Modification of beef quality through steer age at slaughter, breed cross and growth promotants

Exploring the effects of ageing on instrumental and sensory characteristics of meat from Lidia breed females: A comparative study of two commercial types

The aim of this study was to assess the influence of ageing on instrumental and sensory qualities in Longissimus thoracis et lumborum (LTL) from heifers (n = 200) and cows (n = 100) of Lidia breed. The animals were slaughtered as heifers (24-48 months) or cull cows (> 48 months). For instrumental analysis, pars Thoracis aged at 7, 14 and 28 days was used; for sensory analysis, pars Lumborum aged at 14 and 28 days was evaluated. Heifers showed redder and yellower meat (P < 0.05) and cows showed slightly higher Water Holding Capacity (WHC): Thawing Loss (TL) = P < 0.05; Drip Loss (DL) = P < 0.01; Pressure Loss (PL) = P < 0.01; Cooking Loss (CL) = P < 0.05. Ageing generated changes in meat colour, with increases in lightness (L*, linear pattern, P < 0.001) and oscillations in a* and b* (quadratic patterns; P < 0.05 and P < 0.001, respectively). Ageing affected TL (increasing, P < 0.001) and PL (decreasing, P < 0.05), and generated a significant improvement in Warner Bratzler Shear Force (WBSF) values (P < 0.001). Commercial type revealed changes in consumer panel ratings for flavour (P < 0.05), juiciness (P < 0.01), tenderness (P < 0.001) and overall acceptability (P < 0.001), with better results in these parameters for cull cows. In contrast to the usual, ageing did not affect the sensory traits. There was no significant interaction between commercial type and ageing time, except for beef flavour, which worsened with ageing (P < 0.05).

Evaluating the Shelf Life and Sensory Properties of Beef Steaks from Cattle Raised on Different Grass Feeding Systems in the Western United States

Consumer interest in grass-fed beef has been steadily rising due to consumer perception of its potential benefits. This interest has led to a growing demand for niche market beef, particularly in the western United States. Therefore, the objective of this study was to assess the impact of feeding systems on the change in microbial counts, color, and lipid oxidation of steaks during retail display, and on their sensory attributes. The systems included: conventional grain-fed (CON), 20 months-grass-fed (20GF), 25-months-grass-fed (25GF) and 20-months-grass-fed + 45-day-grain-fed (45GR). The results indicate that steaks in the 20GF group displayed a darker lean and fat color, and a lower oxidation state than those in the 25GF group. However, the feeding system did not have an impact on pH or objective tenderness of beef steaks. In addition, consumers and trained panelist did not detect a difference in taste or flavor between the 20GF or 25GF steaks but expressed a preference for the CON and 45GR steaks, indicating that an increased grazing period may improve the color and oxidative stability of beef, while a short supplementation with grain may improve eating quality.

Post-slaughter indicators of meat productivity and chemical composition of the muscular tissues of bulls receiving corrective diet with protein-vitamin premix

The problem of increasing the production of beef to provide the population with domestically-produced meat is mainly being solved by selective breeding of dairy and combined breeds. Therefore, there is a need for the development and introduction of complex measures to increase meat productivity of young cattle, especially regarding the completeness of diet and optimal content of mineral elements in it. The study was conducted on bulls of the Ukrainian Black-Spotted Dairy breed starting from the age of 6 up to the age of 15 months. At the end of the experiment, the animals were slaughtered, 5 from each group. The study was aimed at determining the effect of the protein-vitamin premix Intermix Fattening on the slaughter parameters, morphological composition of carcass and flesh composition by quality grades, chemical composition of the muscle tissue. Statistical analysis of the results revealed that feeding bulls with the supplement increased pre-slaughter live weight by 7.1% and slaughter weight by 9.8%. After meat separation, more edible parts of carcass were obtained in the absolute value. The weight of paired carcass was 9.5% higher. Intake of the diet with protein-vitamin premix influenced the bulls’ characteristics of growth and development of musculature and bones, intensity of fat deposition, leading to 10.8% increase in flesh and no statistical decrease in the yield of bones compared with the carcass weight. Muscle-bone ratio equaled 4.27 in the control, and 4.56 in the experimental animals. Meatiness index of the young animals that had received the supplement with the diet was higher by 11.1%. Flesh of carcasses of bulls belonging to the experimental group had higher content of valuable grades of beef. We obtained 27.3% more flesh of the highest quality and 11.5% of the first-grade quality. In the muscle tissue and the longissimus of the bulls that had been consuming the premix, the concentration of dry matter was higher by 0.78%, and protein by 0.85%. Use of the Intermix protein-vitamin premix would lead to an increase in live weight of animals, and therefore significantly increase the yield of meat and improve the morphological composition of the bulls’ carcasses.

