title: Laying performance, digestibility and plasma hormones in laying hens exposed to chronic heat stress as affected by betaine, vitamin C, and/or vitamin E supplementation.
abstract: Heat stress had a negative effect on laying hens' performance, thus this research was to study the influences of betaine (Bet, 1000 mg/kg betaine), vitamin C (VC, 200 mg/kg ascorbic acid), and vitamin E (VE, 150 mg/kg α-Tocopherol acetate) and their possible combinations on egg production, digestibility of nutrients, plasma hormones and reproductive organs of dual-purpose hens exposed to chronic heat stress. Two hundred and eighty eight hens and thirty-six cocks from 32 to 48 weeks of age were divided into nine treatment groups of four replicates, each containing eight hens and one cock. One group was kept under thermo-natural condition and the eight others were kept under chronic heat stress (CHS). One of these eight was used as a negative control, while the others were supplemented with VC, VE and/or betaine and their possible combinations. Body weights, laying rate, feed intake, and feed conversion ratio in hens reared under CHS rooster without any supplementation during 32 to 48 weeks of impairment (P = 0.0052) were recorded. Hens reared under heat stress and fed a diet supplemented with either Bet, VC, VE or combination of the supplements increased production traits. However, hens supplemented with VC showed the greatest production traits. Plasma glucose, estradiol-17 (E2), progesterone (P4), tri-iodothyronine (T3) and thyroxine (T4) decreased in hens reared under CHS and fed a diet with no supplementation compared to the other treatments (P = 0.001). Liver weights, spleen weights, thyroid gland weights, ovary weights, oviduct weights and oviduct lengths were lowest in hens reared under CHS and fed a diet with no supplementation (P = 0.0480). In conclusion, dual purpose hens reared under CHS and supplemented with VC at 200 mg/kg diet and Bet at 1000 mg/kg enhanced the laying performance and combated CHS.
authors.affiliation: Arid Land Agriculture Department, Faculty of Meteorology, Environment and Arid Land Agriculture, King Abdulaziz University, P.O. Box 80208, Jeddah, 21589 Saudi Arabia.
authors.forename: Youssef A
authors.initials: YA
authors.lastname: Attia
authors.affiliation: Animal and Poultry Production Department, Faculty of Agriculture, Damanhour University, Damanhour, Egypt.
authors.forename: Abd El-Hamid E
authors.initials: Ael-H
authors.lastname: Abd El-Hamid
authors.affiliation: Department of Poultry Nutrition, Animal Production Research Institute, Ministry of Agriculture and Land Reclamation, Agriculture Research Center, Giza, Egypt.
authors.forename: Ahmed A
authors.initials: AA
authors.lastname: Abedalla
authors.affiliation: Department of Poultry Nutrition, Animal Production Research Institute, Ministry of Agriculture and Land Reclamation, Agriculture Research Center, Giza, Egypt.
authors.forename: Marfat A
authors.initials: MA
authors.lastname: Berika
authors.affiliation: Arid Land Agriculture Department, Faculty of Meteorology, Environment and Arid Land Agriculture, King Abdulaziz University, P.O. Box 80208, Jeddah, 21589 Saudi Arabia.
authors.forename: Mohammed A
authors.initials: MA
authors.lastname: Al-Harthi
authors.affiliation: Department of Animal Nutrition, Faculty of Veterinary Medicine, Erciyes University, Kayseri, Turkey.
authors.forename: Osman
authors.initials: O
authors.lastname: Kucuk
authors.affiliation: Department of Animal Nutrition, Faculty of Veterinary Medicine, Firat University, Elazig, Turkey.
authors.forename: Kazim
authors.initials: K
authors.lastname: Sahin
authors.affiliation: Department of Poultry Nutrition, Animal Production Research Institute, Ministry of Agriculture and Land Reclamation, Agriculture Research Center, Giza, Egypt.
authors.forename: Baha M
authors.initials: BM
authors.lastname: Abou-Shehema
keywords: Betaine; Heat stress; Laying hens; Performance; Vitamin C; Vitamin E