Effect of phytase supplementation to diets varying in chloride level on performance, litter moisture, foot pad score, and gait score of growing turkeys

Phytase was examined as a means to improve turkey performance in diets with high Cl by modifying dietary electrolyte balance. Nicholas turkey toms (10 poults/pen; 10 replicates per pen) were fed corn-soy-distillers dried grains with solubles-canola meal-based diets (DDGS/CM) with varying Cl (0.2, 0.3, 0.4, or 0.5\%) and phytase (0 or 500 phytase units/kg of diet), making 8 treatments (4 x 2 factorial). A ninth treatment was a corn-soy based diet (CS) with 0.3\% Cl and without phytase (positive control). The diets were formulated to contain similar AME(n) and digestible amino acid levels for each of 5 feeding periods (2 to 5, 5 to 8, 8 to 11, 11 to 14, and 14 to 17 wk of age) and fed in mash form. Turkey BW, ADG, ADFI, and feed conversion ratio (FCR) were determined for each pen along with litter moisture, foot pad, and gait scores. An ANOVA was conducted to determine the effects of Cl, phytase, and their interaction. Turkey BW, ADG, and ADFI decreased in a linear or curvilinear manner with increasing diet Cl (P < 05). At 17 wk of age, litter moisture and foot pad score showed a cubic trend with diet Cl (P < 0.05). Phytase improved FCR during 8 to 11 wk and increased litter moisture at 11 wk of age (P < 0.003). Phytase modified the FCR response to Cl during 2 to 5 and 14 to 17 wk of age at the 2 lowest levels of dietary Cl (P < 0.05). Turkeys fed CS had better BW and FCR through 17 wk of age compared with those receiving DDGS/CM at 0.3\% Cl. Based on BW, minimum dietary electrolyte balance based on Na, K, and Cl was found to be 247, 217, 200, and 171 mEq/kg during 5 to 8, 8 to 11, 11 to 14, and 14 to 17 wk of age, respectively. The present findings emphasized the importance of considering Cl, phytase, and associated dietary electrolyte balance in turkey diets containing high levels of alternative byproducts.