Lamb growth rate on annual and perennial ryegrasses

Abstract

In autumn of 3 consecutive years, tetraploid annual and diploid perennial ryegrasses were sown, and over 6 weeks in each spring the growth rates of 11 month old Romney cross lambs grazing the different ryegrasses were compared. Lamb liveweight gains on annual ryegrasses (364 g/day) were lower (P<0.05) than on perennial ryegrasses (407 g/day). However, because growth rates of annual ryegrasses were greater than for perennials, they supported a higher stocking rate and produced an extra 95 kg of liveweight/ha over the grazing period. Keywords: annual ryegrass, perennial ryegrass, maize supplementation, lamb growth rates