Joint analysis of the influence of CYP11B1 and DGAT1 genetic variation on milk production, somatic cell score, conformation, reproduction, and productive lifespan in German Holstein cattle
2007
Kaupe, B. | Brandt, H. | Prinzenberg, E.M. | Erhardt, G.
Recent publications indicate genetic variation in milk production traits on proximal BTA14, which cannot be explained solely with genetic variation in the DGAT1 gene. To elucidate these QTL effects, animals from a German Holstein granddaughter design (18 families, 1,291 sons) were genotyped for CYP11B1 (V30A) and DGAT1 (K232A) polymorphisms. Frequencies of alleles of maternal descent were estimated for CYP11B1V (0.776) and DGAT1K (0.549). Allele substitution effects (α/2) were first calculated for both alleles in separate models and then in a joint model. From the joint analysis, CYP11B1V effects on fat content (+0.04%) and protein content (+0.01%) were positive. Effects on milk yield (-82 kg), fat yield (-0.5 kg), and protein yield (-1.9 kg) were negative. Compared with the individual analysis, DGAT1K effects on fat content (+0.28%), protein content (+0.06%), and milk yield (-258 kg) were reduced; fat yield (+10.8 kg) was enhanced; and protein yield (-3.8 kg) was reduced. In the joint analysis, allele substitution effects of CYP11B1V and DGAT1K together explained more of the variation in milk production traits than DGAT1K alone. Further significant effects were found for CYP11B1V and DGAT1K among 6 reproduction traits and 14 conformational traits. These observations indicate a possible negative influence of DGAT1K on maternal nonreturn rate, and thus, on length of productive life.
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