Managing all the extra dairy calves in the spring was one of the key topics of discussion in the second session at the Teagasc national dairy conference. Andrew Cromie of the ICBF said there were now 540,000 calves born in February compared with 270,000 calves three years ago and that big increase brings its own issues.

First up to tackle the subject was University of Melbourne researcher Natalie Roadknight. She outlined the early life slaughter model that works across New Zealand and Australia. Some calves travel 1,000km to a slaughter plant in Australia as very young calves. She said EU regulations are much stricter than either Australia or New Zealand and that the risk to the reputation of a country such as Ireland to pursue this model is probably too great.

Listen to "Dr. Stephen Butler at the Teagasc National Dairy conference" on Spreaker.

In Australia, there are no real alternatives to this model and the dairy industry there is in a very bad place at the moment so options are limited for managing these extra calves. The rearing option for Australia depends on beef and grain prices and when in drought this model won’t stack up.

Andrew Cromie outlined the steps the ICBF has taken to create a dairy beef index that will allow farmers pick between AI sires next spring. His key message was that there are options between breeds and within breeds to choose sires that will deliver €150 to €200 extra carcase value and the dairy beef index should help farmers identify these sires.

Sexed semen

Stephen Butler, a researcher at Teagasc Moorepark, explained the results of a trial carried out using sexed semen last spring. More than 8,000 straws were used across 160 herds in a trial costing over €200,000. Unsexed semen was compared with sexed semen that had 4m sperm per straw. The 4m technology is supposedly much better than the 2m sperm per straw used in the 2013 trial. Ten bulls were used for the trial. Some of these bulls were based in Ireland and the semen shipped out. The other bulls were based in England and Holland and hence semen didn’t have to be shipped for sexing. We don’t have a sexing laboratory in Ireland.

The actual conception rates were 46% for sexed semen compared to 60% for conventional semen (See graphs). Stephen also found the semen which was transported was more variable in quality than that of bulls standing at stud where the semen was sexed. So the marketing message was found not to be correct in this trial. I understand similar results were found in a large-scale trial in New Zealand.

Heat behaviour and timing

But that isn’t the end of the sexed semen story. When Stephen divided out the cows used in the trial, he found that in 25% of the herds the sexed semen produced better conception results than ordinary semen. This led Stephen to conclude that heat behaviour and timing of AI is much more important when using sexed semen.

He said: “We know sexed semen is not viable for 24 hours. The process of sexing means the semen only needs an hour in the reproductive tract of the cow before it is ready for fertilisation, so timing is more critical. The guide should be to inseminate the cow between 14 to 20 hours after heat onset.

Farmers can’t use sexed semen the same way as ordinary semen. Maybe we need to target highly fertile animals only and maybe synchronise these cows and use timed AI as a solution to achieving better conception rates.”

Comment

Sexed semen – let’s get the four key issues right

The sexed semen results, while disappointing, still don’t rule it out as an option for farmers.

Should farmers and the industry be willing to accept slightly lower conception rates if it solved some of the negative issues experienced in New Zealand and Australia around calves?

The message was clear on sexing – we need to use good sires, in a national laboratory, on fertile cows and maybe we need to look deeper on the timing of AI. If we got these four critical issues right then I believe we would be close to having a product that could compete with ordinary semen.

At the moment, as an industry we are not getting closer to solving some of these issues. The development of a dairy beef index is positive but then again this will be only used by dairy farmers when enough female replacements have been bred.

Already fertility, milk solids, health and calving ease are on the ticket for replacements.

The best we can hope is for farmers to use this index for the second half of the breeding season.

Other speakers

Teagasc grass message

Joe Patton reinforced the Teagasc grass message. He said: “Very different things are happening on some farms and what’s happening on the ground might be different to what’s appropriate for the farm. The additional margin from those animals over and above what grass you can grow must be tested. The message remains the same – match growth rate with stocking rate and don’t get bored with it. I would caution against driving on stocking rate and get better at the grass model is the message.”

Measurement methods

Mike Dineen a west Cork researcher working at Cornell University, said new feed measurement methods are bringing answers and more questions but all reinforce the quality grass-fed message. He said we are learning that quality grazed grass is extremely digestible and we may need to carry out more research on how we can complement grass-based systems.