A comparison of two-cut and three-cut systems of silage making for beef cattle using two cultivars of perennial ryegrass

Abstract

Two randomized-block experiments have been carried out to examine the effects of increasing the digestibility of grass silage offered to beef cattle by harvesting three crops of grass after shorter growth intervals rather than two crops after longer growth intervals. In experiment 1 early-cut silages were harvested on 1 June, 16 July and 24 August, and late-cut silages on 20 June and 22 August 1979. In experiment 2 the early-cut silages were harvested on 19 May, 2 July and 20 August, and the late-cut silages on 5 June and 12 August 1980. Early- and late-cut silages were made from each of two cultivars of perennial ryegrass (cultivars Cropper and Talbot). The silages were unwilted and had formic acid applied at 2.5 1/t fresh crop.In experiment 1 the silages were offered ad libitum, both unsupplemented and supplemented with 2·2 kg concentrates per head daily, to 88 cattle of mixed beef breeds and mean initial live weight 337 kg, in a 2 × 2 × 2 factorial design. In experiment 2 the silages were offered ad libitum and supplemented with 2·4 kg of concentrates per head daily to 56 Charolais × (Aberdeen Angus × Friesian) cattle of mean initial live weight 351 kg, in a 2 × 2 factorial design. Grass cultivar did not significantly affect silage intake or animal performance but intake, live-weight gain and carcass gain were significantly higher for the early-cut than for the late-cut silages in both experiments. In experiment 1 silage dry-matter intakes were 6·33, 5·12, 5·80 and 4·67 (s.e. 0·124) kg/day; live-weight gains were 0·72, 0·89, 0·47 and 0·76 (s.e. 0·029) kg/day; and carcass gains were 0·46, 0·60, 0·27 and 0·48 (s.e. 0·016) kg/day, for the unsupplemented and supplemented early-cut silages, and the unsupplemented and supplemented late-cut silages, respectively. In experiment 2 silage dry-matter intakes were 5·49 and 4·95 (s.e. 0·056) kg/day; live-weight gains Were 0·95 and 0·76 (s.e. 0·033) kg/day; and carcass gains were 0·67 and 0·50 (s.e. 0·17) kg/day, for the early- and late-cut silages, respectively.