187 Ileal and total tract digestibility of amino acids and minerals in growing pig diets supplemented with phytase enzyme

While positive effects of phytase supplementation on mineral digestibility are typically observed, the effects on amino acid (AA) digestibility have been inconsistent, which might be related to the concentration of dietary phytate among other factors. Therefore, an experiment was conducted to determine the apparent ileal digestibility (AID) and standardized ileal digestibility (SID) of crude protein (CP) and AA, apparent total tract digestibility (ATTD) of calcium (Ca) and phosphorus (P), and standardized total tract digestibility (STTD) of P in growing pigs fed with phytase enzyme (PE; Alltech, Nicholasville, KY). A negative control (NC) diet based on corn, soybean meal, and distillers dried grains with solubles that contained 1.00% phytate (0.27% phytate-bound P) was formulated to meet or exceed nutrient requirements of growing pigs. Three additional diets were formulated by supplementing the NC diet with 452, 1,356, or 2,713 FTU/kg of PE. Twenty-four ileal-cannulated growing barrows (29.38 kg ± 2.83) were allotted to a balanced change-over design with four experimental diets and two 14-d periods, resulting in six pigs per diet in each period with a total of 12 observations per diet. The initial 6 d of each 14-d period was considered an adaptation phase. Fecal and urine samples were collected during d 7, 8, 9, and 10. During d 13 and 14, ileal digesta samples were collected. Data were analyzed using the PROC GLIMMIX of SAS (v 9.4) using barrow as the experimental unit. The model included diet as the main effect and period as random effect. Preplanned contrasts were used to evaluate linear and quadratic effects of PE supplementation. AID and SID of CP, Arg, His, Lys, Phe, and Glu were marginally higher with PE (linear, P < 0.100). Similarly, the AID and SID of Tyr rose (quadratic, P < 0.050) with incremental concentrations of PE. In addition, AID and SID of Trp, Cys, and Ser were marginally higher (quadratic, P < 0.100) up to 1,356 FTU/kg of PE concentration and then lower when 2,713 FTU/kg of PE was fed. Moreover, with dietary inclusion of PE, ATTD and STTD of P (quadratic, P < 0.010), and ATTD of Ca (linear, P < 0.001) were higher. Results from this study suggest that increasing PE from 0 to 2,713 FTU/kg in corn, soybean meal, and distillers dried grains with solubles based diets fed to growing pigs results in greater digestibility of CP, AA, Ca and P.