A comparison of the effects of electrical, captive bolt or percussion stunning on the incidence of blood splash in lambs

Three-hundred-and-three lambs were divided into three equal groups. Half the lambs in each group were not weaned before slaughter and the weaned half were slaughtered a week later. Lambs in one group were head stunned electrically before slaughter; in the second group lambs were stunned with a captive bolt pistol and in the third group they were percussion stunned before slaughter. Carcasses, gall-bladders, hearts and duodenums were inspected for blood splash after slaughter. A few small haemorrhages were detected in 57% of the electrically stunned lambs, in 30% of the captive bolt stunned lambs and in only 16% of the percussion stunned animals. Although no splash of commercial significance was found in any carcass, 25% of the electrically stunned lambs had detectably splashed carcasses, whilst only 1% of percussion-stunned lambs had splashed carcasses with captive bolt stunned lambs being intermediate in carcass splash incidence. These results show that stunning method affects the incidence of blood splash.     

The effects of mixing,transport and duration of lairage on carcass characteristics in commercial bacon weight pigs

On arrival at the factory commercial crossbred pigs were subjected to various treatments: (i) penned in producer lots; (ii) mixed with pigs from another producer and (iii) mixed and subjected to an additional transport of 1-1.5h duration. Groups of pigs were killed on the day of arrival or after overnight lairage. Carcass parameters including pH₁ (pH 45 min post mortem) and pH_u (pH 20 h post mortem) values of the Longissimus dorsi (LD) and adductor muscles were taken post mortem. Mixing and transport had no statistically significant effect on any of the carcass parameters measured, although overnight lairage resulted in significant decreases in hot carcass weight, killing-out percentage and liver weight. The incidence of carcasses classified as pale soft and exudative [PSE (muscles with a pH₁ of 5.9 or less)] or dark firm dry [DFD (muscles with a pH_u of 6.2 or greater)] was high after both normal and overnight lairage. pH₁ and pH_u values of the LD and adductor muscles were not significantly affected by mixing or transport. Statistically significant differences in the incidence of DFD between treatment groups were observed. In general the incidence of DFD increased more after overnight lairage in pigs penned in producer lots, than in pigs penned in mixed producer lots.     

Effect of beef ultimate pH and large structural protein changes with aging on meat tenderness

This study investigated the effect of ultimate pH (pH_u) in beef on the degradation of large structural proteins during refrigerated storage using SDS-PAGE. M. longissimus dorsi from bull carcasses were selected and classified into three groups: low pH_u (≤ 5.79), intermediate pH_u (5.80–6.19) and high pH_u (≥ 6.2) muscles. Samples were then stored at − 1.5 °C for 1, 2, 7, 14, 21 and 28 days. Meat tenderness was measured at each aging time. Depending on meat pH_u, different protein patterns and degradation rates of structural proteins were found. Rapid changes of large structural proteins took place within 48 h post mortem. Besides titin and nebulin, degradation of filamin was clearly revealed. Two more large protein bands corresponding to myosin family members also exhibited fast decline with storage time. It suggested that the fast degradation of these proteins is a key factor in the improvement of meat tenderness.     

Effect of pelvic suspension on the instrumental meat quality characteristics of red deer (Cervus elaphus) and fallow deer (Dama dama) venison

The effect of pelvic and Achilles tendon suspension of red and fallow deer carcasses on meat quality parameters were compared. Venison was evaluated from red deer stags (n = 14), bucks (n = 14) and fallow deer does (n = 10) between 12 and 36 months old. Immediately after slaughter, carcasses were split down the dorsal midline and assigned to one of the two hanging methods and pH and core body temperature measured. Twenty-four hours post-slaughter muscles were excised. Venison from fallow deer and red deer stags pelvic-suspended had significantly lower (P < 0.001) cooked shear force values than Achilles hung carcasses. There was no significant difference between hanging technique for other characteristics measured. These data indicated that pelvic suspension should be adopted by the deer industry to increase tenderness of venison.     

