Effects of halothane sensitivity on mobility status and blood metabolites of HAL-1843-normal pigs after rigorous handling.

The objective of this study was to determine if HAL-1843-normal pigs that respond abnormally to halothane anesthesia were more likely to become nonambulatory (NA) when subjected to rigorous handling than pigs that exhibit a normal response to halothane. After a 1,100-km transport, pigs exhibiting low (HS-L; n = 33), intermediate (HS-I; n = 10), and high (HS-H; n = 47) sensitivity to halothane were moved through a 36.6-m long aisle that was 2.1 m wide at each end and 0.6 m wide in the middle 18.3 m. Ten groups of 8 pigs were briskly moved down the aisle and back 4 times, receiving a minimum of 1 electrical prod per pass (8 prods/pig). Before testing, rectal temperature was measured, open-mouth breathing and skin discoloration were visually evaluated, and a blood sample was collected from each pig. After the test, the pigs were returned to their pens, and the same measurements were taken immediately posttest and 1 h posttest (no blood at 1 h posttest). Pigs that were HS-H were more prone to becoming NA compared with HS-L pigs (P < 0.02). Regardless of halothane status, a greater number of pigs exhibited open-mouth breathing and skin discolorations immediately posttest than at the pretest or 1 h posttest times (P < 0.05). No differences were observed in blood metabolites between the different halothane sensitivity categories. However, pigs that became NA had elevated blood levels of creatine phosphokinase, lactate, glycerol, nonesterified fatty acids, ammonia, and urea nitrogen before testing (P < 0.05). Collectively, these data suggest HS-H pigs are more susceptible to becoming NA than HS-L. The elevated pretest blood metabolites of NA pigs suggest that they were in a hypermetabolic state that predisposed them to becoming NA.

The effects of halothane sensitivity on carcass composition and meat quality in HAL-1843-normal pigs.

Objectives of this study were to determine the incidence of halothane sensitivity in pigs that are homozygous normal at the ryanodine receptor nucleotide 1843 (HAL-1843-normal) and the relationships between halothane sensitivity and carcass composition or meat quality. In Exp. 1, piglets (Lines A, B, C, and D; n = 168, 170, 168, and 169, respectively) were obtained from mating a HAL-1843-normal sire line to four HAL-1843-normal dam lines. In Exp. 2, piglets from Lines A and B (n = 87 and 90, respectively) were included with piglets (Lines E, F, G, and H; n = 94, 92, 89, and 89, respectively) obtained from mating four HAL-1843-normal sire lines to a single HAL-1843-normal dam line. Pigs were subjected to 3% halothane at approximately 9 wk of age. In Exp. 1, limb rigidity, blotching of the skin, and muscle tremors were visually assessed, and based on these criteria, halothane sensitivity (HS) was observed in 48% of the pigs. To better characterize this response, a scoring system was developed and used in Exp. 2. Using this system, 25, 42, and 33% of the pigs in E and 40, 33, and 27% of the pigs in Line G were categorized as HS-low (HS-L), HS-intermediate (HS-I), and HS-high (HS-H), respectively. In Lines F and H, 13 and 18% of the pigs were HS-I, and 0 and 2% were HS-H, respectively. No consistent effects due to HS were observed in carcass composition or meat quality; however, when a subset of pigs from Exp. 2 were subjected to more extensive handling and transportation before slaughter, ultimate pH was lower and drip loss was higher in LM from HS-H compared with HS-L pigs (P < 0.05; n = 71). These results demonstrate that some pigs are sensitive to halothane anesthesia even in the absence of the known HAL-1843 polymorphism. Additionally, halothane sensitivity may be associated with inferior pork quality under adverse antemortem conditions.

A research note on radio frequency transponder effects on bloom of beef muscle.

This study was designed to determine if radio frequency transponders affect the bloom of tray-packed beef muscle. A radio frequency identification (RFID) passive transponder was applied to the overwrap film of beef strip loin steaks. Overwrapped tray packs were vacuum packaged and stored for two days at 4 °C. Samples were removed from the vacuum package and CIE L(*), a(*), and b(*) values were measured through the overwrap until CIE a(*) values stabilized (40 min). Overwrap was removed and CIE L(*), a(*), and b(*) values were measured directly below the RFID and an adjacent control area for 40 min. All CIE L(*), a(*), and b(*) values were statistically different (P<0.05) directly below the RFID when compared to the adjacent control area. The greatest differences were observed in the initial values and may be of consumer concern. After achieving full bloom (40 min post-overwrap removal), the difference between these areas were negligible.

Pork quality variation is not explained by glycolytic enzyme capacity.

Our objective was to determine if increased glycolytic enzyme capacity accommodates rapid glycolysis, which leads to inferior pork color and water-holding capacity. Progeny from HAL-1843 free Duroc (n=16) or Pietrain (n=16) sires were harvested over a 2-week period. Coupled enzyme assays were used to quantify total capacity of pyruvate kinase (PK) and phosphofructokinase (PFK) in the sarcoplasmic fractions and crude homogenates of longissimus muscle (LM), respectively. Capacity of PK was not correlated with LM pH (20, 45, 180 min or 24 h), purge, drip loss, or CIE L* (P > 0.2). However, PFK capacity was inversely related to fluid loss (P<0.05). This finding was unexpected, but may result from PFK becoming partially denatured and inactivated by 20 min postmortem in samples that undergo a rapid pH decline. These data indicate that lighter pork color and reduced water-holding capacity are not associated with an increase in the capacity of enzymes that catalyze regulated steps of glycolysis.