Effects of dietary clenbuterol and salbutamol on meat quality in veal calves

Sixty male calves were assigned to one of four treatments, including (1) an untreated control, (2) clenbuterol; 1·6 mg/(calf.day), (3) and (4) salbutamol: 60 and 100 mg/(calf.day). Animals were milk-fed during 24 weeks, and β₂-agonists (BA) treatment occurred during the last 4 weeks including a 3-day withdrawal period before slaughter. Under identical feed intake amongst groups, treatments with BA had significantly positive effects on carcass weights and dressing percentages. BA induced muscle hypertrophy as evidenced by an improved EUROP carcass classification, 1 19–24% higher m. longissimus loin eye area and higher muscle protein/DNA and protein/RNA ratios. Through a dilution effect, this might explain the lower haem content of the m. semimembranosus and m. longissimus lumborum (LL) and diminished Hunter a^* value (redness) of the latter muscle. A higher ultimate pH was found in the m. semitendinosus and m. psoas major of BA-treated calves. The m. longissimus thoracis glycogen content appeared to be lowered by salbutamol. No effects of BA were encountered for water-holding properties of this muscle. Significantly higher shear force values (31–45%) for treated animals were measured for the LL which were parallelled by higher initial values for the calpain-inhibiting activity of calpastatin and a decrease of the μ-calpain/calpastatin ratio. EUROP fatness of carcasses and LL intramuscular fat content tended to be lowered by both BA. Effects of clenbuterol and of the higher salbutamol dose, which on a molecular base was administered at a 70 times higher level, were roughly of a comparable order. The lower dose mostly had intermediate effects. This means that in veal calves, clenbuterol is biologically more potent than salbutamol.     

Calpains from thaw rigor muscle

Pre-rigor beef M. Longissimus lumborum and diaphragma were frozen at −70 °C and thawed at different temperatures and the activities of extracted calpains and the toughness of heated meat compared with those in chilled muscle.

Fresh muscle contained about 14 μg of μ-calpain/g and was unaffected by freezing, but was reduced after thawing. Rapid thawing at 30 °C for 20 min reduced the μ-calpain to 14%. When cooked from the frozen state, extensive shortening occurred and tender meat was obtained.

By storing at −3 °C for 1 day, thaw-shortening was prevented, but tougher meat obtained. The μ-calpain decreased to 70% whilst the m-calpain was unaffected. Toughness decreased after further storage at −3 °C, as did the μ-calpain. The latter changes were similar to those during development of rigor mortis and ageing of non-shortened meat stored at 4 °C. Variation in calpain activity, rather than in sarcomere length, are likely to be the cause of toughness variation in thaw rigor muscle.     

Effect of high power ultrasound and ageing on the physical properties of bovine Semitendinosus and Longissimus muscles

Tenderness is an important meat quality parameters and the use of high power ultrasound to disrupt muscle structure may prove effective for reducing both myofibrillar and collagenous toughness. The experiment was carried out with Longissimus lumborum et thoracis and Semitendinosus muscles from 3 to 4 year old steers. Uncooked beef samples (60 × 40 × 20 mm) were treated with high power ultrasound (24 kHz, 12 W/cm²) for up to 240 s, and aged for up to 8.5 days before evaluation of pH, drip loss, cook losses Warner–Bratzler shear (WBS), compression hardness, and colour. Ultrasound treatment significantly reduced WBS force and hardness, but significantly increased pH. Ageing significantly reduced hardness and WBS force, but there was no significant interaction between ultrasound treatment and ageing time. Ultrasound treatment did not affect any of the colour parameters (L^*a^*b^*, chroma and hue) but the ageing time significantly increased the lightness, chroma and hue. There was no significant effect of ultrasound treatment on drip loss, but it did significantly reduce the cook and total loss. During ageing, cook loss and total losses significantly increased. The results suggest that high power ultrasound is capable of reducing objective texture measurements of beef without compromising the other quality parameters investigated.     

