Optimal timing and management for dairy heifers

There are a number of financial benefits to breeding dairy heifers at the optimal time. Determining when to breed a dairy heifer takes time and effort. However, getting it right will add dollars to a producer’s bottom line.

Numerical age helps guide timing decisions for breeding. However, research indicates a more accurate and effective measure for the perfect time to breed a dairy heifer is weight. Weight is a better indicator of the heifer’s stage of sexual maturity.

Ideally, the heifer is bred between 14 to 15 months and calves close to 24 months. Though in reality, this varies from heifer to heifer. Still, it is worth planning to try to reach the ideal.

In order to determine the best time to breed a dairy heifer, producers should assess the animal’s weight and structural development. 

Achieving the proper calving weight, requires producers to plan for steady development of their replacement heifers. “I like a lean, structural consistent pattern of growth,” Reagan Bluel, dairy field specialist with the University of Missouri Extension, said. “It is important to routinely measure or monitor the rate of growth to make sure she is reaching that ideal point of weight at calving.” 

The suggested weights and heights at breeding and at maturity vary from breed to breed. For Holstein heifers, researchers suggest a pre-calving weight of 1,350 pounds so the animal will maintain a post-calving weight of 1,250 pounds.

If a heifer calves with a less than ideal body weight, some of her energies will target her own growth instead of pouring it all into milk production. “They are going to be growing still if they are below 1,250 pounds post-calving, 1,350 pounds pre-calving weight,” Michael Looper, Ph.D., Head of the Department of Animal Science at the University of Arkansas, explained. “If they are lower than that, they are going to be putting nutrients toward their own bodies.” In addition, heifers that calve before they are mature may have problems with dystocia. 

One way to reach the desired calving weight is to determine the general mature body weight of the herd. Then start feeding the replacement heifers toward that goal. “There is a science to it and also an art to it. Every situation, every case, every farm is individual and unique in a sense,” Looper stated. 

If producers are growing their own replacements, they should have an idea of the herd’s average mature weight. Once producers establish their herd’s mature weight, they can use that weight as a target weight for their heifers to reach at 24 months.

Constant monitoring of growth is an essential part of the pre-breeding management of dairy heifers. There are several ways to track weight gain. Those include; periodically weighing heifers on a scale, measuring them with girth tape and asking someone who doesn’t routinely see the heifers to assess them. 

When feeding the heifers to get them to their desired weight, pushing them too fast, too soon can cause problems in the long run. “If they get above 2 pounds, average daily gain, what tends to happen is fat deposits in the mammary gland and that decreases milk yield,” Looper said. Experts suggest working with a nutritionist to balance the protein in the ration to ensure heifers achieve proper structural growth without putting on too much fat. 

The development of replacement heifers requires a substantial investment of time and money. Factors that could be a cause for culling prior to breeding include, contracting a serious case of pink eye, losing one quarter of udder due to mastitis and failing to meet the herd’s quality standards. 


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