1Central Avian Research Institute Izatnagar-243 122, India
2Department of Animal Science, MJP Rohilkhand University, Bareilly, India
*Reprint request: Dr. Chandra Deo, Tel: +91–581-230 0204/230 3223; Fax: +91–581-244 7321, E-mail: deocari@rediffmail.com
An experiment was conducted to study the effect of feeding different levels of phosphorus (P) and its subsequent depletion at varied levels on growth performance and blood biochemicals of finishing broilers. Initially, three test diets were prepared from the basal diet containing practical feedstuffs and supplemented with variable dicalcium phosphate to achieve 0.3, 0.4 and 0.5% available phosphorus (AP) and were tested during starting phase (0–21 d) period by introducing each diet in twelve groups having 9 chicks each. Additionally, nine more test diets were also prepared by depleting 25, 50 and 75% of P levels of each diet that had been tested during starting phase. Thus, during finishing phase (22–42 d) a total of 12 test diets were tested in a factorial manner (3x4) having three levels of AP (0.3, 0.4 and 0.5%) and four levels of depletion (0, 25, 50 and 75%) of each AP levels. Each treatment had three replicates of 8 chicks. Results indicated significantly (P<0.05) higher body weight gain at 50% than other levels of P depletion. No significant effect was evident on body weight gain due to different P levels. Significant (P<0.05) interactions between levels and depletion of P were noticed on body weight gain. Feed intake and feed conversion ratio did not differ significantly due to either main effects or their interactions. Serum alkaline phosphatase activity, and levels of calcium and phosphorus differed significantly (P<0.05) due to different levels of P depletion. Serum phosphorus concentration increased (P<0.01) with increased levels of P in the diet. Similarly, the serum phosphorus levels were significantly lower at all the levels of P (25 to 75%) of phosphorus depletion than the undepleted. The results of this study suggest that the P level in broiler finisher diet can be reduced upto 50% irrespective of AP levels during the starter phase. Further, the broilers need at least 0.15% AP during finishing phase (22–42d) for optimum growth performance.
Broilers, Depletion, Finisher, Growth, Phosphorus
