Effects of mannan oligosaccharide and Curcuma xanthorrhiza essential oil on the intestinal morphology and stress indicators of broilers subjected to cyclic heat stress

چکیده مقاله

An experiment was carried out that was intended to explore the growth performance, nutrient retention, and heat stress biomarkers of finishing broilers under cyclic heat stress (HS) as modulated by the supplementation of mannan oligosaccharide (MOS) and Curcuma xanthorrhiza essential oil (CXEO). Two hundred and forty 21-day-old Ross 308 male broilers were allocated to four experimental treatments, each of which was replicatedsixtimeswith10broilersperreplicate.Thedietsincludedacontrol(CON),CON+5gofMOSkg−1, CON+400mg of CXEOkg−1 of feed, and CON+5g of MOSkg−1+400mg of CXEOkg−1. From day 22 to 42, birds were subjected to cyclic HS by exposing them to 33◦C for 10h (from 07:00 to 17:00LT) and 22◦C from 17:00 to 07:00. Dietary treatments did not have an effect on average daily feed intake, feed conversion ratio, the duodenal histomorphology, and relative visceral weights. Body weight, average daily gain, villus length, crypt depth, and the villus-length-to-crypt-depth ratio in the jejunum were significantly increased in birds fed MOS or MOS+CXEO diets (p<0.05). The relative bursa weight of the control birds was lower (p<0.05) compared to those fed the MOS diet. Compared with CON, dietary treatments reduced corticosterone and creatine kinase levels, the heterophile-to-lymphocyte ratio, and mRNA levels of heat shock protein 70 in the breast muscleandjejunum(p<0.05).ItwasconcludedthatdietarysupplementationofeitherMOSorCXEOaloneor in combination may reduce some of the harmful effects of HS in broiler chicken