Calpain-calpastatin and toughness in M. longissimus from electrically stimulated lamb and beef carcasses

Shear strength, pH, temperature, μ-calpain, m-calpain and calpastatin levels were measured over a two-week post-slaughter period in Longissimus lumborum et thoracis (LD) from six lamb and six beef carcasses. All carcasses were subjected to high voltage electrical stimulation. The toughness of the beef LD determined by a MIRINZ tenderometer at 24 h post-slaughter showed a strong correlation (r=0.91) with pH of the LD at 3 h. Beef LD toughness at 14 days was correlated (r=0.84) with initial m-calpain levels. In both lamb and beef, LD toughness at 4 and 14 days respectively was also correlated with initial levels of calpastatin (r=0.85, 0.83, respectively). The strong correlation between calpastatin and the rate of tenderisation indicates that the calpain system is closely linked to the proteolytic breakdown of myofibrillar proteins. There is also evidence of an interaction between pH and μ-calpain activity. The μ-calpain, m-calpain, calpastatin, pH and temperature kinetic changes which occurred during the post-mortem ageing of beef and lamb LD were applied to a computer program which predicted rate of meat tenderisation by calculating in situ calpain activity. The closeness of fit between the predicted rate of meat tenderisation and the observed tenderness values of beef and lamb LD indicates that the post-mortem activity of μ-calpain is the major determinant of variations in tenderness. However, application of the meat tenderisation predictive program to LD from individual animals revealed that the program was not sufficiently robust for this use.     

Calpains and calpastatin from cold-shortened bovine M. longissimus lumborum

Sections of beef longissimus lumborum from four animals were held after 1 hr post mortem at either 0 ° (cold-shortened) or at 15 °C (controls). After 24 hr, the levels of μ- and m-calpains were the same in both treatments and about 30% and 85% of their initial levels respectively. The level of calpastatin at 24 h was higher in cold-shortened (100%) than in controls (60% of its initial level). During subsequent storage at 4 °C, the activities of calpains and calpastatin decreased similarly in extracts from both cold-shortened and control muscles. The similar levels of μ-calpain during the first 24 hr post mortem but at the lower temperature suggest that there is less activity under cold-shortening conditions. This, combined with the increased calpastatin levels, would produce less proteolysis by the calpain system. Reduced proteolysis is therefore a factor which should be considered in an understanding of the mechanism of cold-shortening toughness.     

Muscle composition of steers treated with the β-agonist, cimaterol

The effect of the β-adrenergic agonist, cimaterol, on the nature and amount of collagen in three individual muscles (Longissimus dorsi, Vastus lateralis and Semitendinosus) from young steers was investigated.

β-Agonist-treated animals showed similar rates of liveweight gain to those of control animals but the weight and protein content of the Longissimus dorsi and Vastus lateralis muscles were significantly increased (muscle weights 1216 versus 1494 g, P < 0·05; 514 versus 642 g, P < 0·01, respectively, for control and cimaterol animals). The Semitendinosus muscle, however, showed no significant increase in weight or protein content (P > 0·05).

The total collagen content and the proportion of heat-soluble collagen varied considerably between muscles, but no significant muscle × treatment interactions were detected (P > 0·05). Cimaterol treatment reduced total muscle collagen content (controls 15·2, cimaterol 12·5mg/g fresh tissue, P < 0·05) and also reduced the percentage of heat-soluble collagen (controls 18·9%, cimaterol 13·0%, P < 0·05).     

Serine peptidase inhibitors, the best predictor of beef ageing amongst a large set of quantitative variables

For consumers, tenderness is the most important sensory attribute of beef meat and, though to a lesser extent, of pork. Tenderness is therefore by far the most common cause of its unacceptability. The major challenge for the beef industry is to evaluate the toughness of the meat as soon as possible after death. In this context, the aim of the present work was to develop an equation to predict the myofibrillar ultimate resistance of raw meat.

The study was done on the Longissimus muscle from twenty three 19 months-old Charolais bulls grown in the same INRA farm. Muscles excised within 1 h post-mortem were vacuum packed and stored at 15 °C during 24 h and then transferred to 4 °C until used. The activities of lactate dehydrogenase, citrate synthase and myofibrillar Mg–Ca dependent ATPase, the levels of lactate dehydrogenase enzyme, myoglobin, myosin types I, IIa and IIb, cysteine and serine peptidase inhibitors, the pH, the osmolarity, the expressible juice, μ-calpain, m-calpain and calpastatin and meat toughness were measured. According to the physical method used here, the force measured on raw meat represents the resistance of the myofibillar structure.

