Resumen

RUIZ, M.R. et al. Proximate chemical composition and fatty acid profiles of Longissimus thoracis from pasture fed LHRH immunocastrated, castrated and intact Bos indicus bulls. S. Afr. j. anim. sci. [online]. 2005, vol.35, n.1, pp.13-18. ISSN 2221-4062.

This study was carried out to evaluate the effect of a luteinizing hormone-releasing hormone (LHRH) fusion protein vaccine vs. surgical castration on the chemical composition and fatty acid profile of beef cattle (Bos indicus) slaughtered at three years of age. Thirty bulls (Nellore-cross) were divided into three groups: immunized against LHRH fusion protein, castrated or left intact (control). These animals were 24 months old at the initiation of the study and ranged on Brachiaria grass in Mato Grosso, Brazil. Meat of intact bulls presented a lower fat content compared to castrated or surgically castrated animals. For the immunized and surgically castrated animals there were differences in fat and cholesterol concentrations. Although the fatty acid profiles of the three treatments were similar in composition, there were differences in the concentrations of some fatty acids (miristic, C14:0; stearic, C18:0; linolenic, C18:3n-3; and eicosapentaenoic, C22:5n-3). Meat samples of surgically castrated animals had less polyunsaturated (PUFA) and monounsaturated (MUFA) fatty acids (8.2 and 37.7%, respectively), higher saturated (SFA) fatty acids (52.2%) and a lower PUFA/SFA ratio (0.16) and were different compared to intact and immunized bulls. The PUFA/SFA ratio increased as the fat content decreased. On the other hand, surgically castrated bulls had a higher lipid and lower cholesterol contents. It is concluded that immunization against LHRH using new recombinant LHRH fusion proteins could be an alternative to physical castration to improve carcass quality in cattle production.

Palabras clave : Beef bulls; polyunsaturated fatty acids; Nellore; LHRH immunocastration; chemical composition.

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