Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.657907
Title: Estimation of genetic parameters for beef cattle in UK herds
Author: Mohiuddin, Ghulam
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1995
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Abstract:
Data from British Simmental cattle collected by the Meat and Livestock Commission (1969-91) from 1142 herds were utilised to estimate phenotypic, genetic and environmental parameters for various performance traits. The importance of maternal effects on the performance of these animals was also evaluated. The performance traits considered in the study were birth weight, 200-day weight, 400-day weight, ultrasonic backfat depth (backfat depth) and muscling score. Restricted Maximum Likelihood individual animal model procedure was followed throughout, accounting for all known genetic relationships between animals, selection decisions and non random matings. Average birth weight obtained from the analysis of 31213 records was 40 kg, whilst 200-day weight and 400-day weight averaged 285 kg and 517 kg, respectively. The corresponding values for backfat depth and muscling score were 3.12 mm and 10 points, respectively. For univariate analysis, 6 different animal models (i.e. including or excluding maternal additive genetic effects or maternal permanent environmental effects or direct-maternal genetic covariance) were fitted to determine the relative significance of these different random effects. The average estimates (± s.e.) of the direct heritability (hA2), the maternal heritability (hM2), the covariance between direct additive genetic and maternal additive genetic effects as a proportion of the phenotypic variance (cAM) and the proportion of phenotypic variance ascribable to maternal permanent environmental effects (c2) for birth weight were 0.25±0.02, 0.06±0.01, -0.05±0.01 and 0.07±0.01, respectively. The correlation between direct additive genetic and maternal additive genetic effects (rAM) was -0.45. For 200-day weight and 400-day weight, the inclusion of a direct-maternal genetic covariance did not give a significant improvement in the log likelihood. The estimates of hA2, hM2, cAM, c2 were 0.26±0.02, 0.05±0.01, -0.02±0.01 & 0.05±0.01 for 200-day weight and 0.35±0.03, 0.04±0.01, -0.03±0.01 & 0.03±0.01 for 400-day weight, as obtained from the most comprehensive model (model 6). The estimates of rAM for the two traits were -0.14 and -0.27, respectively.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.657907  DOI: Not available
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