The use of a high pressure waterjet combined with electroimmobilization for the stunning of slaughter pigs: Some aspects of meat quality

It is considered that waterjet stunning may be a humane stunning method to apply in slaughter facilities. An experiment was conducted in a slaughterhouse to examine the effects of waterjet stunning combined with electroimmobilization during exsanguination on the occurrence of haemorrhages in the muscles and on meat quality.Slaughter pigs (n = 31) were stunned by waterjet (3900 bar) in a V-type restrainer and immobilized electrically (40 V) during exsanguination. Control animals (n = 39) were stunned automatically and electrically (600 V) using the same restraint device.At 45 min post mortem the pH in the semimembranosus (SM) and longissimus dorsi (LD) muscles was significantly lower (p < 0·01), while rigor mortis and temperature in the SM and LD were significantly higher (p < 0·05 and p < 0·01, respectively) in the carcasses of pigs stunned with the waterjet as compared to control pigs. At 18 h post mortem the ultimate pH of the LD was lower (p < 0·05), while scatter (fibre optic probe) and filter paper test values of the LD were higher (p < 0·01) in carcasses of pigs stunned with the waterjet. Fewer haemorrhages were observed in the shoulders of pigs stunned with the waterjet.The results of this experiment suggest that waterjet stunning, when combined with electroimmobilization, may be a suitable method to stun pigs in a slaughterhouse. However, further studies are required to improve the meat quality.     

Some neural and behavioural aspects of electrical and mechanical stunning in ostriches

Different electrical and mechanical stunning procedures were studied in ostriches to determine the effectiveness of the method. Fifty-eight South-African Black ostriches were equipped with EEG electrodes and stunned with three different electrical head-only methods and with a new captive needle pistol, using air pressure. The first stunning procedure consists of two trials. In the first trial a total of 45 ostriches were stunned with a voltage of 200 V (spiked electrodes) during 1 s. Unfortunately, in 10 animals the electrodes were disconnected. A general epileptiform insult on the EEG followed by recovery was observed in 20 ostriches. Another eight animals died after recovery and five showed an iso-electric line and were dead. The total duration of the insult was 25±10 s. The measured current was 463±120 mA. In the second trial a constant current of 400 mA was administered to 13 ostriches. In one animal the electrodes were disconnected. Eight out of 12 animals showed a general epileptiform insult, two of them showed an iso-electric line and two did not show the characteristics of a general epileptiform insult. The total duration of the insult on the EEG was 21±8 s. The measured current was 365±91 mA and the voltage 191±27 V. During the second stunning procedure four and seven ostriches were stunned with 200 V (spiked electrodes) and 48 V (blunt electrodes), respectively, during approx. 6 s. They all died. In addition, a group of 20 ostriches stunned with captive needle pistol using air pressure showed unconsciousness after stunning by the appearance of theta and delta waves tending to an iso-electric line on the EEG trace. It is recommended to use at least 500 mA to stun ostriches effectively and to use a short stun-stick interval or to kill them by a long stunning duration. The captive needle pistol, using air pressure, can be an alternative for electrical head-only stunning.     

The effect of electrical stunning and slaughter on the electroencephalogram of sheep and calves

To study the application of electroencephalography (EEG) for the assessment of insensibility during stunning and slaughter, recordings were made on sheep that were slaughtered by throat cutting, electrically stunned head-only and allowed to recover, electrically stunned head-only followed by throat cutting or electrically stunned head-to-back. The same experiments were repeated on calves (1–6 weeks old) except some calves were stunned and allowed to recover before final stunning and throat cutting.

After the throat cut, sheep became insensible (i.e. EEG < 10 μV) at 8–22 s but the calf EEG did not fall below 10 μV until 79 s after the cut. With head-only stunning/recovery, high-amplitude EEG waves (electroplectic fit) continued for 47 s (sheep) and 33 s (calves) post stun. A quiescent period followed, which then developed into a period of moderate-amplitude EEG signals, so that, at 50 s post stun, the EEG usually exceeded 50 μV and often had bursts of 150 μV activity. After head-only stunning/throat cutting, the electroplectic fit was shortened (39 s in sheep, 23 s in calves) and the EEG took at least 50 s to fall below 10 μV. With sheep stunned head-to-back, which stops the heart, and thus should cause immediate, permanent insensibility, the EEG took longer to fall below 10 μV (52 s) than after throat cutting. These results suggest that electrical stunning of sheep and calves causes a prolonged increase in the post-stun EEG amplitude. Therefore, during slaughter, stunned animals have larger amplitude EEG signals than unstunned animals, and EEG criteria developed for judging the sensibility of unstunned animals cannot be used for those that are electrically stunned.     

