Now that calves are weaned and pregnancy checks are occurring, it’s time to start thinking about selecting replacement heifers to breed in the spring. Due to the differences in goals and needs between operations, there is no one size fit’s all selection equation that producers can follow. However, there are some common characteristics and questions that all producers should consider to help them select replacement heifers strategically and not at random.
Select heifers born early in the calving season that will reach puberty and first estrus before their younger herd mates. These females are then also more likely to become bred and calve earlier in subsequent years, consistently weaning more pounds and being more profitable than later calving counterparts.
Replacement heifers should contain the best genetics in your herd. Analyzing the genetics of her sire and dam are good places to start selecting these high quality genetics. Scrotal circumference (SC) of the sire is associated with heifer puberty, as there is a moderate negative correlation between larger SC and earlier attainment of puberty. On the dam side disposition, calving ease, udder quality and milking ability are important parameters that should be analyzed. By selecting heifers from cows that are easy to care for and can take care of their calves, you will also select for longevity and see her daughters and granddaughters being retained in consecutive years.
While it is important for some weight be placed on phenotype, it should not be where the most focus is placed during heifer selection. But while we are looking, we want to strive for selecting structurally correct females that can get around the pasture to graze. Heavy structured and large footed females, with a more correct angle to their shoulder and hock will rise to the top. Size of the heifer is also important to consider. What will be her mature size and maintenance cost? Does your operation have the resources and environment to support her? In this case, if the older females being selected are also larger, they may require more input to be maintained in the herd than smaller framed counterparts. However, small females can be very inefficient also. Having a good balance between the heifer’s phenotype, weight per day of age, as well as the cows mature size is important for profitability and efficiency of the cow herd.
Are you maintaining or expanding the size of your cow herd?
The answer to this question will help you decide how many replacement heifers should be kept. If the size of the cow herd is to be maintained, the culling rate should equal the replacement rate right? Not necessarily. No matter if you are maintaining or expanding your herd, it is best to keep 10 – 15% more replacement heifers than actually needed, to account for the 5 – 10% of females that will be late bred or never become pregnant at all. This way you will have enough to replace culled females, as well as extras to expand the herd or be marketed. In addition, if more females become pregnant than you need, you can increase selection pressure on which females have the best genetics to add to the cow herd.
How will I develop them?
Replacement heifers are one of the most important management groups in the herd and it can be a costly investment to develop heifers that won’t provide returns for two years. Therefore, making sure you have the resources and management to develop them correctly is vital to attaining genetic progress in your herd. When resources are limited to develop heifers, custom heifer development companies are available to complete the development for a cost. Also, if you have the resources but need assistance designing a heifer development protocol, contact an SDSU Extension Livestock Specialist.