Hormonal Regulation of the Oestrous Cycle of Cattle

Roche, J; Austin, E.J.; Ryan, M. F.; O'Rourke, Mary T.; Mihm, M.; Diskin, M.G.

doi:10.1111/j.1439-0531.1998.tb01348.x

Cited by 5 publications

(1 citation statement)

References 26 publications

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“…To improve fertility and save labour, various pharmaceuticals to control the oestrous cycle and to treat reproductive disorders are extensively used in many herds, e.g. [6,7]. During the last decades the productivity of dairy cattle has increased considerably in many countries, not least because of progress due to genetic improvement.…”

Section: Introductionmentioning

confidence: 99%

Reproductive performance of Norwegian cattle from 1985 to 2005: trends and seasonality

Refsdal¹

2007

Acta Vet Scand

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Declining reproductive performance is a serious breeding concern in many countries. To reveal the situation in Norwegian cattle, trends in reproductive performance were studied using insemination . However, return rates 0-3 days post insemination (RR0-3) increased from 6 to 12% in the same period (p < 0.001). NR60 was higher and the RR0-3 was lower in the summer season compared to the winter season during the whole period. A fertility index (FS), has been calculated from the herd recording files each year from 1989 to 2005. The average FS-index did not show a significant trend and the calving interval was also fairly constant between 12.4 and 12.6 months during this period. The average interval from calving to first and last insemination, respectively, increased from a low of 79 and 102 days in 1990 to a high of 86 and 108 days in 2005. Both intervals were consistently longer for cows in first lactation than for cows in later lactations. The percentage of inseminated animals reported culled because of poor fertility decreased from 6.0% in 1989 to 4.6% in 1996 and thereafter again increased to 6% in 2005. In conclusion, most fertility measures, mainly comprising the Norwegian Red (NRF) breed, show a relatively high level of reproductive performance with a positive or a relatively constant trend during the last two decades.

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Section: Introductionmentioning

confidence: 99%