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.     

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.     

Effect of stun duration and current level applied during head to back and head only electrical stunning of pigs on pork quality compared with pigs stunned with CO(2)

The effect of current, duration and method of application of manual electrical stunning on pork carcass and meat quality attributes in comparison with stunning pigs with CO₂ was investigated. Two experiments were conducted using a total of 96 Large White×Landrace boars (homozygous dominant for the halothane gene). In Experiment 1, 48 pigs were allocated to one of six stunning treatments: CO₂ (90% in air), electrical stunning (ES) using head only (HO) tongs delivering current at a frequency of 50 Hz at 1.3 or 2.0 A for 4 s and 0.9, 1.3 or 2.0 A for 19 s. Higher drip loss occurred in M. longissimus thoracis et lumborum (LTL) muscles from ES pigs, except those stunned with 0.9 A for 19 s, compared with pigs stunned with CO₂. The incidence of pale, soft exudative (PSE) meat was higher in ES pigs, except those stunned at 1.3 A for 4 s, compared with CO₂ stunned pigs. In Experiment 2, 48 pigs were allocated to one of six stunning treatments: ES using a head to back (HB) handpiece delivering current at 1.3 or 2.0 A for 4 s and 0.9 or 1.3 A for 10 s; HO 1.3 A for 4 s or CO₂. Although stunning treatment did not influence ultimate pH, muscle lightness, tenderness or cooking loss, drip loss and PSE incidence in LTL muscles from CO₂ stunned pigs were lower compared with ES pigs. Overall, ecchymosis and bone fractures were more prevalent in ES pigs compared with CO₂ stunned pigs. This research identified that stunning pigs with CO₂ compared with manual ES lowered the incidence of bone fractures, ecchymosis, PSE and drip loss of pork.     

Effect of electrical stunning on meat and carcass quality in lambs

The effect on meat quality and the presence of haemorrhages were assessed in head-only electrically stunned and non-stunned lambs. Colour (L?, a?, b?), muscle ultimate pH (pHu), chilling losses and carcass weight at 45 min and 24 h were not significantly different between treatments. However, the amount of blood lost relative to live body weight and the killing-out were significantly higher (P<0.05) in electrically stunned lambs compared with non-stunned lambs. No carcasses with petechiae, ecchymosis, haematomas and bone fractures were found in either treatment. On the other hand, the incidence of hearts with petechiae was significantly (P<0.05) higher in electrically stunned lambs compared with lambs slaughtered without prior stunning. It is concluded that meat quality and the incidence of haemorrhages are unaffected by head-only electrical stunning for 3 s at a constant voltage of 250 V.     

The efficacy of pulsed ultrahigh current for the stunning of cattle prior to slaughter

We present results from the development of a new system of reversible electrical stunning of cattle. A single-pulse ultra-high current (SPUC) was generated from a capacitance discharge current spike of at least 5000 V at 70 A, for approximately 50 ms. Ninety-seven cattle were stunned in three experimental protocols. With improvements made to the design of the stun box and charge delivered, 38 cattle were either stunned and immediately jugulated or monitored for signs of reappearance of brain stem reflexes at which point a concussion stun was administered. This use of the SPUC charge, provided as a biphasic-pulse waveform, resulted in a high level of stunning efficacy, with unconsciousness lasting for up to 4 min. These results were supported by EEG data taken from a subsequent cohort of stunned cattle. The SPUC stun also apparently eliminated post-stun grand mal seizures that can occur following short-acting conventional electrical stun, with its associated negative consequences on operator safety and meat quality.     

Comparison of CO(2) stunning with manual electrical stunning (50 Hz) of pigs on carcass and meat quality

