It’s been noted over and over. Good heifer reproductive performance is essential to overall herd performance and profitability. That’s because successful dairies have quality replacements entering the herd on time and at minimal cost. Plus, heifer reproductive performance can act as a signal to indicate the general function of total herd reproduction.

However, it’s easy to overlook heifer reproduction and focus on the reproductive performance of lactating cows. After all, these animals generate income every day, while payback on your investment in heifers doesn’t begin to appear until after they’ve calved.

Whether or not your dairy struggles with reproductive performance, use the following recommendations to assess the effectiveness of your program and to determine where heifer reproductive performance can improve.

1. Focus on animal performance

While it’s important to keep heifer-raising costs in line, be careful not to skimp on heifer needs. Post-weaning heifers need to receive adequate nutrition so they achieve desired growth. For example, by 6 months old, heifers should average at least two pounds of gain per day.

Monitor average daily gains per pen and work with your nutritionist to develop best-cost rations that prevent stunted or overconditioned heifers. Animals on either end of this spectrum do not reach their production potential when they become lactating cows, nor do they offer the efficient, cost-effective growth needed to excel in today’s dairy economic environment.


Research shows that every month calving is delayed beyond a 22-month target costs you about $190 per animal due to lost production, fewer days of productive life and additional rearing costs.

If you have problems with your heifers achieving or exceeding desired weight gains, it may be time to meet with your nutritionist and rework – or at least re-evaluate – your rations.

2. Assess stocking rates

Once you’ve established that basic ration needs are being met, assess stocking rates. In herds that struggle with heifer reproductive performance, stocking density can play a key role in solving problems.

Keep stocking densities below 125 percent in raising pens or pens with pregnant heifers to prevent animals from competing too much for feed. This ensures each heifer receives adequate nutrition for growth and development.

In the breeding pen, stocking density must not exceed 100 percent to ensure the ideal environment for nutrition and management. It is also important the breeding pen have enough headlocks for all heifers so breeding technicians can properly perform heat detection and artificial insemination.

Also keep an eye on pen cleanliness and maintenance. Animals should not be subjected to excessive mud and manure.

3. Evaluate grouping strategies

Some dairies with exceptional animal uniformity are able to successfully group animals based on age. But animal size is what really matters.

Therefore, be sure pens contain heifers of similar height and weight for more effective management. Keep a hipometer, tape measure or weight tape handy and measure heifers periodically to ensure animals within a pen are growing at similar rates.

You don’t need to measure each heifer, just take a representative sample. For example, in a pen of 50 heifers, measure and track five to 10 animals. You can also make a mark on a wall at the desired height, then visually monitor heifers as they walk by the mark to gauge how close they are to the target height. Regroup as necessary based on size and as space allows.

4. Breed on size

Just as with grouping strategies, size is the key when it comes to breeding decisions. Depending on breed and individual herd dynamics, heifers should be about 49 to 51 inches at the withers and about 60 percent of their dam’s mature bodyweight at breeding. This should result in heifers that are about 85 percent of their dam’s mature bodyweight at calving.

While heifers often begin to show signs of estrus at 40 to 50 percent of mature bodyweight, be patient and wait to breed until she hits that 60 percent threshold. Don’t guess to determine breeding eligibility; use the previously mentioned tools to monitor this goal.

While age is not the determining factor for breeding decisions, tracking animal age at breeding and calving will tell you if heifers are growing at acceptable rates. Again, you don’t want heifers entering the milking herd too early or too late since both have a negative effect on animal performance and profitability.

One way to track how well you hit the mark is to create a graph that correlates milk yield of first-lactation cows according to age at calving for each animal that enters the herd. You’ll soon be able to see the calving age at which heifers are the most productive on your dairy.

5. Monitor breeding routines

Once you’ve evaluated animal performance, take a look at the people involved in your heifer breeding program. When troubleshooting, it’s important to know who is responsible for breeding, the protocol being used, protocol adherence, heat detection (if used) criteria and, finally, breeding technique.

Work with farm personnel and advisers to provide continuing education opportunities on proper protocol methods, heat detection and breeding techniques.

6. Monitor goals and progress

Of course, no evaluation would be complete without examining reproductive performance records. Begin by looking at heifer conception rates for first service. It is reasonable to expect to see a first-service conception rate of 60 percent, a heat detection rate of about 70 percent and a 21-day pregnancy rate of 40 to 42 percent.

Also take a look at heifer pregnancy loss. Data suggest that a 3 percent pregnancy loss is achievable; it should at least be kept at 5 percent or below.

Monitor these parameters monthly, if possible. If any interventions or management changes take place, it is important to determine the effectiveness of these actions.

Keep in mind a number of new synchronization protocols have been designed for heifers that can improve productive performance in recent years. These may offer opportunities, especially if heat detection is a challenge on your dairy. It all depends on your management approach. Ask your veterinarian or reproduction adviser which one is the ideal strategy for your herd.

In conclusion, look at all of these factors as part of the overall picture of heifer reproductive performance. Oftentimes we may think one thing is the cause of the problem, but it ends up being something entirely different.

Keeping an open mind allows you and your team to look at the challenge from all angles and find a solution you otherwise may have missed.

Good luck with your heifer reproductive management and breed with excellence! PD

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PHOTO: Create a graph that correlates milk yield of first-lactation cows according to age at calving for each animal that enters the herd. You’ll soon be able to see the calving age at which heifers are the most productive. Photo by PD staff.

  • Dr. Glaucio Lopes

  • Reproduction Specialist
  • Accelerated Genetics