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

摘要

An experiment was carried out that was intended to explore the growthperformance, nutrient retention, and heat stress biomarkers of finishingbroilers under cyclic heat stress (HS) as modulated by the supplementation ofmannan oligosaccharide (MOS) and essential oil(CXEO). Two hundred and forty 21-day-old Ross 308 male broilers wereallocated to four experimental treatments, each of which was replicated sixtimes with 10 broilers per replicate. The diets included a control (CON),CON + 5 g of MOS kg, CON + 400 mg of CXEO kg offeed, and CON + 5 g of MOS kg + 400 mg of CXEO kg.From day 22 to 42, birds were subjected to cyclic HS by exposing them to33 °C for 10 h (from 07:00 to 17:00 LT) and 22 °C from17:00 to 07:00. Dietary treatments did not have an effect on average dailyfeed intake, feed conversion ratio, the duodenal histomorphology, andrelative visceral weights. Body weight, average daily gain, villus length,crypt depth, and the villus-length-to-crypt-depth ratio in the jejunum weresignificantly increased in birds fed MOS or MOS + CXEO diets(  0.05). The relative bursa weight of the control birds was lower (   0.05) compared to those fed the MOS diet. Compared with CON, dietary treatments reduced corticosterone and creatine kinaselevels, the heterophile-to-lymphocyte ratio, and mRNA levels of heat shockprotein 70 in the breast muscle and jejunum (  0.05). It was concluded that dietary supplementation of either MOS or CXEO alone or incombination may reduce some of the harmful effects of HS in broiler chickens.