Is the productivity of cows heterozygous for the cholesterol deficiency gene low?
2019
Kudo, S. (Obihiro University of Agriculture and Veterinary Medicine (Japan). Department of Clinical Veterinary Medicine) | Moriyama, S. | Suzuki, S. | Inokuma, H.
As cholesterol deficiency (CD) of Holstein-Friesian cows is an autosomal recessive disorder, clinical symptoms should not occur in heterozygous individuals. However, the serum total cholesterol (TC) level in healthy heterozygous bulls has been reported to be lower than that in wild-type animals. In the present study, serum TC and milk production of healthy heterozygous cows were evaluated to clarify the effect of heterozygosity on milk production. A total of 93 (14.9%) among 718 clinically healthy cows on five farms were found to be heterozygous. The serum TC level of the heterozygous group was significantly lower than that of the wild-type group. In one of the two farms where milk production data were available, the corrected 305-day milk yield of heterozygous cows was significantly lower than that of wild-type cows. In another farm, the corrected 305-day milk yield of heterozygous cows was numerically lower than that of wild-type cows. The corrected 305-day milk fat, protein and solids-not-fat percentages were higher or significantly higher in the heterozygous group compared with wild-type cows. There were no differences in open period or insemination frequency between the two groups.
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