Einfluß von Booroola-Merinos auf Fettgehalt und -qualität der Schlachtkörper bei Kreuzung mit Merinofleischschafen

Abstract. Title of the paper: The effect of Booroola on fat content and fat quality of carcasses in crosses with German Mutton Merinos
Taking actual consumer demands into consideration possible influences of fecundity genes, like that of the Australian Booroola Merino (FecB), on fat content, fat distribution and fat quality of lamb carcasses are of special interest. Within a project investigating the introgression of the FecB-gene into German Mutton Merino (GMM) in total 144 male lambs with different portions of Booroola (B) were tested between 1995 and 1997. The animals were fed ad lib. a pelleted grain mixture from 20 up to 42 kg body weight. There are no differences in kidney fat percentage, subcutaneous fat thickness, percentage fat of the loin as well as intramuscular fat (IMF) between carcasses of B-crosses (1/8 or 1/16 B) and GMM. Differences in the fat score disappear in lambs of the third backcross generation. The offspring of heterozygous carriers has a higher percentage of intermuscular fat and less IMF. B-crosses show lower melting points in IMF and kidney fat, which corresponds with changes in the fatty acid composition. Also the ratio between linoleic and linolenic acid was higher, especially in the offspring of gene-carriers. In general the differences between GMM and the involved B-crosses are small and unfavourable estimations of the carcass quality by the consumers are unlikely. Obvious there is no pleiotropic effect of the FecB-gene on fat content, distribution and quality. Correlated effects appear only in a few traits and show no evidence in crossbred lambs with even or less than 1/16 B.