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The intrinsic properties (those extant at the time of slaughter) of bovine skeletal muscle as they relate to the subsequent quality attributes of beef are reviewed here. Attributes of bovine skeletal muscle that ultimately affect toughness, colour, fat content, flavour, juiciness, and nutritive value of beef are discussed. The dynamic nature of muscle development, particularly with regard to structure and composition, is highlighted. Variation in development of muscle structure and composition due to inherited (genetic) factors and environment (particularly nutrient supply) are described. Examples are given of the implications of sources of variation due to animal genotype, age, nutrient supply, and hormonal environment on muscle cellularity and growth, fibre type, connective tissue composition and structure as they affect meat quality attributes. Key intrinsic properties of muscle include muscle type, cellularity, size, myofibre type, connective tissue composition and structure, glycogen and fat content and proteolytic activity. Activity of the calpain system at slaughter is seen as an important attribute. Regulation of myofibrillar and connective tissue proteolysis in vivo are discussed together with implications for subsequent meat quality. Amongst the on-farm environmental factors, nutritional history and developmental pathway are identified as factors that can be responsible for significant variation in the intrinsic properties of muscle that contribute to variation in toughness, colour and fat content, and thus consumer liking of beef. |
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