Brain tissue fragments in jugular vein blood of cattle stunned by use of penetrating or nonpenetrating captive bolt guns

Although the incidence of bovine spongiform encephalopathy in cattle continues to decline in the United Kingdom, it remains important to maintain vigilance of all potential routes of transmission of infection to humans. Initial studies have demonstrated a potential risk of carcass contamination with brain tissue following the use of captive bolt gun stunning in cattle. The objective of this study was to further explore these initial findings particularly in regard to captive bolt guns currently in use in the United Kingdom. Brain tissue fragments or elevated levels of a marker protein for brain tissue were detected in venous blood samples from 4% (95% confidence interval, 1.6 to 9.8%) of cattle stunned by penetrating captive bolt gun and from 2% (95% confidence interval, 0.6 to 7%) of those stunned by nonpenetrating captive bolt gun.     

Control of the bacteriological condition of calf brain. I. Impact of improving hygiene

Sixty calves of the Dutch Friesian (FH) breed were stunned mechanically. Without previously having been stunned, another 30 calves were stuck according to the Jewish rite. Upon opening of the skulls (1–2 h post mortem) brains of mechanically stunned calves were collected either conventionally (n = 30) or ‘hygienically’ (n = 30), i.e. using a fresh pair of surgical gloves during each removal to avoid cross contamination. For ritually slaughtered animals only the hygienic procedure was followed. Samples of 10 g were excised from undamaged hemispheres and in the mechanically stunned treatment group also from the site of impact of the captive bolt. After storage in polystyrene trays at 3 ± 1°C for 7 days sampling was repeated. Bacteriological examination included the assessment of aerobic colony counts at 30°C for 3 days (ACC-30) and 4°C for 14 days (ACC-4) and Enterobacteriaceae colony counts at 37°C for 20 h (ECC). In conventionally collected samples the ACC-30 and ACC-4 were 3.8 and 3.0 log₁₀ cfu g^?1 at day 1 and 6.2 and 6.4 log₁₀ cfu g^?1 at day 8. With hygienic collection these counts were reduced by approximately 1 log unit. Whilst by conventional practice the ECCs, at day 1 and 8 were 2.6 and 4.8 log₁₀ cfu g^?1 these counts were 1.8 and 2.6 log₁₀ cfu g^?1 for hygienic practice. In samples excised from the site of impact of the captive bolt the hygienic procedure had similar, though less marked effects. On day 1 brains from ritually slaughtered animals had a bacteriological contamination similar to that found in the hemispheres of mechanically stunned calves. However, whilst at day 8 their mean ECCs were 3.4 and 3.5 log₁₀ cfu g^?1 the percentages of plates ‘positive’ for Enterobacteriaceae were only 10% in the ritually vs. 53% in the mechanically stunned group. The Enterobacteriaceae in this case were composed of psychrotrophic non-pathogenic genera of environmental origin. Salmonella was not isolated from any sample.     

Small heat shock protein degradation could be an indicator of the extent of myofibrillar protein degradation

The objective of the present study was to evaluate the relationship between small heat shock proteins (sHSP) degradation and tenderness development of beef loins at different ultimate pH (pH_u). A total of twelve loins (M. longissimus dorsi) from steers were obtained at 1 day post mortem. Shear force and proteolysis of each loin were analyzed at 1 and 28 days post mortem. The loins at intermediate pH_u (5.8 to 6.0) showed more variation in tenderness compared to the loins at low pH_u (< 5.8), where few samples were still tough (> 10 kgF) at 28 days. The intact sHSP20 was more pronounced (P < 0.05) in the intermediate pH_u loin compared to the low pH_u counterpart. Further, high correlations between the degradation of both sHSP and myofibrillar proteins were observed (e.g. r = 0.94; degraded sHSP27 and degraded desmin). The result of this study suggests that the extent of sHSP degradation could be an indicator of myofibrillar protein degradation and tenderness.     