The effects of carbon dioxide stunning on carcass and pork quality attributes were compared with the effects of manual electrical stunning using either head-only or head-to-brisket electrodes. A total of 30 Large White×Landrace boars (homozygous dominant for the halothane gene) were randomly allocated immediately prior to slaughter to one of three stunning treatments: carbon dioxide (90% CO(2)), head only (HO; 1.3 A for 4 s at a frequency of 50 Hz) or head to brisket (HBR; 1.3 A for 4 s at a frequency of 50 Hz) electrical stunning. The pH of the M. longissimus thoracis (LT) muscle measured at two sites [between the fifth and sixth thoracic vertebrae (Site 1) and the last thoracic rib (Site 2)] at 40 min post-slaughter was lower (P<0.001) in HBR stunned pigs compared with both CO(2) and HO stunned pigs. No differences in ultimate pH of the LT at either measurement site were found due to stunning method. However, a faster (P<0.05) relative rate of pH decline was found in the LT at Site 1 from HBR stunned pigs compared with CO(2) stunned pigs. No difference in the relative rate of muscle pH decline (P>0.05) between stunning methods was found in the LT muscle at Site 2. Pork from HBR stunned pigs was paler (P<0.05) and had a higher (P<0.001) percentage drip loss compared with pork from HO and CO(2) stunned pigs. LT muscles from HBR stunned pigs had lower (P<0.001) WB shear force values compared with pork from HO stunned pigs (6.57 vs. 8.12 kg, S.E.D. 0.49). Carcass quality was improved by CO(2) stunning, with less (P<0.05) ecchymosis-affected pork trimmed from shoulder primals compared with electrically stunned pigs. These results indicate that manual electrical stunning of pigs using HO tongs and CO(2) stunning reduced percentage drip loss, reduced muscle lightness and reduced the rate of muscle pH decline compared with pigs manually electrically stunned using HBR tongs.     

Electrical stunning of veal calves

A total of sixty-two calves with body weights of 200 kg and with preimplanted ECoG electrodes on the dura mater, were electrically stunned using various currents, voltages and stunning equipment. To stun 90% of the calves effectively, a current strength of 0·87 A is estimated to be necessary when using scissor model tongs. Effective stunning means immediate (within 1 s) induction of unconsciousness by a general electroplectic insult. Atrial fibrillation is a frequently occurring phenomenon after electrical stunning when the electrodes are placed between the eye and the ear. The relatively short duration of the insult in calves compared with pigs, as well as the clonic spasms occurring 10s after stunning, are major drawbacks to the practical application of electrical stunning of veal calves. The experiments show that these drawbacks can be eliminated by modifying the form and position of the electrodes.     

Stunning and shackling influences on quality of porcine Longissimus dorsi and Semimembranosus muscles

Seventy-one barrows of three porcine genotypes (nn, Nn and NN genotypes with respect to halothane) were electrically stunned on the right side and randomly assigned to one of three treatments during the bleeding process (prone, PR; shackled left, SL; or shackled right, SR) to investigate the influence of both shackling and stunning on ultimate meat quality. PR carcasses had less side-to-side variation in 40 min pH than either SL or SR carcasses. Shackling contributed to a decreased 40 min pH in the semimembranosus (SM) and posterior longissimus dorsi (PL). The effects of stunning appeared to be additive when combined with shackling, tending to lower pH in the mid-longissimus dorsi (ML; P <- 0·10). The ‘free’ side of the shackled carcass also had significantly lower 40 min pH in the ML, PL and SM locations when compared to PR sides. Genotype had no influence on shackling since there was no treatment by genotype interactions. Despite significant effects on post-mortem metabolism (indicated by the differences in 40 min pH) shackling alone had little influence on overall ultimate meat quality of the carcass. Depending on the sampling location, soluble protein and L^* and b^* values varied among treatments. Shear force and a^* values were similar among treatments, but PR and SL carcasses had significantly lower expressible juice and drip loss compared to SR carcasses. These results suggest that, although shackling alone has little effect on meat quality, in combination with electrical stunning, shackling can lead to a decrease in meat quality.     

致昏电压对兔肉品质的影响研究

采用100、75、65、55V和人工致昏(对照组)的宰杀方式,研究其对兔肉品质的影响,结果表明:不同致昏电压对兔肉pH值的影响差异不显著(p>0.05),只有75V致昏组与100V致昏组间宰后1h的背最长肌pH值差异显著(p<0.05);宰后1h,不同致昏电压对兔背最长肌的肉色亮度L*值、红度a*值、黄度b*值和后腿肉的L*值、a*值的影响差异不显著(p>0.05);宰后24h,75V致昏组的肌肉颜色鲜红,而人工致昏组和100V致昏组的肌肉颜色较苍白;100V致昏组的滴水损失最大,为3.738%,而75V致昏组的最小,为2.420%;蒸煮损失最大的为100V致昏组,最小的为55V致昏组,其次是75V组;肌肉嫩度最好的是75V致昏组,最差的是人工致昏组。     

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.     

