J. S. Sands

Determining the equivalent phosphorus released by an Escherichia coli-derived phytase in broiler chicks

Seven-day-old male Ross 308 broiler chicks were used in a 14-d experiment to determine the equivalency value of a new phytase using corn-soybean meal based diets. The experimental diets consisted of positive control (PC) or negative control (NC) diets which were formulated to contain 5.0 or 1.2 g kg-1 non-phytate P, respectively, with a total P of 7.7 or 3.9 g kg-1, respectively; and respective calcium levels of 10.0 or 7.6 g kg-1. The test diets were formulated by the addition of monosodium phosphate (MSP; analyzed to contain 224.0 g kg-1 P) to the NC diet to supply 0.5, 1.0, or 1.5 g of P kg-1 diet, and phytase was added to the NC diet at 500 FTU or 1000 FTU kg-1 at the expense of corn starch. Each diet was randomly assigned to eight cages of four birds each. Body weight gain (BWG) showed both linear and quadratic increase (P < 0.05) with increasing level of dietary P or phytase supplementation (450 to 656 or 603 g, respectively). Feed efficiency (g BWG/g feed intake) increased linearly (P < 0.05) with ...

Responses of pigs to Aspergillus niger phytase supplementation of low-protein or high-phytin diets.

Growth and N utilization responses of pigs to Aspergillus niger phytase supplementation of low-protein or high-phytin diets were examined in 2 experiments. In the first experiment, 6 diets arranged in a 3 x 2 factorial with Aspergillus niger phytase at 0, 600, or 1,200 units/kg and dietary protein at 160 or 200 g/kg; and 12 pigs (growth) or 6 pigs (N utilization) per diet were used to test the hypothesis that phytase ameliorates dietary protein effects on growth and nutrient balance. In the second experiment, 4 diets arranged in a 2 x 2 factorial of phytase at 0 or 1,200 units/kg and phytin P at 2.2 g/kg (3.2 g/kg of total P) or 3.9 g/kg (4.9 g/kg of total P); and 12 pigs (growth) or 8 pigs fitted with ileal T-cannulas in a replicated 4 x 4 Latin square (for ileal digestibility of AA) per diet were used to test the hypothesis that increased phytin depresses nutrient utilization and phytase addition ameliorates these effects. Whereas reduced dietary protein depressed (P < 0.001) BW gain and N utilization, phytase in low-protein diet did not alleviate these effects. Although phytase ameliorated phytin-induced reduction in ileal P digestibility (P < 0.001), this was not accompanied by any change in ileal AA digestibility. Given that phytase improved (P < 0.001) P, but not N utilization of diets fed in both studies, phytase-induced improvement in BW gain of pigs fed low-phytin P diets is independent of changes in N utilization.

Relative bioavailability of phosphorus in low-phytate soybean meal for broiler chicks

A 14-d chick bioassay was conducted to estimate the relative bioavailability (RBV) of P in a low-phytate soybean meal (LPSBM) using slope-ratio techniques. A corn-soybean meal basal diet was formulated to supply total P and Ca at 3.3 and 10.5 g kg-1, respectively. Three reference diets were formulated by the addition of 0, 0.5 or 1.0 g kg-1 total P from monosodium phosphate (MSP). Four test diets were formulated by the addition of 0.5 or 1.0 g kg-1 total P from LPSBM or soybean meal (SBM). The additions of MSP, LPSBM, or SBM were made at the expense of corn starch. A diet consisting of the basal diet plus supplemental methionine, lysine, threonine and tryptophan was also included to confirm that response to diets containing LPSBM or SBM was not due to the higher concentration of amino acids in those diets. Each diet was randomly assigned to six replicate cages of four birds. Birds were fed from 1 to 3 wk of age. Body weight gain (P < 0.01) and feed intake (FI, P < 0.05) increased linearly as supplemental ...