Effect of mannan-oligosaccharides (MOS) supplementation on performance, immunity and HSP70 gene expression in broiler chicken during hot-dry summer

An experiment was conducted on broiler chicks (n=120), reared in cages on a standard diet up to 14^th day of age and thereafter up to42^nd day(14-42d) on test dietswith or without MOS. The14^th dayold chickswere randomlydistributed into three dietary treatment groups viz., T₁ (control diet), T₂ (control diet with MOS @ 0.3%) and T₃ (control diet with MOS @ 0.5%). Each dietary treatment comprised of four replicates of eight birds each. Experiment was carried out during hot-dry summer. It was found that production indices improved (P<0.001) significantly during all phases. Cellular and humoral immunityat 28^th dayof ageimproved significantly(P<0.05) dueto MOS supplementation. Thepercentage of hemoglobin, protein, AST and ALTincreased significantly(P<0.001) in MOSsupplemented group at 28^th aswell as42^nd dayofage. While H: L ratio, serum corticosterone and cholesterol levels decreased significantly (P<0.001) in MOS supplemented groups. Supplementation of MOS at the both levels caused significant (P<0.001) down regulation of HSP70 expression in jejunum tissues during 28^th and 42^nd day. Based on this study it was concluded that supplementation of 0.3% MOS in broiler diets significantlyimproved their performanceand welfareduring heatstressed conditions.