The incidence of dark cutting beef in Sweden

The incidence of DFD (Dark, Firm, Dry) in Swedish cattle was studied at four abattoirs and the influence of some parameters of special interest for the development of DFD were evaluated. The pH was measured in a total of 2686 carcasses of different categories. Carcasses with a pH(24) ≥ 6·2 were classified as being DFD. Only for electrically stimulated carcasses could the pH(24) be considered to be the ultimate pH value. DFD incidences of 3·4% and 13·2% were recorded as overall means for electrically stimulated and non-stimulated carcasses, respectively. The highest incidence was found in young bull carcasses having almost twice as high an incidence of DFD compared with the other categories. Considering seasonal variations, the highest incidence of DFD was found in the period May to August but significant differences in pH were found only for short lairage times. Overnight lairaging increased the incidence of DFD. However, the influence of the lairage time is closely related to the lairage conditions and needs further study.     

Effect of breed on the muscle glycogen content and dark cutting incidence in stressed young bulls

Observations have shown relevant differences in the behaviour of Brown Swiss bulls and Pirenaico bulls. Because temperament is involved in the development of dark cutting beef (DC), the aim of this study was to investigate the influence of breed on muscle glycogen content and on the incidence of DC condition. Twenty-four Brown Swiss bulls and 24 Pirenaico bulls were used. The animals were divided into a stressed group (S) and a control group (C). In group S, bulls were mixed with unfamiliar animals overnight before slaughter. In group C, bulls were slaughtered immediately after arrival at the abattoir. The results show that the glycogen concentrations in m. longissimus dorsi and m. sternomandibularis from unstressed animals were similar in both the Brown Swiss and the Pirenaico breeds. The muscle glycogen concentration was depleted in all stressed bulls, nevertheless some low concentrations were insufficient to adversely affect the meat ultimate pH value. Finally, there was no influence of breed on the incidence of the dark cutting condition.     

黑切牛肉的诱因及预防措施

早在20世纪30年代,黑切牛肉就引起了人们的注意,由于它异常的品质特征使得牛肉的商品价值下降,在当今的肉牛屠宰加工业中这个问题依然存在。本文阐述了促使黑切牛肉形成的几个主要因素：应激反应、糖原消耗、激素注射及宰前操作,并提出了可能的预防措施。同时也对其他一些可能造成黑切牛肉的因素作了概述。     

The behaviour and blood profile of bulls which produce dark cutting meat

Thirty British Friesian bulls (12 months old), in groups of 6 or 12, were mixed with unfamiliar animals for 16 h preslaughter. Before and during mixing, blood samples were collected and behaviour was monitored. The ultimate pH (pHu) was measured in the m. Longissimus dorsi (LD) 24 h after slaughter. Thirteen carcasses were dark cutting (DC, pHu≧6) and 17 were normal (pHu<6). DC carcasses came from animals which exhibited over twice the total number of agonistic interactions (P<0.001) and showed more dominant behaviour (P<0.001) than animals producing normal carcasses. There was no difference in the blood profile of DC and normal bulls before mixing. However, DC bulls had higher levels of creatine phosphokinase (P<0.001), free fatty acids (P<0.001) and β-hydroxybutyrate (P<0.01) in the blood samples collected after mixing. Overall, pHu was correlated with total activity (r=0.71, P<0.001) and dominance scores (r=0.70, P<0.001). The conclusion is that the cause of DC in mixed groups of bulls is primarily behavioural. Muscle glycogen stores are depleted when blood-borne metabolites are inadequate to fuel the intense or prolonged muscular activity associated with agonistic behaviour.     

Ultrastructural and biochemical changes in electrically stimulated dark cutting beef

In dark cutting beef, with a high ultimate pH, ultrastructural and biochemical changes were followed during the very early post-mortem period in non-stimulated and electrically stimulated muscles. The consumption of ATP was extremely rapid in the electrically stimulated dark cutting muscle. In these samples pronounced changes in the ultrastructure were seen in the form of heavy contractions and complete disorganization of the tissue. The changes could have been caused by a combined effect of super-contractions and proteolytic activity. The changes seen in electrically stimulated samples were not reflected in improvements of the instrumentally evaluated tenderness.     

An estimate of the incidence of dark cutting beef in the United Kingdom

Eight slaughterplants with throughputs ranging from 20 to 300 animals per day were examined to estimate the incidence of dark cutting beef in the United Kingdom. Four thousand, eight hundred and sixteen animals were surveyed and information concerning animal category, source, season and preslaughter handling conditions recorded. Muscle samples were removed to estimate glycogen concentration and after incubation, ultimate pH. The overall incidence of dark cutting (pHu ≥ 6·0) was 4·1%. Increased incidence was associated with short (≤ 20 miles) and long (≥ 150 miles) transport distances. Slaughter on the day of arrival rather than overnight lairage also increased the incidence. Plants were classified into small (killing ≤ 50 animals per day) or large (killing ≥ 100 per day). Eighty per cent of the animals slaughtered passed through the large plants, and a higher incidence was also associated with these plants. Bulls had the highest incidence and heifers the lowest. A seasonal effect was recorded with the highest incidence found between July and October. The results, however, indicate that factors in addition to those examined are also important.     