Stepwise linear regression was used to determine the best equation (p < 0.05) for predicting toughness at 6 days post-mortem. A 6-variables predictive equation including serine peptidase inhibitors (partial R² = 0.4), the rate (partial R² = 0.25), and the extent of pH decline (partial R² = 0.03), the at death LDH activity (partial R² = 0.24), the extent of increase in osmotic pressure (partial R² = 0.13), and the rate of μ-calpain activity loss (partial R² = 0.09), explained 70% of the variability in meat toughness at 6 days post-mortem. This equation was developed from 20 animals and the other 3 animals, chosen randomly, were used to validate it. The absolute need for a predictive model of meat toughness and the nature of the serine peptidase inhibitors together with their potential target enzymes are discussed.     

Influences of the method of housing bulls on their body composition and muscle fibre types

The influence of the type of housing (loose or tying-type) was studied in relation to body composition and muscular characteristics of bulls. 34 young bulls (18 Salers and 16 Limousins) were divided into two groups with equal breed representation and equal mean growth rates, to 10 months of age. One group was housed in tying-type housing (short stalls 1·8 m² per animal) and the other in loose housing (6·5 m² per animal). Samples of semitendinosus (ST) and longissimus thoracis (LT) muscle were taken at slaughter at 16 months. The lactate dehydrogenase (LDH) and isocitrate dehydrogenase (ICDH) activities were measured. The proportion of isoforms LDH-M and LDH-H were determined for each muscle. Total collagen content and solubility were measured for ST alone. Fibres were classified by ATPase myofibrillar and succinate dehydrogenase activities into SO (slow oxidative), FOG (fast oxidative glycolytic) or FG (fast glycolytic), and by immunohistochemistry by reaction with monoclonal antibodies specific to slow and fast myosin heavy chain reactions into I, IIC, IIA, IIAB and IIB fibres. Compared with animals in tying-type housing, animals in loose housing presented the following: fewer carcass adipose deposits (p<0·01); for ST muscle, more collagen (p<0·01) and a reduced glycolytic metabolism, as indicated by lower LDH activity (p<0·10) and a lower proportion of FG fibres (p<0·10). In both ST and LT muscles, loose housing resulted in an increased percentage of IIC fibres (p<0·05) but did not alter the proportions of fast fibres. Modifications in ST alone were increased percentage of IIA fibres (p<0·10) and IIAB fibres (p<0·01) and a lower percentage of IIB fibres (p<0·01). Thus, for a given rate of growth, the type of housing (loose or tying-type) influenced contractile characteristics, especially in muscles involved in movement.     

Calpains and calpastatin distribution in bovine, porcine and ovine skeletal muscles

The concentration of calpain II and calpastatin was determined in various beef, lamb and pork muscles showing very different metabolic and contractile types as assessed by measurement of lactic dehydrogenase (LDH), citrate synthetase (CS) and ATPase activities. The calpain II: calpastatin ratio, which is a good index of the efficiency of this proteolytic system, was also determined.

A species comparison revealed that while calpastatin level was lowest in pork, the ratio of calpain II to calpastatin was highest in this species. For both determinations, lamb was intermediate followed by beef. Conversely, the amount of calpain II was very similar in the three species.

In beef and pork, calpain II content decreased as muscle ATPase and LDH activities rose; and conversely increased with CS activity; whereas in lamb, the amount of this enzyme was highest in red muscles regardless of their speed of contraction. Except for masseter muscle, a comparable distribution was observed for calpastatin in beef and pork muscles. In lamb, the calplastatin concentration was highest in slow-twitch red muscles, intermediate in fast-twitch red muscles and lowest in fast-twitch white muscles. Variability of the calpain II: calpastatin ratio with muscle ATPase, LDH and CS activities appeared to be both muscle and species dependent. As results for masseter muscle are rather unexpected, especially in beef and lamb, this muscle was considered separately.

The present findings are discussed with regard to the conditioning rate of meat from different species and, within one species, from different muscles. It was concluded that the conditioning rate may be correlated positively to calpain II: calpastatin ratio and negatively to calpastatin content. In contrast, no relationship seems to exist between meat ageing rate and calpain concentrations.     

The influence of high post-mortem temperature and differing ultimate pH on the course of rigor and ageing in pig Longissimus dorsi muscle

This study was performed in order to assess the effect of temperature and differing ultimate pH (pH_u, 24 h post mortem) on the development of rigor mortis in pig Longissimus dorsi muscle. The rigor development (isometric tension and shortening) was measured continuously during the first 24 h post mortem, using an apparatus wherein muscle strips were held at constant temperatures of 12 or 35°C. pH_u was manipulated by adrenaline injections preslaughter.

