Holstein Association USA recognizes the importance of identifying heritable, sometimes undesirable, unique genes in Holstein cattle, to provide breeders with the tools they need to make informed breeding decisions. Use the free tools below to learn more about genetic testing and research animals to see if they have been tested as carriers or non-carriers for various traits, or may potentially be a carrier based on their pedigree. For more information, call Holstein Association USA customer service at 800.952.5200.

Dairy researchers have discovered six haplotypes impacting fertility; referred to as HH1, HH2, HH3, HH4, HH5 and HH6, these haplotypes are believed to cause embryonic or fetal death when present in homozygous form, i.e., the offspring inherits the haplotype from both the sire and dam. In a herd, this would appear as if a cow did not conceive, resulting in greater days open and lower conception rates. Researchers have found that these haplotypes never occur in homozygous form amongst any living animal (that had their genome tested; the group researchers studied). That scenario is highly unlikely based on population probabilities, unless affected animals did not survive to birth.

Holstein Association USA encourages breeders to pay attention to pedigrees, work to learn the status of their animals, be mindful of the status of service sires in their herd, and avoid mating carriers of individual haplotypes to carriers of the same haplotype. It is possible for fertility rates to be improved by carefully selecting matings to avoid the chance of potential offspring inheriting the lethal version of a haplotype impacting fertility. Discovery and labelling of these haplotypes is a benefit of genomic testing, and gives breeders the opportunity to improve the genetic quality of the breed through careful mating.

Haplotype Impacting Fertility 6 (HH6) — Newly Reported in December 2018

A new Haplotype Impacting Fertility (HH6) was discovered by French researchers, and first reported on at the 2018 International Committee for Animal Recording (ICAR) meeting. The current frequency of HH6 in U.S. data is 0.5 percent, according to CDCB data. French researchers traced HH6 back to BIS-MAY S-E-L MOUNTAIN-ET (USA M 2070579), and USDA-AGIL researchers traced HH6 back further to his maternal grandsire CAL-CLARK BOARD CHAIRMAN (USA M 1723741), then four generations further back to GRAY VIEW SKYLINER (USA M 1244845), born in 1954. The fertility effects of HH6 were confirmed using CDCB data from 371 carrier sire x carrier maternal grandsire matings, with a larger than expected 9% +/- 2% drop in conception rate.

HH6 will be reported out with the other haplotypes starting in December 2018, and results will be available for all genomic tested animals at that time. Holstein breeders may find the status of their animals using the Family Tree Search on the HAUSA web site, or Enlight® users may also find the information there. Read more about HH6 on the CDCB web site.

• Read more detailed information about the haplotypes impacting fertility and
  how breeders can use the information to make more informed mating decisions.
  
  
• Haplotypes Affecting Fertility and their Impact on Dairy Cattle Breeding Programs, by Dr. Kent A Weigel
  

Use the Family Tree Search to view haplotype status of individual animals.

In December 2023 the haplotype for Early Onset Muscle Weakness Syndrome (HMW) will be included with genomic evaluations.

This condition is characterized by an inability of a calf to stand or if assisted, remain standing.

The haplotype codes of 0 to 4 are being used to denote an animal’s status on Holstein Association USA’s reports, as noted below.

Codes for haplotype associated with Muscle Weakness

German researchers discovered and reported on a deleterious haplotype in Holsteins, causing young calves to die if homozygous, at the July 2015 Interbull meeting. Researchers concluded that heterozygous animals have reduced cholesterol, but homozygotes have no cholesterol and survive only a few months.

The haplotype carrying the defect is difficult to track because both the normal version and the defected version occur frequently. The two haplotype versions look identical when examining only the surrounding marker genotypes. Pedigree information, in combination of having knowledge of the haplotype status of earlier ancestors, allows for an accurate determination.

Codes of 0 to 4 are being used to denote an animal’s haplotype status.

A direct gene test for Cholesterol Deficiency is also available; please call Holstein Association USA for more information. Animals who have been tested with the direct gene test will have a two-character code indicating their results; TC means the animal has been tested free of Cholesterol Deficiency using the direct gene test, and CD means the animals has been tested with the direct gene test and confirmed to be a carrier. Holstein Association USA recommends that any breeding stock animals who have been tested as a carrier for the haplotype be tested with the direct gene test to confirm their status.