Biomarkers and biosensors for the diagnosis of noncompliant pH,dark cutting beef predisposition,and welfare in cattle

Meat quality can be affected by stress, exhaustion, feed composition, and other physical and environmental conditions. These stressors can alter the pH in postmortem muscle, leading to high pH and low-quality dark cutting (DC) beef, resulting in considerable economic loss. Moreover, the dark cutting prediction may equally provide a measure for animal welfare since it is directly related to animal stress. There are two needs to advance on-site detection of dark cutters: (1) a clear indication that biomarker (signature compounds) levels in cattle correlate with stress and DC outcome; and (2) measuring these biomarkers rapidly and accurately on-farm or the abattoir, depending on the objectives. This critical review assesses which small molecules and proteins have been identified as potential biomarkers of stress and dark cutting in cattle. We discuss the potential of promising small molecule biomarkers, including catecholamine/cortisol metabolites, lactate, succinate, inosine, glucose, and β-hydroxybutyrate, and we identify a clear research gap for proteomic biomarker discovery in live cattle. We also explore the potential of chemical-sensing and biosensing technologies, including direct electrochemical detection improved through nanotechnology (e.g., carbon and gold nanostructures), surface-enhanced Raman spectroscopy in combination with chemometrics, and commercial hand-held devices for small molecule detection. No current strategy exists to rapidly detect predictive meat quality biomarkers due to the need to further validate biomarkers and the fact that different biosensor types are needed to optimally detect different molecules. Nonetheless, several biomarker/biosensor combinations reported herein show excellent potential to enable the measurement of DC potential in live cattle.     

Singular and combined effects of electrical stimulation, post-mortem ageing and blade tenderisation on the palatability attributes of beef from young bulls

Thirty Santa Gertrudis bulls (approximately 15-18 months old) were slaughtered, dressed and split into siides. The right side of each carcass was electrically stimulated (ES) with seventeen impulses (1·8s impulse duration; 1·8s interval between impulses) of 550 V (AC) and 5 A while the left side served as a non-stimulated control (not-ES). At 24h post morten, USDA quality and yield grade data were obtained from each side. On the second day post mortem, all sides were fabricated and strip loins, top sirloin butts and ribeyes were obtained from each side for post-mortem ageing and blade tenderisation studies. Steaks were removed after a post-mortem ageing period of 4 or 18 days and before (not-BT) or after blade tenderisation (BT) for sensory panel evaluations or shear force determinations. ES sides had more youthful lean maturity (P < 0·0001), higher marbling (P < 0.·002), higher USDA quality grades (P < 0·0.0001) and finer-textured lean (P < 0·002) than did not-stimulated (not-ES) sides. ES significantly improved (P < 0·05) palatability traits in two of twenty-four comparisons; BT significantly improved palatability traits in twelve of twenty-four comparisons and 18-day post-mortem ageing significantly improved palatability traits in seven of twelve comparisons. No significant reductions (P < 0·05) in shear force values were observed for steaks from ES versus not-ES sides while significant reductions (P < 0·05) were observed for steaks from BT versus non-BT cuts (four of six comparisons) and for steaks from cuts aged for 18 versus 4 days (ten of twelve comparisons). BT and 18-day post-mortem ageing were more effective for increasing palatability or for decreasing shear force requirements than was ES; however, ES greatly improved lean colour of meat from bulls.     

Eating quality of young bulls from three Spanish beef breed-production systems and its relationships with chemical and instrumental meat quality

Sensory characteristics of longissimus thoracis muscle from three local Spanish beef breed-production systems and their relationships with chemical and instrumental meat quality traits were studied. Young bulls of Bruna dels Pirineus (BP; n = 69), Avileña-Negra Ibérica (A-NI; n = 70) and Morucha (MO; n = 70) breeds were reared in their own production systems. MO breed showed the highest water holding capacity and also the highest thawing loss and haem pigment content (P < 0.001). No differences in moisture and protein contents were found among breeds. A-NI showed the highest intramuscular fat (IMF, P < 0.05) and total collagen (P < 0.001) contents, whereas BP showed the lowest IMF content (P < 0.05) and the highest collagen solubility (P < 0.001). Beef flavour, tenderness and juiciness accounted for the eating quality differences among the three breed-production systems. Meat from A-NI was rated significantly higher (P < 0.01) for beef flavour and tenderness than that from BP and MO animals. Furthermore, MO showed the lowest juiciness (P < 0.001) which could be due to its higher thawing loss. Within the three breeds, thawing loss was negatively correlated with juiciness and, likewise cooking loss with juiciness and tenderness (P < 0.05). The canonical discriminant analysis showed that the three breeds were significantly different (P < 0.05) from each other according to sensory attributes, which justifies their involvement in different protected geographical indications (PGI).     

