Meat characteristics and stress of bison slaughtered in a mobile or stationary abattoir

Abstract

Meat characteristics and physiological stress measurements in bison exposed to different ante-mortem treatment groups and reasons behind the rapid discolouration of fresh bison meat (compared to beef) were examined. It was hypothesized that bison slaughtered on farm (dispatched in pen, MLAPEN, or confined then dispatched MLACON) through a mobile location abattoir (MLA), would have favourable meat characteristics and lower stress levels than those transported to a stationary abattoir (LAND). It was also hypothesized that differences in fatty acid profile, vitamin E levels, and oxidative properties of bison meat compared to beef, are related to the observed difference in retail shelf life. A higher incidence of carcasses graded as “dark” were observed in the LAND group. Improved tenderness measured through shear force (MLACON 7.28 kg and MLAPEN 7.40 kg vs. LAND 9.43kg) and initial tenderness sensory scores (MLACON 4.95, MLAPEN 4.55, vs. LAND 3.93; where 8= extremely tender and 1= extremely tough) was seen in the MLA groups. The lowest blood cortisol level was found in MLAPEN group compared to the MLACON or LAND groups (71.16 nmol/L, 124.17 nmol/L and 139.50 nmol/L respectively; P<0.01). Bruising was found in all treatment groups, however less was found on the MLA groups compared to the LAND group. Fatty acid composition was significantly different between bison and beef for all the fatty acids measured. The inherent tissue traits of bison were linked to poorer performance in the retail environment when compared to beef. Bison meat had higher polyunsaturated fatty acid levels, and a lower omega 6:omega 3 ratio than beef. Bison also had a lower total fat and higher pigment and vitamin E levels. Stepwise regression models included some of these traits and accounted for a significant proportion of the variation in metmyoglobin (R2 = .689), % discolouration (R2 = .737) and appearance (R2 = 0.676) between d 0 and d 3 in retail. An improved understanding of the effects of ante mortem handling and the inherent characteristics of bison meat will improve animal welfare and help create an improved eating experience for the consumer.