caa a22 4500 38806062X CHVBK 20180307125119.0 cr unu---uuuuu 161130e199804 xx s 000 0 eng 10.1017/S1357729800009462 doi S1357729800009462 pii (NATIONALLICENCE)cambridge-10.1017/S1357729800009462 The effects of age at slaughter, genotype and finishing system on the biochemical properties, muscle fibre type characteristics and eating quality of bull beef from suckled calves [Elektronische Daten] Muscle fibre characteristics and biochemical properties of muscle recovered from young bulls of two genotypes (Aberdeen Angus × and Charolais ×), reared on two different diets (silage-based and barley-based) and slaughtered at varying ages between 10 and 19 months of age were established. These analyses were restricted to samples ofm. longissimus lumborum (LI) recovered at 48 h post mortem, vacuum packed and stored at 2°C for 14 days. Biochemical measurements included intramuscular fat content, intramuscular collagen content and its solubility, haem pigment concentration, sarcomere length and myofibril fragmentation. Muscle fibre type was classified according to the contractile nature of thefibres and their metabolic properties. Intramuscular fat content increased (P < 0·01) with age at slaughter and at a fixed age was greater for Angus × than Charolais × bulls (211·5 v. 295·8 mg/g dry matter, P < 0·01). Total intramuscular collagen and its solubility tended to decrease with age (P < 0·01). Differences in haem pigment concentration in samples of LI were detected between genotype (3·99 v. 3·59 mg/g for Angus × and Charolais × bulls; P × 0·01) and diet (3·97 v. 3·62 mg/g for bulls given barley and silage; P < 0·01), and increased with age at slaughter (P < 0·01). There was a significant increase in eye muscle cross-sectional area with increasing slaughter date (P < 0·01) and this was paralleled by an increase in cross-sectional area of individual muscle fibres (P < 0·001). Differences in cross-sectional area of individual muscle fibres between genotype and diet were small and inconsistent. Charolais × bulls had a greater percentage area of fast twitch glycolytic fibres than Angus × bulls (54·3 v. 49·3%; P < 0·01) and a smaller percentage area of slow twitch oxidative fibres (15·8 v. 18·9%; P < 0·05). Beef tenderness was positively correlated (r = 0·48; P < 0·01) with the frequency of slow twitch oxidative fibres and negatively correlated (r = -0·38; P < 0·05) with the frequency offast twitch glycolytic fibres. Copyright © British Society of Animal Science 1998 bulls nationallicence genotypes nationallicence muscle fibres nationallicence slaughter age nationallicence Maltin C. A. Rowett Research Institute, Bucksburn, Aberdeen AB21 9SB Sinclair K. D. Scottish Agricultural College, Ferguson Building, Craibstone Estate, Bucksburn, Aberdeen AB21 9YA Warriss P. D. University of Bristol, Department of Meat Animal Science, Langford Road, Bristol BS18 7DY Grant C. M. Rowett Research Institute, Bucksburn, Aberdeen AB21 9SB Porter A. D. Rowett Research Institute, Bucksburn, Aberdeen AB21 9SB Delday M. I. Rowett Research Institute, Bucksburn, Aberdeen AB21 9SB Warkup C. C. Meat and Livestock Commission, Winterhill House, Snowdon Drive, Milton Keynes MK6 1AX Animal Science Cambridge University Press 66/2(1998-04), 341-348 1357-7298 66:2<341 1998 66 ASC https://doi.org/10.1017/S1357729800009462 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1017/S1357729800009462 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Maltin C. A. Rowett Research Institute, Bucksburn, Aberdeen AB21 9SB NATIONALLICENCE 700 1- Sinclair K. D. Scottish Agricultural College, Ferguson Building, Craibstone Estate, Bucksburn, Aberdeen AB21 9YA NATIONALLICENCE 700 1- Warriss P. D. University of Bristol, Department of Meat Animal Science, Langford Road, Bristol BS18 7DY NATIONALLICENCE 700 1- Grant C. M. Rowett Research Institute, Bucksburn, Aberdeen AB21 9SB NATIONALLICENCE 700 1- Porter A. D. Rowett Research Institute, Bucksburn, Aberdeen AB21 9SB NATIONALLICENCE 700 1- Delday M. I. Rowett Research Institute, Bucksburn, Aberdeen AB21 9SB NATIONALLICENCE 700 1- Warkup C. C. Meat and Livestock Commission, Winterhill House, Snowdon Drive, Milton Keynes MK6 1AX NATIONALLICENCE 773 0- Animal Science Cambridge University Press 66/2(1998-04), 341-348 1357-7298 66:2<341 1998 66 ASC CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-cambridge