Intensive, feed efficient finishing systems which slaughter beef animals at younger ages could substantially reduce the global warming impact of UK suckler herds, according to modelling work undertaken by Jimmy Hyslop at SAC.

Dr Hyslop told delegates the modelling had assessed a range of beef production systems, based on five potential suckler herd management strategies, dairy x beef suckler cows (Dx), pure bred beef cows (PB), a three-way rotational beef breeding crossing strategy (RO), a composite beef breeding strategy and a future beef herd management strategy based on the use of sexed semen (SS).

For the PB, RO, CO and SS systems replacement heifers were assumed to be homebred while for the Dx strategy replacement heifers were assumed to be bought as calves and reared in the system.

Also, on top of these five herds, simulations were also conducted according to either 12, 18, 24 or 30-month weaned calf finishing systems, giving a total of 20 system combinations.

Figures were generated for an assumed suckler herd of 100 cows, plus all associated heifer replacements along with all weaned calves to slaughter and methane and ammonia were simulated on the basis of methods adopted by the Intergovernmental Panel of Climate Change.

Both herd system and feeding system significantly influenced the global warming potential of the simulated herds, explained Dr Hyslop. “Feeding system in particular progressively increased the average global warming potential from 316t/year to 462t/year, with the largest effect being seen within the Dx and SS herds.”