By Debbie James

A Welsh dairy farmer supplying milk to a cheese processor says identifying cows within his herd with a gene thought to improve cheese clotting times could allow him to tap into a potential new income stream.

David Williams sells milk produced by his herd of 300 spring-calving Jersey Friesian crossbreds at Clawdd Offa, Northhop, Flintshire, on a manufacturing contract to the Arla creamery at Llandyrnog.

In cheese making, the clotting action of rennet is improved by different variants of kappa-casein alleles present in the milk.

The BB allele is sought after by cheesemakers because overseas research has shown that it can increase cheese yield by 10 per cent compared to milk with the least desirable allele, AA, and also speed up renneting time by up to 25 per cent .

Affordable technology now exists which allows farmers to profile their cattle for a kappa-casein genotype through hair sampling.

As a Farming Connect Focus Farm, Clawdd Offa embarked on a project to identify which cows carry one of three kappa casein alleles in a bid to maximise its milk contract and to produce the right type of milk for his buyer.

Within the herd at Clawdd Offa the test identified 27 cows with the BB allele and 8 AA cows. There were 15 identified with the AB allele, a genotype which has intermediate properties between AA and BB.

Establishing which cows carry the most desirable kappa casein genotypes will help to inform Mr Williams’ future breeding decisions.

He is already maximising his milk contract by selling high constituent milk, achieving bonuses for butterfat and protein levels, but this research could add further value in future if he can produce milk from more cows that are carriers of the kappa-casein alleles better suited for cheese production, he says.

“There could be a bonus or premium for BB milk in future,’’ he says.

It could future-proof the farm business by creating a point of difference, Mr Williams adds.

As well as analysing which cows carry kappa casein genes, the project went a step further by testing the influence of these genes on rennet coagulation time, firmness and texture.

But the results were not consistent – in one of two trials the AB milk was the quickest to react and form clots.

The project team at the Food Technology Centre at Llangefni believe that higher milk solids in this batch may have had an influence – it had total solids of 16.45 per cent compared to 15.78 per cent for AA milk and 15.06 per cent for BB.

The researchers conclude that the protein, fat and solids levels of the milk produced by the three kappa-casein gene variety cow groups were not sufficiently matched to be able to rule out clotting effects due to these differences alone.

“The protein contents in the three types of milk from both the milk deliveries varied from 4.10 to 4.89 per cent , the fat from 5.71 to 6.98 per cent , and total solids from 14.95 to 17.04 per cent ,’’ says the author of the project report, Sian Davies, of Kite Consulting.

The findings, she says, show that further research is needed into the potentially positive effect of the kappa-casein BB gene.

“It may be that using milk towards the end of the annual lactation period caused issues with higher than average fat levels and total solids levels,’’ she says.

The kappa-casein effects may be more pronounced in different breeds of cattle, or with specific types of cheese production, she adds.

Improving cheese yield and reducing the clotting time would be beneficial for the whole supply chain.

Rhys Davies, Dairy Technical Officer at Farming Connect, says this project should interest a number of other cheesemakers across Wales.

“It has shown that there are ways a dairy farmer can seek to ensure the best return in their milk cheque, through producing the best milk possible for cheese production,’’ he says.


120-hectare tenanted farm on a three-generational tenancy

80 hectares grazing platform

40 hectares of offlying land for rearing youngstock, stock bulls and producing silage

Cows milked once a day on a grass based system

150 replacement heifer reared annually together with stock bulls