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

Abstract

1998). The effects of age at slaughter, genotype and nishing system on the biochemical properties, muscle bre type characteristics and eating quality of bull beef from suckled calves. AbstractMuscle fibre characteristics and biochemical properties of muscle recovered from young bulls of two genotypes (Aberdeen Angus Xand Charolais X), 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 the fibres and their metabolic properties. Intramuscular fat content increased (P < 0-01) with age at slaughter and at a fixed age was greater for Angus X than Charolais X 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 X and Charolais X 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 X bulls had a greater percentage area of fast twitch glycolytic fibres than Angus X 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 of fast twitch glycolytic fibres.

New Insights into Muscle Fibre Types in Casertana Pig

“…Particularly, our study shows that Pm muscle and Rb muscles have a high percentage of SO fibre types. A positive correlation between the proportions of type I fibres and sensory assessed tenderness in beef (Maltin et al 1998) and pork (Ockerman et al 1984) has been found. Similar to other authors (Kiessling and Hansson 1983), our study shows that the Ld muscle is a typical white muscle in which fast-twitch glycolytic fibres dominate.…”

Comparison of cloned and non-cloned Holstein heifers in muscle contractile and metabolic characteristics

“…So the results from this study, namely the lack of changes in % MyHC IIa and IIx isoforms between 8 and 12 months of age, were in agreement with the literature. A conversion from fast to slow muscle fibre types was described from 19 months of age onwards in young bulls (Maltin et al, 1998;Jurie et al, 2005), indicating a modification of contractile type. These changes in the frequencies of different fibre types with age are accompanied by changes in area and percentage of total muscle area of each fibre type, and in muscular metabolism as indicated by metabolic enzyme activities (Jurie et al, 1995 and.…”

The effect of genotype on muscle fibre characteristics of m. longissimus lumborum of fatteners

“…Studies in pigs (Karlsson et al, 1993) and cattle (O'Halloran et al, 1997) fibres (red fibres -type I) and toughness in study on bulls (Renand et al, 2001). Moreover, a positive relationship between the frequency or percentage area of red fibres and sensory tenderness and negative relationship between the frequency of white fibres and tenderness has been reported in cattle (Maltin et al, 1998). Other studies suggest that differences between the same muscles may only be evident in specific breeds of any one species.…”