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ARS Home » Plains Area » Miles City, Montana » Livestock and Range Research Laboratory » Research » Publications at this Location » Publication #153702
Title: EVALUATING NEW MEASUREMENTS OF FERTILITY IN BEEF COWSY

Author
item Geary, Thomas
item Perry Jr, George

Submitted to: Research Update for Fort Keogh Livestock and Range Research Laboratory
Publication Type: Popular Publication
Publication Acceptance Date: 10/1/2002
Publication Date: 1/15/2003
Citation: GEARY, T.W., PERRY JR, G.A. EVALUATING NEW MEASUREMENTS OF FERTILITY IN BEEF COWSY. RESEARCH UPDATE FOR FORT KEOGH LIVESTOCK AND RANGE RESEARCH LABORATORY. p. 49-50. 2003.

Interpretive Summary: Loss of pregnancy early in gestation appears to be a major source of reproductive inefficiency among beef and dairy cattle. Prevention of these losses requires characterization of the losses with regards to when and why they occur during gestation. Use of ultrasound allows pregnancy diagnosis as early as 25 days after breeding. Additionally, because fertilization rate is approximately 90% and pregnancy rates at day 25 are generally less than 75%, losses must occur before day 25 of gestation. However, about a 20% incidence of early embryonic mortality has been reported in dairy cows from day 28 to day 98 after insemination following the Ovsynch estrus synchronization protocol. Frequent ultrasound pregnancy diagnosis of beef cows revealed that cows ovulating smaller follicles (<12 mm) tended to have lower initial (d 25)pregnancy rates and increased embryonic mortality. Further studies evaluating whether ovulating follicle size are related to synchronization strategies or genetic differences between cows will be conducted.

Technical Abstract: Loss of pregnancy early in gestation appears to be a major source of reproductive inefficiency among beef and dairy cattle. Prevention of these losses requires characterization of the losses with regards to when and why they occur during gestation. Use of ultrasound allows pregnancy diagnosis as early as 25 days after breeding. Additionally, because fertilization rate is approximately 90% and pregnancy rates at day 25 are generally less than 75%, losses must occur before day 25 of gestation. However, about a 20% incidence of early embryonic mortality has been reported in dairy cows from day 28 to day 98 after insemination following the Ovsynch estrus synchronization protocol. Frequent ultrasound pregnancy diagnosis of beef cows revealed that cows ovulating smaller follicles (<12 mm) tended to have lower initial (d 25)pregnancy rates and increased embryonic mortality. Further studies evaluating whether ovulating follicle size are related to synchronization strategies or genetic differences between cows will be conducted.