Effect of postmortem tenderization strategies (pretumbling, blade tenderization, moisture enhancement) on processing yield parameters and eating quality of selected hip and loin muscles from youthful and mature beef carcasses

Several muscles from mature beef carcasses have been identified as failing to provide adequate tenderness required for a satisfactory consumer eating experience. Postmortem processing strategies can help improve the tenderness and subsequent eating quality of mature beef muscles. The current study was undertaken to investigate the impact of processing strategies (blade tenderization [BT], pretumbling [PT], and moisture enhancement [ME]), alone and in combination, on processing yield and eating quality-related parameters of selected loin and hip muscles (gluteus medius [GM], longissimus lumborum [LL], semimembranosus [SM], and biceps femoris [BF]) from youthful and mature beef cattle. Results indicate that muscles from mature beef were inherently less tender (P < 0.05), but some tenderization procedures produced meat that was similar in tenderness to that of youthful cattle. Of the different tenderization strategies evaluated, BT followed by ME (injection of a salt/phosphate solution) was the most effective strategy for improving (P < 0.05) tenderness of tougher muscle cuts such as BF and SM. Moisture enhancement alone improved tenderness (P < 0.05) and juiciness (P < 0.01) of SM, GM and LL, but with the exception of samples tenderized prior to injection, was not effective (P > 0.05) in BF muscles. No additional tenderization of GM and LL samples was observed (P > 0.05) by combining PT or BT with ME. Combining PT or BT with ME; however, was effective (P < 0.05) to control the increased purge loss observed following ME treatment in SM and LL muscles. Pretumbling as a single treatment was ineffective (P > 0.05) in all of the muscles, and only treatments that included BT were sufficient to effect an increase (P < 0.05) in tenderness of BF.

The impact of different Hormonal Growth Promotants (HGP) on desmin degradation and collagen content of various muscles from pasture and feedlot finished steer carcasses

The impacts of several hormonal growth promotants (HGP) on Warner-Bratzler Shear Force (WBSF), desmin degradation ratio (DDR) and collagen content (COLL) were assessed. Treatments within feedlot and pasture finished steer carcasses (n = 60, n = 40, respectively) were control (CON-100-F and CON-400-P), oestradiol HGPs (OES-100-F and OES-400-P) and trenbolone acetate/oestradiol HGPs (TBA+OES-100-F only). The longissimus lumborum (LL), gluteus medius (GM), infraspinatus (IS), semitendinosus (ST,) and the LL and biceps femoris (BF) were collected from feedlot and pasture finished steers, respectively. All muscles were aged between 3 and 35 days. The LL from TBA+OES-100-F carcasses had increased WBSF and decreased DDR, which varied in magnitude with ageing (P < 0.05). The GM from OES-100-F steers also had lower DDR (P < 0.05). The feedlot HGP treatments had no impact on the WBSF of the IS, ST or GM and no impact on COLL in the LL. The OES-400-P had no impact on WBSF, DDRor COLL for both muscles (P > 0.05).

A preliminary investigation of the contribution of different tenderness factors to beef loin, tri-tip and heel tenderness

The objective of this study was to identify the relative contribution of tenderness factors for three beef muscles with similar tenderness ratings. Longissimus lumborum (LL), tensor fascia latae (TF) and gastrocnemius (GC) were collected from 10 USDA low Choice beef carcasses and assigned to a 5 or 21 days aging period (n = 60). Sarcomere length, troponin-T degradation, collagen content, mature collagen crosslink density, intramuscular lipid content and trained panel analysis were measured. Correlation and multivariate regression analysis indicated each muscle has a specific tenderness factor that contributed to the overall tenderness evaluated by trained panelists. The equations indicated LL tenderness was driven by lipid content (P < .05); TF tenderness was driven by collagen content (P < .05). GC tenderness was driven by proteolysis (P < .01), and only collagen content can be casually used as an overall tenderness predictor for all three cuts.

