Evaluation of Magnesium Sulphate in Broiler Chicken During Hot-Dry Summer Using Zoo Technical, Molecular and Physio-Biochemical Tools

To evaluate the role of magnesium sulphate in mitigating heat stress, it was tried at two level in diets during hot (April-May, 31.0±0.7° to 37.0±1.4°C, Rh, %: 58.0±1.3–70.1±0.6) summer. Broiler chicks were reared on a standard diet up to 14 days of age and thereafter chicks were randomly distributed into three dietary treatments viz., T1 (Control group: Standard diet), T2 (standard diet with magnesium sulphate @ 1.2 g/kg) and T3 (standard diet with magnesium sulphate @ 2.4 g/kg) and reared upto 42 days of age. Each dietary treatment was fed to four replicated groups of 8 birds each and one more replicate to study blood metabolites and HSP70 gene expression. The humoral and cell mediated immune response was studied on 28^th day. Hematological and blood biochemical parameters were studied on 28^th and 42^nd day of age. Serum corticosteron level was also estimated at 42^nd day of age. Expression of HSP 70 in jejunum tissues were studied on 28^th and 42^nd day of age using Real time PCR. Significant improvement was seen in live weight gain (P<0.01) at 2.4 g/kg and FCR (P<0.001) in 1.2 or 2.4 g/kg magnesium sulphate supplemented groups. The percentage of haemoglobin, protein (P<0.001), AST (P<0.001) and ALT (P<0.001) increased significantly while H: L ratio, serum corticosteron (P<0.001) and serum cholesterol decreased significantly at 4^th and 6^th week of age due to magnesium sulphate supplementation. Significant down regulation of relative expression of HSP 70 in jejunum tissues (at 4^th and 6^th week of age) was observed in magnesium sulphate supplemented group. Based on this study it is suggested that supplementation of magnesium sulphate in heat stressed broilers will improve performance and welfare.