Getting dairy replacement heifer weights back on track
Do you know the weights of your dairy weanling and yearling heifers? Knowing the weights of your replacement dairy animals and reaching target weights on time is critical for successful calving at two years of age. George Ramsbottom, Teagasc dairy specialist has the advice
Heifer weights
Having replacement heifers at the correct weight for age at the start of August is critical to their long-term future in the dairy herd. February-born weanling and yearling heifers should be 30% and 70% respectively of their pre-calving body weight on August 1st if they’re to be successfully calved at two years of age.
So assuming a pre-calving weight of 540 kg, this equates to approximately 162 kg for the weanling and at least 385 kg for the in-calf heifer. Target 1st August weights for heifers of different maintenance sub index are detailed in the following table.
Table 1: Target weights for 1st August for February born dairy replacement heifers of different maintenance sub index.
The Advice
Identify lighter heifers for priority grazing and supplementation.
As a rough rule of thumb, separate weanling and yearling heifers that are approximately 5% and 10% or more below target respectively.
For replacement heifers with a maintenance sub index of €10, the threshold weights for weanling and yearling heifers are weights of less than 160 kg and 360 kg respectively. There is still plenty of time to ensure that they catch up with their heavier counterparts before the winter.
Supplementation
In terms of supplementation, on good quality grass, energy rather than protein is the limiting factor. Feeding 1-2 kg of a compound ration or rolled barley per head per day should be sufficient to increase their growth rate and ensure that they are quickly back to target. Weigh the heifers again after 6 weeks or so to check on the change in liveweight.
Quite often some of the lighter heifers can rejoin the heavy group again after a period of intensive feeding.
You might also like to read the Dairy Newsletter - July 2022 here
The Teagasc Dairy Specialists issue an article on a topic of interest to dairy farmers every Monday here on Teagasc Daily. Find more on Teagasc Dairy here