Effects of in-yolk-sac administration of carvacrol on cholesterol resorption from yolk residuals and physiological adaptive indicators in broiler chicks exposed to neonatal fasting

Abstract. Three hundred and twenty Ross 308 male broiler chicks were used to examine effects of in-yolk-sac (IYS) administration of carvacrol on cholesterol resorption from yolk and physiological adaptive responses of broiler chicks subjected to post-hatch fasting periods of up to 72 h. Effects of the four experimental treatments, namely non-handled control (NHCON), sham injection control (SICON), polysorbate-80 injection (POLS), and carvacrol injection (CARV), were examined in 5 replicates of 10 birds each. Liver proportional weight was greater in carvacrol-injected chicks compared with other birds 24 h post-hatch (P < 0.05). The mean blood glucose concentration was 199.0 mg dL⁻¹ when chicks were removed from the hatcher baskets, and decreased in all birds after being subjected to a 72 h post-hatch fasting. However, the slope of decrease in serum concentration of glucose was slower in carvacrol-injected birds than in the other birds, and they had a greater plasma glucose level compared with NHCON and SICON birds after 72 h post-hatch fasting. Lower plasma cholesterol levels were observed in carvacrol-treated chicks compared with those subjected to the other treatments at 72 h post-hatch (P < 0.05). Blood concentration of calcium (Ca) was greater in carvacrol-injected birds at 24 h post-hatch than in NHCON and SICON birds (P <  0.05), but at 72 h it significantly increased in all birds, with the exception of carvacrol-treated chicks, which had significantly lower blood Ca concentration (11.17 mg dL⁻¹) compared with other birds (P < 0.05). Blood potassium concentration increased in polysorbate-80 and carvacrol-injected chicks 24 h post-hatch compared with the NHCON and SICON birds (P <  0.05). In conclusion, the results of the current study revealed that there was no direct interaction between cholesterol and carvacrol leading to reduced cholesterol absorption from yolk sac in newly hatched broiler chicks.