Short Communication: Quantitative Trait Loci Analysis on 17 Nonproduction Traits in the New Zealand Dairy Population

Seven New Zealand Holstein-Friesian families and two Jersey families, a total of 274 sires, were analyzed in a granddaughter design for marker-quantitative trait loci associations.For 17 nonproduction traits (management, size, and conformation traits), an acrossfamily analysis was undertaken using multimarker regression procedures.Threshold levels were set empirically by permuting the data.A quantitative trait locus for stature was identified on chromosome 14, which was significant at the 15% experimentwise level (suggestive linkage).The quantitative trait locus was identified to be segregating in three of the nine families.(Key words: dairy cattle, quantitative trait loci, nonproduction traits)Abbreviation key: MAS = marker-assisted selection, NPT = nonproduction traits, QTL = quantitative trait loci.The most economically important characteristics of dairy cattle are production traits.However, nonproduction traits (NPT) contribute to the overall economic performance of a dairy cow through their impact primarily on voluntary culling and, therefore, longevity.Several studies have identified significant genetic correlations between certain conformation traits and survival rate or herd life (9).In New Zealand, the only significant genetic correlations between NPT and cow survival were between farmer-scored traits (adaptability to milking, temperament, milking speed, and overall opinion) and survival rates from the first to second and second to third lactations (4).Since the discovery of highly polymorphic markers, genome-wide scans have detected quantitative trait loci (QTL) affecting production traits in dairy cattle (5).