Frequency of the HAL-1843 mutation of the Ryanodine Receptor gene in dead and non-ambulatory/non-injured pigs on arrival at the packing plant

¹ Department of Animal Sciences, University of Illinois, Urbana 61801

^* To whom correspondence should be addressed. E-mail: mellis7{at}ad.uiuc.edu.

	Abstract

Four Midwestern packing plants (designated as plants A, B, C, and D) were visited on 53 occasions and tissue samples were collected from a total of 2,019 pigs to determine the frequency of the HAL-1843 mutation of the Ryanodine Receptor gene in dead (DOA), non-ambulatory/non-injured (NANI), and Normal animals. The pigs sampled came from ~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 weight/load of 125 (SD 7.02) kg/pig. Frequency of animals with the HAL-1843 mutation was low with only 2.7% of pigs being either homozygous recessives (nn; 0.45%) or carriers (Nn; 2.3%) for the mutation and 97.3% of pigs being homozygous for the normal allele (NN). The mutation was present in all 3 classes of pig with 1.81% of Normal, 1.90% of NANI, and 4.68% DOA animals having at least 1 copy. Two of the plants (A and C) had a higher frequency (P < 0.05) of carrier (3.72 and 3.49 vs. 1.08 and 1.01 for plants A, C, B, and D, respectively) and homozygous recessive (0.98 and 0.87 vs. 0.00 and 0.00, respectively) animals than the others (plants B and D). There was a higher frequency (P < 0.05) of carriers in DOA animals than in the Normal or NANI pigs (3.73 vs. 1.69 and 1.52 for DOA, Normal, and NANI, respectively). The 55 pigs that had at least 1 copy of the mutation came from 53 different farms and, therefore, the mutation was relatively widespread, being present in ~11% of farms sampled. Although the HAL-1843 mutation is still present in commercial pig populations in the U.S., its low frequency in DOA and NANI pigs suggests that it is not a major cause of these transport losses.

Key Words: dead, HAL-1843 mutation, non-ambulatory, pigs, transport losses