| Project/Area Number |
17580279
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Clinical veterinary science
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| Research Institution | Yamaguchi University |
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Principal Investigator |
NAKAO Toshihiko Yamaguchi University, Faculty of agriculture, Professor (30094824)
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| Project Period (FY) |
2005 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2006: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2005: ¥2,400,000 (Direct Cost: ¥2,400,000)
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| Keywords | dairy cow / postpartum ovarian cycles / prolonged luteal phase / delayed first ovulation postpartum / progesterone / fertility / first ovulation postpartum / 分娩後卵巣機能 / 黄体機能 / 卵巣静止 / 不受胎 / 受胎 |
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| Research Abstract |
A total of 344 dairy cows from 11 dairy farms across Japan were investigated for 12 months for their resumption of ovarian cycles postpartum to show the incidence of prolonged luteal phase after first ovulation and for the factors causing the prolongation. Prolonged luteal phase was diagnosed based on milk progesterone profiles indicating the presence of CL for 21 days or longer after the formation. Incidence of prolonged luteal phase after first ovulation in 344 cows was 10.2 %, while 41.6 % had normal resumption of ovarian cycles and 36.9 % showed delayed first postpartum ovulation. Cows with prolonged luteal phase showed lower first AI conception rate, and pregnancy rate within 100 days postpartum than cows with the normal ovarian cycles (P<0.05). Among 11 herds, five herds had 11 to 22 % incidence of prolonged luteal phase, whereas six other herd had almost no incidence. All the five herds with incidence of prolonged luteal phase were using free-stalls and their average milk yield was relatively higher. On the other hand, all of the six herds with no incidence had relatively lower milk yield and four of the six were using tie-stalls. Within a herd, heavier and higher producing cows with normal BCS and body weight changes after calving were more prone to the prolongation of luteal phase, while cows with decreasing body weight and BCS showed the delay of first ovulation postpartum. Nutritional state of cow during dry period and at parturition and high milk production are likely major factors causing the prolonged luteal phase after postpartum ovulation. Both PGF2α and estradiol benzoate administered intramuscularly were effective to induce estrus with normal fertility in cows with prolonged luteal phase. Thus pathophysiology of prolonged luteal phase after first postpartum ovulation was partly described and practical methods of treatment was suggested.
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