Effect of complete diets or separate feeding of long straw and concentrates on the performance of beef cattle

Abstract

In a previous experiment, with different types of straw and different levels of concentrates in mixed diets, it was demonstrated that steers could achieve growth rates in excess of 1.2 kg/day using diets containing up to 0.45 straw, Kay et al (1988). Few farms are equipped for complete diet feeding and so an experiment was set up to ascertain whether similar performances could be achieved when feeding loose-mix concentrates with long straw.Thirty-six Hereford x Friesian heifers of 350 kg initial mean liveweight were allocated to one of four diets. The diets contained ammonia treated or untreated straw of the spring barley variety Doublet and were offered in either a complete mixed form containing 0.45 straw, or as long straw and concentrates fed separately with the concentrate mix consisting of barley, molassed beet pulp, fishmeal, urea, molasses and minerals. Ammonia treatment was carried out in an oven with 0.03 anhydrous ammonia for 24 hours. Complete diets were effected by processing straw through a tub grinder before transfer to a mixer wagon. Complete diets were offered ad libitum. Concentrates in the other diets were offered twice daily at a rate equivalent to that consumed by animals on the complete diets. Liveweight and feed intake data were recorded.