Dose dependent effect of GnRH analogue on pregnancy rate of repeat breeder crossbred cows

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.

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“…2002; Villarroel et al . 2004; Kharche & Srivastava 2007; Dochi et al . 2008) have already been reported in a number of studies.…”

Section: Discussionmentioning

confidence: 99%

Analysis of some factors affecting fertility levels in a high‐producing dairy herd in south‐western Japan

Yusuf

Nakao

Long

et al. 2010

Animal Science Journal

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“…Although the incidence of repeat breeding [1][2][3][4][29][30][31], its causes [3,4,6,10,13], and treatment [15,23,[32][33][34] have already been reported, the present study is apparently the first to provide a detailed assessment of reproductive performance in repeat breeders. That their reproductive performance was poorer than in normal fertility cows was predictable a priori, based on the definition of repeat breeders.…”

Section: Discussionmentioning

confidence: 99%

Reproductive performance of repeat breeders in dairy herds

et al. 2010

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“…hCG application is done to animals during the insemination or luteal period in order to provide the rupture of Graafian follicle, to abolish functional insufficiencies of corpus luteum and to rise the endogenous progesterone production to the most effective level, and as a result of these applications it has been stated that pregnancy rate has increased in some studies [17][18]. In the same way, with the GnRH application before, during and post insemination in different days, it has been notified that pregnancy rate has been increased by means of stimulating folliculogenesis, ovulation and luteal structures [19][20][21].…”

Section: Introductionmentioning

confidence: 99%