The effects of electrical stunning and percussive captive bolt stunning on meat quality of cattle processed by Turkish slaughter procedures

The effects of electrical and percussive captive bolt stunning both on initial and up to 14 days post mortem meat quality of Friesian young bulls were studied. The first group (NS; n=10) were slaughtered without stunning under Turkish slaughter procedure (these animals were slaughtered under conditions acceptable to the appropriate ethics committee) in a modern abattoir. In the second group (ES; n=10) animals were electrically stunned. In the third group (PS; n=10) animals were stunned with percussive captive bolt. Meat quality was assessed by examining muscle glycogen concentration, pH and WHC. Also cooking loss, texture parameters and consumer sensory properties were assessed at 24 h, 4, 7 and 14 days post mortem. Meat colour as L^*, a^*, b^*, C^*, h^* values were evaluated at 0, 48 h, 3, 5, 7, 9 and 14 days post mortem. Pre-slaughter handling affected muscle glycogen concentration (P<0.05). Animals in electrical and percussive captive bolt stunned groups had higher muscle glycogen concentrations compared to animals in the non-stunned group (P<0.05). Although pre-slaughter handling did not affect significantly pH_{24 h} and WHC, differences were significant for cooking loss, colour coordinates and texture parameters at some storage times. For all sensory attributes (odour, flavour, tenderness and overall acceptability) at all ageing periods (24 h, 4, 7 and 14 days) the percussive stunned (PS) group was significantly superior to the non-stunned (NS) group. The electrically-stunned (ES) group also tended to be superior to the NS group although not all differences were statistically significant. These results indicate that percussive captive bolt stunning of cattle improved meat quality compared with cattle electrically stunned using head only tongs and those non stunned under approved Turkish slaughter procedure.     

Beef carcasses with larger eye muscle areas,lower ossification scores and improved nutrition have a lower incidence of dark cutting

This study evaluated the effect of eye muscle area (EMA), ossification, carcass weight, marbling and rib fat depth on the incidence of dark cutting (pH_u > 5.7) using routinely collected Meat Standards Australia (MSA) data. Data was obtained from 204,072 carcasses at a Western Australian processor between 2002 and 2008. Binomial data of pH_u compliance was analysed using a logit model in a Bayesian framework. Increasing eye muscle area from 40 to 80 cm², increased pH_u compliance by around 14% (P < 0.001) in carcasses less than 350 kg. As carcass weight increased from 150 kg to 220 kg, compliance increased by 13% (P < 0.001) and younger cattle with lower ossification were also 7% more compliant (P < 0.001). As rib fat depth increased from 0 to 20 mm, pH_u compliance increased by around 10% (P < 0.001) yet marbling had no effect on dark cutting. Increasing musculature and growth combined with good nutrition will minimise dark cutting beef in Australia.     

The influence of slaughter method on the residual blood content of meat

The effect of slaughter method on the residual haemoglobin content of the M. longissimus dorsi and the amount of blood lost at exsanguination of sheep was investigated. The influence of stunning method (electrical, 90 V, or captive bolt pistol), pithing and bleeding-out position were examined. Sheep bled lying lost more blood than those bled hanging and electrically-stunned animals lost more blood than those stunned with a captive bolt pistol; pithing had no effect. The residual haemoglobin content of the muscle did not vary significantly between methods and there was no relationship between it and the amount of blood lost at slaughter.     

Consumer evaluation of venison sensory quality: Effects of sex,body condition score and carcase suspension method

Intact fallow bucks (n = 20) and non-pregnant fallow does (n = 24) (Dama dama), in the body condition score (BCS) of 2, 3 and 4 (lean, prime and fat) and rising 2 year old red deer stags (n = 26) (Cervus elaphus) of the same BCS range (2–4) were used in this study to determine the impact of sex, BCS and method of carcase suspension on consumer perception of venison quality. Consumers were asked to evaluate cooked meat samples (M. gluteus medius) on an unstructured line scale for colour, flavour, tenderness, juiciness and overall liking. Meat from both fallow deer and red deer was preferred by consumers when carcases had hung by the pelvic suspension (PS) method compared with the Achilles tendon (AT) method of hanging (p < 0.001). Consumers also noted a difference in colour between sexes in fallow deer venison, with venison from 36 month-old does being darker (p = 0.015), and preferred venison from does over 18–24 month-old bucks. There was a significant difference in the consumer scores for tenderness in red deer stags of BCSs 2 and 4 (p = 0.05) with panellists determining BCS 4 animals to be more tender; however no tenderness differences were observed for fallow deer does compared with bucks.     

