عنوان مقاله [English]
نویسندگان [English]چکیده [English]
Twenty-four Holstein male calves (BW=217±57kg) were employed to evaluate the effects of rapeseed oil supplementation on growth, carcass as well as on meat quality and fatty acid content of longissimus thoracis muscle in a completely randomized design. The calves were divided into three groups and allocated to three diets of: a corn/barley-based diet (C); a diet containing 2% (DM basis) rapeseed oil (LC); and one containing 4% (DM basis) rapeseed oil (HC). Feed offered was recorded daily, the calves were weighed monthly and slaughtered after 4 months of trial. The obtained data indicated that dry matter intake was greater for steers fed C diet than for those fed LC and HC (P<0.05), but feed efficiency was lower for steers fed C diet rather than LC and HC (P<0.05). There were no differences (P>0.05) observed in average daily gain, hot carcass weight, and in longissimus muscle area. No differences were observed (P>0.05) in carcass readings except for back fat in which calves fed the HC diet had more back fat as compared to those fed the C diet. There were significant differences observed in meat quality of longissimus thoracis muscle, i. e. the ether extract was significantly increased (P<0.05) while crude protein and moisture significantly reduced due to being fed LC and HC. The use of rapeseed oil had no effect on muscle ash content (P>0.05). Fatty acid composition was affected by treatments, Feeding LC and HC diets increased (P<0.05) the percentages of C18:0 and C18:1 while decreasing (P<0.05) the percentages of C14:0 and C16:1. There were no differences (P>0.05) observed in the percentages of C14:0, C17:0, C17:1, C18:2, and C18:3 of the treatments. Concluding from the economic aspects of the study, ause of 4 percent (DM basis) of rapeseed oil in the diet of growing male calves is recommendable.