Extending the Grazing Period for Bulls, Prior to Finishing on a Concentrate Ration: Composition, Collagen Structure and Organoleptic Characteristics of Beef

Abstract

The biochemical and organoleptic characteristics of the longissimus thoracis muscle from suckler bulls (n = 56) finished on a concentrate-based system (C) or raised in a pasture-based system (P) incorporating 99 (P99), 162 (P162) or 231 days (P231) of grazing prior to indoor finishing on the concentrate-based diet were investigated. Age at slaughter increased with increasing period at pasture. Intramuscular fat concentration was lower (p < 0.001) for P99 than for C, P162 and P231 bulls, which did not differ. Soluble collagen proportion was lower (p < 0.01) for P162 and P231 than for P99 and C bulls. Collagen cross-link content was higher (p < 0.05) for P231 than for P99 and C bulls and for P162 than for C bulls. The proportion of type I muscle fibres was higher (p < 0.01) for P231 and P162 than for P99 and C bulls. Sensory tenderness was higher (p < 0.001) for C and P162 than for P99 and P231 bulls and overall liking was higher (p < 0.01) for C than for P99 and P231 bulls but similar to P162 bulls. Extending the grazing period to 162 days did not negatively influence the sensory qualities of beef compared to the intensive concentrate-based system.

The effect of extended post-mortem ageing on the Warner–Brazler shear force of longissimus thoracis from beef heifers from two sire breeds, slaughtered at 20 or 25 mo of age

“…The effect of later slaughter (increasing slaughter age/weight) on IMF content and collagen solubility was as expected (Maltin et al, 1998;Mezgebo et al, 2019). The time interval in this study and that of Maltin et al (1998) was not sufficient to alter the muscle fibre distribution seen in Mezgebo et al (2019). The increase in glycolytic enzyme activity (LDH and PFK) and decrease in oxidative enzyme activity (CS) due to later slaughter which was not seen in Mezgebo et al (2019) may reflect the higher energy density in the pre-slaughter diet of the heavier/older heifers.…”

“…In contrast to the present study, Keady et al (2017) reported lower WBSF for LT from Angus-sired steers than from Belgian Blue sired steers after 14 d ageing, which likely reflects the greater difference in IMF content in the two studies. The effect of later slaughter (increasing slaughter age/weight) on IMF content and collagen solubility was as expected (Maltin et al, 1998;Mezgebo et al, 2019). The time interval in this study and that of Maltin et al (1998) was not sufficient to alter the muscle fibre distribution seen in Mezgebo et al (2019).…”

“…The time interval in this study and that of Maltin et al (1998) was not sufficient to alter the muscle fibre distribution seen in Mezgebo et al (2019). The increase in glycolytic enzyme activity (LDH and PFK) and decrease in oxidative enzyme activity (CS) due to later slaughter which was not seen in Mezgebo et al (2019) may reflect the higher energy density in the pre-slaughter diet of the heavier/older heifers. In support of this suggestion, when late maturing bulls were slaughtered at the same age from pasture or a high energy ration, carcass weight differed but the LT from the heavier animals had a more glycolytic and less oxidative metabolism (Moloney et al, 2017).…”

Contribution of connective tissue components, muscle fibres and marbling to beef tenderness variability in longissimus thoracis, rectus abdominis, semimembranosus and semitendinosus muscles

“…Although many study groups have investigated the relationship between the composition of connective tissue in TCol, ICol, CLs and meat tenderness, the conclusions made have not been clearly established . This is for several reasons, including the large variability of tenderness within muscles, time of ageing and cooking method, as well as the rearing practices of the animals .…”

“…17 Although many study groups have investigated the relationship between the composition of connective tissue in TCol, ICol, CLs and meat tenderness, the conclusions made have not been clearly established. 4,36,37 This is for several reasons, including the large variability of tenderness within muscles, time of ageing and cooking method, as well as the rearing practices of the animals. 13,38 Overall, the studies did not always specify the location of sampling within the muscle, which is very important, 39 nor the exact conditions of ageing and the method or conditions of cooking.…”