Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/31/2016
Publication Date: 9/1/2016
Citation: Cole, J.B., Null, D.J., Van Raden, P.M. 2016. Phenotypic and genetic effects of recessive haplotypes on yield, longevity, and fertility. Journal of Dairy Science. 99(9):7274-7288.
Interpretive Summary: Research using many DNA markers and fertility records identified several new genetic disorders in dairy cattle in recent years. This study examined the relationship of those disorders to traits of economic importance in US Ayrshire, Brown Swiss, Holstein, and Jersey cattle. Four of the 5 disorders originally shown to have undesirable effects on fertility also had significant associations with fertility in the current study. Effects were generally small even when statistically significant. Avoidance of carrier-to-carrier matings is adequate to minimize economic effects of these disorders, but new strategies will be needed as the number of disorders grows.
Technical Abstract: Phenotypes from the August 2015 US national genetic evaluation were used to compute phenotypic effects of cholesterol deficiency (CD) and 17 other recessive haplotypes in Ayrshire (AY; n=1), Brown Swiss (BS; n = 5), Holstein (HO; n = 10), and Jersey (JE; n = 2) cattle on milk, fat, and protein yields, somatic cell score (SCS), single-trait productive life (PL), daughter pregnancy rate (DPR), heifer conception rate (HCR), and cow conception rate (CCR). The form of the recessive CD haplotype (harmful or normal) was assigned based on genotype and pedigree analysis. A total of 30,928 HO were heterozygous for the harmful haplotype, 275 were homozygous for the harmful haplotype, 25,077 were heterozygous for the recessive haplotype but parental origin could not be determined, and 358 were homozygous for the recessive haplotype but parental origin could not be determined. Carriers of AH1 had higher milk yield than non-carriers. In BS, significant haplotype effects were BHD for increased fat and SCS; and BHM for increased milk, fat, and DPR, and decreased protein and HCR. A number of associations were noted for HO haplotypes, including increased protein, DPR, and CCR with HCD; HH0 with increased fat and CCR; HH1 with decreased DPR and CCR; HH2 with increased fat; HH3 with decreased protein and SCS; HH4 with increased DPR; and HHC with decreased fat. The JH1 haplotype was associated with increased fat production, and JH2 with lower CCR. Only 1 of the 5 haplotypes originally identified as having deleterious effects on fertility (HH1) also had a significant association with fertility in the current study. Effects of the recessive haplotypes studied were generally small even when significant. At present, avoidance of carrier-to-carrier matings probably is adequate to minimize economic effects of these recessives, but more sophisticated strategies will be needed as the number of known disorders grows.