First Lactation Performance and Herd Life
نویسندگان
چکیده
منابع مشابه
Phenotypic relationship of yield and type scores from first lactation with herd life and profitability.
Milk records from Ayrshire, Brown Swiss, Guernsey, Jersey, and Milking Shorthorn cows that first calved between 18 and 35 mo were combined with scores for linear type traits collected before 43 mo during first lactation to study herd life and lifetime profitability. Profitability (discounted relative net income) was the value of milk, calves, and cow salvage minus fixed costs, operating costs, ...
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The relationship of first score and length of life in the herd was measured in Holstein females two or three years of age at first classification. The regression of herd life (number of times classified) on the first over-all type score (nearly all values were between 65 and 90 points) was 1.7 months. Correlation between first classification score and herd life was approximately 0.2, indicating...
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The purposes of this study were to estimate the effects of risk factors on stillbirth parturition and evaluatethe effects of stillbirth on lactation performance in Holstein dairy cows. Data were obtained from a dairycattle herd located in Isfahan province, Iran. The logit of the probability of stillbirth was modeled usinglogistic regression and the effect of stillbirth on lactation performance ...
متن کاملGenetic parameters for first lactation milk yields at three levels of herd production.
A multivariate linear model was used to estimate sire variance and covariance components and residual variance components for first lactation milk yield and logarithms of yield at three herd production levels using Restricted Maximum Likelihood with the Expectation-Maximization algorithm. Data for four separate analyses were 305-d, mature equivalent first lactation milk records from cows sired ...
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Genetic and environmental (co)variance components for 4% FCM yield were simultaneously estimated by REML for grade cows from herds stratified by within-herd SD for 305d mature equivalent milk and time period. Data were lactation records from 299,441 daughters of 2489 AI b d s that calved for the first time from 1970 to 1985 in California, New York, or Texas. Sire and residual variance component...
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ژورنال
عنوان ژورنال: Journal of Dairy Science
سال: 1964
ISSN: 0022-0302
DOI: 10.3168/jds.s0022-0302(64)88827-5