Across breed evaluation of dairy cattle
B.L. Harris, J.M. Clark and R.G. Jackson
Livestock Improvement Corporation LTD, Private Bag 3016,
Hamilton, New Zealand.
Proceedings of the New Zealand Society of Animal Production, 1996,
56: 12-15
Genetic analysis of dairy cattle has been undertaken using an animal
model including pedigree records since 1940 and performance records since
1986. The animal model analyses all breeds and breed crosses
simultaneously allowing accurate estimation of hybrid vigour effects for
milk production, liveweight, four survival traits and 16 linear type traits.
The animal model allows the effects of induction, age at calving and herd-
year-season to be taken into account when estimating an animalís breeding
and production values. The breeding value estimates of all animals
regardless of breed are on the same scale allowing direct comparison of
Holsteins and Jerseys, for example. The results of the animal model
analysis are expressed in terms of individual animal performance, eg. kg of
milk fat per cow.
Three selection indices have been developed to identify the most
economically efficient animals under New Zealand pasture based farming
systems. To identify the best animals for breeding herd replacements in the
future the breeding worth index is used. To rank cows on lifetime
profitability the production worth index is used and to rank cows on current
lactation profitability the lactation worth index is used. The indices have
been developed using a whole farm model which takes into account the
future revenue and cost streams to rank the animals on net income per unit
of feed.
Keywords: NZSAPAB;
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Last Updated 18-03-1997