Effect of including linseed in a concentrate fed to young bulls on intramuscular fatty acids and beef color

The effect of varying concentrate composition to include 5% linseed and 200 IU of vitamin E on the growth performance, fatty acid composition, and muscle color during shelf life was assessed in 46 young Pirenaica bulls finished to two fatness levels. Adding 5% linseed lowered the dressing rate without altering daily gain or carcass classification. It likewise did not alter the total saturated, monounsaturated, or polyunsaturated fatty acids in the intramuscular fat, though the percentage of α-linolenic acid and n − 3 fatty acids increased significantly while the n − 6 fatty acid to n − 3 fatty acid ratio decreased. Higher subcutaneous fat cover depth at slaughter increased the total percentage of oleic acid and monounsaturated fatty acids without affecting the percentage of saturated or polyunsaturated fatty acids. Adding 200 IU of vitamin E in addition to linseed did not alter the color of film-wrapped fresh meat during storage in darkness.     

Further investigations into the relationship between ultimate pH and tenderness for beef samples from bulls and steers

Samples of longissimus dorsi muscle from 150 cattle comprising Friesian bulls and steers and Charolais × Angus cross steers, were used to investigate the nature of the relationship between ultimate pH and beef tenderness under conditions where cold-shortening was avoided. A modified Warner-Bratzler (WB) shear machine with a square- rather than a vee-blade enabled several aspects of tenderness to be evaluated, including peak force (PF), initial yield force (IY), PF-IY, and an index of total work done. The two steer groups differed little in meat quality characteristics, but, in terms of six major hindquarter cuts, the Charolais cross group yielded 14·3% more meat per unit live weight, due to a combination of a superior dressing-out percent and a higher cutability. Relative to Friesian steers, the bulls produced beef with a higher ultimate pH (P < 0·001), and after adjustment to a common pH, the bull beef was tougher for all WB parameters except PF-IY. Cooking loss was higher for beef from bulls after adjustment for pH. Although reduced by pH adjustment, beef from bulls remained significantly darker than that from steers (P < 0·05) based on reflectance measurements. Maximum toughness in terms of PF, IY, and work index was at an ultimate pH of 6·0-6·1, but the peak was much less clear for PF-IY. The decline in tenderness with an increase in ultimate pH to 6·2 was associated with a decrease in sarcomere length. This result supports a previous suggestion that shortening explains, at least in part, the lower average tenderness at intermediate pH values.     

Influence of sampling on steroid hormone patterns of beef from bulls and steers

Three different muscles (Longissimus dorsi, Semitendinosus, Extensor carpi ulnaris) of bulls and steers, which represent different parts of the carcass and which have differing properties (function, proportions of fat and connective tissue), were analysed with GC-MS for their contents of testosterone, cortisol, cortisone, pregnenolone, dehydroepiandrosterone, progesterone, hydroxyprogesterone, androstenedione, dihydrotestosterone, epitestosterone and androsterone. No difference in the hormone patterns could be detected between the three muscles. However, the enrichment of beef samples with inter- and intramuscular fat decreased the levels of the polar corticosteroids, whereas the levels of lipophilic steroids were increased. The patterns of the lipophilic sex steroids, their precursors and metabolites, which can be used to determine the sexual origin of beef and which might prove useful in evaluating residues of administered steroid hormones, seem to be less affected by the beef sample's fat content, however.     

Maximizing the impact of dairy and beef bulls through breeding technology

Both biological and monetary considerations influence adoption of new breeding technologies. Therefore, genetic, reproductive, and economic factors that determine productivity of dairy and beef operations are reviewed. Improved sire evaluation programs, more efficient artificial insemination, and effective natural service are discussed and related to the present and future impact of dairy and beef bulls. Potential benefits of heterosis, artificial control of reproduction, improved bull management, computers, and multidiscipline research also are suggested. The dramatic impact of artificial insemination on genetic improvement and profitability of most commercial dairy herds is outlined. The uncertain expansion of beef artificial insemination is examined. Comparisons of dairy and beef industries indicate that expectation of similar results from the same animal breeding technologies are unwarranted. Dairy artificial insemination is and should continue to be economically feasible for commercial operations. Commercial beef producers will use little artificial insemination and rely on natural service bulls until precise human control of conception in the bovine is cost effective.     