The effectiveness of high frequency electrical stunning in pigs

Two commercially-available high frequency electrical stunners producing either AC sinewaves (146 V; 1592 Hz) or DC squarewaves (162V; 1642 Hz) having different waveforms were tested for their effectiveness in stunning pigs and compared with conventional 50 Hz sinusoidal waveforms. Seventy-nine pigs were stunned using the highest voltage settings, allowed to recover, and the duration of insensibility was assessed from behavioural signs. It was found that the pigs were adequately stunned by this method even though some physical responses differed from 50 Hz stunning. An additional experiment was conducted on three pigs to examine whether the epileptic brain activity (indicative of unconsciousness) occurred following high frequency stunning and to assess the effects on visually evoked responses. It was confirmed that high frequency stunning produced epilepsy and unconsciousness and appeared therefore to be acceptable from an animal welfare standpoint. However, the average stunning to sticking intervals were shorter with high frequency stunning compared with 50 Hz stunning.     

The effect of stunning method on the incidence of PSE meat and haemorrhages in pork carcasses

Two commercial pig abattoirs (A and B) equipped with a head-only and head-to-chest electrical stunning systems, and two (C and D) equipped with compact carbon dioxide (CO(2)) stunning systems, were visited during 3 days to evaluate the effects of the stunning system on meat quality and haemorrhages. Meat quality was evaluated by measuring muscle electrical conductivity (PQM) and colour (Minolta Chromameter) at 2 and 7 h post mortem (abattoirs A and C, and B and D, respectively). PQM and colour were measured in 2486 and 2321 loins respectively. Also ultimate pH (pHu) was measured in 2395 loins at 24 h post mortem. Haemorrhages were evaluated by recording the incidence of petechiae, ecchymosis and haematomas, bone fractures were also recorded. A total of 1980 shoulders, 3943 loins, and 5438 hams were inspected. In the abattoirs equipped with the electrical stunning systems, a higher (P<0.05) incidence of potentially PSE meat (PQM>6) was found compared with the abattoirs equipped with CO(2) stunning. Likewise, the loins from electrically stunned pigs were paler than those from CO(2) stunned pigs (P<0.05). Electrical stunning increased the incidence of petechiae in the loin and the ham (P<0.05). No shoulder, loin or ham with bone fractures was found in the abattoirs studied. Therefore, CO(2) stunning reduces the incidence of PSE meat and of petechiae on muscle fascia of loins and hams, compared with electrical stunning. However, petechiae are not of great importance because they can be removed from the affected commercial cuts.     

Electrical stunning of sheep

In seventy Texel breed sheep with a live weight of about 43 kg electrocorticogram (ECoG) electrodes were implanted in the dura mater. The day after the operation the sheep were electrically stunned with scissor model tongs on the head. Various currents and voltages were used. A current strength of 0·33 A was statistically estimated to stun 90% of the sheep effectively, which means an immediate induction of a general epileptiform insult. The duration of an insult, using 600 V, is significantly longer than using 300 V, although the shortest duration was 23 s and 22 s, respectively. In all instances a paroxysmal ventricular tachycardia was observed after stunning. In the interests of animal welfare, electrical stunning of sheep should be performed with an amperage of at least 0·5 A (160 V) and throat cutting should take place within 16 s.     

Halothane genotype, pre-slaughter handling and stunning method all influence pork quality

Seventy-six Landrace and four Large White × Landrace pigs (n=80) of 90-134 kg liveweight were randomly allocated to a 2×2×2 factorial experiment to determine the effect of halothane genotype [heterozygous for the halothane gene (Nn) and homozygous dominant (NN)], pre-slaughter handling (minimal and negative) and stunning method (CO(2) stunning and electrical) on pork quality. The rate of muscle pH decline post-slaughter of the m. longissimus thoracis et lumborum (LTL) muscle was faster in Nn pigs compared with NN pigs (0.86 and 0.30 pH units/h, respectively). Pork from Nn pigs was also paler in colour, had higher percentage drip loss and purge and lower sarcoplasmic and myofibrillar protein solubility compared with NN pigs. Pork from CO(2) stunned pigs had a lower drip loss compared to pork from electrically stunned pigs (5.80 and 7.28%, respectively?- means of both genotypes combined). Tenderness of pork assessed at 24 h post-slaughter was not influenced by genotype, pre-slaughter handling or stunning method. However, pork from Nn pigs aged for 5 days post-slaughter was less tender than NN pigs (5.84 and 4.84 kg, respectively). Pale, soft and exudative pork was produced in all negatively handled Nn pigs, regardless of stunning method. The average amount of ecchymosis-affected muscle trimmed from carcasses of electrically stunned pigs was higher compared to pigs stunned with CO(2) (65 and 0.7 g, respectively). These data indicate that although halothane status was the most important factor influencing pork quality, pre-slaughter handling and stunning method also influenced meat and carcass quality.     

