Some farmers are utilising AI to secure appropriate genetics for heifer calving ease. Simon Glennie takes a look at both the practicalities and the numbers.

As we approach bull sale time, a few farmers will no doubt be lamenting the need to buy another bull to go over the 15-month heifers. In a lot of cases the bull used last year will be too big to go across the heifers next season and while the genetic package is there to deliver a smaller calf at birth, the bull has simply grown too large to perform the role.

Usually a premium is charged for the bulls that are used across heifers as calving ease is given high priority.

Relatively few bulls have the required growth rate traits coupled with smaller birth weight or shorter gestation lengths associated with calving ease. The bulls that do are sought after but this doesn’t stop them growing too big to mate the heifers as the bulls mature. The consequence is a significant skewing of the cost of bulls to mate heifers naturally. Farmers can use these bulls over their MA cows and often do but they are usually compromising growth in doing so.

‘With a relatively small gap between the cost to service heifers naturally and by AI, its not surprising to see farmers taking up the opportunity to include an AI component in their beef operations.’

With dairy farmer counterparts using AI over more than 90% of the national herd, we must ask why there has not been at least some effort to gain by AI in our commercial beef herds. The sheer power of genetic progress alone has fast tracked productivity in dairy. Herds are traded on their relative genetic merit so the value gained is not just in the vat but also in the balance sheet.

Beef farming is different from the roles beef cows typically play to the simplicity and fit with other enterprises. Consuming the poorest of feeds and having a calving date more aligned with feed availability than market timing, beef cows work hard for their place.

Enterprise profitability is much about low cost, ease of labour and the role that cows play in pasture management for other enterprises. The sheer mental challenge of embarking upon an AI programme with additional yardings is not something that traditional beef farmers would choose to take on. However, some beef farmers are doing just that and have seen benefits that might surprise those traditionalists.

A common stepping stone is the mating of the heifers which is much simpler without the burden of calves at foot. While there are additional yardings, the job is relatively straightforward and the benefits include a very condensed calving and better calves.

Of the successful conceptions to AI (somewhere about 50-65% to a single round) the calves are born in a short period (less labour to check) and also early which allows more time to recover and conceive in the subsequent mating.

The cost to buy the straws and inseminate the cows is reasonable, particularly when the merit of the bull is considered. Unfortunately, there is still a requirement for follow up bulls and due to the synchronisation of the cows, the bull power to cover is still considerable. One option is to split the job to make better use of the chaser bulls. While the labour costs rise and there is more travel for the technician, the reduction in chaser bulls is generally of greater value.

In the case of heifers, bull cost can be as high as $125/head by the time the premium paid is considered along with the high turnover rate. Based on sourcing good genetics for $20/straw, the cost of AI is broadly similar and including labour works out at $163/heifer providing bull power can be halved.

The actual cost of the AI is about $88/head from which we could expect a 55% conception rate or $163/conception to AI. The balance of the cost is the need to provide follow up bull power (we have worked on 50% of the original bull cost and have included two AI runs in the AI costs to allow this)

Example of annual servicing costs for heifers are included in the table. Bull costs are per heifer per year where the assumption is made that a $2000 premium over average is paid to buy a superior bull. AI costs include straws, drugs and an allowance for technician travel which is doubled for the two-run example.

Where a larger portion of the resulting progeny are able to enter the herd as replacements the advantage is compounded and the herd improves. Some farmers report significantly better weaning weights in the AI calves.

However, those calves not born to AI are usually later born and as a result, not as heavy at weaning. Overall, with half of the calves born to heifers carrying superior genetics, we could expect a better wean weight. Other factors such as a condensed calving and potential to rotate mobs earlier also have a value.

With the shift to market premiums for meat quality, the potential also exists to extract a superior price per kilogram due to the potential in the animal. With a relatively small gap between the cost to service heifers naturally and by AI, it’s not surprising to see farmers taking up the opportunity to include an AI component in their beef operations.

• Simon Glennie is a farm consultant with AbacusBio.