Strategies to combat heat stress in Isa Brown layer hens: Unveiling the roles of vitamin A, vitamin E, vitamin K, vitamin C, selenium, folic acid, and in combination

Due to their efficient insulation, lack of sweat glands, relatively quick metabolic rate, and heightened sensitivity to heat, the poultry industry faces a serious problem with heat stress. Combining vitamins has been demonstrated to be more effective than implementing a single vitamin in reducing the effects of heat stress. This study aimed to investigate the efficacy of the multivitamin combination in feed on the growth performance, egg quality, and antioxidant enzymes in laying hens exposed to heat stress. A total of 28 Isa Brown strains aged 18 weeks were randomly designated into seven groups with four replications, i.e., (C-) normal temperature group, (C+) heat stress group, and the others with the administration of vitamin A and E (AE), vitamin K and C (KC), vitamin C and E (CE), vitamin E and selenium (ESE), and vitamin C and folic acid (CAF). Feed intake, feed efficiency, eggshell thickness, shape index, haugh unit (HU), yolk, and albumen index were evaluated at 22, 23, 24, and 25 weeks. Meanwhile, antioxidant enzymes were quantified at 22 and 25 weeks. As a result, feed intake was reported a significant improvement in the AE and CE groups compared to the C+ group. Meanwhile, the feed efficiency was reported to be efficient in the CE and ESE groups. Based on egg quality evaluation, we reported significant shell thickness in the CE, ESE, and CAF groups compared to the C+; yolk index was reported slightly significant results in the AE and CAF groups; albumen index and HU were reported to increase significantly in the CAF group. Meanwhile, superoxide dismutase (SOD), malondialdehyde (MDA), and GPx activity were ameliorated significantly in the ESE and CAF groups. Combinations of multivitamins can thereby enhance feed intake, feed efficiency, egg quality, and antioxidant activity. The CE, ESE, and CAF groups were found to have made equivalent improvements in the eggshell thickness, shape index, HU, yolk, and albumen index.