title: Feeding frequency affects stress, innate immunity and disease resistance of juvenile blunt snout bream Megalobrama amblycephala.
abstract: This study aimed to evaluate the effects of feeding frequency on stress, innate immunity and disease resistance of juvenile blunt snout bream Megalobrama amblycephala (average weight: 9.92 ± 0.06 g). Fish were randomly assigned to one of six feeding frequencies (1, 2, 3, 4, 5 and 6 times/day) following the same ration size for 8 weeks. After the feeding trial, fish were challenged by Aeromonas hydrophila and cumulative mortality was recorded for the next 10 days. Daily gain index of fish fed 3-5 times/day was significantly higher than that of the other groups. High feeding frequencies induced significantly elevated plasma levels of both cortisol and lactate. Fish fed 3-4 times/day exhibited relatively low liver catalase and glutathione peroxidase activities as well as malondialdehyde contents, but obtained significantly higher reduced glutathione levels and post-challenged haemato-immunological parameters (include blood leukocyte and erythrocyte counts as well as plasma lysozyme, alternative complement, acid phosphatase and myeloperoxidase activities) compared with that of the other groups. After challenge, the lowest mortality was observed in fish fed 4 times/day. It was significantly lower than that of fish fed 1-3 times/day, but exhibited no statistical difference with that of the other groups. In conclusion, both low and high feeding frequencies could cause oxidative stress of juvenile M. amblycephala, as might consequently lead to the depressed immunity and reduced resistance to A. hydrophila infection. The optimal feeding frequency to enhance growth and boost immunity of this species at juvenile stage is 4 times/day.
authors.affiliation: Laboratory of Aquatic Nutrition and Ecology, College of Animal Science and Technology, Nanjing Agricultural University, No. 1 Weigang Road, Nanjing 210095, Jiangsu Province, People's Republic of China.
authors.forename: Xiang-Fei
authors.initials: XF
authors.lastname: Li
authors.affiliation: Laboratory of Aquatic Nutrition and Ecology, College of Animal Science and Technology, Nanjing Agricultural University, No. 1 Weigang Road, Nanjing 210095, Jiangsu Province, People's Republic of China.
authors.forename: Hong-Yan
authors.initials: HY
authors.lastname: Tian
authors.affiliation: Laboratory of Aquatic Nutrition and Ecology, College of Animal Science and Technology, Nanjing Agricultural University, No. 1 Weigang Road, Nanjing 210095, Jiangsu Province, People's Republic of China.
authors.forename: Ding-Dong
authors.initials: DD
authors.lastname: Zhang
authors.affiliation: Laboratory of Aquatic Nutrition and Ecology, College of Animal Science and Technology, Nanjing Agricultural University, No. 1 Weigang Road, Nanjing 210095, Jiangsu Province, People's Republic of China.
authors.forename: Guang-Zhen
authors.initials: GZ
authors.lastname: Jiang
authors.affiliation: Laboratory of Aquatic Nutrition and Ecology, College of Animal Science and Technology, Nanjing Agricultural University, No. 1 Weigang Road, Nanjing 210095, Jiangsu Province, People's Republic of China. Electronic address: wbliu@njau.edu.cn.
authors.forename: Wen-Bin
authors.initials: WB
authors.lastname: Liu
mesh_terms: D000822:Animal Husbandry / Q000379:methods*; D000818:Animals; D003530:Cyprinidae / Q000502:physiology*; D005247:Feeding Behavior; D007113:Immunity, Innate / Q000502:physiology*; D013312:Stress, Physiological / Q000502:physiology*; D013997:Time Factors
keywords: Blunt snout bream; Feeding frequency; Innate immunity; Oxidative status; Stress