Non-Cycling Cows

Cows that do not come on heat at the optimal time for mating cost money and time. These cows can
prevent farmers from achieving their target six-week in-calf rate (seasonal/split calving) or 100-day in-calf rate (all-year-round calving) by decreasing the key drivers of in-calf rates:

Three-week submission rate (seasonal/split calving)
80-day submission rate (all-year-round calving)
Conception rate

These drivers are important, but the submission rate has a bigger impact because management
more readily influences it. Good heat detection is essential to reach submission targets, but too many
non-cyclers will hold back herds with good heat detection rates.

About 25% of late calving cows may need to be treated as non-cyclers. It should be less than 10% for
cows calving in the first four weeks from the planned start of calving date.

Pre-mating detection

Poor submission rates can be a consequence of too many non-cyclers in a herd at the planned start of mating date. Doing pre-mating heat detection gives farmers the option of managing a non-cycling problem early for better results. This is also a great opportunity to train staff in heat detection before mating starts.

A practical way to do pre-mating heat detection is to tail paint all the cows with one colour 4–5 weeks before mating start date. Apply a second colour once or twice a week to cows that have lost their paint and top up the original colour as required. After three weeks, all the cows with the original colour are non-cycling cows and can be treated.

Treatment options for cows not detected on heat are being frequently updated as further trial results become available. This means that farmers should consult their ReproRight advisor or vet experienced in synchrony programs about current recommendations for each product.

More information on non-cycling cows can be found on the Conditions of the Reproductive System page and in Section C (p. 90-94) and Appendix A3 (p. 186-189) of the InCalf Book for Dairy Farmers (2nd ed) - that can be downloaded below.