JWSS - Journal of Water and Soil Science

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This experiment was conducted to determine the requirements of vitamin supplement and available phosphorus in broiler chickens from 42 to 56 days of age. In a completely randomized design, with a 3×3×3 factorial arrangement, 270 one-day-old commercial broiler chicks were divided into 27 groups (replicates) with 9 treatments, 3 replicates and 10 chicks in each group. Each of the nine diets was given to each treatment from 42 days of age. Levels of vitamin supplement were 0.5, 0.25, 0% and available phosphorus levels were 0.27, 0.22, 0.16%. Diets were isocaloric and isoprotein. Group weight and feed consumption of each replicate were determined after 42 and 56 days of age and daily gain, daily feed consumption and feed conversion were calculated. Percent of carcass components and tibia ash were determined.

Results indicated that removal of vitamin supplement from 42 to 56 days of age did not have any significant effects on daily gain, daily feed consumption, feed conversion, live weight, viscera, abdominal fat, carcass weight, wings, neck and back bone. Also, reduction of available phosphorus did not have any significant effect on daily feed consumption, feed conversion, live weight, viscera, abdominal fat, carcass weight, breast meat, femurs, wings, neck and tibia ash. Interaction between vitamin and phosphorus were significant for daily gain, daily feed consumption, live weight, wings, neck and tibia ash (P<0.005) and were highly significant for breast meat, femurs, and back bone (P<0.00l).

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Effect of supplemental phytase on phosphorus and protein utilization and performance of broiler chickens fed on eight different wheat varieties were evaluated. The phytate contents of wheat varieties were determined. In a completely randomized design with a 8*3 factorial arrangement, 384 day-old commercial male brioler chicks (HubbardPeterson) were divided into 96 groups, four chicks per group. Each of the 24 experimental diets (eight varieties) and three levels of phytase (zero, 500 and 1000 FTU/Kg) were given to four replicates for a period of 21 days. At 21 days of age, chickens of each replicate were weighed and killed by cervical dislocation. Ileal contents were collected and analyzed for P, N, phytate and chromic oxide. Left tibia of two birds in each replicate were removed, pooled and stored at -20^oC for bone ash determination. There was a significant (P<0.03) difference in phytate contents between different wheat varieties. Effect of wheat varieties on body weight, feed conversion ratio and bone ash was significant (P<0.05). Added phytase improved body weight, feed consumption, feed conversion ratio and bone ash significantly (P<0.05). Phytase added at 500 FTU/Kg, improved protein digestibility significantly (P<0.01), but increasing the supplement to 1000 FTU/Kg had no further effect. Difference between enzyme levels (500 and 1000 FTU/Kg) was not significant regarding body weight, feed consumption, feed conversion ratio and bone ash. Overall addition of phytase to the diets containing wheat caused an improvement in performance, protein digestibility, and phytase phosphorus utilization in broiler chickens, and can, therefore, be used in diets to reduce feed cost and environmental problems.