It is once again getting to the time of the year when the growth performance of heifer calves needs to be checked.
This should be done for a number of reasons, including to make sure that they are at the correct weight for breeding and that they have no issues with parasites.
Failing to achieve weight targets may result in the heifer being unsuitable for breeding.
Heifer calves’ weight targets were often set by determining the average weight of mature cows in the herd. However, farmers should now begin using their heifers’ maintenance economic breeding index (EBI) figure for this.
The maintenance figure has a direct correlation with weight, meaning that the weight of an animal can be determined by its maintenance sub-index.
Mature cow weight 500kg 550kg 600kg 650kg Maintenance sub-index €30 €20 €10 €0
Based off the maintenance sub-index figure, a calf’s mature cow weight can be determined.
Using this figure you can determine the weight this calf should be at six-months of age, which a February-born calf is coming up to.
Age Percentage of final weight €30 €20 €10 €0 Six months 30% 150kg 165kg 180kg 195kg 15 months 60% 300kg 330kg 360kg 390kg 24 months 90% 450kg 495kg 540kg 585kg
If your heifer has a maintenance sub-index of €20, at six-months of age she should be weighing 165kg.
So before weighing your heifer calves, it may be a good idea to look at the maintenance figure.
This should give you a more accurate figure as to how much the calves should weigh at the different key stages.
For calves that are on or ahead of target, it may be possible to take them off concentrates if they are still being fed.
However, calves that are behind target need preferential treatment. These calves need to be offered the best grass and a high-quality concentrate.
It is important for these animals to catch up with the rest of the calves ahead of housing later in the year.
It will be far easier to get these calves caught up at a younger age, rather than waiting until they are older.
If there are a large number of calves behind target it is important that you look into any possible causes.
Parasites, summer scour or sickness when they were in the shed may all be possible causes.