A new review by Inspire Cattle Solutions finds that the evidence supports the optimum range to target Age at First Calving (AFC) is 22-25 months:
- Below this can reduce yields up to 800kgs in the first lactation
- Above this can reduce yields up to 600kg in the first lactation
- AFC greater than 25 months can reduce survival to second lactation
- AFC of 22-24 months supports better first service conception rates
What does this mean in terms of value to dairy farmers?
Aiming for target weights and carefully monitoring growth during heifer rearing pays off sooner than you think: When Lactation 1 cows get to day 150-180 in milk, they can OVERTAKE the older cows in yield (this is called first lactation persistency). Therefore, they can bring the AVERAGE herd yield above your TMR target and create more profitable milk. Plus, cows, that dry off at higher yields tend to give higher yields in the next lactation (as long as transition is managed well).
So, when you next walk through the barn, look at each stall slot and ask whether or not it could be occupied by a more profitable cow. Reaching AFC targets can ensure you have replacements to be able to make this choice!
REFERENCED ARTICLE:
https://veterinaryevidence.org/index.php/ve/article/view/248Mike Steele, (2020), “Age at First Calving in Dairy Cows: Which months do you aim for to maximise productivity?” Veterinary Evidence, 5 (1), https://doi.org/10.18849/ve.v5i1.248 Open Access
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