Performance of growing steers fed either hay or silage supplemented with canola or fish meal
One hundred and eighty-six crossbred steers (194.4 ± 1.5 kg) were used to determine the effect of protein supplementation of medium-quality grass hay or silage on performance during wintering and compensatory growth during the grazing period. All steers received the hay or the silage ad libitum during the 182-d wintering period. They were also fed fixed quantities of one of three supplements: C, a control with no supplemental protein; CM, a canola meal; and FM, a fish meal containing supplements. Daily amounts of supplementation were fixed to supply to each steer the same amount of barley (85 g 100 kg−1 BW), of dry molasses (15 g 100 kg−1 BW) and of minerals, vitamins and Bovatec (10 g 100 kg−1 BW). The protein supplements CM and FM supplied the equivalent of 95 g of crude protein daily 100 kg−1 BW compared with 15 g 100 kg−1 BW for the control. Expressed as g kg−0.75, forage DM intake was 13.3% higher when fed as hay than as silage (P < 0.0001). Protein supplementation increased forage DM intake when fed as hay (P < 0.02) but not when fed as silage. Average daily gains (ADG) tended to be 5.8% higher for steers fed hay than for those fed silage (P = 0.06). Protein supplementation markedly improved ADG (P < 0.0001). When hay was fed, no differences were found in ADG between CM and FM supplementation; however, FM supplementation produced higher ADG than CM when silage was fed (P < 0.001). Feed efficiency was not affected by the type of forage fed, but it was higher for steers receiving protein supplementation (P < 0.001), the effect being more evident when the forage was fed as silage (P < 0.001) than when fed as hay (P = 0.07). Compensatory gains were obtained when the steers were taken out to pasture in early spring; steers fed silage, which obtained smaller ADG during wintering, showed higher ADG in pasture (P < 0.01). After 62 d grazing, the effect of protein supplementation during winter on body weight had almost disappeared. Key words: Protein supplementation, forages, cattle, growth