초수정 및 초임월령이 홀스타인 육성우의 번식성적에 미치는 영향

다국어 초록 (Multilingual Abstract)

Presently, the first pregnancy age of dairy heifers attended National Dairy Herd Improvement Program (NDHI) in Korea has increased, and more research have been requested to evaluate the possibility of decreasing the first pregnancy age of dairy heifers. Accordingly, this study was investigated the effects of the month of age at the first service and pregnancy on the reproductive efficiency of Holstein heifers. For these, the reproductive performance of heifers was analyzed by evaluating the effects of first insemination service at 12-14 months of age (12 month old), 15-16 months of age (15 month old), 17-19 months of age (17 month old), and > 20 months of age (20 month old) in Holstein heifers. The service numbers per conception in the first insemination months were 1.85±1.22, 1.59±0.77, 1.58±0.72, and 1.76±0.97 times at 12, 15, 17 and 20 months of age, respectively. The conception rates in the first service were 51.2, 57.8, 54.8, and 52.9% at 12, 15, 17 and 20 months of age, respectively. The conception ages were 453.2±78.9, 512.1±75.9, 590.1±98.0, and 713.0±74.5 days in the heifers serviced firstly at 12, 15, 17 and 20 months of age, respectively. There was significantly difference in the conception age among groups (p<0.05). The cumulative conception rates in the heifers serviced firstly at 12, 15, 17 and 20 months of age were 51.21, 57.8, 54.8 and 53.0% by the first service, 29.8, 30.1, 32.3, 23.5% by the second service, and 19.0, 12.1, 12.9 and 23.5% by the third service, respectively. The service numbers per conception in the first pregnancy months were 1.31, 1.55, 2.0, 2.05 times at 12, 15, 17 and 20 months of the first service age, respectively. The service numbers per conception in the 12 and 15 months of age were significantly lower than those in the 17 and 20 months of age (p<0.05). The rates of repeat-breeder were 6.0, 11.3, 22.0, and 41.0% in the heifers serviced firstly at 12, 15, 17 and 20 months of age, respectively. These results demonstrate that first pregnancy of Holstein heifers should be conducted at 15 months of age, because the age at first pregnancy in heifers can be substantially influenced through implementation of reproductive management and performance.

목차 (Table of Contents)

• ABSTRACT
• Ⅰ. 서론
• Ⅱ. 재료 및 방법
• 1. 공시동물
• 2. 공시재료
• 3. 초수정 및 초임월령
• 4. 조사방법
• Ⅲ. 결과 및 고찰
• 1. 초수정월령에 따른 수태당 수정횟수
• 2. 초수정월령에 따른 첫수정시 수태율
• 3. 초수정월령에 따른 초임일수
• 4. 초임월령에 따른 누적수태율
• 5. 초임월령에 따른 수태당 수정횟수
• 6. 초임월령에 따른 저수태우의 발생율
• Ⅳ. 요약
• 사사
• Ⅴ. REFERENCES