Meat and sensory quality of major muscles from Angus, Charolais, and Angus crossbred steers with high and low residual feed intake

Effects of residual feed intake (RFI) and genetic group on growth, carcass, and meat quality characteristics of bovine longissimus lumborum (LL), triceps brachii (TB), semimembranosus (SM), and gluteus medius (GM) muscles were investigated using 72 purebred Angus, purebred Charolais, and Angus crossbred steers (n = 24 per genetic group) classified as either high (inefficient) or low (efficient) RFI (n = 12 high and low RFI steers within genetic group). There was no RFI effect (P > 0.05) on growth, carcass, and meat quality measurements except high RFI steers had the highest dry matter intake (P < 0.05), and low RFI TB was rated as having reduced beef flavour intensity and sustained juiciness (P < 0.05). Purebred Angus and Charolais LL and GM had lower shear force values (P < 0.05) than Angus crossbreds and ageing reduced mean shear force values except in TB. For TB, SM, and GM, Angus crossbred steers had the highest mean beef flavour intensity scores, and Charolais SM and TB were less tender than those of Angus crossbred (P < 0.05). Overall, RFI did not influence most meat quality traits; therefore, low RFI animals may contribute to reducing feed costs or environmental impact without compromising meat quality and palatability.

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

BACKGROUND

The current study evaluated the subcutaneous fatty acid (FA) composition of calf- and yearling-fed steers with or without growth promoting implants. Crossbred steers (n = 112; 267 ± 5.0 kg) of the same contemporary group were allocated to one of four production system and implant strategy based treatments in a completely randomized design with a 2 × 2 factorial arrangement of treatments.

RESULTS

There were no interactions (P > 0.05) between production systems and growth promoting implants for the total and individual subcutaneous FA. Yearling as opposed to calf finishing reduced (P < 0.05) subcutaneous proportions of C20:3n-6, trans (t)12-18:1, C14:0, several minor cis-monounsaturated FA (c-MUFA; c9-14:1, c11-16:1, c11-18:1, c12-18:1, c13-18:1, c9-20:1 and c11-20:1), and increased (P < 0 .05) subcutaneous proportions of t11c15-18:2, total and individual branched-chain FA. Subcutaneous fat from steers implanted with growth promotants had higher (P < 0.05) proportions of total polyunsaturated FA (PUFA), total n-6 PUFA, C18:2n-6 and individual t-18:1 isomers (t6 to t10) compared to non-implanted steers.

CONCLUSIONS

Overall, current findings show that production systems and growth promotants led to only minor differences in subcutaneous FA composition of beef steers.

Changes in tenderness and cathepsins activity during post mortem ageing of yak meat

Tian, J.-C., Han, L., Yu, Q.-L., Shi, X.-X. and Wang, W.-T. 2013. Changes in tenderness and cathepsins activity during post mortem ageing of yak meat. Can. J. Anim. Sci. 93: 321–328. Very little research has been conducted on yak meat tenderization. In this study we investigated the changes in physical characteristics (e.g., pH, water-holding capacity, texture profile analysis, shear force) and cathepsins L, B and H activities in the tenderization process. These traits were quantified in longissimus dorsi muscle from 10 yaks during 192 h post mortem. Samples were aged at 4°C for 0, 12, 24, 36, 48, 72, 120, 168 and 192 h. pH decreased (P<0.05) from 6.84 to 5.54 in the first 72 h and did not change significantly during the next 120 h. Water-holding capacity showed an overall decreasing trend (P<0.05). Shear force decreased? (P<0.05) and myofibrillar fragmentation index increased? (P<0.05), and it was concluded that ageing can improve yak meat tenderness. Our results on texture profile analysis showed a decrease in hardness (P<0.05), springiness (P<0.05) and chewiness (P<0.05), reflected in a progressive softening during ageing (P<0.05). Cathepsins L, B and H activity showed an increased trend (P<0.05). In conclusion, our results show potential roles for cathepsins L, B and H in the tenderization process. This study provides further insights into the tenderization process of yak meat, which may ultimately be used for the advantageous manipulation of the process.

Contribution of myofibrillar and connective tissue components to the Warner-Bratzler shear force of cooked beef

Myofibrillar (MF-SF) and connective tissue (CT-SF) peak shear forces were interpolated from Warner-Bratzler shear force (SF) deformation curves of cooked bovine M. gluteus medius (GM) and M. semitendinosus (ST) from 112 crossbred steers in a 2×2×2 factorial experiment examining the interactions between slaughter age, growth promotants and breed cross (British versus Continental). Mixed model analyses, Pearson correlations and stepwise multiple regression identified relationships between shear forces, meat quality measurements and production treatments. Connective tissue contribution to SF increased with slaughter age and implantation in the ST and with slaughter age only in the GM. Myofibrillar contribution to SF increased with slaughter age for the ST and with Continental genetics for the GM. Variation in ST SF and MF-SF was best described by muscle weight, which increased with animal age, while GM SF and MF-SF variation was best described by cooking loss, indicating that ST and GM SF were most affected by connective and myofibrillar proteins, respectively.