Copies of 16 publications from the thesis, authored and co-authored by the author, included as appendix. / Includes bibliographical references (leaves 195-220). / 1 v. (various pagings) : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Examines 3 hypotheses: that the lipid levels and fatty acid composition of meat produced in Australia may vary between cattle genotypes, ages, sexes, seasons, and anatomical sites of sampling; that genetic variation may be sufficiently large to warrant selective crossbreeding of dams to different sire genotypes as an improvement strategy in the proportion of monounsaturated fatty acids in beef; and, that genotype differences in bovine tissue may exist when phospholipid and triacylglycerol fractions of total lipids are analysed separately, regardless of fatness of the cattle. Genetic variation in fatty acid composition of 7 different cattle breads were examined in experiments using non-lactating cows, yearling steers, yearling heifers and weaner calves. Breed differences were found in the muscle and adipose tissues when phospholipid and triacylglycerol fractions were analysed separately regardless of the fatness of the cattle. Differences in age, sex, season and anatomical site were also significant. The study concludes that breed differences in fatty acid composition are related to fatness and stage of maturity such that early-maturing cattle are fatter, contain higher proportions of unsaturates, and have softer fats with low melting points than lean, late-maturing cattle. It is recommended that total lipids be separated into triacylglycerol and phospholipid fractions and analysed separately. Desturation indexes could be used as a biochemical marker for beef breeding decisions, and genetic parameters presented used for future selection indices for fatty acids in carcass quality assessment. / Thesis (Ph.D.)--University of Adelaide, Dept. of Animal Science, 1999

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