Performance, carcass characteristics and chemical composition of beef affected by lupine seed, rapeseed meal and soybean meal.

To test the effects of different protein sources and levels on performance, carcass characteristics and beef chemical composition, concentrates with three protein sources [Lupine seed (L), Rapeseed meal (R) and Soybean meal (S)] and two protein levels ['normal protein' (NP) or 'high protein' (HP)] were fed to 36 Simmental calves. Calves initially weighed 276 +/- 3.9 kg and averaged 6 months of age and were randomly allocated to the six treatments. Maize silage was offered ad libitum and supplemented with increasing amounts of concentrates (wheat, maize grain, protein sources, vitamin-mineral mix). Normal protein and HP diets were formulated to contain 12.4% and 14.0% crude protein (CP) dry matter (DM) respectively. At the end of the fattening period of 278 days, the final live weight averaged 683 +/- 14.7 kg. Neither level of protein nor its interaction with protein sources had any effects on most of the traits studied. Feeding the R diet significantly increased final weight, average daily gain (ADG), DM intake and CP intake in relation to the L diet; no differences were observed between the L and S diets for these measures. No differences were observed between the R and S groups in final weight or ADG, but the calves fed the R diet consumed more DM and CP than the calves fed the S diet. Bulls fed R diet had higher carcass weight and dressing percentage than the L groups, and no significant differences were detected between the S and L groups. Chemical composition of the Musculus longissimus dorsi was not significantly affected by source of protein. Also, the major saturated fatty acid (SFA) (C16:0 and C18:0) did not significantly differ among the three treatments. Samples from R group had significantly higher proportions of C16:1 t9, C18:1 c11, C18:2 c9 t11, C18:3 c9, 12, 15 and SigmaC18:1 t fatty acids in relation to L and S groups. Although polyunsaturated fatty acid/SFA ratio was similar for the three dietary groups, n-6/n-3 ratio and Sigman-3 fatty acids content were significantly greater for bulls fed R diet in relation to those fed L and S diets.