Heat stress is a challenge that is set to become more significant as the impact of climate change gathers pace, veterinary consultant, Dr. Tom Chamberlain has warned.
According to Chamberlain, the symptoms of heat stress include a fall-off in milk yield, reduced fertility and enhanced lameness problems.
He warned: “Significant reductions in milk yield can be discerned quite quickly, once temperatures exceed 20°C. In some cases, the fall-off in output can exceed 20% of what would be expected on a daily basis.
“Assuming all input costs remain unchanged while this is happening, the net loss to the businesses concerned is significant. Food wastage levels will go through the roof.
“Cows impacted by heat stress will stand up and start puffing as a way of trying to lose heat. In doing this, their metabolism, particularly in regard to the functioning of the rumen becomes unbalanced.
“They are fundamentally changing their physiology. This is reflected in the fact that impacted animals will stop chewing their cud.”
Heat stress
Other symptoms of heat stress include a reduction in fertility and conception rates and an increase in problems linked to lameness.
Chamberlain added: “Studies carried out on a farm in South Wales, where the cows are robotically milked, have confirmed a fall-off in conception rates during heat wave events.
“On the farm in question, the management objective is to have a flat line production profile the year round. The calving policy has been developed to meet this requirement.”
He also detailed that enhanced rates of lameness in dairy herds constitute a longer-term impact of heat stress.
“Cows impacted by heat stress will stand up in an attempt to cool themselves.
“In turn, this puts more pressure on their hooves, which will manifest itself in the form of enhanced lameness problem some three months later,” he added.
Research
The challenge of dealing with heat stress was one of the one of the key points discussed during a briefing to members of Guild of Agricultural Journalists by Chamberlain in Northern Ireland.
The briefing was hosted by Brett Martin at the plastic sheet manufacturer’s factory at Newtownabbey in Co. Antrim.
The business specialises in the development of bespoke roofing and cladding systems for use within agriculture.
Chamberlain is working with Brett Martin to assess the impact of the company’s specifically developed Marlon CST Heatguard roofing material.
His work indicates that the use of the new material produces a 70% reduction in the predicted loss of milk yield caused by heat stress in cows, when compared to traditional fibre cement roofing.
According to Brett Martin’s head of strategic development, Robin Black, the benefit of the roofing for farmers will increasingly become important in relation to climate change.
Martin is also launching a low carbon version of the Marlon sheets, which is produced from a bio-based, carbon neutral polymer which replaces 89% of the fossil content.