WORKSHOP REPORT Report of the first workshop on the genetic map of bovine chromosome 1 J F Taylor, A Eggen, A Aleyasin, S M Armitage, W Barendse, J E Beever, M D Bishop, R A Brenneman, B M Burns, S K Davis, K Elo, B Harlizius, S M Kappes, J W Keele, S J Kemp, B W Kirkpatrick, H A Lewin, R Z Ma, R A McGraw, D Pomp, R T Stone, Y Sugimoto, A J Teale, D Vaiman, J Vilkki, J L Williams, C-C Yeh, M C Zanotti Summary A report of the first workshop on the genetic map of bovine chromosome 1 (BTA1) is pre- sented. Five laboratories contributed 31 962 informative meioses from 70 loci. Thirty-two loci which had been typed by at least two laboratories were used to construct a framework genetic map with a likelihood ratio support of at least 1000:1 for locus order. The resulting sex- averaged framework map contained 26 loci and spanned 163 . 6cm. The lengths of the female and male maps were 159 . 5cm and 165 . 3cm, respectively, and there was evidence for an expansion in the telomeric one-third of the male map. Of the four cases where order for closely linked loci differed among the maps produced for each of the contributing laboratories, a consensus order was obtained for three in the framework map. The average genetic distance between framework loci on the sex-averaged map was 6 . 3cm. Keywords: bovine, genetic linkage, BTA1 Introduction Sufficient bovine microsatellite markers have now been developed and mapped to chromo- somes to provide a medium resolution genetic map of the bovine genome (Ma et al. 1996; Barendse et al. 1997; Kappes et al. 1997). These maps provide a fundamental molecular tool for the localisation of genes influencing disease or quantitative trait phenotypes (QTLs, or quanti- tative trait loci) to a specific chromosome interval without knowledge of the identity of the gene(s) or of the molecular basis of their expression. However, the capacity of each of these maps to resolve marker order and the precision with which the map distance between markers can be estimated is limited by the number of co-informative meioses among the marker loci within each map. Disagreements in estimated locus order and genetic distances among loci exist between the published maps and it is important that these locus orders are resolved for positional cloning studies. While recombination frequencies among markers may differ between the published genetic maps due to pedigrees, sampling variation and data errors, differences in estimated locus orders are more likely to be due to sampling effects and data errors (Beever et al. 1996; Taylor et al. 1997). A series of chromosome workshops have been initiated for the purpose of integrating the existing genetic data from several mapping populations to construct consensus maps of each chromosome. The first workshop orga- nised for this purpose constructed a framework genetic map of BTA23 which included 12 loci for which locus order could be supported with a likelihood ratio exceeding 1000:1 (Beever et al. 1996). Interest in BTA1 as the focus of the second chromosome workshop stems from the localisation of the gene responsible for horn development (Georges et al. 1993; Schmutz et al. 1995; Brenneman et al. 1996; Harlizius et al. 1997) and the localisation of a QTL influencing milk yield (Georges et al. 1995) to the centromeric half of the chromosome. Not only would a framework map of BTA1 assist in aligning the existing genetic maps of BTA1 in the regions identified as containing these loci, but it will provide a resource for future mapping studies. Materials and methods Genotype data from five bovine pedigrees were submitted to the workshop-organising labora- tories at Texas A&M University and ABS Global Inc. All data were submitted in a standardised format for analysis by CRIMAP V.2.4. (Green et al. 1990). A total of 31 962 informative meioses from 70 loci were represented in the Animal Genetics, 1998, 29, 228±235 J F Taylor R A Brenneman B M. Burns S K Davis C-C Yeh Department of Animal Science, Texas A&M University, College Station, TX 77843±2471, USA M D Bishop A Eggen y,z D Vaiman z yABS Global Inc., 6908 River Rd, DeForest, WI 53532, USA; zLaboratoire de Ge Âne Âtique bio- chimique et de Cytoge Âne Âtique, INRA CRJ, 78350 Jouy-en-Josas, France A Aleyasin S M Armitage W Barendse CSIRO, Division of Tropical Agriculture, Gehrmann Labora- tories, University of Queens- land, Brisbane, Australia J E Beever H A Lewin R Z Ma Department of Animal Sciences, University of Illinois at Urbana- Champaign, 1201 West Gregory Drive, Urbana, IL 61801, USA K Elo J Vilkki Animal Breeding, Institute of Animal Production, Agricultural Research Centre, 31600 Jokioi- nen, Finland B Harlizius Department of Animal Breeding and Genetics, Bunteweg 17p, D- 30161 Hannover, Germany S M Kappes J W Keele R T Stone USDA-ARS, U.S. Meat Animal Research Center, Clay Center, NE 68933±0166, USA S J Kemp Department of Genetics and Mi- crobiology, University of Liver- pool, Donan Laboratories, Liverpool, L69 3BX, UK B W Kirkpatrick Department of Meat and Animal Science, University of Wiscon- sin, 1675 Observatory Drive, Madison, WI 53706, USA R A McGraw Department of Physiology and Pharmacology, University of Georgia, Athens GA 30602, USA D Pomp Department of Animal Science, University of Nebraska, Lincoln, NE 68583±0908, USA Y Sugimoto Shirakawa Institute of Animal Genetics, Idakura, Nishigo, Nishishirakawa, Fukushima 961, Japan A J Teale International Livestock Research Institute, PO Box 30709, Nairobi, Kenya J L Williams AFRC Roslin Institute, Roslin, Midlothian EH25 9PS, UK M C Zanotti Istituto di Zootecnica, Facolta di Medicina Veterinaria, Universita degli Studi di Milano, Via Celor- ia 10, 20133 Milano, Italy ã 1998 International Society for Animal Genetics 228 Correspondence: J F Taylor. Accepted 5 January 1998