Pre-slaughter stress arising from on-farm handling and its interactions with electrical stimulation on tenderness of lambs

The effect of electrical stimulation of lamb carcasses (n=269) or its absence (n=257) on shear force of m. longissimus thoracis et lumborum (LT) was monitored during ageing in pasture-fed merino lambs (n=526). The lambs were slaughtered on four different days allowing durations of between one to 10 days of recovery from pre-slaughter handling (yarding, weighing and crutching) that affected ultimate pH (pH(u)). The right LT was removed 20-40min post-slaughter, tightly-wrapped in cling film (prevents the muscle cross-section increasing and thus minimising shortening) and rapidly cooled to 15°C to enter rigor mortis and age. At 0, 4, 24 and 72h post-slaughter, pH measurements and samples for shear force measurement were taken. Pre-slaughter handling had a significant negative effect on pH(u) and several days recovery were required for pH(u) to reach values associated with optimal meat quality as reflected by pH(u). Lambs with one and three days recovery (no significant difference between them) had a pH(u)>5.7 in 50% of the muscles and 19.4%>pH(u) 5.8. Whereas, in lambs with 8-10 days recovery (no significant difference between them), only 8% had a pH(u)>5.7 and 3.1%>pH(u) 5.8. Within each slaughter day electrically stimulated lambs were always more tender than non-stimulated lambs. For non-stimulated muscles at 72h, shear force values >40N occurred for 11.2% of the muscles: for electrically stimulated muscles at 72h, shear force values >40N occurred for 1.9% of the muscles. The rates of tenderisation were slower for intermediate pH(u) values resulting in higher shear force values at all ageing durations. With ageing at 72h for intermediate pH(u), non-stimulated muscles (n=38) 17.64% were >40N and for stimulated muscles (n=34), 7.9% were >40N.     

Colour stability of bovine Longissimus and Psoas major muscle as affected by electrical stimulation and hot boning

From eight electrically stimulated and eight non-stimulated cows the righthand-side longissimus and psoas major muscles were hot boned within 1 1 2 h post mortem, vacuum packaged and chilled and storred at 1±1°C. Immediately after slaughter, the lefthand carcass-sides were blast-chilled for 1 1 2 h and subsequently chilled at 1±1°C until the following day. After cold boning, the longissimus and psoas major muscle were packaged, chilled and stored as the hot boned muscles. After 12 days of storage, steaks, cut from the primals, were displayed at 1±1°C under continuous illumination (300-400 lx). Colour measurements after 0, 2 and 4 days of display revealed a significant (p<0·10) effect of time of boning on non-stimulated psoas major muscle (lower values for a (?), b (?) values, chroma and %R630-%R580). Significant effects of electrical stimulation were not observed. Changes in hue tended to be more pronounced when the meat had been stimulated. Changes in chroma were largest (p<0·10) is non-stimulated, hot boned psoas muscle. Analysis of variances showed that in the longissimus muscle significant effects (p<0·10) of time boning and electrical stimulation were present. The effect of time of boning was often influenced by the use of electrical stimulation. Changes in hue and chroma indicated that hot boned samples had a higher colour stability than cold boned controls, especially when the carcasses had not been stimulated electrically. The observed differences in colour stability were rather small in all treatment groups and are not expected to present any practical merchandising problem.     

Effect of muscle restraint on sheep meat tenderness with rigor mortis at 18°C

The effect on shear force of skeletal restraint and removing muscles from lamb m. longissimus thoracis et lumborum (LT) immediately after slaughter and electrical stimulation was undertaken at a rigor temperature of 18°C (n=15). The temperature of 18°C was achieved through chilling of electrically stimulated sheep carcasses in air at 12°C, air flow 1-1.5 ms(-2). In other groups, the muscle was removed at 2.5 h post-mortem and either wrapped or left non-wrapped before being placed back on the carcass to follow carcass cooling regimes. Following rigor mortis, the meat was aged for 0, 16, 40 and 65 h at 15°C and frozen. For the non-stimulated samples, the meat was aged for 0, 12, 36 and 60 h before being frozen. The frozen meat was cooked to 75°C in an 85°C water bath and shear force values obtained from a 1 × 1 cm cross-section. Commencement of ageing was considered to take place at rigor mortis and this was taken as zero aged meat. There were no significant differences in the rate of tenderisation and initial shear force for all treatments. The 23% cook loss was similar for all wrapped and non-wrapped situations and the values decreased slightly with longer ageing durations. Wrapping was shown to mimic meat left intact on the carcass, as it prevented significant prerigor shortening. Such techniques allows muscles to be removed and placed in a controlled temperature environment to enable precise studies of ageing processes.     

