Factors influencing the welfare and carcass and meat quality of pigs 2. Mixing unfamiliar pigs

Abstract

Mixing pigs from different social groups is known to cause turmoil which often results in skin lacerations as well as dark, firm and dry meat. Nine hundred and sixty commercial crossbred pigs were used for this experiment, divided into eight consignments. Within each consignment the pigs were divided into groups of about 15. The pigs in each group had coexisted for at least 6 weeks prior to slaughter. Thirty min before loading for slaughter, groups of pigs were either mixed with unfamiliar pigs or not mixed. Similarly, on arrival at the abattoir, groups of pigs were either mixed or not mixed. Hence there were four possible treatment combinations: pigs mixed with unfamiliar animals at loading, mixed at unloading, mixed at both points, or pigs which had remained in their social groups for at least 6 weeks prior to slaughter. Carcasses were dressed according to normal practice. After 20 h in the chiller room carcasses were assessed for skin blemish and fibre optic probe (FOP) values were measured in the longissimus dorsi muscle. Mixing pigs at either loading or unloading, or at both points, had no significant effect on the FOP value, but it did have a significant effect on the frequency of skin blemish values. Skin blemish values increased due to mixing at the farm (+0-36, Meat and Livestock Commission scale) however mixing at both places did not have an additive effect. The results indicate that the ideal movement system might be to keep pigs in their farm pen social groups until the point of slaughter.

The effects of handling and group size on welfare of pigs in lairage and their influence on stomach weight, carcass microbial contamination and meat quality

“…In this study, climbing behaviour was observed more often than turning around at this stage, as a result of the combined effect of electric goading and reduced space allowance. It is well documented that when space is decreased, turning around is limited and pigs try to escape from the stressor (the electrical shock and the handler in this study) by climbing over the backs of other pen mates in search of protection within the group (Guise and Penny 1989;Lambooj and Engel 1991).…”

Effect of pre-slaughter overnight feed withdrawal on pig carcass and muscle quality

“…Pre-slaughter fasting without mixing results in a low frequency of skin blemishing due to fighting, whereas mixing, with or without fasting, has a substantial negative effect on the frequency of skin blemish scores (Murray and Jones 1994;Warriss 1996;Guise and Penny 1989). Although not always commercially practical, the extent of fighting due to mixing can be minimised by keeping pigs in small groups (Barton-Gade et al 1996), by optimising stocking density and by limiting the length of lairage at the abattoir (Geverink et al 1996).…”

The effect of mixing, feed restriction and genotype with respect to stress susceptibility on pork carcass and meat quality

“…Each week pigs from at least two of the three genotypes were allocated to each For personal use only. Mixing (Guise and Penny 1989;Karlsson and Lundstrom 1992) and fasting (Jones et al 1985;Fischer et al 1986;Murray et al 1989;Eikelenboom at al. 1991) …”

“…Yet, the pH at 45 min post-slaughter, the colour and the drip loss of the longissimus muscle were unaffected. Guise and Penny (1989) found that Fibre Optic Probe (FOP) values were not affected by mixing prior to shipping from the farm or after arriving at the abattoir, whereas mixing prior to leaving the farm increased the frequency of skin blemishes.…”