The effects of selection for lean growth and the halothane allele on carcass and meat quality of pigs transported long and short distances to slaughter

Carcass and lean quality traits were studied in two genetic lines of pigs in which the halothane allele n was segregating with the normal allele N. One line had been selected for high growth rate and low backfat depth and the other line maintained as an unselected control. Pigs of the three segregants NN, Nn and nn from both lines were grown at two locations, one near the abattoir (1 h by road) and the other far (10 h) from the same abattoir. Pigs from both locations were fasted for 20 h before slaughter. Relative to control line pigs, those from the selected line had lower backfat depths, greater ham weights, eye muscle areas and carcass lengths but lower dressing percentages. The n allele had little effect on carcass traits but for lean quality traits, the n allele acted additively to increase acidity, paleness, water lost through drip, centrifugation and cooking and to reduce cured yield. Independently of the n allele, selection for lean growth increased the incidence of dark, firm and dry (DFD) pork. This was highest in carcasses of NN pigs from the selected line grown far from the abattoir. nn pigs from the control line grown near the abattoir produced the most pale, soft, exudative (PSE) pork

The effects of selection for lean growth and the halothane allele on carcass and meat quality of pigs transported long and short distances to slaughter

Carcass and lean quality traits were studied in two genetic lines of pigs in which the halothane allele n was segregating with the normal allele N. One line had been selected for high growth rate and low backfat depth and the other line maintained as an unselected control. Pigs of the three segregants NN, Nn and nn from both lines were grown at two locations, one near the abattoir (1 h by road) and the other far (10 h) from the same abattoir. Pigs from both locations were fasted for 20 h before slaughter. Relative to control line pigs, those from the selected line had lower backfat depths, greater ham weights, eye muscle areas and carcass lengths but lower dressing percentages. The n allele had little effect on carcass traits but for lean quality traits, the n allele acted additively to increase acidity, paleness, water lost through drip, centrifugation and cooking and to reduce cured yield. Independently of the n allele, selection for lean growth increased the incidence of dark, firm and dry (DFD) pork. This was highest in carcasses of NN pigs from the selected line grown far from the abattoir. nn pigs from the control line grown near the abattoir produced the most pale, soft, exudative (PSE) pork

Plasma and muscle cortisol measurements as indicators of meat quality and stress in pigs

Post-slaughter blood samples and muscle samples were collected from pigs slaughtered at the completion of a live-animal performance trial. There were two lines of pigs in which the halothane allele (n) was segregating. The lines were a lean line selected for rapid lean growth and an unselected fat line. There were homozygous normal (NN), homozygous halothane positive (nn) and heterozygous (Nn) genotypes in both lnes. Cortisol was measured in the plasma of the blood samples and in muscle juice obtained by high-speed centrifugation. Meat quality was assessed using pH, colour, fibre-optic probe, drip loss and cure yield measurements. Plasma cortisol concentrations in the fat line were significantly (P < 0·05) greater than thosein the lean line but concentrations did not differ significantly for the three halothane genotypes. Carcasses classified as dark, firm and dry (DFD) had significantly (P < 0·05) greater muscle cortisol concentrations than those classified as normal. Plasma and muscle cortisol concentrations of carcases classified as pale, soft and exudative (PSE) did not differ significantly from those classified as normal. Correlations between muscle cortisol and meat quality attributes were generally highly significant (r = 0·31 to r = 0·51, P < 0·001) There was a highly significant correlation (r = 0·73, P < 0·0001) between plasma and muscle cortisol concentrations

Responses in carcass lean pH at 24 hours post-mortem in lines of Large White pigs selected for growth rate on a fixed ration over a set time

A restricted maximum likelihood analysis applied to an animal model showed no significant differences (P > 0.05) in pH value of the longissimus dorsi measured at 24 h post-mortem (pH24) between high and low lines of Large White pigs selected over 4 years for post-weaning growth rate on restricted feeding. Genetic and phenotypic correlations between pH24 and production and carcass traits were estimated using all performance testing records combined with the pH24 measurements (5.05-7.02) on slaughtered animals. The estimate of heritability for pH24 was moderate (0.29 ± 0.18). Genetic correlations between pH24 and production or carcass composition traits, except for ultrasonic backfat (UBF), were not significantly different from zero. UBF had a moderate, positive genetic correlation with pH24 (0.24 ± 0.33). These estimates of genetic correlations affirmed that selection for increased growth rate on restricted feeding is likely to result in limited changes in pH24 and pork quality since the selection does not put a high emphasis on reduced fatness

The effect of the Halothane gene on performance, carcass and meat quality in a fat and a lean line of pigs

The performance, carcass and meat quality of two lines of pigs in which the halothane allele (n) was segregating were studied. The lines were a lean line selected for rapid lean growth and an unselected fat line. Heterozygous (Nn) and homozygous normal (NN) segregants in both lines were compared in an environment of high temperature and pre-slaughter transport stress. Relative to the fat line, the lean line grew faster, ate more, was a more efficient converter of food and produced leaner carcasses. It also produced less acid and darker lean with less water loss. The halothane allele had a much greater effect in the lean than the fat line. It reduced appetite, growth rate and food conversion ratio and increased the acidity, paleness and water loss from lean. In both lines, but particularly in the lean line, the halothane allele increased the incidence of death in transit to slaughter

The effect of the Halothane gene on performance, carcass and meat quality in a fat and a lean line of pigs

The performance, carcass and meat quality of two lines of pigs in which the halothane allele (n) was segregating were studied. The lines were a lean line selected for rapid lean growth and an unselected fat line. Heterozygous (Nn) and homozygous normal (NN) segregants in both lines were compared in an environment of high temperature and pre-slaughter transport stress. Relative to the fat line, the lean line grew faster, ate more, was a more efficient converter of food and produced leaner carcasses. It also produced less acid and darker lean with less water loss. The halothane allele had a much greater effect in the lean than the fat line. It reduced appetite, growth rate and food conversion ratio and increased the acidity, paleness and water loss from lean. In both lines, but particularly in the lean line, the halothane allele increased the incidence of death in transit to slaughter