Quantifying the relative contribution of ante- and post-mortem factors to the variability in beef texture

Abstract

This study aims to investigate the relative contribution of ante-and post-mortem factors to the final quality of beef. In all, 112 steers (four breed-crosses) were arranged in a 2 3 2 3 2 factorial experimental including production system, growth implant and b-adrenergic agonist strategies. Carcasses were suspended by the Achilles tendon or the aitch bone and meat was aged for 2/6/13/21/27 days (longissimus muscle) or 2/27 days (semimembranosus muscle). Meat quality traits related to beef texture were measured. Statistical analyses were developed including ante-and post-mortem factors and their relative contribution to the variability observed for each measured trait was calculated. The main factor responsible for the variability in sarcomere length was the suspension method (91.1%), which also influenced drip-loss (44.3%). Increasing the percentage of British breeds increased (P , 0.05) the intramuscular fat content in longissimus muscle, but only when implants were not used. Thus, the breed-cross, implant strategy and their interaction were responsible for .58% of the variability in this trait. The variability in instrumental and sensory tenderness was mainly affected by post-mortem factors (carcass suspension, ageing time and their interaction), explaining generally , 70% of the variability in these traits. Breed-cross was the second most important effect ( ,15%) when carcass suspension was not considered in the model, but still ageing time was responsible for a much larger proportion of the variability in tenderness (.45%). In conclusion, post-mortem handling of the carcasses may be much more effective in controlling beef tenderness than pre-mortem strategies.Keywords: ageing, b-agonist, carcass suspension, finishing, implant ImplicationsUnder the conditions simulated in this study, including breed-cross, production system, use of implants and/or b-agonists, carcass suspension and ageing time in a single study has been able to explain more than 70% of the variability in beef tenderness. Therefore, a large amount of the inconsistency in beef tenderness at the consumer level could be controlled by manipulating these factors. Moreover, the large amount of variability already explained and the possibility of quantifying the impact of each factor on the final tenderness opens the door to a new way of approaching beef quality manipulation. Besides the potential use of this information for breeding programs or development of new production systems, understanding the effect and interactions of the different factors present in the production chain is the first step in developing palatability assurance critical control point systems.

Relative contribution of electrical stimulation to beef tenderness compared to other production factors

“…The effect of β-adrenergic agonist was minimal (<1%) for all three variables. In a previous study by Juárez et al (2012), using the same experimental design but with carcass suspension as the early postmortem intervention, similar results were reported for shear force values and sarcomere length. Regarding sensory traits, the effect of aging was lower and the effect of the suspension treatment and its interaction with aging was higher than observed when electrical stimulation was used.…”

“…The management of the animals has been previously described in detail by Juárez et al (2012). Briefly, 112 steers (4 breed-crosses: >75% Continental, 50-75% Continental, 50-75% British, >75% British) were arranged in a 2 × 2 × 2 factorial experimental design including production system (12-13 mo, grain finished calf-fed vs. 18-20 mo, grain finished yearling-fed), implant (not implanted vs. implanted with 200 mg progesterone and 20 mg estradiol benzoate at weaning followed by 120 mg of trenbolone acetate and 24 mg estradiol after every 80-90 d interval until slaughter), and β-adrenergic agonist (no ractopamine vs. 200 mg ractopamine head −1 d −1 for 28 d before slaughter).…”

“…Controlling for location effects, longissimus muscles were fabricated into steaks in order to analyze instrumental and sensory tenderness at 2, 6, 13, 21, and 27 d after slaughter. Samples were also used to evaluate sarcomere length and collagen content using methodologies described by Juárez et al (2012). Briefly, steaks were grilled (Garland Grill ED30B, Condon Barr Food Equipment Ltd., Edmonton, AB) to an internal temperature of 71°C.…”

“…The degree of fatness, nested within treatments, was used as a covariate. The adjusted multiple R 2 was calculated, as described by Juárez et al (2012). Individual factors were then removed from the model, and the decrease in the R 2 value was used to calculate the relative contribution of a given factor on the variability observed for each measured trait.…”

Subcutaneous fatty acid composition of steers finished as weanlings or yearlings with and without growth promotants

“…More specifically the objectives were to determine the extent reduced adiposity can influence concentrations of rumen derived FA such as conjugated linoleic acid (CLA), trans ( t )-18:1 isomers and branched-chain FA (BCFA). This report is part of a detailed study which also investigated greenhouse gas emissions [14], economic profitability [15], carcass merit traits [4], beef quality attributes [16] and beef texture [17]. …”