SPERMOVA (Aug 2016)
Estrategies to improve fertility in cattle: artificial insemination following estrus versus timed artificial insemination
Abstract
Artificial insemination (AI) is currently the major biotechnique used worldwide to disseminate superior genetics and to improve reproductive efficiency in bovine herds. Conversely, reports from different parts of the world indicate low pregnancy rates in cattle submitted to AI, due to both mistakes in heat detection or a high incidence of anestrous. In dairy cattle, the use of AI following visual detection of estrus is relatively easier to be used because their routine of management is intense (milking two to three times a day), allowing a frequent contact with cows for estrus observation. However, for beef cattle, the implementation of AI programs based on estrus detection is harder to be used because of several management conditions. Beef cows are frequently raised extensively, with great walking distances between their pasture to the corral where the AI is performed, the number of employers designated for cattle management is reduced and they have several activities besides reproduction. Because of the necessity of at least two periods of estrus observation per day and the conduction of cattle to the corral around 12 h following estrus detection to be inseminated, the AI is somehow unfeasible in beef farms. The development of timed AI (TAI) enabled insemination of cows in commercial scale, because it allows the programmed AI of large number of cows in the same day without the need for estrus detection. Besides, the use of TAI in early postpartum dairy and beef females reduces the interval partum-conception and, consequently the interval between parturitions, which has a dramatic effect on farm economic return. For beef cattle, TAI also brings the advantages of concentrating around half of the conceptions at the first days of the breeding season and stimulating cyclicity and a synchronous estrus return in cows that did not become pregnant at TAI. Thus, the calving season is also concentrate in the best periods of the year to generate offspring with greater weight and potential of development. TAI programs are currently important tools of reproductive management to improve reproductive performance of cattle. The adequate incorporation of these programs has the potential to enhance reproductive efficiency of livestock and consequently increase overall productivity of the farm.
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