Studies on the muscles of meat animals I. Differences in composition of beef longissimus dorsi muscles determined by age and anatomical location

Abstract

1. The longissimus dorsi muscles of cattle have been analysed for moisture, intramuscular fat (and its iodine number), nitrogen (total, myofibrillar, sarcoplasmic, soluble non-protein and stroma), myoglobin, total soluble phosphorus and ash; ultimate pH and buffering power were also determined.2. At birth, in the region of the 4th, 5th and 6th lumbar vertebrae, total, myofibrillar, sarcoplasmic and soluble non-protein nitrogens have attained 87, 76, 71 and 25% of their mean adult values, respectively; the concentration of stroma nitrogen diminishes by 50%, between birth and maturity.3. The mean adult values (fat-free basis) for sarcoplasmic (0·9%) and myofibrillar (1·9%) protein nitrogen, for total nitrogen (3·6%) and for moisture (76·8%) are atained at approximately 5 months, 7–10 months and 18 months of age, respectively; moisture on a whole tissue basis decreases fairly regularly as intramuscular fat increases.