Identification of halothane genotypes by calcium accumulation and their meat quality using live pigs

Rheological characteristics of fresh and frozen PSE, normal and DFD chicken breast meat

1. Textural and rheological differences among broiler breast meat ranging from pale, soft and exudative (PSE) to dark, firm and dry (DFD) in their fresh and frozen (and thawed) forms were investigated. 2. The PSE meat showed significantly higher lightness values and lower pH and water holding capacity values than normal and DFD meats; DFD meat was also significantly different from normal meat. 3. During cooking, PSE meat lost significantly more liquid and produced a softer gel than normal or DFD meats; texture profile analysis parameters were lower for the PSE meat. 4. The storage modulus values (G', rigidity of elastic response of the gelling material) showed that DFD meat produced a more rigid gel during cooking (especially above 54 degrees C) and later during cooling (back to 30 degrees C) compared with the PSE meat. 5. Freezing resulted in a trend of lower G' values before, during and after cooking. The results indicated that meat proteins were damaged during freezing and PSE meat was more severely affected, or that more protein denaturation occurred in the PSE meat.

The use of halothane gas to identify turkeys prone to developing pale, exudative meat when transported before slaughter

Halothane screening has been used in the swine industry to identify animals susceptible to stress and prone to developing pale, soft, exudative (PSE) meat. This study evaluated the ability of halothane to identify stress-susceptible turkeys prone to developing PSE meat when reared to market age and transported before slaughter. Male Nicholas turkeys (n = 1,286) were exposed to 3% halothane for 5 min at 4 wk of age in two trials. Birds were classified as halothane sensitive (HAL+) or halothane nonresponder (HAL-), in which HAL+ birds showed signs of muscle rigidity in the legs upon removal from halothane gas, and HAL- birds showed no stiffness response. Approximately 3.5% (45) of the turkeys were HAL+. All HAL+ birds and an equal number of HAL- birds were grown until 20 wk of age. Immediately prior to slaughter, all birds were transported in coops on a flatbed trailer for 2 h and then immediately slaughtered upon arrival at the processing plant. Breast muscle pH (0, 1.5, and 24 h postmortem) and L* value (1.5 h and 24 h postmortem) were measured on the fillets. Drip loss and cook loss were also determined on marinated and nonmarinated breast fillets from each carcass. There were no significant mean differences in any parameter measured between the HAL+ and HAL- turkeys. However, the HAL+ turkeys had a greater percentage of fillets with L* values >51 compared with the HAL- turkeys. These results suggest that either halothane response is only a limited predictor of PSE meat in turkeys or that transportation is not an appropriate stressor to induce the PSE condition.

The development of pale, exudative meat in two genetic lines of turkeys subjected to heat stress and its prediction by halothane screening

Previous research has indicated that seasonal-type heat stress (HS) can contribute to the development of pale, soft, exudative (PSE) meat in fast-growing turkeys and that halothane exposure may identify stress-susceptible animals. This study evaluated the ability of halothane screening to identify stress-susceptible birds prone to developing pale, exudative meat when reared to market age. Two lines of turkeys (n = 292), one selected for rapid overall growth (BODY) and the other for large breast muscle yield (BREAST), were exposed to 3% halothane for 5 min at 2 to 4 wk of age and were raised together until 16 wk of age. Approximately 10% of both BODY and BREAST birds were sensitive to halothane. Between 16 and 20 wk, all of the halothane sensitive (HAL+) and half of the halothane nonresponders (HAL-) were exposed to an HS environment of 30 to 36 C (night/day), whereas the other half of the HAL- birds were kept at an ambient temperature of 13 to 21 C (night/day). All birds were slaughtered at 20 wk of age, and samples were collected for pH, L* value, drip loss, cooking loss, and shear value. The BREAST strain had 5% greater breast percentage than the BODY strain, and there were no differences in ready-to-cook yields between any treatments. The HAL+ HS birds had significantly lower muscle pH (0 h) and significantly higher L* values at 2 h postmortem compared with HAL- HS birds in the BREAST strain; however, there was no difference in L* value at 24 h postmortem. The HAL- HS birds had significantly lower muscle pH (0 h and 2 h) and significantly higher L* values at 2 h postmortem compared with HAL- controls in the BODY strain. The HAL- HS BREAST birds had significantly higher drip loss than HAL- controls. No differences in shear value were found among any treatments. The incidence of PSE (2-h L* values >52) was significantly higher in HAL+ HS birds (34.7%) compared with HAL- HS birds (13.4%). These results suggest that halothane sensitivity early in life is associated with HS susceptibility and the development of pale meat when birds are slaughtered at market age. These results also suggest that halothane screening may be better at predicting the development of PSE meat during HS in the strain selected for large breast yield rather than rapid overall growth.