Growth and carcase composition of yearling cattle fattened on combinations of hay, grain and NPN in a feedlot and on grain supplemented pastures

Abstract

Hereford steers aged 10 to 12 months were fattened on a range of diets including two types of hay (pasture hay, oaten hay), three types of grain (oats, wheat, barley), four levels of oats (1/2, 1 and 1 1/2 per cent of liveweight per day and ad libitum) and non-protein nitrogen as a supplement to the oaten hay. In addition, two groups of steers were grazed on pasture and one of these was supplemented with oats at the rate of 13 per cent of liveweight per day. The experiment was conducted at the Pastoral Research Station in western Victoria. Steers fed pasture hay, either alone or with oats, gained at a faster rate than steers fed oaten hay, alone or with oats. As the level of grain in the rations increased, liveweight gains of the steers increased. The steers given the highest levels of grain (1 1/2 per cent liveweight and ad libitum) produced the most acceptable carcases as assessed by fat cover and the physical properties of the lean. As the level of grain was increased, the conversion of feed to liveweight gain was improved and the time required to reach the desired weight was reduced. Rations of barley, wheat or oats had similar effects on growth rate and carcass composition when they were fed at a rate equal to one per cent of the liveweight of the steers per day. The NPN supplement, biuret, had little effect when fed as a supplement to oaten hay. The feeding of grain as a supplement to pasture doubled the growth rate of the steers. The carcases of steers receiving oat grain on pasture were of comparable quality and produced in a similar time to those of the fastest gaining feedlot groups. The results do not provide any evidence which would justify the practice of confining such steers in a feedlot.