Impact of Phytase and Cholecalciferol Supplementation on the True Digestibility of Phosphorus by Broiler Chickens Fed Some Agro-Based Byproducts

This research is aimed to determine the effects of phytase and vitamin D3 supplementation in Cottonseed Meal (CM) and Rice Husk (RH)-based diets on true phosphorus digestibility (TPD) by broiler chickens (BC). Two studies were conducted with 576 one-day-old broiler chickens using regression analysis to determine the TPD in these diets and the response to phytase supplementation. Six semi-purified diets were formulated to contain 150g, 300g, and 450g each of CM/kg (experiment 1) and RH/kg (experiment 2) with phytase supplied at 0 and 1000 units/kg. A total of 288 BC in each study were allotted to the six diets with six replicates of eight birds in a randomized complete block design. In another study (experiment 3), 125 BC were allotted to five treatments comprising a Positive Control (PC, D1) without CM and four CM-based semi-purified diets (31.5%): Negative Control (NC, D2), NC+vitaminD3 (D3), NC+phytase (D4) and NC+phytase+vitamin D3 (T5) replicated five times. Similarly, 125 BC were randomly allotted to five treatments comprising a PC (D1) without RH and four RH-based semi-purified diets (30%): NC (D2), NC+ vitaminD3 (D3), NC+phytase (D4) and NC+phytase+vitaminD3 (D5). All birds were fed the experimental diets from day 21 to day 28 post-hatch. True phosphorus digestibility was 0.82 for CM and 0.75 for RH without phytase; and 0.95 for CM and 0.92 for RH with phytase. Phytase supplementation resulted in 13.27 and 17.94% increases in TPD; and 12.29 and 13.61% increases in TPR by birds fed the CM and RH diets, respectively. In experiment 3 (CM-based diet), ileal phosphorus significantly (P<0.05) reduced (0.08) with a corresponding increase in the percentage apparent phosphorus digestibility (90. 64) in D3. There was a significant (P<0.05) reduction in excreta phosphorus and a corresponding increase in the percentage of apparent phosphorus retention in the D5. In the RH-based diets, Digestible phosphorus was significantly (P<0.05) improved in D3. Excreta phosphorus was significantly reduced in the supplemented diets. Phytase and Vit D3 supplementation of CM and RH-based diets increased TPD, Digestible P and improved TPR and true ileal phosphorus digestibility in broiler chickens.