UK – Veterinary reports on bull fertility suggest problems are far more common than many would think, UK farmers area being warned this spring.
As many as forty per cent of bulls could have fertility issues, according to beef cattle expert Keith Cutler of Endell Veterinary group, discussing a Scottish veterinarians study.
He said the survey showed that one in ten bulls suffered complete infertility and three in ten were sub-fertile.
This means around 30 per cent of bulls take longer to get cows bulled and inseminate fewer cows.
“We find exactly the same in our practice,” said Mr Cutler. “This is across 150-160 bulls every year – it is much more common that you would think.”
Mr Cutler, who works across Wiltshire, Hampshire and Dorset, is recommending farmers test their bull semen to nip any problems in the bud.
He said costs vary, with some vets charging for time while others charging around £100 - £120 for each bull tested.
“It might sound like a lot of money but if you find your faulty bull it saves a lot of heartache in the end,” added Mr Cutler.
With so much at stake, Mr Cutler stresses that time is key in allowing feet, body condition, reproductive equipment and sperm quality to be maximised to do the job in hand.
He told farmers to put bulls on a rising plane of nutrition seven to eight weeks ahead of the breeding season.
This is to ensure they access energy required for the surge in activity and can cope with seeking out pheromones.
“It takes around six weeks to produce a fully fertile sperm,” he added. “So we need to think about six weeks ahead.”
He recommends that time should also be given to allow lesions on feet or trimmed hooves to recover.
Nutrition and Body Condition
Appropriate body condition scores and energy can be obtained without concentrates providing that grass quality is good enough. However, Mr Cutler said rolled barley or some supplements may be useful for providing extra energy.
He played down specific body condition scores, instead emphasising that obese and skeletal bulls should be avoided.
“Whether they have a body condition score 2.5, 3 or 3.5 it doesn’t matter to me as long as he’s not obese,” said Mr Cutler.
“Too much fat will end up laid down in the scrotum, insulating it and making it hotter, and leading to poor sperm.”
What to Expect From Your Bull
In terms of cow to bull ratio, Mr Cutler pointed to US thinking that a bull’s age in months relates to cows serviced.
However, he cautioned that a young bull of 12 months may not be fully functional, although breed and other factors are at play.
Mr Cutler said: “It’s a rule that they have in the US that the number of cows is the same to number of months in bull age.
“An 18 month old bull should be able to cope with eighteen cows and a mature bull of 35 to 40 months should be ale to cope with 35 to 40 cows randomly cycling.”
However, he said details such as oestrous detection and cycling patterns needed to be taken into account.
“Its important you don’t push a bull too hard, you may spoil the bull for life,” warned Mr Cutler. “A young bull could break his penis serving large adult cows.”
Bulls classed as persistently infected (PI) for bovine viral diarrhoea (BVD) should be known and recorded, as should Johne’s disease, said Mr Culter.
Any BVD, Leptospirosis or Infectious Bovine Rhinotracheitis (IBR) vaccinations should be administered early, with the breeding season in mind.
“Vaccinations and treatments need to be administered sufficiently ahead of the breeding season so any blip in sperm production caused by treatments can have settled down,” said Mr Cutler.
Campylobacter is also an issue, particularly if a bull is coming onto a farm, he added. Washing genitalia is also a good chance to assess reproductive equipment.
Monitoring and Targets
Monitor bulls before and also during bulling. Even though your bull protocol may be perfect, things can still go wrong.
Mr Cutler recommends semen testing all bulls every year.
Mr Cutler said some bulls perform well year in year out, have a great semen test history, look good, have no issues with disease or eating and can be waved through unchecked.
However, he stated: “If you want to be as certain as you can be, test every bull before every breeding season.”
Testes and scrotum can be monitored on farm and the penis can be checked for scabs, erosions and discharges that could signal problems up ahead.
“You are looking for normal sized testes, very slight differences in size doesn’t matter but big differences do,” said Mr Cutler. “Consistency needs to be firm, not hard.
Hard testes often indicate infection and soft testes are often not producing sperm properly, he added.
Success can be seen in cow calving patterns which should be no longer than in twelve week calving periods and ideally nine weeks, added Mr Cutler.
As a rule of thumb, he recommends farmers are getting half the herd calved in 18 days.
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