Achieving target weights is important for heifers; those that fail to reach target before calving will produce less milk in their first lactation and struggle to go back in-calf. In addition, underweight maiden heifers are harder to get in calf.

According to Teagasc, early August marks an important milestone in that rearing cycle for weanling and in-calf replacement heifers as they reach six and 18 months of age respectively.

In the below table, Teagasc outlines the target weights for replacement heifers.

Table source: Teagasc

Teagasc says there are around 100 days for underweight heifers to catch up before winter housing.

To ensure that your heifers hit the target, take the following steps:
  1. Weigh heifers over the next week or two;
  2. Separate underweight heifers from those at or above target weight. There is less competition in a smaller group, which will benefit the smaller heifers;
  3. Give priority grazing and meals to the underweight group;
  4. Re-weigh in six weeks – some heifers will be heavy enough to join the heavy group and some of the heavies may have to join the light group.

Throughout the autumn, Teagasc says, energy rather than protein is limiting at grass, so a high-energy supplement such as rolled barley is an ideal feed with grass. Feed 1-2kg/head/day to the underweight heifers and, where possible, give them the best grass available.

Later on in the autumn, the heavy group – particularly the weanling heifers – may need 1-2kg/day of supplement as well to keep them growing prior to housing.