The histology of blood splash in lamb

Ecchymosis (blood splash), can occur in the carcasses of animals that have been stunned electrically or shot with a captive bolt. While blood splash presents no health hazard, it is likely to detract from the acceptable appearance of the meat. Based on light and electron microscopic studies, ecchymosis has been shown to be due to the localised discharge of blood from ruptured blood vessels into the surrounding muscle tissue. A small proportion of muscle fibres in a splashed region were distorted ( 5 %) with irregular zones of high shortening interspersed with zones of lesser shortening. Such ‘supercontracture’ and its associated blood splash was markedly reduced by neuromuscular blocking agents. It is proposed that through supercontracture of some fibres, a severe strain is placed on adjacent blood vessels, occasionally leading to their rupture and hence to haemorrhaging.     

Small heat shock proteins and toughness in intermediate pHu beef

Bull M. longissimus dorsi (n = 94) categorised into high (n = 28), intermediate (n = 14) and low (n = 52) ultimate pH (pH_u) were aged at − 1.5 °C for 28 days. Shear force was higher and more variable (p < 0.05) in intermediate pH_u samples during ageing. Titin, filamin and desmin degradation was also less extensive in intermediate pH_u samples compared to the other two pH categories. The extent of the decline of HSP20, HSP27 and αβ-crystallin concentrations during post mortem ageing was pH_u related such that high pH_u meat maintained the highest concentration of small heat shock proteins followed by intermediate and low pH_u meat. μ-Calpain autolysis was slowest in intermediate pH_u and cathepsin B activities remained consistently low during ageing in this group (p < 0.05). Meat toughness in the intermediate pH_u group may be attributed to the combination of a larger pool of sHSP with a sub-optimal cathepsin B activity and intermediary μ-calpain activities.     

High glycolytic potential does not predict low ultimate pH in pork

Extent of postmortem pH decline influences meat quality development. To better understand physiological determination of ultimate pH (pH_u), we utilized female and castrated male pigs from a line whose selection index includes differentiated pH_u. All genotypes of AMP-activated protein kinase γ3 subunit (AMPKγ3) V199I site were present. The mutant 199II genotype increased pH_u, but only in castrated males. Genotype affected glycolytic potential (GP), but GP was weakly associated with pH_u. A subset of animals was selected based on low (− Gly) and high (+ Gly) residual glycogen content, and compared with AMPKγ3 200Q, which is associated with low pH_u. Both + Gly and 200Q muscle contained glycolytic substrate at 24 h; however, 200Q muscle generated low pH_u and greater lactate compared to + Gly. Additionally,− Gly and + Gly groups exhibited similar pH_u despite a large difference in GP. In conclusion, high GP does not appear to directly impact the extent of postmortem pH decline.     

Effects of electrical and mechanical stunning methods on meat quality in ostriches

