Effects of amount offered and chopping on intake and selection of sorghum stover by Ethiopian sheep and cattle

Abstract

Experiment 1, with rams (17·0 kg initial weight (M)), and experiment 2, with steers (203 kg M), involved 2 x 2 arrangements of treatments to compare the effect of doubling the amount of stover offered (25 or 50 g/kg M daily) and chopping (unchopped or chopped), upon intake, selection and live-weight change. The stover used was a non-bird-resistant, local variety (Dinkamash). The particle length distribution of the chopped stover (produced by a tractor-driven chaff cutter) was: 90mm, 0·034. The stover was supplemented with minerals and cottonseed cake (sheep, 0·1 kg dry matter (DM) per day; cattle, 0·76 kg DM per day). Experiment 1, over 56 days, involved 48 Menz Highland, 18-month-old, rams, with four replicate pens containing three rams. Experiment 2, over 49 days, used 32, individually penned, Friesian × zebu yearling steers. With rams, doubling the amount offered and chopping increased intake, and the effects were additive (unchopped: 0·98 v. 2·24; chopped: 1·08 v. 1·60 (s.e. 0·071) kg DM per pen per day). With steers, there was an amount × chopping interaction (P