Genetic Analysis of Herd Life in Canadian Dairy Cattle on a Lactation Basis Using the Survival Kit
نویسندگان
چکیده
Longevity is a highly desirable trait that considerably affects overall profitability. With increased longevity the mean production of the herd increases because a greater proportion of the culling decisions are based on production and the proportion of mature cows, which produce more milk than young, cows is increased. An increased longevity enables higher selection intensity of females and thus greater selection response.
منابع مشابه
Factors affecting stillbirth and effects of stillbirth on subsequent lactation performance in a Holstein dairy herd in Isfahan
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 کاملInvestigation of Biological and Economic Changes in Herd of Dairy Cows Using Optimization Models
The aim of this study was to identify the factors affecting the culling of dairy cows and their impact on reproductive performance and costs of the herd so that optimal decisions can be made in replacing dairy cows and thereby increase the annual income of dairy cattle. For this purpose, data collected from four active cattle breeding units in Ardabil province (including biological parameters a...
متن کاملEstimation of Genetic Parameters for Milk Production Trait in Holstein Cows of the Mazandaran Gavdasht Herd Using Test Day Records
Random regression models (RRM) are used for genetic estimations of milk traits in dairy cows. RRM utilize data on traits that are repeated during the time, such as milk trait, which allows of the evaluation of the test day production information. In this study, to estimate genetic parameters for milk production trait, test day records (TDR) were collected from the first lactation of Holstein co...
متن کاملRelationship between United States and Canadian genetic evaluations of longevity and somatic cell score.
Canadian and US evaluations of Holstein bulls were compared for longevity measures (433 bulls) and somatic cell score (354 bulls). Bulls were required to have a birth year of > or = 1975, daughter information from > or = 20 herds, and a reliability of > or = 50% in both Canada and the US. The number of bulls with longevity evaluations was greater for early years because longevity information wa...
متن کاملEstimation of genetic parameters for production traits and somatic cell score in Iranian Holstein dairy cattle using random regression model
In this study test-day records of milk (kg), fat (g), and protein (g) yields, somatic cell score (SCS, cells/ML) collected by Animal Breeding Center of Iran during 2007 and 2009 were used to estimate genetic parameters using random regression model. Models with different order of Legendre polynomials were compared using Bayesian information criterion (BIC).For milk, fat yield and SCS genetic an...
متن کامل