Length of Calving Interval and Average Milk Yield
نویسندگان
چکیده
منابع مشابه
An Optimum Regression Model to Estimate Economic Values for Milk Yield, Milk Yield Persistency and Calving Interval in Dairy Cattle
Emphasis on milk yield (MY) as well as milk yield persistency (MYP) and calving interval (CI) is necessary to achieve more sustainable productionin dairy cattle. Therefore the main objective of this study was to find an optimum regression model to estimate economic values for MY, MYP and CI.Using a deterministic bio-economic model, seventyfiveproduction states differing mainly in MY, MYPand CIw...
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The objective of the present study was to estimate genetic trends for lactation milk yield, persistency of milk yield, somatic cell count and interval between first and second calving in Holstein dairy cows of Iran. The dataset consisted of 210,625 test day and 25,883 first parity cows with milk yield recorded from July 2002 to September 2007 comprising 97 herds in Iran. Breeding values of anim...
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Estimates of genetic correlations were .17 between first lactation milk yield and concurrent calving interval, .10 between second lactation milk yield and first calving interval, and .82 between first and second milk yields. Corresponding phenotypic correlations were .27, .16, and .58. Heritability estimates were .27 and .25 for first and second lactations and .15 for calving interval. Estimate...
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Body condition score (BCS) is a useful tool in assessing the energy status of dairy cattle. Previous research has shown that it is heritable and genetically correlated to reproductive performance. Currently, interest exists in developing selection indexes for fertility that include BCS information. Before such indexes are developed, it is important to assess the genetic covariance between BCS a...
متن کاملRelationships Among Herd Life, Milk Production, and Calving Interval
Whether to select for longer life in the herd or shorter calving interval depends on the genetic and phenotypic relationships among herd life, amount of milk in first lactation, and calving interval. Herd life and average calving intmwal are essentially phenotypically uncorrelated. The phenotypic and genetic correlations of herd life and milk in first lactation ranged from .19 to .25 and from ....
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ژورنال
عنوان ژورنال: Journal of Dairy Science
سال: 1931
ISSN: 0022-0302
DOI: 10.3168/jds.s0022-0302(31)93474-7