Cattle fertility assessments are vital

To improve performance, we must first measure it so we can assess and monitor it on an ongoing basis.

Fertility calculations are complicated by the 12 to 18-month period from joining to branding and weaning.

It is the 2022 joining that produces the calves you brand in 2023.

With the branding months approaching, what should we be recording?

The first fertility assessment to undertake is the pregnancy rate.

If we joined 500 cows in the 2021-22 mating and 430 were pregnant at the June 2022 pregnancy test, the pregnancy percentage calculation would be:

Pregnancy per cent = (430/500) x 100 = 86pc.

If maiden heifers and first-calf cows are run together or with older cows, it is important to record their pregnancy test data separately.

This will make it easier to identify any problems with their performance.

Branding and weaning rates should be calculated off total cows joined.

For 2022-branded calves it is cows joined in 2020-21.

Branding and weaning percentage calculations are based on how many cows are present at the time.

Do not include empty cows removed at pregnancy testing and cow losses.

If the joining of 495-cows in 2020-21 resulted in 400 calves being branded and 394 weaned in 2022, the calving and weaning percentage calculations are:

Calving per cent = (400/495) x 100 = 80.8pc.

Weaning per cent = (394/495) x 100 =79.6pc.

Foetal and calf losses are calculated using the number of cows retained at the previous year's pregnancy test.

Pregnant cows that are sold before calving are not included in the calculations as they did not have the opportunity to produce a calf.

Following the 2020-21 joining of 495 cows, 425 were pregnant at the June 2021 pregnancy test.

If these were all retained to calve the foetal and calf loss calculations are:

Loss - pregnancy test to branding = 425 - 400 = 25.

Loss - pregnancy test to branding per cent = 25/425 x 100 = 5.9pc.

Loss - pregnancy test to weaning = 425 - 394 = 31.

Loss - pregnancy test to weaning per cent = 31/425 x 100 = 7.3pc.

Loss - branding to weaning = 400 - 394 = 6.

Loss - branding to weaning per cent = 6/400 x 100 = 1.5pc.

Assessing fertility in year-round mated herds is more difficult.

It is usually impossible to calculate branding or weaning percentages based on cows mated because, with calves being branded and weaned at each muster, it is difficult to identify the number of cows mated to produce them.

One of the many advantages of controlled mating is it enables better assessment of herd performance.

Some producers calculate branding and weaning percentages based on the cows present at the second round in the previous year.

This approach provides consistency but will not provide true branding and weaning percentages, as cows will have been sold.

In year-round mated herds where pregnancy testing is undertaken and the number of retained pregnant cows is known, foetal and calf loss from pregnancy testing to branding and or weaning can be determined.

It is also important to record foetal age and body condition scores when pregnancy testing so the conception pattern can be seen.

The conception pattern and body condition scores can help identify if disease or poor body condition may have been a problem.

Diseases like vibriosis and trichomoniasis that cause embryonic failure and early abortions can result in delayed conceptions.

Foetal ageing provides the opportunity to identify superior cows which conceive early in the joining and cull less fertile cows if numbers have to be reduced.