Progress 10/01/02 to 12/31/05
Outputs
The objectives of these studies were to determine if novel polymorphisms exist in the skeletal muscle calcium release channel (ryanodine receptor) that affect stress susceptibility, incidence of non-ambulatory (NA) pigs, or pork quality. In Trial I, piglets were obtained from mating a HAL-1843 normal-sire line to four dam lines (Lines A, B, C and D; n= 168, 170, 168 and 169, respectively). In Trial II, piglets from lines A and B (n = 87 and 90, respectively) were included with piglets obtained from mating four HAL-1843 normal-sire lines to one dam line (Lines E, F, G and H; n = 94, 92, 89 and 89, respectively). Pigs were subjected to 3% halothane at approximately 9 wk of age. Halothane sensitivity (HS) was observed in 59% of the pigs (Trial I). To better characterize this response, a scoring system was developed (Trial II): HS-low (HS-L), HS-intermediate (HS-I) and HS-high (HS-H). Using this system, 24, 41 and 34% of the pigs in E and 40, 33 and 27% of the pigs in G
were categorized as HS-L, HS-I and HS-H, respectively. In F and H, 13 and 18% of the pigs were HS-I and 0 and 2% HS-H pigs were observed, respectively. No consistent effects due to HS were observed in carcass composition or meat quality. To determine if HS pigs were more susceptible to stressors, pigs exhibiting low (HS-L; n = 33), intermediate (HS-I; n = 10) and high (HS-H; n = 47) sensitivity to halothane were subjected to an experimental model of rigorous handling. Pigs that were HS-H were more prone to becoming NA compared with HS-L pigs (P < 0.02). A greater number of pigs exhibited open-mouth breathing and skin discolorations immediately post-test than at the pre-test or 1 h post-test periods (P < 0.05) regardless of halothane status. No differences were observed in blood metabolites between the different halothane sensitivity categories. However, pigs that became NA received more prods per pig and had elevated levels of creatine phosphokinase, lactic acid, glycerol,
non-esterified fatty acids, ammonia, and blood urea nitrogen prior to testing (P < 0.05). Following the handling model, pigs were harvested and meat quality data were collected. Initial loin muscle pH was similar, but HS-I and HS-H had a lower ultimate pH and higher loin muscle drip losses than HS-L pigs (P < 0.05). Ryanodine binding assays were conducted to quantify differences in calcium release properties between HS-H (n=18) and HS-L (n=18) pigs. No differences were observed in the dissociation constant or in maximal binding of ryanodine between these two groups. However, a wide range of dissociation constants was observed among pigs. Examination of the entire RYR cDNA sequence revealed no differences in the predicted amino acid sequence that would explain the observed functional differences. Collectively, these data demonstrate that some pigs are sensitive to halothane anesthesia even in the absence of the known HAL-1843 polymorphism and HS-H pigs are more susceptible to becoming
NA than HS-L pigs. Observed genotype-phenotype associations suggest that differences in proteins associated with the ryanodine receptor may be responsible for stress susceptibility associated with NA pigs and inferior meat quality.
Impacts
Halothane sensitivity in pigs has previously been associated with a deleterious mutation (Hal-1843) in the skeletal muscle sarcoplasmic reticulum calcium release channel (RYR1), which results in increased stress susceptibility and a higher incidence of pale, soft and exudative pork products. Identification of halothane sensitivity in pigs that are free of the Hal-1843 mutation suggests that other polymorphisms associated with abnormal calcium regulation may exist. Sequencing of RYR1 cDNA revealed several single nucleotide polymorphisms, but none were predicted to change the amino acid sequence of the calcium release channel protein. Nevertheless, pigs with abnormal halothane sensitivity were more prone to becoming non-ambulatory during rigorous handling, and these pigs also produced inferior quality pork. Additionally, some pigs appear to exhibit hyper metabolic condition(s) that predispose them to becoming non-ambulatory. Understanding the relationship between
halothane sensitivity and increased muscle metabolism in Hal-1843-normal pigs should help identify the biological cause(s) of hyper metabolic condition(s) that result in non-ambulatory pigs and those that produce pale, soft and exudative pork. Each of these problems potentially costs the U.S. pork industry 80 to 100 million dollars per year.
Publications
- Allison, C.P., Johnson, R.C. and Doumit, M.E. 2005. The effects of halothane sensitivity on carcass composition and meat quality in HAL-1843-normal pigs. J. Animal Sci. 83:671-678.
- Allison, C.P., Marr, A.L., Berry, N.L, Anderson, D.B., Ivers, D.J., Richardson, L.F., Keffaber, K., Johnson, R.C. and Doumit, M.E. 2006. Effects of halothane sensitivity on mobility status and blood metabolites of HAL-1843-normal pigs after rigorous handling. J. Anim. Sci. 84:(In Press).
