Frequency of the HAL-1843 mutation of the ryanodine receptor gene in dead and nonambulatory-noninjured pigs on arrival at the packing plant
2008
Ritter, M.J. | Ellis, M. | Hollis, G.R. | McKeith, F.K. | Orellana, D.G. | Van Genugten, P. | Curtis, S.E. | Schlipf, J.M.
Four Midwestern packing plants (designated as plants A, B, C, and D) were visited on 53 occasions, and tissue samples were collected postmortem from a total of 2,019 pigs to determine the frequency of the HAL-1843 mutation of the ryanodine receptor gene in dead (DOA), nonambulatory-noninjured (NANI), and normal animals. The sampled pigs came from approximately 130,000 animals from 454 farms and were transported on 861 trailer loads, with an average of 152 pigs/load and an average pig live BW/load of 125 (SD 7.02) kg/pig. Frequency of animals with the HAL-1843 mutation was low, with only 2.7% of the pigs being either homozygous recessives (nn, 0.45%) or carriers (Nn, 2.3%) for the mutation and 97.3% of the pigs being homozygous for the normal allele (NN). The mutation was present in all 3 classes of pig, with 1.8% of normal, 1.8% of NANI, and 4.7% of DOA animals having at least 1 copy. Two of the plants (A and C) had a greater frequency (P < 0.05) of carrier (3.7 and 3.5 vs. 1.1 and 1.0 for plants A and C vs. B and D, respectively) and homozygous recessive (1.0 and 0.9 vs. 0.0 and 0.0, respectively) animals than the others (plants B and D). There was a greater frequency (P < 0.05) of carriers in DOA animals than in the normal or NANI pigs (3.7 vs. 1.7 and 1.5 for DOA vs. normal and NANI, respectively). The 55 pigs that had at least 1 copy of the mutation came from 53 farms; therefore, the mutation was relatively widespread, being present in approximately 11% of the farms sampled. Although the HAL-1843 mutation is still present in commercial pig populations in the United States, its low frequency in DOA and NANI pigs suggests that it is not a major cause of these transport losses.
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