In the last 15 years, a series of experiments has beencarried out to search for quantitative trait loci (QTL) in New Zealand cattle, sheepand deer. A QTL represents the position on a chromosome where there is a statistically significant genetic effecton a measured trait. This paper reviews data published so far from these QTL trials and from various association studies. Although the measurement of traits (or ‘phenotypes’) and the sampling of tissue or fluid for DNA may be complete, the genotyping of DNA isstill incomplete in most studies; further work may be expected as new DNA genotyping techniques and new genomic data become available, and as funds allow. In cattle, we describe the current status of research for carcass composition, meat quality, pubertal traits, milk yield and milk composition traits, and resistance to facial eczema and bloat. In sheep, we include QTL searches for disease traits (resistance to nematode parasites, facial eczema, ryegrass staggers, and footrot), muscling and carcass composition, reproductive traits, wool traits, and lamb survival. In deer, QTL searches have been carried out for live weights, seasonality and pubertal traits, using measurements from an interspecific hybrid. Generally, significant results have been followed further by finemapping and independent validation, before release to industry. Some of the mapping techniques will be described, with examples. So far, QTLs under study in New Zealand have led to the identification and use of gene-tests or marker-tests for meat tenderness and carcass composition in beef cattle, milk yield and composition traits in dairy cattle, and meat yield %, muscling and litter size genes in sheep.
Proceedings of the New Zealand Society of Animal Production, Volume 67, Wanaka, 153-159, 2007
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