19 July 2002

Fan can reduce trailer hitches

FAN ventilated livestock trailers can reduce mortality rates, lower carcass downgrading and improve welfare of stock being transported by road.

The main problem is heat and moisture being produced by animals in trailers, says Richard Hunter of the Roslin Institute, Edinburgh. "Its not just external conditions which affect their environment.

"For young calves, the problem is avoiding cold stress, while larger animals generate heat in the trailer."

After many years of modelling heat and moisture movements in trailers, Roslin has developed a fan-ventilated vehicle for moving poultry. It is designed to suck out stale air instead of forcing fresh air into the trailer, avoiding the problem of chilling.

It works by air entering through vents at the rear and air moves forwards inside the trailer towards the front where fans remove stale air, he says.

Using fans also means air is removed when the vehicle is stationary, during breaks or in traffic jams. This is the key period, as studies with pigs at the institute found heat levels to rise when stationary, increasing animal stress.

"Despite the extra cost of converting the trailer, it has proved economic for poultry producers by reducing mortality and numbers of carcasses being downgraded. The trailer was also extended in length to carry more birds, helping to spread costs."

Experimental trailers are now being constructed for moving cattle, sheep and pigs. These are currently being tested, Mr Hunter adds. &#42