Effects of stress by unfamiliar sounds on carcass and meat traits in bulls from three continental beef cattle breeds at different ageing times

One-hundred-and-twenty-four young bulls of three Continental beef cattle breeds were used to study the effect of pre-slaughter stress by unfamiliar sounds on carcass traits and quality characteristics of beef aged for three different periods. Stress due to unfamiliar noises had a moderately negative effect on carcass and meat quality. Carcasses from group Stressed had higher (P < 0.05) values of pH₀, pH₂₄, a*, and Warner-Bratzler shear force, and lower (P < 0.05) values of L*, b* and pressure losses than from Unstressed animals. There were significant differences (P < 0.05) among breeds in L*, a* and pressure losses. The ageing time had a significant effect on chromatic variables, WBSF and pressure losses. The cooking losses were not significantly affected by any of the three factors discussed. These results emphasize the importance of implementing appropriate management practices during pre-slaughter handling of cattle in order to reduce any possible risk factor for stress, as well as the different sensitivity of the breeds to similar stimuli.     

Influence of social dominance on production,welfare and the quality of meat from beef bulls

The aim of this study was to assess the effect of social dominance on some indicators of welfare, production and meat quality of young bulls. A total of 60 bulls of the Gasconne breed, 9 months old, housed indoors were used. Indices of success order were calculated to reflect social dominance of each bull into three ranking categories (low, middle and high). Blood samples were taken to measure cortisol, lactate, glucose, creatine kinase, non-esterified fatty acid and neutrophil/lymphocyte ratio (N/L). M. longissimus samples were analysed in terms of pH, water holding capacity (WHC), texture, colour and sensorial attributes. Social rank influenced cattle stress response, which had an effect on productive performance but not on meat quality traits, with the exception of the sensory traits. These results emphasize the importance of implementing best management practices during pre-harvest handling of cattle in order to modulate any possible risk factor for social stress.     

Economic opportunities for using sexed semen and semen of beef bulls in dairy herds

Dairy farmers can increase the number of dairy heifer calves born in their herd by using sexed semen. They can reduce the number of both dairy bull and heifer calves by using beef semen. Long before sexed semen became commercially available, it was believed that it would provide opportunities for increasing genetic level in both herds and populations. In this study, we studied the potential for increasing the genetic level of a herd by using beef semen in combination with sexed semen. We tested the hypothesis that the potential of increasing the genetic level and the overall net return would depend on herd management. To test this hypothesis, we simulated 7 scenarios using beef semen and sexed semen in 5 herds at different management levels. We combined the results of 2 stochastic simulation models, SimHerd and ADAM. SimHerd simulated the effects of the scenarios and management levels on economic outcomes (i.e., operational return) and on technical outcomes such as the parity distribution of the dams of heifer calves, but it disregarded genetic progress. The ADAM model quantified genetic level by using the dams' parity distributions and the frequency of sexed and beef semen to estimate genetic return per year. We calculated the annual net return per slot as the sum of the operational return and the genetic return, divided by the total number of slots. Net return increased up to €18 per slot when using sexed semen in 75% genetically superior heifers and beef semen in 70% genetically inferior, multiparous cows. The assumed reliability of selection was 0.84. These findings were for a herd with overall high management for reproductive performance, longevity, and calf survival. The same breeding strategy reduced net return by €55 per slot when management levels were average. The main reason for the large reduction in net return was the heifer shortage that arose in this scenario. Our hypothesis that the potential for beef semen to increase genetic level would be herd-specific was supported. None of the scenarios were profitable under Danish circumstances when the value of the increased genetic level was not included. A comparable improvement in genetic level could be realized by selectively selling dairy heifer calves rather than using beef semen.     

The tenderness of cooked and raw meat from young and old beef animals

The shortening-toughness relationships for sternomandibularis muscles of young ox and large old bull have been compared. In both, toughness, measured by tenderometer, increases to a maximum at a shortening of 40%, and declines steeply from there at higher shortenings. This characteristic peaked relationship is obtained for ox and bull cooked both at 60 and 80 °C. However, toughness values for meat cooked to 60 °C are only about half those for meat cooked to 80 °C. In contrast to these similarities in the relationships for young and old animals, the rate of toughness increase with shortening in ox is considerably less than in bull. Thus toughness of ox at a given shortening and cooking temperature is considerably lower than that for bull, especially at high shortenings. A further distinction is made between the animals in that raw ox muscle does not give a peaked shortening-toughness relationship, whereas raw old bull does. The results have shown that for longissimus and sternomandibularis muscles a trained taste panel is only sensitive to variations in toughness in the lower half of the range of shear force values determined by tenderometer. In the light of this, live animal characteristics and muscle shortening are both important in determining toughness measured by taste panel.