The rates of pH fall, adenosine triphosphate (ATP) and creatine phosphate (CP) breakdown were markedly increased at 35°C compared to 12°C. For both temperatures, no delay phase was observed with regard to the development of shortening. Rigor resulted in higher maximum isometric tension and shortening and in shorter time needed to reach maximum values at 35°C than at 12°C. The results are discussed in connection with pH, ATP and CP data. The extent of ageing from 2 to 4 days post mortem, estimated through myofibrillar length determinations, was higher for 12°C than for 35°C.

pH_u affected significantly most of the traits under study, but its effect depended in some cases upon the rigor temperature. At 12°C, the traits related to the kinetics of rigor development were significantly affected by pH_u, but this was not the case at 35°C. Maximum isometric tension was significantly related to pH_u at 35°C (r = 0·86, P < 0·001), but such a relationship was not found at 12°C. Myofibrillar lengths were significantly affected by pH_u, but in an opposite manner from one temperature to another. A positive relationship was found at 12°C and a negative one at 35°C.

These results illustrate the importance of the interaction between the extent of pH fall and temperature with regard to post-mortem changes in pig muscle.     

Beef tenderness and sarcomere length

A wide range of muscle glycolytic rates was produced in 60 beef carcasses by applying different forms and periods of electrical stimulation immediately after decapitation; a further seven carcasses were not stimulated. The sides were subjected to normal chilling, and at 48 h one short loin per carcass was taken for tenderness evaluation and determination of sarcomere length (SL).

In the 19 relatively slow-glycolysing loins—those of 3-h pH (pH₃) above 6·3—tenderness extended over almost five panel units on a 1–8 scale, and included both the tenderest two and the toughest 10 muscles of the entire study. In the 48 loins of pH₃ below 6·3, on the other hand, tenderness ranged over only 2·5 units, and on average was a full panel unit higher than that of the high-pH₃ muscles. The most striking difference between the two groups, however, was in the relationship between toughness and shortening; the correlation of panel tenderness on SL was remarkably high in the slow glycolysers (r = 0·84), but negligible in those of faster pH decline (r = 0·16). Thus although shortening occurred to about the same extent and over the same range in both groups, it influenced tenderness and tenderness variability only when glycolysis was quite slow. A loin pH₃ of below 6·3, however, is unusual in non-stimulated carcasses, so slow glycolysis and the very wide tenderness diversity accompanying it must be expected in commercial operations that do not use electrical stimulation.     

Effect of transport time and ageing on aspects of beef quality

Forty-eight bulls were transported by road in groups of eight for approximately 30 min, 3 or 6 h in two replicates. After slaughter, steaks from the longissimus dorsi thoracis of all transported animals were analysed in terms of pH, water-holding capacity, myoglobin concentration, texture at 7 and 14 days of ageing (compression and Warner-Bratzler analyses) and colour of the same surface of meat cut at 24 h post-mortem and allowed to bloom for 24 h and 7 d (L^*a^*b^*, chroma and hue). The myofibrillar resistance of the meat from animals transported 30 min was significantly greater at 20% compression (P<0.05). The maximum load and a^*b^* and chroma were all lower for meat aged 14 days.     

The effects of electrical stimulation and ageing on beef tenderness

Seventeen beef carcasses from cattle with a range of breeds, ages and body conditions were used in this trial. The four treatments applied to each carcass were control (C), electrical stimulation (ES), ageing for 28 days (A) and electrical stimulation plus ageing for 28 days (ES + A). Post-mortem muscle pH was measured at 0, 0·5, 4 and 24h post-stimulation. Significantly lower muscle pH values (P < 0·01) were achieved by the stimulated carcass side sompared to the unstimulated side at 0·5 (pH 6·47 vs. 6·91) and 4 h (pH 5·96 vs. 6·44) post-stimulation.

Warner-Bratzler shear and taste panel methods were used to assess the tenderness of Longissimus dorsi muscle samples from each of the four treatments. The ES, A and ES + A treatments were significantly more tender (P < 0·01) than the control treatment. The ES and the A treatments resulted in a similar improvement in tenderness compared to the control. The ES + A treatment was significantly more tender (P < 0·01) than the ES treatment alone, but there was no significant difference in tenderness between the A and the ES + A treatments.     

