More than half the UK’s dairy calves are housed individually before weaning to reduce disease risk. But new research proves pair housing’s benefits.
Melanie Jenkins reports...
It is often believed that housing dairy calves together can be detrimental to health and productivity, but a recent study, funded by AHDB Dairy, has shown it reduces stress and eases the transition to adulthood.
As rearing heifers is a costly part of dairy production accounting for about 10 per cent of overall costs, any ways to improve the process could boost profits considerably.
Sarah Bolt, membership development manager at Kingshay, which carried out the research, explains other studies had previously demonstrated that keeping young calves in individual pens could impair solid feed intakes.
She says: “It can also reduce their ability to cope with challenges such as weaning and regrouping – and stress is going to be detrimental to production.”
Social isolation is proven to be stressful, with the Welfare of Farmed Animals Regulations 2007 specifying that calves over eight weeks old must be housed in groups.
Ms Bolt says: “It is a requirement that calves have visual and tactile contact with those of a similar age but, at eight weeks old, these calves may have already spent a significant amount of time with little close contact with other animals.
“Calves as young as two days old have been observed to interact with other calves and early life experiences can have long-lasting effects.”
For the study, Ms Bolt examined the impact of early and late ‘pair’ housing against individual housing, looking at calf health, concentrate intake, daily liveweight gain and the distress response to weaning.
The study allocated 40 female Holstein-Friesian calves to one of three housing groups:
■ Eight calves were housed individually until day 55,
■ 16 were housed individually then paired five days post-birth,
■ 16 were housed individually then paired 28 days post-birth.
The calves were all fed four litres of milk replacer a day until day 21, when this was increased to six litres a day, at a rate of 150g of milk replacer per litre of water.
During the study, the feed intake, weight gain, health and behaviour were monitored and recorded.
All calves were weaned gradually over three days between day 48 and day 50 then, on day 55, they were all moved to pens of five.
Vocalisation was used to measure distress, explains Ms Bolt.
“It is a distress response to weaning and we observed this was strongest in the individually housed calves.”
Individual calves vocalised four times more than the calves paired on day five and twice as much as those paired on day 28.
“This shows that the early paired calves were much less stressed by weaning. This is thought to be due to a concept called social buffering or social support – an experience is less stressful on an individual if the experience is shared with another.”
Despite the difference in stress response the study did not find any statistical difference in concentrate intake over the course of the study between the treatments.
“There also was no statistical difference between the daily liveweight gain of the different groups between days zero and 55, or health through respiratory and faecal scores. This demonstrates that, whether calves are housed individually or in pairs, there is no detriment to health or production,” says Ms Bolt.
However, the study did flag some areas for attention, she points out.
“The mode of feeding needs to be considered to reduce cross-suckling, which can potentially increase the spread of infection. Teat feeders, especially with low flow rates, are likely to reduce cross suckling compared to bucket feeding.”
On the back of the study and others from around the world, Tesco changed its Livestock Code of Practice, requiring its Tesco Dairy Group suppliers to rear their calves in pairs or groups.
Though this was welcomed by some suppliers, others with single-calf hutches said it would require extra work to adapt their current systems.
Ms Bolt is quick with her answer to this: put two individual hutches together in a double-sized pen.
Strong social bonds are obviously an important part of healthy heifer development, she adds.
“In the UK and Europe, about 60 per cent of dairy calves are housed individually, but allowing full social contact between calves as soon as possible after birth should be adopted more widely in the industry. Adopting this approach could provide benefits to welfare, without compromising production and health.”
TIM Potter, of Westpoint Farm Vets, says it is important to pick the right system for the farm.
“I have seen all the different systems work equally well when managed properly.”
Accommodation needs to provide suitable shelter, including keeping the calf dry, having good drainage and allowing for decent air supply.
“You can undo anything good with poor management.”
Dr Potter points out that studies on individual versus pair housing are a bit conflicting.
“Pair housing helps with the social aspect. But less so in terms of disease and production. There are always times we would advise calves to be individually housed, such as for disease management.
But requirements for calves to have nose-to-nose contact means there is still potential for disease to spread in individual systems.”
However, pair or small group housing does allow for better observation of animals and less labour, he says.
“Protocols will go back to individual farms, but it is about optimising the system when handling, feeding and with space allowance. Ultimately, it is about minimising stress as this can suppress immunity, increase susceptibility to disease and negatively impact how well vaccines take.”
Protocols for weaning will depend on the feeding system, but it needs to be a gradual step down rather than sudden removal, explains Dr Potter.
“What farmers are aiming for is not a set number of days but instead an idea of weight, performance and feed intake.
Intake wants to be at least 1.5-2kg a day before weaning to maintain growth rates.”