Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 9 of 9 for “"Genetic trends"”.
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Genetic Parameters and Genetic Trends of Female Fertility in Icelandic Dairy Cattle
… by calving interval, has been included in the genetic evaluation of Icelandic dairy cattle since 1993. In spite of this an unfavourable genetic trend is seen and, recent implementation of test-day models for the genetic evaluation of milk production has changed the premise of using calving …
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Evaluation of phenotypic and genetic trends in weaning weight in Angus and Hereford populations in Virginia
… in Virginia were used to evaluate phenotypic and genetic trends for adjusted weaning weight (AWWT), weaning weight ratio (WWR) and deviation of AWWT from the mean AWWT of the contemporaries (DEVN). Two approaches, namely the regression techniques and maximum likelihood (ML) procedure were taken to …
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Genetic Parameters for Udder and Teat. Type Traits in Icelandic Cattle Breed
… The main objective of this study was to estimate genetic parameters for udder and teat type traits of Icelandic Cattle, but also to describe the traits’ phenotypic structure, to estimate their genetic trends, and to review the current breeding value estimations of udder and teats for Icelandic …
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Caracterização dos motivos de descarte e estimativas de parâmetros genéticos para longevidade de vacas da raça holandês
… to identify culling reasons and estimate related genetic parameters. Analyzing culling reasons can improve management and selection in dairy cattle breeding programs. This study evaluated 34 culling reasons in Holstein dairy herds. Data from 3,096,872 Holstein cows culled in 9,683 Canadian herds …
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Selection to improve spring fertility in a crossbred sheep population
… 5 years; 63 sires and 420 dams were represented. Genetic parameters were estimated by restricted maximum likelihood (REML) using various animal models. Heritability estimates for spring fertility ranged from .07 to .11. Litter size heritability was .05 for fall lambing and .10 for all lambings. …
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Genetic Parameter Estimates of Milkability Traits in South African Holstein Cattle
… of South African dairy cattle and their genetic parameters in the population have not been estimated. The primary objective of the study was to estimate genetic parameters for milkability traits in South African Holstein cattle. Data consisted of production and milkability records of 1 …
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Factors affecting the accuracy and stability of sire proofs from progeny test herds
… was investigated. Individual phenotypic and genetic records of first crop and non-first crop cows in 3449 herds participating in the AI stud's young sire sampling program from 1971 to 1987 were used to characterize the sampling program, to estimate genetic trend across and within the progeny …
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Development of a multi-breed heifer pregnancy genetic evaluation in beef cattle
… across several beef breed associations. These HP genetic evaluations typically rely on categorical exposure (1 = exposed; 0 = not exposed) and pregnancy outcome (1 = pregnant; 0 = not pregnant) data and involve the use of threshold animal models (TM) to convert these binary observations to an …