By: Brent Plugge, Extension Educator, University of Nebraska
No matter when you calve, controlling the breeding and the subsequent calving season has many benefits.
- A shortened calving season provides producers a better opportunity to offer improved management and observation of the cow herd, which should result in fewer losses at calving.
- Shortened calving periods also facilitates improvements in herd health and management such as uniformity in timing of vaccinations and routine management practices resulting in decreased labor requirements.
- Another benefit is that cow nutrition can be improved by grouping cows according to stage of gestation and feeding each group accordingly.
- An additional benefit is that the calf crop will be more uniform in age and size which can lead to an advantage in the market place.
Research on shortening the calving season
A large body of research shows that calves born in the first 21 days of the calving season will weigh more at weaning than those born during the second 21-day period.
Recent work from the University of Nebraska demonstrated this advantage. The research also showed the impacts of a shortened calving season beyond weaning. Calving records were collected between 2000 and 2008 at the Gudmundsen Sandhills Laboratory near Whitman, Neb. These records were used to determine the effect of estrous synchronization on calving distribution and the impact of time of calving on carcass characteristics. More synchronized cows calved during the first 21 days compared to non-synchronized cows, and calves born to synchronized dams were heavier at weaning.
Calves born in the first 21 days of the calving season had greater carcass weights, marbling scores, and yield grades than later born calves. In addition, the percentage of steers grading premium choice or greater and the total carcass value declined as time of calving increased.
This University of Nebraska study, found in the 2010 Beef Cattle Report, shows that estrous synchronization with natural breeding resulted in cows giving birth earlier, and calves born earlier in the season were heavier at weaning and produced a heavier, more valuable carcass.
Estrous synchronization as a management tool
Estrous synchronization is one management tool to shorten and manage the breeding and calving season. Choosing an estrous synchronization system that can be used with artificial insemination or with natural breeding can be difficult as a number of protocols for synchronizing estrous are available.
Traditional protocols are designed to mimic or control the corpus luteum on the ovary.
New protocols have been designed to control ovulation and/or the follicular waves that occur on the ovary during the 21-day estrous cycle.
Estrus synchronization systems vary in cost, labor requirements, and effectiveness.
One consideration when choosing an estrus synchronization protocol is determining if sufficient labor and facilities are available to successfully implement the protocol. Do you have adequate facilities? Do you have enough labor to observe estrus and sort cows two or more times daily or do you need to use timed-insemination? Is a technician available and for how many days? If labor and technician time is limited chose a system suitable for timed-insemination. If labor and technicians are not a limiting factor, then you might consider an estrus synchronization system that is suitable for insemination after estrus is detected.
Another consideration is cost. Cost for estrus synchronization protocols can vary significantly. The cheaper systems typically require more labor and are less effective. It can also be argued that breeding after estrous detection or with a timed AI yield similar pregnancy rates, thus one difference in cost may be associated with the labor involved. This would of course be dependent upon what rate you charge the labor.
Beef Reproduction Task Force recommendations and tools
To help producers determine an effective estrous synchronization protocol the Beef Reproduction Task Force provides recommendations for estrus synchronization protocols. These recommendations are found at the website Applied Reproductive Strategies in Beef Cattle. The Beef Reproduction Task Force is a multi-state extension group, whose objective is to provide timely information regarding applied reproductive strategies in beef cattle.
The protocols are updated annually and current recommendations can now be found on the site.