adequate in amino acids. Feed efficiency was improved (P < .05) by phytase addition to the amino acid-deficient diet but not to the amino acid-adequate diet. Pigs fed the low-CP, amino acid-fortified diet gained as fast and as efficiently as those fed a 19.5% CP (1.19% lysine) positive-control diet.