Effect of electrical stunning methods on petechial haemorrhages and on the blood pressure of lambs

Electrical stunning of lambs to render them unconscious and insensible to pain can result in blood splash (spots of blood in muscles) or speckle (petechial haemorrhages in fat or connective tissue overlying the muscle). Stunning through electrodes applied to the head causes mainly blood splash with some speckle, while currents applied head-to-back or head-to-foreleg can produce speckle without blood splash. To identify the causes of speckle, animal movement and blood pressure changes that occur during stunning were measured. Three different stunning methods were employed: head-only, head-to-back and head-to-foreleg. Head-only stunning, which does not stop the heart and produces a moderate amount of speckling, was accompanied by elevated arterial blood pressures up to 300 mm Hg, and venous pressures up to 100 mm Hg. The carcass became rigid on stunning but reflex kicking occurred when the hind legs were shackled. Head-to-back stunning, which stops the heart, produced a momentary arterial and venous blood pressure rise during the stun, as a result of thoracic pressure changes, followed by a decline in pressure to 40-50 mm Hg. The muscles became markedly rigid due to direct stimulation of the loin and spontaneous kicking was absent following current switch off, although spontaneous coughing persisted. Stillness associated with head-to-back stunning was accompanied by the highest incidence and severity of speckling, whereas head-to-foreleg stunning, which also stops the heart, resulted in less muscle contraction and was accompanied by the least incidence and severity of speckling. Kicking was also eliminated if sufficiently high currents were used. Stopping the heart with KCl before a head-to-back stun lowered arterial blood pressure to 20-30 mm Hg and markedly reduced speckle. Abolition of nervously mediated muscle movement with curare before stunning resulted in no observable speckle in head-only stunned lambs but, in the head-to-back stunned lambs, there was a low incidence of speckle in the loin as a result of the muscle being directly stimulated to contract. The results from this study are consistent with the view that speckle is a result of vigorous movements between muscles during stunning, causing a shearing and rupture of blood vessels in the fat and connective tissues, thus allowing the muscles to squeeze out blood. The incidence of speckle does not appear to be related to blood pressure during stunning.     

Studies on the Criollo goat of Northern Mexico: Part 2-Physical and chemical characteristics of the musculature

Groups of castrate male Criollo goats were slaughtered at 12, 16, 20 and 24 kg liveweights after being reared on natural rangeland with concentrate supplementation.

After slaughter the carcasses were chilled for 24 h at 2°C, and the total lean was dissected from the left halves of the carcasses. The total lean was subjected to a proximate analysis. M. biceps femoris and M. longissimus dorsi muscles were dissected out of the right halves of the carcasses. Various physical and chemical quality parameters, such as Warner-Bratzler shear values and tristimulus colour values, were measured on these muscles in addition to hydroxy proline analysis, for the estimation of collagen content.

The moisture content of the total lean decreased steadily with increasing slaughter weight to a level of approximately 76% in the heaviest group. Ash and protein content tended to fall, with intramuscular fat increasing to approximately 16% of the wet tissue weight. The ultimate pH of the two muscles was high in all the slaughter groups, being usually higher than 6·0. Generally, shear values did not change between the slaughter groups in the two muscles.

The data indicate that slaughtering castrate male Criollo goats at 24 kg instead of 8 kg does not exert deleterious effects on the parameters of physical and chemical quality investigated.     

Effect of electrical stunning or sticking without stunning on the microstructure of zousoon, a Chinese semi-dry pork product

The microstructure of muscle fibers from pigs killed following electrical stunning was compared to that from pigs killed after tying-resting and sticking. Examination of the muscle fibers demonstrated that electrical stunning resulted in contracture bands that caused tearing and fragmentation of the myofibers/myofibrils. On the other hand, tying-resting and sticking was not accompanied by microstructural fragmentation of the muscle fibers. Results indicate that electrical stunning of hogs causes fragmentation and breakage of the muscle fibers so that the meat is not suitable for production of Zousoon-a semi-dry shredded Chinese pork product and other similar items prepared from prerigor pig muscle. Heating and drying intensify the deteachment of the myofibrils from the muscle fiber bundles, which is caused mainly by electrical stunning or stimulation and improper conditioning following slaughter. The combined effects of electrical stunning and heating-drying appear to be responsible for the fragmentation of the muscle fibers/myofibrils and contribute to the unsuitability of prerigor muscle from electrically stunned pigs for use in the production of Zousoon. Since sticking of pigs without stunning does not meet humane slaughter standards, alternative animal welfare slaughter procedures should be examined from the standpoint of their usefulness in producing Zousoon.