Non-cycling cows are cows not detected in heat either in the pre-mating period or during the mating period.
Non-cyclers can reduce the 6 week in calf rate because they do not contribute to a high 3 week submission rate and they reduce the first service conception rate.
Non cycling cows are often those cows that calved late, had calving associated complications or lost weight after calving.
Because non-cycling cows cycle eventually they contribute to a more spread out mating and calving if you do not manage them appropriately!
The graph below shows the impact of the six week in-calf rate on non-pregnant percentage.
How does a spread out calving affect your herd?
A high 6 week in calf rate has the biggest influence on your herd empty rate. Early calving cows get in calf earlier.
A protracted calving has a large influence on reproductive profitability. For every 1% increase in 6 week in calf rate there is a $4/cow benefit. For example, a 400 cow herd lifts the six week in-calf rate from 65% to 78%. This equates to $28,800 profit from extra days in milk, replacements etc.
The best approach to managing non-cycling cows is to prevent them occurring in the first place. This means managing calving associated diseases early and optimising nutrition between calving and mating.
If you can reduce the percentage of your herd that is not cycling, you are more likely to be able to treat them all with CIDR devices. This is probably the most profitable way of treating non cyclers.
Different farms have different requirements so please discuss the prevention and management of non-cycling cows in your herd with your veterinarian.