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Department of Dairy Science, Ohio State University and Ohio Agricultural Research and Development Center, Columbus 43210
ABSTRACT
Genetic and phenotypic relationships were estimated on a profit function for 933 Holstein cows. Methods of selection among cows were investigated for profit per day of herdlife. The profit function included production, reproduction, and body weight. Heritability for profit/day during first lactation was .50 ± .12 compared to .28 ± .10 for milk/day in the first lactation. Correlations (genetic, phenotypic) between first lactation and lifetime records per day of herdlife were (.93, .74) for milk production and (.79, .65) for profit. Correlations between milk/day-first and profit/day-life were (.85, .55). Correlations for total lifetime production and profit were (.95, .97) and per day of herdlife were (.94, .87). Herdlife compared to lifetime traits had larger correlations with profit/day than yield/day (.64 versus .40, .69 versus .48) indicating the profit function contained important factors related to herdlife besides lactation performance. Correlations between age at first calving with total lifetime production and profit were negative (-.15 to -.32, -.16 to -.07), suggesting an increase in these traits can be expected in selection for younger age at first calving. Genetic gain expected in profit/day of life from selection on profit/day-first lactation was 24% more efficient than milk/day-first. A simplified profit function may be effective for increasing profitability in dairy production by selection.
1 Journal Article Number 129-75, Ohio Agricultural Research and Development Center.
2 Department of Animal Sciences, Punjab Agricultural University, Ludhiana (Punjab), India.
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