|Van vleck, Lloyd|
Submitted to: Midwestern Section of the American Society of Animal Science
Publication Type: Other
Publication Acceptance Date: 2/1/2004
Publication Date: 3/1/2004
Citation: Snowder, G.D., Van Vleck, L.D., Cundiff, L.V., Gregory, K.E., Bennett, G.L. 2004. Effect of heterozygosity on the incidence of bovine respiratory disease [abstract]. Jouranl of Animal Science 82(Suppl. 2):36. Interpretive Summary: No interpretive summary required.
Technical Abstract: Bovine respiratory disease (BRD) is the leading cause of calf mortality. Breed differences in susceptibility to BRD are known but effect of heterozygosity is unknown. Effects of heterozygosity by breed type (B, British; C, Continental; I, Bos indicus) and general combining ability of 16 breeds were evaluated. Records of 71,140 purebred and crossbred calves over a 20 year period were analyzed with a single trait model using REML. Fixed effects in the model included a three factor combination (year, age of dam, and sex of calf) and calving difficulty code. Breed type heterozygosity (BB, BC, BI, CC, CI) of the calves and dams were calculated and included as 10 regression variables. Permanent environmental effect of the dam to account for repeated calving records was included. Random effects included animal and maternal genetic and maternal permanent environmental effects. The average annual incidence of BRD was 10.5%, ranging from 3.3 to 22.5%. Incidence of BRD was significantly less for all crossbred calves compared to purebred calves. Calves of BC and BI descent had less incidence of BRD than BB calves. Crosses within C or I types did not differ. Heterozygosity of dam increased BRD incidence when compared to purebred dams. Calves of CC dams had a significantly higher incidence of BRD than calves of purebred and other crossbred dams. Of the 16 breeds evaluated for general combining ability, Galloway, Red Poll, Saler, and Longhorn sired crossbred calves had the lowest BRD incidence. Limousin and Friesian crossbred calves had the highest BRD incidence. The general combining abilities of the Friesian, and Belgium Blue breeds for decreasing BRD incidence due to maternal heterozygosity were significantly better than several other breeds. Calf and maternal heterozygosity from Bos indicus breeds did not reduce the incidence of BRD. Reductions in incidence of BRD can result from choice of breeds to take advantages of type of combining ability.