Carcass and muscle characteristics of beef cull cows between 4 and 9 years of age

Abstract

The effects of age and breed on carcass and muscle characteristics of cull cows slaughtered at the same fattening state between 4 and 9 years of age were analysed in four French breeds: Aubrac (AU), Charolais (CH), Limousin (LI), and Salers (SA). Muscle characteristics were determined in three muscles: longissimus thoracis (LT), semitendinosus (ST) and triceps brachii (TB). They included: (1) the % frequency, cross-sectional area and % area of the different fibre types classified according to their contraction rate and metabolic properties (slow twitch oxidative (SO), fast twitch oxidative glycolytic (FOG) and fast twitch glycolytic (FG)), (2) the isocitrate dehydrogenase (ICDH) and lactate dehydrogenase (LDH) activities, representative of oxidative and glycolytic metabolism respectively, and (3) the total and insoluble collagen contents. Whatever the age of the animals at slaughter, the same carcass composition, fibre characteristics (% frequency, area, % area) and metabolic enzyme activities were obtained whatever the muscles considered. In contrast, important differences between breeds were observed in carcass composition (muscle, fat, bone) and enzyme activities. CH cows presented the highest final live weight and LI carcasses were characterized by higher muscle weight, lower fat and bone weights and more glycolytic muscles. Among the muscle characteristics, collagen was the most influenced by age and breed in a breed and muscle dependent manner respectively. AU and LI cows exhibited lower total and insoluble collagen contents than CH and SA cows, particularly at 6 to 7 years of age and for the LT and ST muscles. Thus collagen could explain an important part of the variability in meat quality from cull cows. In conclusion, results of this study provide consistent data on muscle characteristics of cull cows, few studies were available until then.

Growth performance, carcass traits and meat quality of bulls and heifers slaughtered at different ages

“…Higher total collagen contents were reported for bulls compared to steers (Cross et al, 1984b) and for bulls compared to cows of the same breeds (Jurie et al, 2005(Jurie et al, , 2006, apparently due to the effect of different testosterone levels. This supports our finding that the MLL samples of heifers contained less total collagen than those of bulls.…”

Effect of muscle type, sire breed, and time of weaning on fatty acid composition of finishing steers1

“…The 2 skeletal muscles analyzed in this study vary widely in muscle characteristics including muscle fiber type. Jurie et al (2006) showed that the STN had a greater percentage of fasttwitch glycolytic fibers, whereas the LM had a greater percentage of slow-twitch oxidative fibers. Muscle fiber types are dynamic, constantly changing in proportion as the animal ages, but muscle type is a reflection of the energy requirements of the muscle (Hocquette et al, 1998;Oddy et al, 2001).…”

Muscle and genotype effects on fatty acid composition of goat kid intramuscular fat

“…However, this practice is expensive for what it is generally obtained from one muscle only, being longissimus thoracis et lumborum the most common reference muscle. Other muscles represent different anatomical regions and divergent functionalities (postural and motor muscles), which may affect their fatty acid profile (Costa et al, 2008;Jurie et al, 2006;Lefaucheur et al, 2006;Hocquette, 2006).…”