SHOREVIEW, Minn. — Over the last 10 years, there has been a big emphasis to grow heifer calves faster and better in order to maximize performance and health of the animal over its lifetime.Most dairymen follow some of this trend, but at least one specialist says these bigger heifers are not being bred early enough in many situations to take full advantage of the more aggressive calf growth.Jason Leonard, calf and heifer specialist with Land O’Lakes Purina Feed, said many heifers are still being bred at the same age as before even though they could easily be bred two to three months sooner based on size.And breeding too late can create increased metabolic problems at calving such as ketosis, as well as lower milk production and wasted money on feeding the heifers.
Breeding based on size of the heifer could help eliminate these types of problems. The following are size benchmarks Leonard recommends farmers consider:Start by getting an average weight on the mature (third plus lactation) animals in your herd. Heifers can be bred when they weigh 55 percent of the mature herd size. Wither height of the heifers should also be at least 49 inches tall (Holsteins) to insure proper frame. Heifers should weigh around 85 percent of mature herd size after they deliver the calf and reach at least 53 to 54 inches tall (Holsteins) at the withers.These breeding benchmark numbers can typically be hit by 13 to 15 months of age on most farms which would allow the heifers to calve at 22 to 24 months of age when bred by size.Leonard said some well-managed farms may hit these targets earlier, but breeding less than 13 months of age is something that needs to be given proper thought and management consideration.
If you take the initiative to measure your herd and find that you have open heifers past these benchmarks, there could be a silver lining for you, he adds.Beef markets today are still strong and could be a way to generate some extra cash flow by selling open heifers that might be too old or too big for breeding. As long as you would still have enough replacement heifers left on the farm for your herd numbers and you start breeding by size, selling open heifers is a viable option.For example, a 100-cow dairy with a 35 percent annual cull rate would need only 70 total heifers to maintain herd size if the age at first calving is 24 months. This same herd would only need 64 heifers if the age at first calving is 22 months.