Ameliorative effect of zinc and multistrain probiotic on muscle and bone characteristics in broiler reared under cyclic heat stress

Abstract

From day 22, a total of 280 day-old broiler chicks were allotted to seven groups with five replicates till 42 days. The groups were designated as T1, thermoneutral zone; T2, heat stressed (HS); T3, HS + zinc (Zn) supplementation (30 mg/kg); T4, HS + Zn (60 mg/kg); T5, HS + probiotic; T6, HS + probiotic + Zn (30 mg/kg); T7, HS+ Zn (60 mg/kg) + probiotic. The results revealed that muscle pH, muscle fiber diameter (MFD) and muscle fiber cross sectional area (MFCSA) were significantly (P<0.05) higher in T2 compared to all other treatments under HS. Drip losses was significantly (P<0.01) lower in the treatment groups compared to T2. Muscle fascicle diameter (MFSD) and muscle fascicle cross sectional area (MFSCSA) were significantly (P<0.01) lower in T2 and T3 while higher (P<0.01) in all other treatments under HS condition. Muscle fiber number (MFN) was significantly (P<0.05) higher in T2, T5 and T7 compared to the control. Wall thickness, diameter and medial canal diameter increased significantly (P<0.01) in T6. However, tibiotarsal index decreased significantly (P<0.01) in T5. In conclusion, Zn and probiotic ameliorated the negative effect of HS. However, the bone parameters were not greatly affected by HS and the supplements.