| 報告時間：2025-6-20 |
| 報告地點：Room 407 |
| 指導老師：Chih-Feng Chen/Chuen-Yu Cheng |
| 學生：Tsai-Hsuan Lee |
| 摘要 |
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The culling of billions of male chicks due to low economic value in meat production has raised ethical concerns, prompting interest in dual-purpose breeds as a potential solution. Native chickens, adapted to local environments, can also be used in crossbreeding to improve broiler and layer production, thereby enhancing economic benefits. Furthermore, some studies have shown that low-protein diets may not negatively impact egg production. The aim of this study was to investigate the effects of feeding a low-protein diet on production performance, egg quality, immunity, and fecal nitrogen content in dual-purpose chicken. A 3×2 factorial design experiment was conducted using 3 genotypes of chicken and 2 levels of crude protein diet (CP) (17 and 19%). The three genotypes of laying hens, were the Taiwan Country Chicken broiler-type B strain (B), commercial Lohmann LSL-Ultra Lite (L) and the hybrid of these two strains (the roosters were L and the hens were B; LB). The 17% CP diet used in this experiment was lower than the nutritional requirements provided by the commercial feeding manual. Together this formed 6 treatment groups with 60 birds each. Egg production data was collected from 19 to 45 week of age, with egg quality parameters were measured at weeks 25, 35, and 45 of age. The Sheep Red Blood Cells (SRBC) immune response and fecal nitrogen were measured at weeks 38 and 45, respectively. The egg production rate of the L strain was the highest, followed by the LB strain (P<0.05). Both LB and L were able to maintain consistent laying performance regardless of dietary protein content. At 45 weeks of age, LB exhibited the highest egg weight among all breeds (P < 0.05). At 25, 35, and 45 weeks of age, the albumen height of LB and L was significantly higher than that of B (P<0.05). Moreover, at 45 weeks of age, hens fed 17% CP exhibited a significantly darker yolk color than those fed the 19% protein diet (P<0.05). L had the higher antibody response to SRBC compared to B (P<0.05). However, there was no significant difference in fecal nitrogen content between the diets fed 17% crude protein and 19% crude protein (P>0.05). In conclusions, LB exhibited intermediate performance in terms of laying performance and egg quality traits among all breeds. The 17% low-protein diet enhanced yolk color without adversely affecting laying performance, egg quality, humoral immune response, or fecal nitrogen content. The LB chicken showed potential as a dual-purpose breed capable of maintaining performance on a low-protein diet. |
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