Pigs from 4 farms were slaughtered at 2 abattoirs, each with 2 slaughter handling systems. Pigs at abattoir 1 were electrically stunned, either in a floor pen holding 5 pigs or a race restrainer. A straight race 1m wide led to the floor pen. A stepped collection pen and single file race led to the race restrainer. At abattoir 2 a single file curved race led to a floor pen with electrical stunning and a circular collection pen led to a double race and dip-lift C02 stunner. Each replicate involved 2 farms sending 50 pigs to each abattoir. There were 16 replicates (3200 pigs). Stun system had a significant effect on the development of early rigor, muscle pH, muscle colour and skin blemish (GLM Analysis of Variance). At abattoir 1, pigs slaughtered through the race restrainer had a greater tendency to develop early rigor and more skin blemish. Pigs slaughtered through the race restrainer also had lower pH in the m. longissimus dorsi at both initial and ultimate readings post mortem. In general, pH readings were higher than would be expected in the pig m. longissimus dorsi. Muscle reflectance was higher in the m. longissimus dorsi of pigs slaughtered through the race restrainer at both initial and ultimate readings. Significant differences between means at abattoir 1 (two-sample t-tests) are contained in Table 1. At abattoir 2, the floor pen produced carcases with a greater tendency to develop early rigor and more skin blemish. There were no significant differences in muscle pH or colour. Significant differences between means at abattoir 2 (two-sample t-tests) are contained in Table 2.
Live changes in muscle glycogen concentration of steers due to feeding and fasting as determined through serial biopsies of the Longissimus dorsi muscle
