The effects of castration, preslaughter stress and zeranol implants on beef: Part 1—The texture of loin steaks from bovine males

Abstract

A total of 144 male crossbred calves were allocated to four castration or implant treatments (unimplanted bulls; unimplanted steers; bulls implanted with zeranol at 100 days of age and reimplanted at intervals of 69, 93, and 56 days thereafter; bulls implanted with zeranol at 168 days of age and reimplanted at intervals of 93 and 56 days thereafter) and two preslaughter shipping treatments (minimum preslaughter stress with cattle shipped and slaughtered within 4 h of leaving the feedlot pen; normal preslaughter stress with cattle mixed, trucked 160 km, and slaughtered up to 24 h after leaving the feedlot pen). These cattle were slaughtered and striploins of these steaks were removed after 6 days of post-mortem aging. Evaluations of these steaks were then conducted using both an experienced laboratory taste panel and a highly trained professional texture profile panel. Results indicated that: (1) the differences that existed in palatability between steaks from unimplanted bulls and steers were primarily due to differences in textural properties directly related to tenderness; (2) increases in preslaughter stress levels were detrimental to the eating quality of both intact males and castrates; (3) zeranol implants had little effect on the textural properties of bull steaks when minimum levels of preslaughter stress were applied; (4) zeranol implants in combination with normal levels of preslaughter stress resulted in steaks which readily broke down to a wide range of particle types many of which were inappropriate and detracted from a well balanced beef texture, thereby more than offsetting the beneficial effects observed on textural properties directly related to tenderness, thus, reducing the texture amplitude; and (5) the influence of the combination of zeranol implants and normal preslaughter stress on textural properties may be manifested through the production of ‘dark cutting’ beef.