Managing heifers and cows: Part 3

Heifers and first calvers need good nutrition and extra care, such as keeping them in separate herds, if you want to have mature cows that grow out to their full genetic potential for size.

Heifers are usually mated at either 15 or 27 months to calve down for the first time at two or three years respectively. They can be brought to a bull when they reach at least 60% of mature weight. The age at which a heifer reaches this target will depend on the level of nutrition (amount and type of feed available), the breed, the age at which she cuts her teeth, and the time of year she was born.

First-calf cows (cows that have calved only once and are brought to the bull for the second time) have notoriously low conception rates. Worldwide, the inter-calving period (ICP) between the first and second calf has been shown to be longer than subsequent ICPs. Inadequate nutrition may also contribute to this.

BREEDING HEIFERS EARLY

One way of overcoming this difficulty is to breed first-calf cows four to six weeks before the main herd. This will compensate for the extended first ICP and allow extra time between the first and second calf for the dam to build up body reserves and to grow.

In addition, by breeding first calvers ahead of the main herd, you will avoid the loss of good genetic material if you have a policy of culling all skips (cows diagnosed open at the time of pregnancy diagnosis).

However, in cases where first-calvers are run with mature cows, or where calves of first-calvers are not weaned before the main herd, mating firstcalvers ahead of the mature cows does not achieve its aim of improving their conception rates. If anything, failing to wean calves from first-calvers mated earlier places additional stress on animals still in their growing phase.

Another problem with breeding first-calvers ahead of the main breeding season is that the breeding season is timed to synchronise fodder production with the needs of the mature cows. By breeding first-calvers earlier, you will not be able to match their nutrient requirements to the fodder production of the farm unless you provide them with supplemental feed.

In practice, it may be be better to breed first-calvers with the main herd and at the same time to ensure there is adequate feed for all the animals on the farm.

If you mate the first-calvers with the main breeding herd, you will need to retain more heifers each year to compensate for the additional loss of first-calvers that do not reconceive.

Keeping heifers and first-calvers in separate herds allows younger, growing animals access to betterquality feed and an equal opportunity to reach feed or lick troughs.

• Source: Beef Production: The Basics – Heifer and Cow Management. Retrieved from kzndard.gov.za > Publications > Production Guidelines > Beef Production.

FW ARCHIVE Heifers can be mated when they reach at least 60% of their mature weight. The age at which this occurs is determined by the quality of their feed, the type of breed and other factors.