Factors affecting the rate of metmyoglobin accumulation in pre-packaged beef

Factors affecting the rate of discoloration of pre-packaged beef have been compared quantitatively in a number of experimental animals. Inter-muscular variability is the most important single factor and ranges from the stable M. longissimus dorsi to the unstable M. psoas major, the degree of discoloration of the latter muscle being almost eight times greater after 96 h storage at 0°C. Among other intrinsic factors studied, age post mortem has a slight accelerating effect while pH, within the narrow range exhibited by experimental animals, has no effect. Inter-animal variability also has an effect, but only a slight one.

Of the extrinsic factors studied, temperature is most important from a practical standpoint, the degree of discoloration after 96 h storage at 10°C ranging from two to five times that at 0°C, depending on the muscle. Light produces only a minor accelerating effect but UV produces serious discoloration in all muscles within hours, even at 0°C. Slight differences exist between packaging films but these are not commercially significant.     

The effects of spray and blast-chilling on carcass shrinkage and pork muscle quality

Combinations of blast- and spray-chilling of pork carcasses were compared to spray-chilling at conventional chilling temperatures with regard to carcass shrinkage during chilling and pork muscle quality. In experiment 1, pork sides were spray-chilled at 1°C for the first 10 h (40 spray cycles of 60-s duration every 15 min) of cooling or blast-chilled at −20°C for 1, 2 or 3 h followed by spray-chilling for 9, 8 or 7 h duration, respectively. All pork sides were then chilled to 24 h post mortem at 1°C. Experiment 2 followed the same procedures as experiment 1, except that −40°C was used as the blast-chill temperature.

Carcass shrinkage was similar for all treatments in experiment 1 at 24 h ranging from 0·5–0·7 g 100 g⁻¹. Blast/spray-chilling increased the rate of chilling and reduced the rate of post-mortem pH decline in two muscles (longissimus thoracis, LT and semimembranosus, SM) compared to the combined conventional/spray-chill treatment. Carcasses that were blast-chilled for 3 h had LT muscles that were darker with a higher protein solubility, less drip loss, shorter lengths and higher shear values compared to those from carcasses in the conventional/spray-chill treatment. In experiment 2, carcasses blast-chilled for 3 h at −40°C recorded a weight gain at 24 h of 0·4 g 100 g⁻¹, compared to a weight loss in all other treatments (0·2–0·4 g 100 g⁻¹). Muscle colour was darker in both the LT and SM of carcasses blast-chilled for 3 h at −40°C compared to carcasses from the conventional/spray-chill treatment, but most other measurements of muscle quality showed an inconsistent response to chilling treatment.     

Dietary tea reduces the iron content of beef

We hypothesized that the lightness of Japanese beef was related to the concentration of heme iron. In Experiment 1, six Japanese Black heifers were allotted randomly to one of three treatment groups: a basal concentrate ration (40% flaked corn) or the same diet and either 2 kg/d wheat bran or 0.5 kg/d green tea. After feeding the diets for 174 d, the cattle were slaughtered and the M. longissimus thoracis, M. semimembranosus, and M. gluteus medius were sampled for meat color, iron, and lipid content. The iron content of the M. semimembranosus from the tea-fed cattle was lower than in M. semimembranosus from the control cattle, and a* (redness) and √(a^*2+b^*2) (saturation) values were lower in M. semimembranosus from bran- and tea-fed cattle than in control cattle. Treatment main effects (across muscles) indicated that inclusion of tea in the diet increased intramuscular lipid and reduced the muscle iron content. There was a significant negative correlation (r²=0.79) between muscle iron content and L^* value (lightness). For Experiment 2, the effect of beef breed type on meat color and iron content of M. longissimus thoracis was investigated using stored meat samples from six breeds from a previous fattening experiment done under a high nutritional plane. Muscle iron content was significantly lower in Japanese Black cattle than in Japanese Black × Holstein or Japanese Black × Japanese Black/Holstein. There was no relationship between muscle iron content and intramuscular lipid content (r²=0.001). In Experiment 3, samples of M. longissimus dorsi were obtained from 17 Wagyu crossbred and 3 Angus crossbred cattle fed a corn concentrate diet in the USA for 148 d. Iron content of the M. longissimus thoracis from Japanese Black and Japanese Brown × Holstein cattle fattened in Japan was significantly less than the iron content of M. longissimus dorsi from cattle raised in the USA. Overall, the data indicate that it is possible to lower muscle iron, and lighten muscle color, by feeding green tea to Japanese cattle; also, there may be a genetic basis for the lower iron, and lighter color, of beef produced in Japan.     

