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Transitioning to a Polled Herd

28 May 2012

Transitioning to a polled herd may take 30 years by visual selection but this time can be cut significantly by using the poll gene marker test, according to the Australian Beef CRC.

The recent release of the Beef CRC’s Australian Poll Gene Marker test will significantly increase the rate at which cattle breeders can poll their herds.

On average, 89 per cent of tests in polled Brahmans return an informative (or non-ambiguous) result. The test is also proving informative (72-74 per cent) in Charolais, Droughtmaster, Hereford, Santa Gertrudis and Tropical Composite breeds.

Transitioning to a polled herd may take up to 30 years using visual selection for polledness, however simulation studies suggest the Australian Poll Gene Marker test may reduce the time to as little as four to eight years.

Tamworth breeder and livestock agent Neil Watson, of Watasanta Santa Gertrudis stud, has been selecting for polledness since establishing his stud 27 years ago.

Mr Watson estimates 90 per cent of his herd is polled but this includes ‘true polled’ (PP) and heterozygous polled (PH) animals. He offers around 50 bulls for sale each year. Up until now he hasn’t been able to differentiate between the genotypes.

“It’s disappointing when you use a polled bull out of a polled female by a polled sire and he throws you a percentage of horned calves. I’ve seen breeders outlaying $20,000 to $30,000 for polled bulls at sales and ending up with half of their calves horned which must be very disappointing,” Mr Watson said.

“Now we can identify the PPs, they are the sires we’re going to use.”

Mr Watson believes all Santa Gertrudis stud breeders are aiming for a polled herd.

“At bull sales in the last few years a top horned bull will be lucky to sell or make the reserve, and an inferior polled bull will come into the sale ring and make at least double that price. Buyers are chasing the poll gene.”

Key factors driving demand for polled cattle include improved handler safety, reduced carcass bruising and hide damage, and dehorning is labour and time intensive and can adversely affect animal productivity and welfare.

Mr Watson believes horned animals are a significant occupational health and safety issue, particularly in the north on larger holdings. He said the setback a dehorned calf suffers is also costly.

“Dehorned calves will sulk for up to a week and they’ll lose condition, whereas polled calves will just go ahead. Even if it’s a five to 10 per cent setback in weight, that adds up,” he said.

Mr Watson plans to use the Australian Poll Gene Marker test on bulls only. He selects females for type and will not be testing their horn status.

“It’s a bit like everything, if you concentrate on one trait you’ll lose too much,” he said.

Given the high percentage of “true polled” and heterozygous polled animals in his herd already, Mr Watson will use PP tested bulls to increase the “true polled” status of his herd. All of this year’s weaner bulls will be tested for the poll gene marker and their poll status will be provided along with their BREEDPLAN figures at sale.

“I can see a financial reward in it for us and our clients will be guaranteed of product at the other end,” he said.

Mr Watson plans to use the test until about 90 percent of his herd are “true polled” but believes this will occur relatively quickly, possibly within a few years. By using PP bulls in a herd with horned (HH), heterozygous polled (PH) and homozygous polled (PP) females, all progeny will be polled (PP and PH).

Continual use of PP bulls over generations will quickly result in a high percentage of PP animals and low percentage of PH animals, without the need to test and cull females on genotype.

The percentage of PH females would be highest in older female groups and 50% of their progeny would be PH carriers. Depending on the initial proportion of HH and PH females in the breeding herd, testing of bull progeny from older females may need to occur until female carriers are eventually culled from the herd.

There are a few challenges for breeders using the Poll Gene Marker test including additional labour, recording and testing costs. The test requires hair samples and horn status of animals to be tested, and costs $33 (including GST) per animal at UQ AGL, or a reduced rate is available for bulk samples of through breed societies. The test cost may vary at other commercial laboratories.

Mr Watson believes some breeders will probably be a bit disappointed with the percentage of “true polled” animals in their herds to begin with, particularly if their top bulls are PH, but in the long run they will have the most to gain by identifying or introducing PP bulls into their herds.

He said some breeders also believe the gene pool is too limited if you select for polled animals, but in Mr Watson’s experience this is not the case.

All BREEDPLAN traits are recorded in the Watasanta stud and Mr Watson says his polled animals have got growth and carcass performance. The majority of Watasanta bulls are sold into commercial herds in central and northern NSW and southern, central and western Queensland.

Starting from next year his clients can select for tested horn status along with BREEDPLAN figures on his bulls.

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