Document Type : Research article
Authors
1
Department of Veterinary Public Health, Faculty of Veterinary Medicine, Zagazig University, El-Zeraa St. 114; 44511, Zagazig, Egypt,
2
Department of Animal Behavior and Husbandry, Faculty of Veterinary Medicine, South Valley University, Qena, 83523, Egypt.
Abstract
This study examined the effect of the different group sizes on the titers of some immunological indicators and welfare status in two strains of Lohmannlayers. A total 558 layers (279 Lohmannbrown and 279 Lohmannselected leghorn), aged 50 weeks were homogenously classified into four groups, where 360 birds (180 Lohmannbrown and 180 Lohmannselected leghorn) in 6 cages (60 layers/cage “5 m2”) and 198 birds (99 Lohmannbrown and 99 Lohmannselected leghorn) (33 layers/cage “2.8 m2”) with the same floor space relatively.The antibody titer of avian encephalomyelitis, avian meta-pneumonia, infectious bronchitis and mycoplasma synovia were higher in small group (33 birds) than large group size (60 birds). However, the differences didn’t reach the significance. In the other hand, the Lohmannselected leghorn was more susceptible to avian encephalomyelitis, infectious bronchitis and mycoplasma synovia due to the increase in its antibody titers, while the antibody titers of avian meta-pneumonia and mycoplasma gallisepticum were higher in Lohmannbrown. In large group size, the scores of plumage condition were referred to the best, especially in Lohmannbrown. Furthermore, the changes in feet condition in Lohmannbrown were better than Lohmannselected leghorn, especially in large group. In order to achieve the full genetic growth potential, layers must be reared under optimal group size. Therefore, any deviation of the optimum management condition of layers may impair their performance, cause immunosuppression, and change their physiological responses leading to increase their susceptibility to diseases.
Keywords
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