Calf values helped by using EBVs for selection

Using Estimated Breeding Values (EBVs) and paying close attention to bull health can improve fertility and give more pounds per calf.

Bull are all to often selected on the basis of their looks. However, such a strategy does not give the full picture, explained Liz Genever, EBLEX beef scientist, speaking at an EBLEX, Shepton Vet Group, Xcel Vet-supported event at Norwood Park Farm, Glastonbury.

“There is no doubt you must like the look of a bull and be happy with how it moves, but EBVs should be used as a complementary tool to visual observations.

“When purchasing a bull, use EBV benchmark data to see how he compares to all UK recorded bulls for that breed.”

EBVs show the genetic value of an animal and can be used to predict whether the progeny will be good or bad for a specific trait. They include values linked to ease of calving and beef scores, such as 400-day growth and muscle depth.

“Bull selection should be focus driven,” stressed Dr Genever. “EBVs should be used to target specific breeding goals, such as reducing days to slaughter and increasing carcass weight.”

Norwood Park Farm is in the early stages of building up its genetic base. In the long term, beef farmer, Martin Harrison, aims to maximise carcass traits and milk production.

To achieve this, bought in Holstein Friesian x British Blue heifers will be crossed with Limousin bulls on their second service. “This will combine good hybrid vigour and milk production with the good growth and carcass weight of the limousin,” says Mr Harrison.

The two Limousin bulls on this farm have both been selected with this aim in mind, said Dr Genever.

“Mr Harrison is growing weaned calves for sale, so it is important to have good early growth rates. Rosecroft Adonis has good 200 day and 400 day growth rate values and therefore a good beef value. If we were aiming to sell at carcass, then you would need to select good fat and muscle depth EBVs, too.

“Westcroft Vicarage has good maternal traits including calving ease and calving value, so is an excellent choice for breeding good replacements.” A bull with a positive 200 day milk EBV would also make a suitable sire where female replacements are being retained for breeding.

Ultimately, using EBVs to select bulls has a financial value. “You will have to pay a higher price for the top 1% of bulls, but the bonuses you will achieve in terms of carcass weight and maternal qualities far outweigh the costs,” Dr Genever added.

“In fact, selecting a bull in the top 10% for growth and carcass traits will add an extra value of £17.10 a calf compared to using a bull in the bottom 25%.”

However, a bull will only reach its full potential and produce good quality replacements when it is well looked after, says Paddy Gordon of Shepton Vet Group.

By maintaining bull health you will maximise fertility rates and retain bulls within the herd for longer, reducing bull costs a calf.

“We rely heavily on a bull to maintain in calf rates so it is essential he is well looked after. Be proactive when checking bulls – check testicle size and look for lumps and diseases.”

About 30% of bulls have depressed fertility, so it is essential to do regular performance tests to see whether he is up to the job.

“I would recommend doing an annual semen count six weeks before he is due to start service. At about £100 a test this is well worth the investment. If you don’t you run the risk of extending calving intervals,” said Mr Gordon.

“For a 100-cow herd, by having a first service pregnancy rate of 40% instead of 75% and increasing the period during which 98% of cows calve from nine to 24 weeks, you will produce calves 23kg lighter at weaning. This means 23kg of beef not sold, costing £26 a cow.”

Targeting infectious diseases which could potentially depress fertility is also essential. “Assess the disease risk to your herd and discuss an appropriate vaccination plan with your vet.

“When you are vaccinating for a specific disease such as BVD or IBR, be sure to vaccinate six weeks before a bull is due to serve to prevent disruption.”