The effect of electrical and captive needle air pressure stunning methods on some meat quality parameters was examined in ostriches under practical conditions. One hundred and fifteen ostriches were used in three experiments. The ostriches were stunned either electrically (head only) or by using a captive needle with air pressure. In the first experiment the ostriches were stunned at 90 V (～effectively 52 V), 200 V and by captive needle using air pressure. In the second experiment voltages of 175 and 200 V were applied and a captive needle stunning method using air pressure. In the third experiment the birds were stunned at 175 V with a short stun/stick interval. Experiments 2 and 3 were performed in a different slaughterhouse from experiment 1. Meat quality was assessed by measuring the pH, temperature and colour at 45 min and 18 h post mortem and by determining water binding capacity and haemorrhage score at 18 h post mortem in the big drum, tender loin and triangular filet muscles. The measured stunning parameters in the first experiment were 204±96 mA (～52 V) during 11±1 s and 556±85 mA (～200 V) during 6±0 s. The stun/stick interval was 136±38 s. The rigor mortis value in the tender loin and both pH(1) and pH(2) in the big drum, tender loin and triangular filet muscles were (p<0.05) lower when stunned with air pressure compared with electrical stunning. Moreover internal light scattering remained higher. The measured currents in the second experiment were 561±226 mA (～173 V) during 6±2 s and 518±120 mA (～200 V) during 6 s. The stun/stick interval was 39±12 s. The pH at 45 min and 18 h differed (p<0.05) in the tender loin and triangular filet muscles as did the temperature at 45 min in the three muscles between the different stunning groups. The stunning in the third experiment was carried out with 548±180 mA during 6±2 s. The stun/stick interval was 5±2 s. After the short stun/stick interval the pH(2) was lower (p<0.05) for the tender loin and triangular filet muscles and the wetness of the filter paper of the big drum was (p<0.05) lower compared with the other groups. Our experiments showed that stunning methods affected several meat quality parameters. Using a high electrical stunning current, captive needle stunning or a short stun/stick interval may positively affect some parameters. More research is necessary to examine effects of pre slaughter handling on meat quality.     

Near infrared spectroscopy as an on-line method to quantitatively determine glycogen and predict ultimate pH in pre rigor bovine M. longissimus dorsi

The potential of near infrared (NIR) spectroscopy as an on-line method to quantify glycogen and predict ultimate pH (pH_u) of pre rigor beef M. longissimus dorsi (LD) was assessed. NIR spectra (538 to 1677 nm) of pre rigor LD from steers, cows and bulls were collected early post mortem and measurements were made for pre rigor glycogen concentration and pH_u. Spectral and measured data were combined to develop models to quantify glycogen and predict the pH_u of pre rigor LD. NIR spectra and pre rigor predicted values obtained from quantitative models were shown to be poorly correlated against glycogen and pH_u (r² = 0.23 and 0.20, respectively). Qualitative models developed to categorise each muscle according to their pH_u were able to correctly categorise 42% of high pH_u samples. Optimum qualitative and quantitative models derived from NIR spectra found low correlation between predicted values and reference measurements.     

Fasting-induced glycogen depletion in different fibre types of red and white pig muscles—relationship with ultimate pH

The aim of the present work was to study the effect of fasting times (0, 24, 48 and 72 h) on glycogen level in different fibre types of a predominantly white (Longissimus, LD) and a predominantly red (Semispinalis, SS) pig muscle, and on ultimate pH (pH_u, 24 h post mortem). Thirty two individually housed Large White castrates (eight pigs per treatment) were slaughtered individually under minimal stressful conditions. Muscle samples were taken during bleeding for enzymic determination of muscle metabolites and histological examination using computerised image analysis. Myofibres were classified by a combination of metabolic (W, white; R, red) and contractile (α, fast-twitch; β, slow-twitch) characteristics. The SS showed higher glycogen depletion after 24 h fasting than the LD (?55 versus ?26%, respectively). No further significant changes in glycogen level were recorded with enhanced fasting times (up to 72 h), although in the SS a marked trend towards glycogen depletion was observed. Fasting for 24 h resulted in significantly increased pH_u in the SS whereas for the LD, a significant increase in pH_u occurred only after 48 h fasting. In response to fasting, significant decrease in histochemical staining intensity for glycogen occurred in the three fibre types of the SS. The βR fibres of the SS showed an almost complete glycogen depletion after 24 h fasting. With increasing fasting time, glycogen was further depleted in fast-twitch fibres (αW and αR). In the LD, only fast-twitch fibres exhibited significant decrease in glycogen level after 24 h fasting. However, this was of a much lower magnitude than that observed in the SS and furthermore, no further variation was recorded with increasing fasting time, regardless of fibre type. The present work is the first to report a significant interaction between muscle type and fasting-induced glycogen depletion in pig. Furthermore, these results demonstrate that within each muscle, the extent of fasting-induced glycogen depletion is strongly fibre-type-dependent.     

