Meat quality of crossbred bulls fed with sorghum silage or sugar cane and slaughtered at two levels of fat thickness/Qualidade de carne de bovinos mesticos alimentados com silagem de sorgo ou cana-de-acucar e abatidos com dois niveis de gordura de cobertura

This study was carried out to evaluate the performance and carcass characteristics of bulls from three genetic groups: Zebu (ZEB), 1/2 Limmousin vs. 1/2 Zebu (LIZ) and 1/2 Angus vs. 1/2 Zebu (ANZ). Bulls were finished in feedlot and fed two diets: sorghum silage + 1.0% concentrate of LW or sugar cane + 1.2% concentrate LW. The bulls were slaughtered at one of two fat thicknesses: 3.4 or 4.8 mm. The bulls of the LIZ and ANZ groups showed higher FBW and ADG. There were no differences in the feed intake and carcass characteristics among the groups. Bulls from LIZ group had a lower fat thickness and higher muscle deposition. There were no differences among groups on carcass characteristics. The bulls fed with sorghum silage had a higher FBW, ADG and carcass weight than those fed sugar cane, while the animals fed sugar cane had a higher DMI and lower feed efficiency. There was no difference in hot carcass dressing between the diets. The sorghum silage or sugar cane did not change carcass characteristics or the meat composition. The FBW and HCD were similar for the two levels of fat thickness. The ADG was higher in bulls with 3.4 mm of fat thickness. Keywords: cattle, fat, genetic groups, silage, sugar cane. Este trabalho foi realizado para avaliar o desempenho e caracteristicas de carcaca de bovinos Zebu (ZEB); 1/2 Limousin vs. 1/2 Zebu (LIZ) e 1/2 Angus vs. 1/2 Zebu (ANZ). Foram utilizados 36 bovinos terminados com duas dietas: silagem de sorgo + 1,0% do PV de concentrado ou cana-de-acucar + 1,2% do PV de concentrado. Os bovinos foram abatidos com dois graus de acabamento (3,4 ou 4,8 mm de espessura de gordura). Os grupos LIZ e ANZ apresentaram maior PVF e GMD. Nao houve diferenca para a ingestao de alimentos, peso e rendimento de carcaca. O grupo LIZ apresentou menor deposicao de gordura e maior deposicao de musculo. Nao houve diferenca entre grupos sobre caracteristicas do musculo Longissimus. Os animais alimentados com silagem de sorgo apresentaram maior PVF, GMD e PCQ. Os animais alimentados com cana-de-acucar apresentaram maior ingestao de materia seca e pior conversao alimentar. Nao houve diferenca para o RCQ entre as dietas. As dietas nao alteraram as caracteristicas de carcaca e composicao da carne. O PVF e rendimento de carcaca foram semelhantes para os graus de acabamento. O GMD foi maior nos animais abatidos com 3,4 mm de gordura. Palavras chave: bovinos, gordura, grupos geneticos, silagem, cana-de-acucar.