On your mark, get set, go
Preparing heifers for breeding starts the day they are born
Getting a heifer to calf at 24 months of age starts the day she is born. Every step in your heifer-rearing process from newborn to weaning to breeding directly impacts the time it takes to get her into the pipeline-and generating profits.
A herd with an average heifer conception rate of 60 per cent and good heat detection should start the breeding program at 13 months to achieve the 24-month goal. This ensures the majority of heifers are pregnant by 15 months.
Getting a heifer in top shape for breeding at 13 months depends on two key factors: nutrition and health-the first 12 months of her life. From birth until she reaches the breeding group, these two factors determine her breeding eligibility and effectiveness in the breeding program.
Generally, a heifer should be at 60 per cent of her mature body weight when first breeding occurs. The recommended weight for a breeding age Holstein heifer is 395 kilograms (870 pounds), and the recommended height 127 centimetres (50 inches). Subpar nutrition and disease in the first few months of her life will greatly affect whether she meets these growth targets.
If your heifers are not reaching growth targets by the time breeding should begin, alter management practices to reach these targets ra ther than breeding them later. Breeding later will put heifers into the milking line later, keeping them on the wrong side of the ledger.
Regularly identifying heifers to be moved into the breeding group is a challenge. Too often, the first mistake is not moving heifers into the breeding group on time. Additionally, many producers fail to do regular pregnancy checks on heifers, leaving their reproductive status unknown. By not pregnancy checking heifers, you may let open animals go unnoticed until they are past 15 months of age.
Establish a protocol to move heifers regularly into the breeding group and check their pregnancy status during every herd health visit. Record this data and upload it to Dairy Herd Improvement (DHI) during test days. DHI can also give you a list of heifers older than 12 months on each test day which will keep you focussing on the heifers that need to be bred.
Sire selection is often overlooked as part of the heifer breeding program. With heifers having the best overall conception rate in the herd, and some of the newest genetics, they provide a unique opportunity to maximize genetic gain at a low breeding cost. When choosing a sire for heifers, pay particular attention to calving ease. First-lactation heifers are more likely to have calving difficulties, making the choice of a calving-ease mating sire critical to the heifer as she begins her productive life and has the resulting calf.
Herd sires are too commonly used on heifers in Ontario. While seen as a low-cost option to get heifers pregnant, herd sires have many costs and risks.
Using a bull removes the opportunity to optimize sire selection, possibly leading to higher inbreeding and less productive cows. Many herds using a herd sire end up having 35 per cent or more of their herd resulting from natural service in a very short time. Moreover, the all-important calving ease becomes the great unknown. Reducing hard calvings and the associated losses is easy with artificial insemination sire selection.
Considering the breeding program begins at 13 months of age and finishes by 15 months of age, you have only three estrous cycles to get your heifers pregnant. This makes estrous detection vital for any breeding protocol. Proper visual heat detection involves watching your heifers for 30 minutes, twice a day. With heifers often out of sight and out of mind, most herds often fail to spend this hour on heat detection.
Over the past decade, many tools have been developed to help you overcome heat detection shortfalls. Electronic activity monitoring accuracy and cost-effectiveness have improved over the past decade, making this option attractive for use with heifers. By keeping tabs on heifers 24 hours a day, you can help bridge some of the heat detection gaps that commonly develop. Estrous synchronization protocols are also available to help you deal with non-cycling animals and problem breeders.
Monitoring is a critical and overlooked part of a heifer breeding program. To manage and focus your resources on the right parts of the breeding program, you need to monitor results.
The industry needs to start using pregnancy rate more effectively for heifer reproduction. Although it is becoming the common measurement for assessing the lactating herd's performance, pregnancy rate is still underused when it comes to heifer reproduction. This one number can sum up your heifer performance by answering two questions:
A pregnancy rate of 36 per cent or more can be achieved with your heifers. Other key numbers we should monitor are age at first breeding, age at first calving, first service conception, overall conception and percentage of first lactation calvings that result in stillbirths. Monitoring these numbers will help you assess what is working well with your breeding, and will also help find opportunities for improvement.
This article first appeared in the Ruminations column of The Milk Producer Magazine, December 2010.
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