Calving at two: Towards life-long fertility

Does calving at two years really improve herd fertility?

The answer is yes!

Good early growth will enable your heifers to reach target bulling weight from 13 months resulting not only in the best fertility before first calving, but those higher levels of fertility will also continue during their first two lactations.

Dairy cows continue to grow until the end of their third lactation. If they haven’t achieved 85% to 90% of their mature body weight at first calving, then they will experience greater nutrient demands for growth thereafter, which could be at the expense of fertility.


Those trends were concluded from a Royal Veterinary College study which consisted of 445 heifer calves recruited from 17 dairy farms. Check out the trends in the following table.

Age at first calving and fertility
  Age at first calving (months)
<23 23-25 26-30 >30
Lactation 1
First service conception rate 47% 42% 39% 32%
Services per conception 2.4 2.2 2.5 3.0
Calving to conception, days 128 117 137 170
Lactation 2
First service conception rate 28% 47% 35% 33%
Services per conception 2.7 2.1 2.6 2.2
Calving to conception, days 127 111 133 144

That’s not all, earlier calving results in extra milk yield. The heifer calving at under 23 months fitted a whole extra lactation into the same time period from birth by calving for a third time at 50 months of age.