Stress-related behaviour, bleed-out times and some meat quality parameters from sheep slaughtered at a commercial abattoir

Author: Y.Z. Njisane & V. Muchenje
Year: 2014
Issue: 1
Volume: 7
Page: 22 - 30

The objective of this study was to determine the effect of breed, gender and age on Stress-related behaviour (AB) of sheep at slaughter, bleed-out times (BT) during exsanguination, and the quality of mutton. The behaviour of 90 castrates and 110 ewes of different age categories (<10months, 11-12 months, >12 months) was observed during three stages of slaughter, at a commercial abattoir. AB was not affected by breed, gender and age. BT was recorded as time intervals between the start of blood flow and the time the flow changed from a constant stream into drips. Ninety meat samples were obtained to measure meat colour, pH24, temperature24, cooking loss, and tenderness. Correlations between bleeding times and meat quality variables were also determined. Ewes had longer (68.5±1.48 s) bleed-out times than castrates (55.2±1.70s). Heavier sheep had longer bleeding times than the lighter ones (r=0.149). Cooking loss (CL) was higher in meat from older sheep and in meat from ewes than from younger sheep and castrates, respectively. Meat from the Dorper breed had the highest CL (39.6±1.38 %) and the lowest Warner Bratzler Shear Force (WBSF) (14.3±3.66 N). Meat from the Merino breed had the highest WBSF (33.9±3.24 N). pH24 was positively correlated to a* and b* colour ordinates. It can therefore be concluded that breed, gender and age had no effect on AB, while these factors affected some quality variables of mutton. Only gender had an effect on bleed-out times. Bleed-out times correlate with animal weight but poorly with the meat quality variables.

Keywords: cooking loss
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