Why farmers should prepare for growing polled bull choice
© Beth Farrell/Genus ABS
Breeding for polled calves is now a practical option, with 12 Holstein sires in the profitable lifetime index (PLI) combining top genetic merit with the polled gene.
Using polled dairy sires to breed calves without horns can remove disbudding from the regular calf management routine.
See also: Advice for ensuring heifers are the correct weight after calving
This saves on cost and labour, reduces stress (for calf and operator) and shows consumers that farmers are pro-active in their attention to calf welfare.
There was a noticeable uplift in use of polled bull sires on UK dairy farms last year, according to AHDB’s head of genetics, Marco Winters.
Data show that in the second half of 2022, the proportion of polled AI sires used rose from 6% to 10%.
“In the past, the choice was limited and if farmers wanted polled genetics, they had to sacrifice genetic gain. Now, if you seek out polled bulls, you can get them,” he says.
The use of genomics has helped to integrate the polled gene into stud breeding programmes.
In the US, artificial insemination company ABS Global claims to have more than 50 polled sires.
Numbers are also increasing in Europe – 30-40% of calves born in Norway are now polled, in Denmark, about 25% of inseminations are with polled bulls, while in Germany, 20% of genotyped calves last year were polled, according to Mr Winters.
“Consumer pressure [in the UK] isn’t there yet, but in time it may come, so it is best to be prepared,” he says.
Breeding challenges
However, despite the ability to breed polled dairy heifers, maintaining this trait is a challenge, he adds.
“Polled is a dominant gene. That makes it easier to breed in, but not always easy to manage. Most bulls on the market are polled carriers, so only 50% of their progeny are born polled.
“If you use a homozygote polled bull (PP), then 100% of the offspring will be polled. However, if you then mate those animals to a traditional bull, only 50% of the offspring will be polled, and the other 50% will have horns.
“Once you start, you have to keep introducing the gene, otherwise you revert to the original horned animal.”
With a narrow gene pool and limited choice for now, Mr Winters says the challenge for the industry is how quickly a stud will find new polled bloodlines.
In the meantime, he says producers should focus on profitability – or easy calving traits in a beef sire – and accept that polled genes come as a bonus.
Polled bonus in Norfolk herd
Some 30% of replacement heifers in Ben Walker’s 180-cow autumn block calving herd at Attleborough, Norfolk were born polled last year. However, he admits this was more by luck than judgement.
The 7,500-litre cross-bred herd is looking for a robust cow that gets back in calf and can graze efficiently.
“Now that we’ve got solids where we want them – 4.92% fat and 3.79% protein – we’re selecting for fertility and mastitis, using quite a few Norwegian Red sires,” he says.
“Polled is a bonus. But it’s one less stress and one less job to do.”
Mr Walker’s milk contract requires all disbudding to be done by two weeks old and he has found it easy to wrongly identify a polled calf, only discovering six months later that it has horns.
He uses a team of sires, comprising one Jersey bull, one black and white and one Norwegian Red on the herd.
Out of 10 Norwegian Red sires he looked at last year, four of them were polled. He opted for Onstad-P.
Dairy replacements are bred using sexed semen from the best 100 cows calving in the first three weeks of the block, which starts on 1 September.