the impact of embryonic thermal manipulation on the intestinal microbiota, morphology, and long bone characteristics of male broiler chickens

Climate change is caused by global warming, which is our most pressing environmental concern. however, some of these modifications will have negative effects on animal welfare and the quality and quantity of poultry products. we examined the effects of different periods of thermal manipulation (tm) during embryogenesis on the european production efficiency index (epei), intestinal microbiota and morphology, and long bone characteristics of ross (308) broilers strain exposed to chronic heat stress (chs). consequently, 608 fertile eggs were utilized in a completely randomized design comprising four treatments and four replicates. 7 to 16 days were spent incubating experimental groups with different tm (for control (0 h), 6, 12, and 18 hours). humidity and temperature were maintained at 65% and 39.5°c. after hatching, male chicks were chosen, housed under standard conditions, and then subjected to chronic heat stress (chs) between 28 and 42 days later. mortality in the tm-treated groups was significantly (p ≤ 0.05) lower than in the control group during chs, and mortality was lowest after 12 hours of treatment. the epei was greater in treated chickens at 12 and 18 hours compared to untreated chickens (p ≤ 0.015). the treatments have no effect on the intestinal microbiota (p ≥ 0.05). the tibial length (p ≤ 0.05) and width (p ≤ 0.048) of birds given 12- and 18-hour treatments increased significantly. ≤  tm caused significant changes in the villus's height and area of the villus (p ≤ 0.05). tm-treated birds had higher villus height than control. it can be concluded that tm may increase the height of villus and long bone characteristics and decrease the mortality rate in broilers exposed to chs due to adaptation and thermotolerance.