Longissimus Muscle Quality, Palatability and Connective Tissue Histological Characteristics of Bulls and Steers Fed Different Energy Levels and Slaughtered at Four Ages

Abstract

One hundred forty-four Angus male calves were assigned to one of five slaughter-age groups: 9, 12, 15, 18 and 24 mo of age. After weaning, one-half of the calves within slaughter age were castrated. One-half of the 12-, 15-, 18- and 24-mo age groups of each sex were further randomly allotted to a high-energy (HE) or low-energy (LE) finishing diet. Eight bulls and eight steers assigned to the 9-mo slaughter group were fed the HE diet only. Samples from the longissimus muscle (LM) were taken at the 12th rib for histological evaluations of fat deposits. Thin sections from the LM at the 11th rib were stained for lipid, collagen and elastin. Steaks from the LM were cooked and evaluated by a sensory panel and sheared by a Warner-Bratzler shear (WBS) device. The 9-10-11th rib sections were separated into muscle, fat and bone. Collagen, elastin and collagen solubility were determined chemically. Bulls had heavier carcasses, less fat and lower sensory scores for tenderness and juiciness than steers. Steers fed the HE diet had lower WBS values than bulls on either diet. Cooking losses were higher for bulls at 12, 18 and 24 mo than for steers. Histological evaluation showed that collagen content was higher for bulls than for steers and higher for cattle fed the LE diet than those fed the HE diet. Among cattle on the HE diet, the 9-mo cattle had more collagen than all older groups. Neither sex nor diet had an effect on elastin content shown by histological evaluation, but 12-mo cattle had the most elastin and the 15- and 18-mo cattle had the least elastin. Collagen content determined by chemical analysis was not affected by sex, diet or slaughter age. Correlation coefficients among histologically and chemically evaluated collagen and elastin and meat traits were too low to be of practical importance. The time-intensive histological techniques used in our study provided little additional information over that obtained from visually evaluated or chemically measured meat traits.

The eating quality of beef from young dairy bulls derived from two breed types at three ages from two different production systems

“…Schönfeldt and Strydom (2011) also showed that age had no effect on the collagen content of South African cattle. The lack of a diet effect on collagen is in accordance with the results of Dikeman et al (1986).…”

“…Similarly, a lack of any effect of age on the collagen content of the longissimus dorsi (LD) muscle from bulls and steers slaughtered at four ages was reported by Dikeman et al (1986). Schönfeldt and Strydom (2011) also showed that age had no effect on the collagen content of South African cattle.…”

Liveweight gain and carcass characteristics of bulls and steers farmed on hill country

“…The higher pH of beef from bulls, and the associated darker colour, is consistent with other studies (discussed by Purchas & Aungsupakorn 1993), but the removal of the significant effect of castration on PF-IY when adjustments were made for pH was not expected. The higher values for PF-IY for bulls in the unadjusted data support evidence that the connective tissue of beef from bulls and steers differs slightly in amount or concentration (Boccard et al 1979;Cross et al 1984;Dikeman et al 1986), as there is evidence that Warner-Bratzler initial yield force (IY) is primarily a measure of myofibrillar toughness, whereas the peak force (PF) is a measure of myofibrillar plus connective tissue toughness (Bouton et al 1977;Bouton et al 1981). Therefore the difference (PF-IY) tends to reflect differences in connective tissue toughness.…”

Effect of nutritional factors on biochemical, structural and metabolic characteristics of muscles in ruminants, consequences on dietetic value and sensorial qualities of meat

“…Similarly, Seideman and Crouse [105] who induced changes in fiber types and diameters by variations in feeding level, did not observe any relationships between fiber characteristics and juiciness. However, Dikeman et al [20] and Keane et al [53] pointed out a positive relationship between juiciness (and tenderness) and muscle fat content. In the latter study, the higher fat content was due to higher carcass weight, and not to an increased feeding level.…”