Author
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ROSATI, A. - ROME, ITALY |
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Van Vleck, Lloyd |
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Submitted to: World Congress of Genetics Applied in Livestock Production
Publication Type: Proceedings Publication Acceptance Date: 8/21/1997 Publication Date: N/A Citation: N/A Interpretive Summary: Milking buffaloes produce milk that has twice the value for production of mozzarella cheese as cows' milk. Knowledge of genetic parameters is necessary both for genetic evaluation of buffaloes for milk and mozzarella yields but also for designing effective selection programs to increase the yield of mozzarella cheese. This study of 10,663 lactation yields of Italian buffaloes estimated these genetic parameters including heritabilit and repeatability. The heritability estimates for milk, fat, protein and mozzarella yields were .11 to .14 which are less than half those usually reported for dairy cattle. The heritability estimates for fat and protein percentages were .17 and .10 which are less than one-third of similar estimtes reported for dairy cattle. These results suggest that selection for improvement of mozzarella yield by traditional methods will be slower than for similar traits in dairy cattle and that new strategies based on biotechnological advances may need to be considered. Technical Abstract: The population of Italian river buffaloes is currently about 200,000. Mozzarella cheese is produced using buffalo milk. Lactations from 1980 up to now were considered in the analysis. After editing, 10,663 lactation records for milk, fat, protein and mozzarella cheese production of river buffalo cows were analyzed using restricted maximum likelihood, by fitting a multiple trait repeated records animal model with a derivative-free algorithm. The number of cows with records was 3,873 with 6,842 animals in the relationship matrix. Three different fixed effects were included in the model: 575 levels of herd and year subclasses, 12 levels of calendar month of calving and 2 levels of number of times milked per day. A cubic covariate was used to adjust for months of age at parity. A quadratic covariate was used to adjust for days in the previous dry period. The averages of milk yields, fat, protein and mozzarella in kilograms and fat and protein percentages of milk yield were 2,286 plus/minus 492.1, 196.9 plus/minus 45.6, 104.7 plus/minus 21.7, 589.1 plus/minus 125.4, 8.59 plus/ minus .85, 4.55 plus/minus .28, respectively. Heritability estimates were 0.14 for milk yield, 0.11 for fat yield, 0.14 for protein yield, 0.13 for mozzarella cheese yield, 0.17 for fat percentage and 0.10 for protein percentage. The proportions of total variance due to permanent environmental effects of the cows for yields of milk, fat and protein and percentage of fat and protein were 0.24, 0.16, 0.29, 0.23, 0.12, and 0.22, respectively. |
