Dr. Dan Stein Gives Part 1 of Estrus SynchronizationTue, 18 May 2021 09:56:06 CDT
Estrus synchronization is a reproductive management tool that facilitates the use of both artificial insemination (AI) as well as natural service. Estrus synchronization is never a substitute for poor nutrition, poor herd health or poor management. For any estrus synchronization program to be implemented successfully, it must be well thought-out and well planned. When using estrus synchronization with AI, producers can capitalize on the superior and proven genetics available with commercially processed semen. For some producers, natural service may be the easiest method of breeding their cows or heifers and estrus synchronization together with natural service may be as beneficial as using AI, as using bulls at a synchronized estrus can be an effective way to tighten the calving period and eventually shorten the breeding season. Producers should keep in mind that when cows are synchronized and bred by natural service, management considerations should be made for the serving capacity of the bull. Also, the failure to identify a sub-fertile bull prior to being turned out will be magnified when a synchronized estrus protocol is incorporated into a natural service breeding program. Pregnancy rates using either bulls or AI after the same synchronization protocol should be similar provided good management practices are utilized in both situations.
The benefits of incorporating estrus synchronization into a breeding program, whether using natural service or artificial insemination include:
∑ Improving management by more easily defining the breeding season and the calving period.
∑ A labor-saving tool if monitoring parturition; females can be grouped by expected date of parturition.
∑ Increasing the time needed for postpartum recovery in cows and first-calf heifers.
∑ Allowing for greater use of superior sires through artificial insemination (AI) or by natural service.
∑ Increasing calf performance and weaning weights due to earlier birthdates in the calving period.
∑ A more uniform calf crop in size and age, which can be a potential advantage at marketing time.
The most limiting factor in AI programs is the proper detection of cows or heifers in estrus or standing heat. Estrus detection can be a very time- and labor-intensive activity, which makes AI programs impractical for some producers. The first step in deciding upon a synchronization protocol is for the producer to decide how much time, if any, is available for estrus detection or if estrus detection is even feasible. Several different types of aids for the detection of standing heat or estrus are available for producers. With some synchronization protocols, estrus detection can be eliminated because animals can be inseminated at a pre-determined time, known as fixed-time AI. Synchronization protocols that incorporate fixed-time AI not only synchronize the estrous cycle, but also induce ovulation at a pre-determined time to facilitate insemination.
There seems to be a concern from some producers that if the females are inseminated on the same day, they will all calve on the same day. Research (see Bader et al. 2005, Journal of Animal Science 83: 136-143) has shown that cows conceived on the same day gave birth to calves during a 16- to 21-day period, dependent upon the respective sire. These distributions indicate successful use of estrus synchronization will not result in an overwhelming number of cows or heifers calving on the same day.
In a Sunup classic from February 2020, Dr. Glenn Selk talks about estrus synchronization and how to choose what program is right for your herd.
A Rancherís Thursday Lunchtime presentation by Dr. Jordan Thomas presented on The Latest in Synchronization and AI Tools and Systems
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