تاثیر سطوح متفاوت اسید بوتیریک محافظت شده در جیره‌ بر عملکرد رشد، متابولیت‌های خون و املاح استخوان درشت‌نی جوجه‌های گوشتی

The purpose of this research was to evaluate the effects of different levels of dietary protected butyric acid (PBA) on growth performance, blood metabolites, calcium and phosphorous of tibia in broilers. Two hundred and seventy day old Ross 308 male broilers divided in 9 treatments and 3 replicates (10 chicks per replicates), in a completely randomized design. Experimental treatments included: (1) control (without additives), (2) 0.1% Bacitracin (positive control), (3) 0.2% PBA in starter period, (4) 0.2% PBA in starter and grower periods, (5) 0.2% PBA in starter, grower and finisher periods, (6) 0.3% PBA in starter period, (7) 0.3% PBA in starter and grower periods, (8) 0.3% PBA in starter, grower and finisher periods and (9) 0.5, 0.4 and 0.3% PBA in starter, grower and finisher periods, respectively. Results indicated that the highest daily weight gain in starter period was related to birds fed 0.2% PBA, having significant difference with birds fed control, 0.3 and 0.5% PBA (p≤0.05). Use of PBA had no effect on body weight and daily weight gain in grower, finisher and total periods. PBA levels and Bacitracin did not effect on feed intake and feed conversion ratio of broilers. PBA did not have significant effect on blood metabolites (except blood plasma calcium) and calcium and phosphorous percentage of tibia at 42 days of age. Based on the taken results, it seems that use of 0.2% PBA as a replacing additive of antibiotic in broiler' diet is useful, especially in starter period.