Genetic selection for bovine chromosome 18 haplotypes associated with divergent somatic cell score affects postpartum reproductive and metabolic performance

摘要

The susceptibility of animals to periparturient diseaseshas a great effect on the economic efficiency ofdairy industries, on the frequency of antibiotic treatment,and on animal welfare. The use of selection forbreeding cows with reduced susceptibility to diseasesoffers a sustainable tool to improve dairy cattle farming.Several studies have focused on the association ofdistinct bovine chromosome 18 genotypes or haplotypeswith performance traits. The aim of this study was totest whether selection of Holstein Friesian heifers viaSNP genotyping for alternative paternal chromosome18 haplotypes associated with favorable (Q) or unfavorable(q) somatic cell scores influences postpartum reproductiveand metabolic diseases. Thirty-six heifers (18 Qand 18 q) were monitored from 3 wk before calving untilnecropsy on d 39 (± 4 d) after calving. Health statusand rectal temperature were measured daily, and bodycondition score and body weight were assessed once perweek. Blood samples were drawn twice weekly, and levelsof insulin, nonesterified fatty acids, insulin-like growthfactor-I, growth hormone, and β-hydroxybutyrate weremeasured. Comparisons between the groups were performedusing Fisher’s exact test, chi-squared test, andthe GLIMMIX procedure in SAS. Results showed thatQ-heifers had reduced incidence of metritis comparedwith q-heifers and were less likely to develop fever.Serum concentrations of β-hydroxybutyrate were lowerand insulin-like growth factor-I plasma concentrationswere higher in Q- compared with q-heifers. However,the body condition score and withers height were comparablebetween haplotypes, but weight loss tended tobe lower in Q-heifers compared with q-heifers. No differencesbetween the groups were detected concerningretained fetal membranes, uterine involution, or onsetof cyclicity. In conclusion, selection of chromosome18 haplotypes associated with a reduced somatic cellscore resulted in a decreased incidence of postpartumreproductive and metabolic diseases in this study. Thepresented data add to the existing knowledge aimedat avoiding negative consequences of genetic selectionstrategies in dairy cattle farming. The underlying causalmechanisms modulated by haplotypes in the targetedgenomic region and immune competence necessitatefurther investigation.