The objective of this study was to investigate the growth- and breed-related changes of muscle fiber characteristics in cattle and their importance to meat quality. Four cattle breeds with different growth impetus and muscularity were reared and slaughtered under experimental conditions. German Angus as a beef type, Galloway as a hardy type, Holstein Friesian as a dairy type, and double-muscled Belgian Blue as an extreme type for muscle growth were used. Between 5 and 17 bulls of each breed were slaughtered at 0, 2, 4, 6, 12, 18, and 24 mo of age. Muscle fiber traits were determined and classified by computerized image analysis, and several measures of meat quality were also determined, including shear force value, meat color, and i.m. fat content. The postnatal growth of semitendinosus muscle in cattle was characterized by a nearly 10-fold increase of muscle fiber area from birth to 24 mo of age. In the first few months after birth, a transformation of type IIA fibers into IIB fibers was found, whereas type I fibers were nearly unaffected by age. The apparent total muscle fiber number of semitendinosus muscle did not increase during postnatal life. These results confirm that the fiber number is determined in embryonic development. Throughout the study, the double-muscled Belgian Blue (BBDM) bulls had almost twice the fiber number of the other breeds, emphasizing a more extensive hyperplasia of muscle fibers during embryonic development in BBDM compared with the other three breeds. The apparent number of type I fibers was, however, not affected by breed, which suggests that the additional fibers found in BBDM postnatally were type IIB and IIA fibers. We did not find significant differences in muscle fiber total number, muscle fiber type frequencies, or meat quality characteristics among breeds, with the exception of BBDM. Having pooled the four breeds, paler meat was related to a higher frequency of type IIB fibers, a lower area of type IIA and type I fiber, and a higher total muscle fiber number. These findings based on data of double muscling give us some hints for biological causes for the variation of meat quality. Further investigation, in particular within each breed, is necessary to identify the superior fiber traits for bovine meat production.

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The adipose tissue development in muscle and the fatty acid composition of intramuscular fat of 200 bulls from three different breeds during growth was investigated. There were significant differences in quantitative and qualitative fat deposition which were genetically caused. The muscle of Galloway and Whiteblue Belgian bulls contained a high n-3 fatty acid content which is positive for human nutrition. During growth an increased deposition of saturated fatty acids into the adipocytes of muscle was observed.

Die Auswirkung unterschiedlicher Haltungs-und Futterungsbedingungen (Weidemast und intensive Stallmast) beim Schaf aufdie Fettsaurezusammensetzung des Fleisches unter besonderer Berucksichtigung der Qualitat des Endproduktes wurde in drei Versuchen gepriift. Das durch Weidehaltung erzeugte Schaffleisch wies einen signifikant hoheren n-3 Fettsauregehalt im Vergleich zu intensiv gemasteten Larnmern auf.Fat composition of lamb. The effect of different feeding systems (extensive on pasture and intensive penned) on fatty acid composition of lamb muscle in relation to final product quality was investigated in three feeding trials. Lambs feeding on grass the muscle fat contained more n-3 fatty acids in comparison to penned sheep. The relative quantities of C18:3; C20:5 and C22:6 were markedly higher in grass finished lambs.Fleisch ist ein nahrstoffreiches bzw. nahrstoffdichtes Nahrungsmittel aufgrund seines Gehaltes an biologisch wertvollem EiweiB, essentiellen Fettsauren, wichtigen Vitaminen und Mineralstoffen, die vom menschlichen Organismus besonders gut genutzt werden konnen. Der Bundesburger verzehrte 1993 (Statistisches Jahrbuch 1994) im Mittel pro Kopf 56,4kg Schweinefleisch, 1,Okg Schaf-und Ziegenfleisch, 19,lkg Rindfleisch und 12,4kg Geflugel. Das Negativimage von Fleisch resultiert vor allem aus dem Fett-und Cholesteringehalt. Die Deutsche Gesellschaft fur Ernahrung empfiehlt eine Energiezufuhr uber Fett von 25 bis 30%. Derzeit werden im Durchschnitt ca. 40% aufgenommen. Diese iiberkalorische Ernahrung, verursacht durch zu viel Fett, zu viel Zucker und zu viel Alkohol, ist weiterhin als Hauptproblem fur die Entstehung ernahrungsbedingter Krankheiten anzusehen. Nach Angaben aus dem Erganzungsband des Ernahrungsberichtes 1992 werden etwa 11% der Gesamtfettaufnahme uber Fleisch und etwa 20% iiber Fleischund Wurstwaren aufgenommen. Der Fettgehalt ist sowohl bei Schweinefleisch als auch bei Rindfleisch in den letzten Jahren deutlich zuruckgegangen. So enthalt das in Deutschland verkaufte Schweinefleisch im Durchschnitt ca. 10,5% Fett, wahrend lOOg Schweineschnitzel nur etwa 1,9% Fett und damit nur 445kJI106kcal aufweisen (ffonike/[7]). Fett ist nicht nur ein Energielieferant, sondern spielt als Trager von Aromastoffen, von fettloslichen Vitaminen (A, D, E, K) und als Losungsvermittler fur Vitamine eine besondere Rolle. Die biologische Wirkung der Fette wird im wesentlichen von den Hauptkomponenten, den Fettsauren, bestimmt. Die

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