In recent weeks, heifer calves have reached a significant milestone as they surpassed the six-months-old mark.
This is a noteworthy milestone for a heifer calf and can be used to determine how they are developing, and whether they are ahead of, or behind their growth targets.
Heifer calves
Many farms determine calves’ target weights by finding out the mature weight of cows within their herd and then working back.
For example, if your average cow weight is 600kg, at six-months-old your calves should be 30% of this weight which is 180kg.
However, an easier way to determine what a calf’s mature weight should be is to look at their maintenance sub-index figure – which has a strong correlation to mature cow weight.
Mature cow weight 500kg 550kg 600kg 650kg Maintenance sub-index €30 €20 €10 €0
Based on the economic breeding index (EBI) 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-old.
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
Targets
Achieving the development targets of your heifer is important to ensure they are at the right weight ahead of breeding in May 2023.
These six-month-old calves are future animals in your milking herd and you want to ensure they are in the ideal condition.
Heifers that are behind target may have fertility issues, meaning they may not go in-calf and you will have lost the time and money you have invested in them.
It is also important to note that you should focus on each individual calf and not the group average.
The group average can be misleading and could potentially hide a number of calves that are behind target.