@conference {40761,
	title = {Potential for profitable use of DNA markers in the New Zealand Dairy Industry},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {56},
	year = {1996},
	month = {Jan},
	pages = {9-11},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = { Annual genetic advance in merit of dairy cattle can be assessed from  selection in four pathways: Bulls to breed Bulls (BB); Cows to breed Bulls  (CB); Bulls to breed Cows (BC); and Cows to breed Cows. It is usually  assumed that breeding merit is determined by actions of a very large number  of genes, each having a small effect (infinitesimal model of inheritance). In  practice, the number may be finite, with a few genes (known as QTLs)  having large effects. DNA technologies allow young animals to be tested  for particular QTLs using markers. Benefits of marker assisted selection were calculated for one additive QTL  over a range of sizes (allele values of 0.25, 0.38, or 0.5 genetic s.d.) and  initial gene frequencies (0.01, 0.10, 0.35). Testing was conducted in the BB,  BC and CB pathways. Strategies were compared using the Net Present  Value of the stream of productive benefits less costs for a 30 year horizon,  assuming one genetic s.d. is worth $160. Superior rates of advance were sometimes achieved at greater cost than  benefits. At a cost of $10 per genotype assessment it was never profitable to  genotype small QTLs. The largest QTL could be profitably used to screen  young bulls before progeny testing except at the lowest starting frequency.  In some circumstances, selection for a QTL resulted in improved medium  term response but reduced long-term response. Knowledge of the size and  frequency of QTLs and a pre-defined time horizon will be essential to  discriminate between profitable and costly applications of this technology. },
	issn = {1176-5283},
	author = {Garrick DJ and Spelman RJ}
}
