Over the past decade, there is an increased priority in growing heifer calves faster and more efficiently in order to maximise the performance and health of the animals over their lifetime.
With that being said, there is one negative outcome of this approach where larger heifers are not being bred early enough to take advantage of this more aggressive calf growth plan.
Breed heifers earlier
Many heifers are still being bred at the same age as before although they could be bred 2 - 3 months earlier based on their size. Heifers bred late will often have metabolic problems at calving such as ketosis and lower milk production. Breeding heifers by size could help address some of these problems.
Here is a rough guideline regarding breeding heifers by size:
First, measure the weight of mature animals in your herd. Heifers can be bred when they weigh 55% of mature herd size.
The wither height of heifers should be a minimum of 49 inches as to ensure proper frame.
After delivering the first calf, heifers should weigh approximately 85% of mature herd size and a minimum of 53 inches tall at the withers.
Most heifers are able to hit these benchmarks at around 13 - 15 months of age, allowing them to calve at age 22 - 24 months. Some very organised farm will hit these benchmarks even earlier. However, breeding at younger than 13 months of age will require proper thought as well as management consideration.
Selling open heifers
As beef markets are still strong, if you measure your herd and find that you have open heifers past these benchmarks, you could generate some extra cash by selling open heifers that might be too old to breed.
So as long as there is enough replacement heifers in your farm, selling open heifers is a viable option. Take a herd of 100 cows with 35% annual cull rate for example. The farm would only need a total of 70 heifers to maintain herd size if the age at first calving is 24 months. This same herd would only need a total of 64 heifers if the age at first calving is 22 months. Hence, if you run your farm efficiently, you would have extra cash, properly sized heifers at breeding and calving as well as better producing first lactation cows and lower heifer rearing costs.