| Summary: | 碩士 === 國立屏東科技大學 === 畜產系所 === 98 === High environment temperature caused a reduction in egg production in laying hens and worsened eggshell quality, whereas intermittent lighting could decrease layers activity and energy consumption of chicken, and thus, eased the heat stress effect in chickens. The objective of the study was to determine the effects of lighting program, environmental temperatures and dietary supplementation of acidifiers on egg production, eggshell quality and behavior of laying hens, used as a reference for feeding management to achieve better production performance. In Experiment 1, a total of seventy-two 118-wk old Hisex laying hens were randomly allocated into six treatments according to their respective body weight. The experimental treatments were treatment 1: non-symmetrical lighting (14L:6D:2L:2D), cyclic temperature 23-29ºC, 0.2% coated acid mixture group; treatment 2: non-symmetrical lighting (14L:6D:2L:2D), cycling temperature 23-29ºC, basal diet group; treatment 3: normal lighting, temperature 23ºC, 0.2% coated acid mixture group; treatment 4: normal lighting, thermoneutral temperature 23ºC, basal diet group; treatment 5: normal lighting, cyclic temperature 23-29ºC, 0.2% coated acid mixture group; treatment 6: normal lighting, cyclic temperature 23-29ºC, basal diet group. During the trial, feed intake, egg production and eggshell quality were determined daily. Behavior observation was conducted 5 d continuously to determine the behavior of eating, drinking, grooming, squatting, slanting sit, dustbathing, scratching, standing, foraging and panting.
In Experiment 2, layers from the previous 6 treatments in Experiment 1 were used and maintained under normal lighting, thermoneutral temperature and fed basal diet group. During the trial, feed intake, egg production and eggshell appearance score were determined daily. Eggshell quality was determined weekly.
In Experiment 3, a total of forty-eight 35-wk old Hy-Line laying hens were randomly allocated into four treatments according to their respective body weight. The experimental treatments were treatment 1: intermittent lighting (symmetrical): 4 (4L:2D), 0.2% coated acid mixture group; treatment 2: intermittent lighting (symmetrical): 4 (4L:2D), basal diet group; treatment 3: normal lighting (16L:8D), 0.2% coated acid mixture group; treatment 4: normal lighting (16L:8D), basal diet group. The temperature treatment was thermoneutral temperature 23ºC. During the trial, feed intake, egg production and eggshell quality were determined daily. In Experiment 1 and 3, before ending the trials, the eggshell and feather of six birds from each treatment were sampled for further analysis. During experimental period, 120 g feed was provided per hen per day.
In Experiment 1, the results showed that under non-symmetrical lighting and normal lighting, thermoneutral temperature 23ºC treatment group, the egg weight and eggshell strength were better (P < 0.001). For dietary acidifier supplementation group, eggshell thickness, eggshell roughness, and abnormal eggs rate were better (P < 0.001) than basal diet group, and body weight loss was much lesser. The unsaturated fatty acid content in eggs from acid supplemental group was higher than basal diet group. For eggshell mineral analysis, the Ca and P content of normal lighting, cyclic temperature group were markedly lower. For behavior observation, non-symmetrical lighting treatment birds, eating and drinking behavior were maximum before the light was turned off at 0830, but stablelized at 1730. Under normal lighting and cyclic temperature treatment, the grooming, scratching and panting behavior increased significantly, whereas squatting, dustbathing and standing behavior were decreased. The squatting and slanting sit behavior were significantly increased in non-symmetrical lighting treatment birds, indicating lesser stress.
In Experiment 2, the follow-up laying rate, eggshell thickness, eggshell roughness of birds from Experiment 1 with non-symmetrical lighting, acid mixture supplemental treatment group were significantly better. In Experiment 3, the intermittent lighting and acid mixture supplemental group had better egg production rate, egg weight, eggshell appearance score than basal diet group. For eggshell strength and thickness, intermittent lighting treatment group was significantly better than normal lighting group. To conclude, under non-symmetrical and symmetrical lighting treatment and dietary coated acid mixture supplementation would improve eggshell quality and egg production rate.
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