Variation in bull beef quality due to ultimate muscle pH is correlated to endopeptidase and small heat shock protein levels

This study set out to determine if ultimate pH (pH_u) affected the performance of intracellular small heat shock protein and endopeptidase dynamics in muscle during beef ageing. Longissimus dorsi muscles from 39 Angus or Limousin × Angus bulls were examined to see if pH_u achieved at 22 h post mortem (rigor) affected tenderness and water holding capacity of beef. Samples were segregated into three pH_u groups termed high (pH > 6.3), intermediate (5.7 < pH < 6.3) and low (pH < 5.7) pH_u beef. More than 30% of bull beef did not achieve acceptable tenderness at 8 days post mortem with this ageing regime. No significant differences in calpain or cathepsin enzyme levels due to meat pH were observed until after 22 h post mortem, but low pH_u beef had elevated caspase 3/7 activity soon after slaughter. At 22 h post mortem, greater levels of μ-calpain enzyme were found in the high and intermediate pH_u beef and cathepsin B levels were superior in the low pH_u beef after 2 days post mortem. Different rates of desmin and troponin T protein degradation were also observed in aged bull beef. Both proteins were degraded within 6 h post mortem for high pH_u beef, but took >3 days post mortem for intermediate pH_u beef. High levels of alpha β-crystallin (aβC) at 22 h post mortem coincided with delayed muscle protein degradation for low pH_u beef. Our results support the hypothesis that aβC shields myofibrils and buffers against endopeptidase degradation of beef structure during ageing.     

Quality characteristics and composition of the longissimus muscle in the short-loin from male and female farmed red deer in New Zealand

Meat quality and composition characteristics are reported for the longissimus muscle from 10 red deer stags and 10 hinds aged about 20 months. All animals were pasture-finished but the stags and hinds came from different farms. The average carcass weight was 3.4 kg greater for the stag group (55.8 vs 52.4 kg; P = 0.04), but measures of GR as a measure of fatness were similar and intramuscular fat content was significantly greater for the hind group (1.12% vs 0.63%; P < 0.0001), as expected. The tenderness of cooked venison in terms of shear force and compression measures was significantly better for venison from the hind group, possibly due to the greater amount of intramuscular fat and slightly longer sarcomeres. The gender groups did not differ in absolute measures of colour or in the rate at which it deteriorated on display. However, the rate of colour deterioration was more rapid than other meats such as beef, as has been demonstrated elsewhere. The average ultimate pH and water-holding capacity were similar for the two groups. Venison from hinds contained more coenzyme Q₁₀, taurine, anserine, carnosine, and vitamin E. Group differences in fatty acid composition of intramuscular fat appeared to be mainly due to levels of fatness, which was greater for the hind group.     

Comparison of the thermal characteristics of connective tissue in loose structured and normal structured porcine M. semimembranosus

The aim of the present study was to characterise the thermal properties of connective tissue in loose structured porcine SM muscles in comparison to normal looking SM muscles and to see whether the meat quality traits were related to the properties of connective tissue. Samples from the muscles with loose structure and light colour were selected by visual assessment and normal looking SM muscles were used as a control (n = 25 loose structured + 25 control). The loose structured muscles had lower ultimate pH (pH_u) than the control muscles. The onset and peak temperatures of thermal shrinkage of intramuscular connective tissue (T_o and T_p, respectively) in loose structured muscles were similar to those of control muscles when the full set of data (25 loose structured + 25 control) were analysed. When the T_o and T_p data from muscles the exhibiting ten lowest and ten highest pH_u values were analysed, the low pH_u muscles (all classified as loose structured) had lower T_o and T_p than the high pH_u muscles (all classified as control) (p < 0.05). Drip loss of loose structured SM muscles (11.1%) was dramatically higher than that of control muscles (3.9%). Collagen content and collagen solubility were similar in loose structured and control muscles. It seemed that changes in the properties of intramuscular connective tissue were more easier found in porcine SM muscles with low pH_u than in SM muscles with high pH_u.