title: Effects of abnormal ovarian cycles during pre-service period postpartum on subsequent reproductive performance of high-producing Holstein cows.
abstract: The primary objective of this study was to investigate the effects of abnormal ovarian cycles during the pre-service postpartum period on subsequent reproductive performance of high-producing Holstein cows. The study was conducted in a commercial dairy farm with approximately 150 lactating cows, in a subtropical region of Japan. Animals were kept in free-stall barn, and fed a total mixed ration. Cows that calved from June 2001 to July 2002 were included in the study. Milk samples were collected twice weekly from 2 to 11 weeks postpartum, and progesterone concentrations in skim milk were determined by ELISA. After a voluntary waiting period of 40 days, cows detected in estrus were bred by artificial insemination (AI). Pregnancy was confirmed by palpation per rectum 40-70 days after AI. Out of a total of 91 cases, 39 (42.9%) had normal ovarian cycles (ovulation within 45 days after calving, followed by normal ovarian cycles), 32 (35.2%) had prolonged luteal phase (i.e. luteal activity for >20 days), and 12 (13.2%) had anovulation or delayed first ovulation (i.e. first ovulation did not occur until >45 days after calving). The remaining (8.8%) had other types of abnormalities. When compared with cows with a normal ovarian cycle, prolonged luteal phase cows had a lower 100 days AI submission rate, conception rate and pregnancy rate (84.2% versus 56.3%; P<0.05, 50% versus 16.7%; P<0.05 and 42.1% versus 9.4%; P<0.01, respectively), and longer intervals to first AI and to conception ( 67+/-6 days versus 98+/-7 days and 95+/-9 days versus 136+/-11 days; P<0.01 for each). Similarly, when compared with cows with normal ovarian cycles, those with anovulation had lower 100 days conception rate and pregnancy rate (50% versus 0%; P<0.05 and 42.1% versus 0%; P<0.01, respectively), and longer intervals to first AI and to conception ( 67+/-6 days versus 93+/-12 days; P<0.05 and 95+/-9 days versus 155+/-14 days; P<0.01, respectively). Survival analysis of the data for calving to conception interval showed that cows with prolonged luteal phase or anovulation were getting pregnant at a slower rate, and took longer to get pregnant than the cows with normal resumption of ovarian cyclicity postpartum. In conclusion, abnormal ovarian cycles during the pre-service period postpartum adversely affected reproductive performance, including AI submission rate, pregnancy rate, interval to first AI, and calving to conception interval in high-producing Holstein cows.
authors.affiliation: Animal Science Laboratory, Graduate School for International Development and Cooperation (IDEC), Hiroshima University, 1-5-1 Kagamiyama, Higashi-Hiroshima 739-8529, Japan.
authors.forename: Hemanta Kumar
authors.initials: HK
authors.lastname: Shrestha
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Nakao
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Suzuki
authors.forename: Tsuneo
authors.initials: T
authors.lastname: Higaki
authors.forename: Masashi
authors.initials: M
authors.lastname: Akita
mesh_terms: D000818:Animals; D002417:Cattle / Q000502:physiology*; D005260:Female; D007315:Insemination, Artificial / Q000662:veterinary; D007564:Japan; D007774:Lactation; D008183:Luteal Phase; D008892:Milk / Q000737:chemistry; D010053:Ovary / Q000502:physiology*; D010060:Ovulation; D049590:Postpartum Period; D011247:Pregnancy; D011374:Progesterone / Q000032:analysis; D012098:Reproduction / Q000502:physiology*; D013997:Time Factors
chemical_list: D011374:Progesterone