Identification of halothane genotypes by calcium accumulation and their meat quality using live pigs

The three halothane genotypes (NN, Nn, and nm) were identified by measuring the capacity for Ca²⁺ accumulation by sarcoplasmic reticulum in whole muscle homogenate preparations of M. longissimus dorsi with a Ca²⁺ specific electrode at 35°C. Significant differences (P < 0·001) in deterioration (%) of Ca²⁺ accumulation, 12% for NN, 35% for Nn, and 81% for nn pigs, were observed after ageing the whole muscle homogenate preparations for 24 h in ice.

Predictions of meat quality in live pigs (n = 34) based on the values for water-holding capacity, assessed as fluid (g/0·5 g wet wt LD), and pH (fluid) by using small biopsy LD samples (Cheah et al. 1993) were performed on all the halothane genotypes. The halothane genotype NN (n = 11) showed a fluid value of 0·37 ± 0·01 and a pH (fluid) value of 6·62 ± 0·03 as compared with 0·61 ± 0·02 and 5·84 ± 0·04, respectively, for the halothane genotype nn (n = 13). The Nn pigs (n = 10) showed fluid (0·49 ± 0·03) and pH (fluid) (6·19 ± 0·11) values between those values observed for the two homozygotes (NN and nn). Predictions of meat quality in live pigs from biopsy LD muscles were confirmed from assessments on post-mortem LD muscles based on pH₁ and fibre optic probe (FOP) measurements.

The extent of deterioration (%) in Ca²⁺ accumulation showed high correlations with fluid (r = −0·861) and pH (fluid) (r = −0·831) in the biopsy LD samples, and with pH₁ (r = 0·663), FOP (r = −0·812), and drip (%) loss (r = −0·777) in the post-mortem LD samples.     

Variability within intramuscular fat content of pigs as measured by gravimetry, FTIR and NMR spectroscopy

In order to determine in vivo intramuscular fat content of pigs' biceps femoris, three methods were compared. Gravimetry and FTIR spectroscopy after total fat extraction from a biopsy (about 400 mg skeletal muscle tissue) and in vivo ¹H NMR spectroscopy after imaging and volume of interest selection were used. Mean values (g fat/100 g fresh tissue) were, respectively, 1·47 ± 0·35 (gravimetry), 1·26 ± 0·33 (FTIR) and 0·51 ± 0·19 (NMR); but NMR-values represented only triglycerides. Within an intramuscular fat range from 1·1 to 2·7 g per 100 g fresh muscle tissue, possible to estimate a calibration line between the in vitro and in vivo data for hybrid piglets of about 18 kg. Repeated in vivo NMR measurements on the same muscle volume showed a mean coefficient of variation of 5·5 ± 2·7%. The coefficient of variation of measurements on different volumes within the same muscle was 14 ± 10%. The mean intramuscular fat content of 18 kg or 100 kg pigs was, respectively, 1·64 ± 0·46 (biceps femoris) and 1·32 ± 0·1 (longissimus dorsi) g per 100 g fresh muscle tissue.     

Relationship between tenderness of three beef Muscles

Toughness was determined instrumentally in Musculus longissimus dorsi (LD), M. semitendinosus (St) and M. semimembranosus (Sm) from 166 commercial beef animals. LD was, on average, more tender than either St or Sm, which were similar, but was also most variable in texture. St was the least variable. Toughness of one muscle was significantly correlated with that of another (r=0.4-0.7) but toughness of one muscle could not be predicted reliably from that of another. Pure Aberdeen Angus, Hereford Friesian cross or Charolais Friesian cross did not differ significantly in toughness and the relationship between muscles was not improved when breeds were considered separately.     

Ultrastructural changes during aging in M. longissimus thoracis from moose and reindeer

Game meat is commonly consumed in Europe but few studies have examined the quality related parameters. In this study we examined the changes in ultrastructure at four times postmortem in M. longissimus from moose (Alces alces) and reindeer (Rangifer tarandus tarandus). The moose were slaughtered during a hunt and reindeer by Swedish standard practices for this semi-domestic animal. Ultrastructural changes occurring in all animals included separation of the sarcolemma from myofibrils, I band breaks, and cytoskeleton breaks; however both I band breaks and cytoskeletal breaks were less common in moose and reindeer than values reported for sheep and beef. Fiber area in the longissimus thoracis muscle was approximately 3270 μm² for moose and 1170 μm² for reindeer indicating that the tenderness of reindeer meat may be largely determined by fiber size.