The effect of silage plant species, concentrate proportion and sugar beet pulp supplementation on the performance of growing and finishing crossbred bulls

Abstract

A 2 × 2 × 2 factorial design was used to study the effects on animal performance of (1) the silage plant species, (2) the proportion of concentrate, and (3) the inclusion of molassed sugar beet pulp (SBP) in a barley-based concentrate. A feeding experiment was conducted using 32 crossbred bulls (Aberdeen Angus × Nordic Red dams sired by Hereford bulls) and lasting 359 days. The experimental silages were harvested from either pure timothy grass (Phleum pratense) or mixed timothy grass and red clover (Trifolium pratense) stands. The bulls were offered silage ad libitum. The two concentrate proportions were 330 and 660 g/kg diet DM. The concentrate used was either rolled barley or a mixture of rolled barley (700 g/kg DM) and SBP (300 g/kg DM). Concentrate proportion and silage plant species had no effect on total intake of the bulls (7.66 kg DM/day, on average) but SBP supplementation increased intake by 5% (P < 0.05). The dietary treatments had no effect on liveweight gain (1120 g/day) or carcass gain (705 g/day) of the bulls. The average carcass weight of the bulls was 405 kg. SBP supplementation increased carcass weight by 3% (P < 0.05) but it was not influenced by concentrate proportion or silage plant species. The dietary treatments had no effect (P > 0.05) on the dressing proportion or carcass conformation of the bulls. The carcass fat score was 13% higher in the bulls fed with pure grass silage compared with bulls fed the grass–red clover silage (P < 0.05), while the concentrate proportion and SBP supplementation had no effect on fat score.