title: Analysis of some factors affecting fertility levels in a high-producing dairy herd in south-western Japan.
abstract: The present study aimed to know whether all cows have been showing declining fertility or only a proportion of cows are attributed to the declining fertility, and to describe factors affecting the level of fertility. A total of 131 cows calved from February 2005 to December 2007 in a dairy herd were examined. Fourteen cows were excluded from the study because of early culling. Of the remaining 117 cows, 47 (40%) conceived within 115 days postpartum after 1-3 artificial insemination (AI) (normal fertility cows), 42 (36%) conceived after 115 days postpartum following 1-3 AI or were culled after 1-2 (sub-fertility cows/culled), and 28 (24%) were inseminated more than three times without detectable genital tract abnormalities (repeat breeders). Calving to conception interval in the normal fertility group was 72 + 3 days, while in the sub-fertility/culled and repeat breeding groups the intervals were 170 + 8 and 259 + 16 days, respectively. Endometritis was the risk factor for sub-fertility/culled (odds ratio (OR) = 3.76). Prolonged luteal phase (OR = 4.08), delayed first ovulation (OR = 6.02), and delayed corpus luteum formation after AI (OR = 8.55) were the risk factors for repeat breeding. In conclusion, 60% cows showed reduced fertility in a herd, while the other 40% had normal fertility. Uterine infection and some ovarian disorders contributed to reduced fertility.
authors.affiliation: Department of Veterinary Medicine, Yamaguchi University, Yamaguchi, Japan.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Yusuf
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Nakao
authors.forename: Su T
authors.initials: ST
authors.lastname: Long
authors.forename: Gokarna
authors.initials: G
authors.lastname: Gautam
mesh_terms: D000818:Animals; D002417:Cattle / Q000502:physiology*; D002418:Cattle Diseases / Q000503:physiopathology; D005260:Female; D005298:Fertility / Q000502:physiology*; D007315:Insemination, Artificial / Q000662:veterinary; D007564:Japan; D010049:Ovarian Diseases / Q000503:physiopathology / Q000662:veterinary; D014591:Uterine Diseases / Q000503:physiopathology / Q000662:veterinary