|Van vleck, Lloyd|
Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract only
Publication Acceptance Date: 2/1/2003
Publication Date: 7/1/2003
Citation: Snowder, G.D., Van Vleck, L.D., Cundiff, L.V., Gregory, K.E., Bennett, G.L. 2003. Estimates of genetic parameters for respiratory disease in beef calves before weaning [abstract]. Journal of Animal Science Supplement 81(1):88. Interpretive Summary: No interpretive summary is required.
Technical Abstract: Respiratory disease is one of the most economically important illnesses affecting growth and survival of calves. The primary objective of this study was to estimate genetic parameters for respiratory disease in beef calves prior to weaning. Health records of 31,000 calves from the Meat Animal Research Center, Clay Center, NE from 1983 to 2001 were evaluated. Cows and calves were monitored daily for health until weaning at approximately 194 d of age. Breed groups consisted of nine purebred breeds (Angus, Braunvieh, Charolais, Gelbvieh, Hereford, Limousin, Pinzgauer, Red Poll, and Simmental), two reciprocal crosses between Angus and Herefords, and three composite breeds (MARC I, MARC II, and MARC III). Respiratory disease was detected by physical examination, necropsy, or laboratory analyses. To avoid multiple incidence records on the same calf which may be due to lingering respiratory disease, only the initial infection during the pre weaning period was considered. Overall average incidence of recorded respiratory disease was 11.6 %. Incidence was highest in Braunvieh (18.1 %) and MARC I (17.8%), a composite breed with one fourth Braunvieh heritage. Herefords and the Hereford x Angus cross had the lowest incidence (4.6 to 7.8 %). Incidence was highest after d 84. Variance components were estimated using REML. Fixed effects included year of birth, age of dam, sex of calf, and breed type. Calf and dam of the calf were considered random effects. Variance due to permanent environmental effects of the dams was not significant. Phenotypic variance for respiratory disease was 0.095. Heritability estimates for the calf direct and maternal effects were low, 0.14 +/- 0.01 and 0.04 +/- 0.01, respectively. Estimate of the direct-maternal genetic correlation was large and negative, -0.93 +/- 0.04. Large and significant breed differences for respiratory disease were found. Within breed, response to selection to reduce the incidence of respiratory disease in calves would be expected to be slow although breed differences suggest a potential to improve resistance by selection or crossbreeding.