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Economic efficiency of Canadian and New Zealand sires in Canadian and New Zealan dairy herds and its relationship with other traits

University of British Columbia

The main objectives of this study were to test for differences in the economic efficiency of daughters of Canadian and New Zealand dairy sires born in herds in either country and to determine the relationships between economic efficiency and first lactation production traits. The data used were extracted from lifetime records of a planned trial involving the mating of 20 proven sires selected from New Zealand and 20 proven sires selected from Canada to cows in 20 New Zealand and 10 Canadian herds. The data consisted of 834 lactation records from 343 cows in Canada and 3621 lactation records from 834 cows in New Zealand. The first stage in the study involved choosing the best growth function for describing the growth curve of each cow and this was used to estimate the liveweight at each calving. The liveweights were then used to estimate feed requirements, which were in turn used in the computation of the economic efficiency measure, Returns/Feed Requirements, for different production periods. The pricing systems used in the provinces of British Columbia and Ontario were considered when computing economic efficiency in Canada. Heritability estimates of the economic efficiency traits, growth and production traits were estimated using animal model DFREML as were the genetic and phenotypic correlations between these in New Zealand. The existence of genotype by environment interaction for the various traits was also tested. Heritability estimates for economic efficiency traits across both countries ranged from 0.12 to 0.34. The genetic correlations between first lactation yield traits and economic efficiency traits in New Zealand ranged from 0.44 to 0.70. Genetic correlation between economic efficiency in the first lactation and lifetime economic efficiency was 0.73. In New Zealand daughters of New Zealand sires had significantly higher lifetime economic efficiency than daughters of Canadian sires. Daughters of both strains did not differ significantly for all other economic efficiency traits in either environments. A significant genotype by environment interaction was found at the macro level for first lactation protein yield and percentage protein. Among economic efficiency traits a significant interaction was only realized for lifetime economic efficiency with British Columbia prices. There was no interaction for any of the other economic efficiency traits and none for mature liveweight. Significant genotype by environment interactions were realized at the micro level for all economic efficiency traits for both strains of sire and for first lactation yield traits among Canadian sires.

Thesis/Dissertation

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2009-05-28

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http://hdl.handle.net/2429/8418

Animal Science

University of British Columbia

UBCV

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