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A corticosterone model was used to study the effects of chronic and repeated stress during the rearing phase on physiology, the onset of lay and performance of laying hens in the subsequent laying period. Two hundred and seventy Hy-line brown layer pullets were reared in environmentally controlled battery cages. At 7, 11, and 15 weeks of age birds were exposed for 1 week to the following treatments in drinking water: corticosterone dissolved in ethanol, ethanol, or untreated water. One week following each treatment, and at 35 weeks of age endocrine, metabolic and haematological tests were conducted. Body weight was measured throughout the study, and egg production was recorded daily throughout the laying period. Plasma corticosterone levels and heterophil to lymphocyte (H/L) ratio were increased after each corticosterone delivery...
A study was undertaken to investigate the ability of two commercial probiotics applied in free-range laying hens (from 18 to 22 weeks of age) in reducing the occurrence of reproductive tract pathologies, and improving hen health and performance. In all, 630 17-week-old brown layers were transferred to a freshly cleaned free-range laying facility, and randomly divided into three groups, with three replicates of 70 birds each. Both probiotics were administered in the drinking water (Groups 1 and 2) on a daily basis for 4 weeks, while Group 3 was left untreated. At 38 weeks of age, the results demonstrated that treatment with either probiotic significantly reduced the occurrence of reproductive tract pathologies (control vs probiotics, 33% vs 22% and 11%; P < 0.01), mortalities (control vs probiotics; 3.8% vs 1.5 and 1.9%; P < 0.01)...
Surveys were conducted with cage and alternative layer production systems to assess the prevalence of fatty liver haemorrhagic syndrome (FLHS). Commercial caged laying hens of different ages from three farms in Queensland were monitored for three months. The mortality rate of flocks ranged from 0.8% (the youngest flock) to 11.6% (the oldest flock). Six hundred and fifty-one birds were necropsied, and approximately 40% of hens died due to FLHS. Hens kept in cages in a controlled environment shed, were at a similar risk of developing FLHS to hens kept in naturally controlled sheds, however, the heavier birds in a flock were more likely to have the condition than lighter birds. In another study, layer flocks kept in cage, barn and free-range housing systems at the University of Queensland facility, were monitored for 50 weeks. Data ...
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