The thesis contains papers on both experimental and theoretical work carried out with the objective of maximizing genetic gain in breeding schemes under a variety of constraints. The experimental work is principally in the context of dairy cattle improvement schemes, whereas the theoretical development in more generally applicable to truncation selection. The work had its origins in the introduction of multiple ovulation and embryo transfer (MOET) in dairy cattle breeding schemes. The initial group of papers concerned the benefits and development of a juvenile predictor of dairy merit. The potential benefit of such a predictor was quantified and shown to offer substantial increases in gain (ΔG) without increasing rates of inbreeding (ΔF). The experimental work developed a new successful approach to the problem via growth hormone release. The association were replicated and an understanding of the association in terms of endogenous growth hormone profiles was demonstrated. The next group of papers developed methods to predict ΔF for selection populations. Initial work compared published and novel 1-generation methods as a means of predicting ΔF and the identification of their shortcomings as predictors. Further papers followed the approach of predicting squared contributions and showed that the method was equivalent to the variance of family size but with a correction for the expected proliferation of lines with selective advantage. Finally, other issues related to constrained breeding schemes were explored including defining acceptable ΔF for populations, the impact of inbreeding on the overall productivity, an examination of the benefit of SRY transgenes, and the relationship of genetic contributions to the selection criteria in commercial data.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:664012 |
| Date | January 1999 |
| Creators | Woolliams, J. A. |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/14703 |
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