Spirometric performance in Belgian Blue calves: II. Analysis of environmental factors and estimation of genetic parameters

Genetic parameters and environmental effects for spirometric variables (SV) in calves were estimated using 734 Belgian Blue calves (15 to 297 d of age ), sired by 20 AI bulls. For each calf, the following SV were measured: 1) the average ventilation (l/min) recorded during the 15 s of maximal ventila tory changes induced by lobeline administration (0.25 mg/kg, i.v.) (15-s MV L); 2) the vital capacity, and the maximal peak expiratory and inspiratory flows recorded after lobeline administration; and 3) the ventilatory reserv e (15-s MVL - ventilation at rest). Analysis of environmental factors showe d age of calf, herd, sex, and vaccination status had significant effects on SV. A sire model and a multiple-trait derivative-free REML procedure were used to estimate genetic parameters for SV, body weight, and muscling score . Heritabilities for SV ranged from 0.28 +/- 0.11 to 0.44 +/- 0.16. Genetic correlations among SV varied from 0.76 to 0.98 and environmental correlati ons from 0.69 to 0.80. Genetic correlations of SV with body weight (0.25 to 0.56) and with muscling score (0.21 to 0.76) were positive, as were enviro nmental correlations of SV with body weight (0.44 to 0.70) and muscling sco re (0.09 to 0.25). These results suggest; that; selection may improve SV wi thout impairing other traits of economic importance.