Milksolids production from cows grazing timothy/white clover in comparison with ryegrass pastures

Abstract

Three experiments were conducted to compare milksolids (MS) production from cows grazing similar herbage allowances of timothy (Phleum pratense)/white clover (Trifolium repens) and perennial ryegrass (Lolium spp.) pastures. Two experiments were shortterm (2 weeks), one in spring 2000 (Experiment 1) and one in autumn 2001 (Experiment 2), and one longerterm (12 weeks) irrigated trial in summer/autumn 2002 (Experiment 3). In Experiment 1, the yield of all milk components; fat, protein, MS, casein and lactose, was greater from timothy/white clover than ryegrass, whereas in Experiment 2, the production of these components from timothy/white clover was less than from ryegrass. The protein content of timothy/white clover was greater than ryegrass in spring (P<0.05) but similar in autumn. In spring, acid detergent fibre (ADF) and neutral detergent fibre (NDF) were similar but in autumn they tended to be higher in timothy/white clover than ryegrass, indicating poorer quality of timothy/white clover relative to ryegrass in autumn. In spring and autumn the digestibility and metabolisable energy (ME) of the two pastures types were similar. In Exper iment 3 the pastures were irrigated. The experiment was a crossover design with the cows grazing each of the timothy/white clover and ryegrass pastures for two, three-week periods. The yield of all milk components was greater from Timothy/white clover than ryegrass. Digestibility and ME were similar for the two pastures but the timothy/white clover pastures had lower NDF and higher water-soluble sugar content than ryegrass. More cows were carried on the timothy/white clover pasture and as a result MS production/ha was increased by 30%. This research identifies an opportunity for greater use of irrigated timothy/white clover pasture in dairying systems not subjected to an Argentine Stem Weevil (ASW) challenge. Keywords: milksolids production, nutrient composition, perennial ryegrass, timothy, white clover