title: Genetic and genomic analysis of hyperthelia in Brown Swiss cattle.
abstract: Supernumerary teats (SNT) are any abnormal teats found on a calf in addition to the usual and functional 4 teats. The presence of SNT has also been termed "hyperthelia" since the end of the 19th century. Supernumerary teats can act as an incubator for bacteria, infecting the whole udder, and can interfere with the positioning of the milking machine, and consequently, have economic relevance. Different types of SNT are observed at different positions on the udder. Caudal teats are in the rear, ramal teats are attached to another teat, and intercalary teats are found between 2 regular teats. Not all teats are equally developed; some are completely functional but most are rudimentary and not attached to any mammary gland tissue. Recently, different studies showed the poly/oligogenic character of these malformations in cattle as well as in other mammalian species. The objective of this study was to analyze the genetic architecture and incidence of hyperthelia in Swiss Brown Swiss cattle using both traditional genetic evaluation as well as imputed whole genome sequence variant information. First, phenotypes collected over the last 20 yr were used together with pedigree information for estimation of genetic variance. Second, breeding values of Brown Swiss bulls were estimated applying the BLUP algorithm. The BLUP-EBV were deregressed and used as phenotypes in genome-wide association studies. The gene LGR5 on chromosome 5 was identified as a candidate for the presence of SNT. Using alternative trait coding, genomic regions on chromosome 17 and 20 were also identified as being involved in the development of SNT with their own supernumerary mammary gland tissue. Implementing knowledge gained in this study as a routine application allows a more accurate evaluation of the trait and reduction of SNT prevalence in the Swiss Brown Swiss cattle population.
authors.affiliation: Qualitas AG, Zug 6300, Switzerland; Centre for Genetic Improvement of Livestock, Department of Animal Biosciences, University of Guelph, Guelph N1G 2W1, Ontario, Canada.
authors.forename: Adrien M
authors.initials: AM
authors.lastname: Butty
authors.affiliation: Qualitas AG, Zug 6300, Switzerland; School of Agricultural, Forest and Food Sciences, Bern University of Applied Sciences, Zollikofen 3052, Switzerland.
authors.forename: Mirjam
authors.initials: M
authors.lastname: Frischknecht
authors.affiliation: Qualitas AG, Zug 6300, Switzerland.
authors.forename: Birgit
authors.initials: B
authors.lastname: Gredler
authors.affiliation: Unit of Animal Genetics, Institute of Agricultural Sciences, Swiss Federal Institute of Technology, Zurich 8092, Switzerland.
authors.forename: Stefan
authors.initials: S
authors.lastname: Neuenschwander
authors.affiliation: Qualitas AG, Zug 6300, Switzerland.
authors.forename: Jürg
authors.initials: J
authors.lastname: Moll
authors.affiliation: Department of Animal Sciences, Research Institute of Organic Agriculture (FiBL), Frick 5070, Switzerland.
authors.forename: Anna
authors.initials: A
authors.lastname: Bieber
authors.affiliation: Centre for Genetic Improvement of Livestock, Department of Animal Biosciences, University of Guelph, Guelph N1G 2W1, Ontario, Canada. Electronic address: cbaes@uoguelph.ca.
authors.forename: Christine F
authors.initials: CF
authors.lastname: Baes
authors.affiliation: Qualitas AG, Zug 6300, Switzerland.
authors.forename: Franz R
authors.initials: FR
authors.lastname: Seefried
mesh_terms: D000818:Animals; D001947:Breeding; D002417:Cattle; D005260:Female; D016678:Genome; D055106:Genome-Wide Association Study / Q000662:veterinary*; D023281:Genomics; D008321:Mammary Glands, Animal; D009558:Nipples
keywords: dairy cattle; genome-wide association; hyperthelia; supernumerary teats