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Catherina Cunnane
Catherina Cunnane
Catherina Cunnane hails from a sixth-generation drystock and specialised pedigree suckler enterprise in Co. Mayo. She currently holds the positions of editor and general manager at That's Farming, having joined the firm during its start-up phase in 2015.
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‘Bull infertility is undoubtedly underestimated’ – Dr Kenny ahead of new study on acidotic diets

The potential acute and chronic effects of acidotic diets on the incidence of inflammatory conditions, such as laminitis and ultimately on lifetime hoof and joint health in bulls will be the focus of a new Teagasc-led project commencing later this year (2023).

That is according to David Kenny of Teagasc’s Animal and Grassland and Research Innovation Centre, Grange, Co Meath, who penned an article on sub-fertile bulls in the state agency’s most recent advisory newsletter.

In his latest research update, he pointed to a separate study in which Teagasc, together with University College Dublin (UCD) and the University of Limerick (UL), have undertaken research into various aspects of bull fertility.

The work, which is an SFI-funded project, investigated optimising the rearing management of young bulls, relating differences in the DNA profile of young bulls with age at sexual development and sperm quality, as well as the biochemical differences in the sperm of mature bulls ranked as either high or low fertility.

According to Dr Kenny, “the project results have yielded much new information on the main factors affecting the fertility of bulls”.

“It has also identified some key biomarkers for the early identification of better fertility and the culling of sub-fertile animals.”

“Such information will be harnessed within the national genomically-assisted cattle breeding programmes for the long-term improvement of bull fertility in Ireland,” he writes.

Culling breeding bulls 

In the newsletter, he also shed light on Irish statistics, which suggest that the primary reasons for the culling of natural service breeding bulls in beef herds.

They were, he wrote, as follows:

  • Injury – 23.2%;
  • Locomotory issues – 21.9%;
  • Infertility per se – 7.2%.

Dr Kenny believes that “infertility is undoubtedly underestimated given that many sterile bulls are now being identified at an earlier stage following the recent adoption of bull breeding soundness evaluations (BBSEs)”.

“Subfertility is estimated to affect 20-25% of bulls. It may be caused directly by low libido, sperm defects, or indirectly by physical factors affecting bull mobility or mating ability.”

Recent Teagasc research has shown that while high-concentrate diets from birth right through to 17-months-old, had no discernible effect on any aspect of sperm production, quality, or fertility measured, research into long-term effects on bull longevity is “warranted”.

Bull fertility

In this news article, we outline why a bull should undergo a BSE, the examination protocol and advice when it comes to buying bulls.

Meanwhile, this piece looks at the causes of sub-fertility in bulls and the arising implications.

We also previously reported that the diagnosing of the fertility of bulls is “an act of veterinary medicine”, Judge McNulty has determined following a hearing.

“Whilst a lay person can take a semen sample, this alone is not sufficient for a fertility assessment,” the VCI report outlines.

“The layperson cannot diagnose fertility having analysed a semen sample or provide a certificate on the diagnosis of the fertility of a bull.”

“This can only be done by a person qualified and eligible to do so, being registered veterinary practitioners.”

Read more on bull fertility testing in Ireland.

A farmer’s changed approach

In our most recent Farmer Focus series, Catherina Cunnane, spoke to Donegal’s Stuart McKeague, who, alongside his father, runs 70 70 commercial Angus suckler cows and 25 pedigree Angus breeding females, with a flock of Belclare-cross ewes and pedigree Texels.

He told us: “This year, we are taking a different approach, which is zero-meal feeding. This year’s shearling ram crop will be the first to be entirely reared on grass with no creep as lambs, no tyfon, meal, or any other supplements are being used.”

“In the past, rams would have been well grazed over the winter, and then meal would be introduced in May, starting at half a kg and building steadily as we near sale time.

“In both cattle and sheep, excessive feeding of a high starch diet is very bad for the feet and causes issues such as laminitis.”

“What people are not as aware of, however, is that you can do unseen damage that may not become apparent until a few years down the line.”

“So, my aim is to produce rams capable of covering more ewes from day one but also rams that last longer and give less bother to their new owners.”

“We usually start selling rams in mid-August, so I suppose we will find out then if the market is ready for this approach.”

Read more on this via this link.

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