Feeding replacement heifers this winter

With many heifers currently housed or planning to be housed in the next two weeks, Teagasc Dairy Specialist, Martina Gormley reminds farmers of the fundaments of hitting replacement heifer target weights and feeding heifers correctly over the winter months.

Now is a good time to get young stock weighed and batched according to weight. Growth rate and liveweight at first calving are important benchmarks in farm management​. Lower weight heifers at first calving have higher risk of hard calving and produce less milk and have a shorter lifespan​. Likewise, having overweight heifers also has negative consequences for survival in the herd.

Based on the heifer’s genetic make-up, the maintenance value in the EBI report gives an indication of the expected cost of growing a replacement and maintaining her as a cow in a dairy herd.

Positive € values for Maintenance sub-index are good, as they indicate lower live weight animals; lower live weight animals have lower feed requirements as they do not need to consume as much to maintain themselves.

This means that they have extra energy available to partition towards milk solids production. From similar intakes, this means lower live weight cows can produce more milk solids than higher live weight cows.

Negative € values are less desirable; they deliver an increase in the live weight of the cow and an associated increase in dry matter requirement to simply maintain themselves, resulting in less energy available to apportion to the production of milk solids.

Table 1 below predicts that a heifer born on the 1^st of February, with a maintenance SI of 10 should be around 175kg on the 1^st of August, 233kg on the 1^st of November and 350kg on the 1^st of May.

Table 1: four example Maintenance SI and predicted live weight of  mature herd

Live weight gains of 0.5kg/day and 0.7kg/day will be required for on target and lighter heifers over the winter period. To ensure this gain, the following needs to be followed:

• Dose heifers on or shortly after housing
• Provide adequate space (400-500 mm per animal)
• Feed concentrate according to silage quality and target weight gain

Table 2: Concentrate feeding level based on silage quality (Source: Teagasc, Grange)