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Progress 01/01/04 to 12/31/04
Outputs
The long-term objective of this research is to determine if novel polymorphisms exist in the skeletal muscle calcium release channel that affect stress susceptibility, mobility status and meat quality of commercial swine. In Trial I, piglets were obtained from mating a HAL-1843 free-sire line to four dam lines (Lines A, B, C and D; n= 168, 170, 168 and 169, respectively). In Trial II, piglets from lines A and B (n = 87 and 90, respectively) were included with piglets obtained from mating four HAL-1843 free-sire lines to a single dam line (Lines E, F, G and H; n = 94, 92, 89 and 89, respectively). Pigs were subjected to 3% halothane at approximately 9 weeks of age. Halothane sensitivity (HS) was observed in 59% of the pigs (Trial I). To better characterize this response, a scoring system was developed (Trial II): HS-low (HS-L), HS-intermediate (HS-I) and HS-high (HS-H). Using this system, 24, 41 and 34% of the pigs in E and 40, 33 and 27% of the pigs in G were
categorized as HS-L, HS-I and HS-H, respectively. In F and H, 13 and 18% of the pigs were HS-I and 0 and 2% HS-H pigs were observed, respectively. No consistent effects due to HS were observed in carcass composition or meat quality. To determine if HS pigs were more susceptible to stressors, 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 eight pigs were briskly moved down the aisle and back four times receiving a minimum of one electrical prod per pass (8 prods/pig). Prior to testing, rectal temperature was measured, open-mouth breathing and skin discoloration were visually evaluated and a blood sample was collected from each pig. Following the test, pigs were returned to their pen and the same measurements were taken immediately post-test and 1 h post-test (no blood at 1h time). Pigs that were HS-H
tended to be more prone to becoming NA compared to HS-L or HS-I (P = 0.14). A greater number of pigs exhibited open-mouth breathing and skin discolorations immediately post-test than at the pre-test or 1 h post-test periods (P < 0.05) regardless of halothane status. No differences were observed in blood metabolites between the different categories of halothane sensitivity (P > 0.05). However, pigs that became NA received more prods per pig and had elevated levels of creatine phosphokinase, lactic acid, glycerol, non-esterified fatty acids, ammonia, and blood urea nitrogen prior to testing (P < 0.05). Following the handling model, pigs were transported to harvesting facilities and meat quality data were collected. No differences were observed in the initial pH, but HS-I and HS-H pigs had a lower ultimate pH and higher drip losses than HS-L (P < 0.05). Collectively, these data demonstrate that some pigs are sensitive to halothane anesthesia even in the absence of the known HAL-1843
polymorphism and suggest HS pigs are more susceptible to becoming NA and producing inferior quality pork.
Impacts
Halothane sensitivity in pigs has previously been associated with a deleterious mutation (Hal-1843) in the skeletal muscle sarcoplasmic reticulum calcium release channel (RYR1), which resulted in increased stress susceptibility and a higher incidence of pale, soft and exudative pork products. Identification of halothane sensitivity in pigs that are free of the Hal-1843 mutation suggests that other polymorphisms associated with abnormal calcium regulation may exist. Identification and elimination of novel polymorphisms in the calcium release channel should reduce the incidence of non-ambulatory pigs and pale, soft and exudative pork products. The latter costs the U.S. pork industry an estimated 88 million dollars per year.
Publications
- Allison, C.P., R.C. Johnson and M.E. Doumit. 2005. The effects of halothane sensitivity on carcass composition and meat quality in HAL-1843-normal pigs. J. Animal Sci. 83:(In Press)
- Allison, C.P., R.C. Johnson and M.E. Doumit. 2004. The effects of halothane sensitivity on carcass composition and meat quality in HAL-1843-free pigs. J. Anim. Sci. 82(Suppl. 2):58.
- Allison, C.P., A.L. Marr, N.L. Berry, D.B. Anderson, D.J. Ivers, L.F. Richardson, K. Keffaber, R.C. Johnson, M.E. Doumit. 2004. Impact of halothane sensitivity on mobility status and blood metabolites of HAL-1843-free pigs following an aggressive handling model. J. Anim. Sci. 82(Suppl. 2):33.
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Progress 01/01/03 to 12/31/03
Outputs
The objectives of this study were to determine the incidence of halothane sensitivity in HAL-1843-free pigs and the relationships between halothane sensitivity, carcass composition and meat quality. In Trial I, piglets (Lines A, B, C and D; n= 168, 170, 168 and 169, respectively) were obtained from mating a HAL-1843 free-sire line to four dam lines. In Trial II, 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 free-sire lines to a single dam line. Pigs were subjected to 3% halothane at approximately 9 weeks of age. In Trial I, limb rigidity, blotching of the skin and muscle tremors were visually assessed. 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 Trial II. Using this system, 25, 42 and 33% of the pigs in E and 40, 33
and 27% of the pigs in 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 pigs, respectively. No consistent effects due to HS were observed in carcass composition or meat quality. However, when a subset of pigs were subjected to more extensive handling and transportation, followed by harvest at plants that utilize electrical stunning, ultimate pH was lower and drip loss was higher in loin muscle from HS-H compared to HS-L pigs (P < 0.05). These data 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.
Impacts
Halothane sensitivity in pigs has previously been associated with a deleterious mutation (Hal-1843) in the skeletal muscle sarcoplasmic reticulum calcium release channel (RYR1), which resulted in increased stress susceptibility and a higher incidence of pale, soft and exudative pork products. Identification of halothane sensitivity in pigs that are free of the Hal-1843 mutation suggests that other polymorphisms associated with abnormal calcium regulation may exist. Identification and elimination of novel polymorphisms in the calcium release channel should reduce the incidence of non-ambulatory pigs and pale, soft and exudative pork products. The latter costs the U.S. pork industry an estimated 88 million dollars per year.
Publications
- Doumit, M.E., Allison, C.P., Helman, E.E., Berry, N.L., Ritter, M.J. 2003. Biological basis for pale, soft and exudative pork. Proc. Reciprocal Meat Conf. 56:9-15. Available at: http://www.meatscience.org/Pubs/rmcarchv/2003/index.html#
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