THE SHEAR FORCE OF VERY-RAPIDLY CHILLED LAMB 2: THE EFFECT OF MUSCLE EXCISION

The effect of chilling rate and muscle excision on the shear force of ovine muscle (M. longissimus thoracis et lumborum) was examined. Conventional chilling involved chilling at 4C for 24 h and very-rapid chilling involved chilling at −20C for 3.5 h followed by conventional chilling for 20.5 h. After 24 h all muscles were aged for a further four days. Approximately 30 min after slaughter, one M. longissimus thoracis et lumborum was excised from each carcass and placed in the same chill as the remainder of the carcass. This gave a total of four different treatments. Shear force was assessed at I and 5 days postmortem by Warner-Bratzler shear force measurement. Excision led to reduced shear force in the very-rapid chilling regime but increased shear force in the conventionally chilled muscles. Aging improved shear force for all chilling treatments. No significant difference was found in the rate of pH fall, between the chilling treatments.     

Effect of glycogen concentration and form on the response to electrical stimulation and rate of post-mortem glycolysis in ovine muscle

The associations between the muscle glycogen concentration and form and the rate of post-mortem glycolysis in ovine muscle were investigated. Twenty-two merino wethers (18-24 months) were allocated to either roughage or concentrate pelleted diets for 34 days prior to slaughter. An exercise depletion/repletion model was applied four days prior to slaughter to generate differences in muscle glycogen levels at slaughter. Muscle biopsies were taken from the m. semimembranosus (SM) and m. semitendinosus (ST) prior to and immediately after exercise for muscle glycogen determination. At slaughter, one side was electrically stimulated and both sides were conventionally chilled for 24h. The pH response to electrical stimulation (ΔpH) and the rate of pH decline adjusted to a constant temperature of 38°C over the initial 6h post-mortem period was determined in three muscles (m. longissimus thoracis et lumborum LTL, SM and ST). In addition, the concentrations of glycogen, proglycogen (PG), macroglycogen (MG) and lactate in the three muscles immediately after slaughter were determined. The glycogen loss due to exercise was influenced by diet (P<0.01; concentrate 63% and roughage 73%) but did not differ between muscles. The rates of repletion significantly varied between muscles (SM>ST) and diet (concentrate>roughage). The available glycogen (glycogen(A)) and MG concentrations at slaughter varied significantly depending on the diet (P<0.01) and muscle (P<0.001). The percentage of MG relative to MG+PG varied between muscles (46%, 50% and 57% for the ST, LTL and SM). The concentration and form of available glycogen at slaughter did not influence the response to electrical stimulation after adjusting for pre-stimulation pH (P<0.01). The ΔpH varied significantly between muscles (0.39±0.03, 0.26±0.02 and 0.20±0.03 for the ST, LTL and SM) after adjusting for pre-stimulation pH. Differences in the temperature adjusted rate of pH decline were observed between the muscles (LTL>SM>ST). Importantly, a positive linear association (P=0.05) was found between muscle glycogen(A) concentration at slaughter and the rate of pH decline (temperature adjusted).     

Effects of Electrical Stimulation on Histochemical Muscle Fiber Staining, Quality, and Composition of Camel and Cattle Longissimus thoracis Muscles

ABSTRACT:  The effects of electrical stimulation on muscle fiber type, meat quality, and composition of Longissimus thoracis muscles from one-humped camels and Dofari Omani cattle of a comparable age range were investigated. A low-voltage electrical stimulation with 90 V, 14 Hz (pulse of 7.5-millisecond duration every 70 milliseconds) 20 min postmortem was applied. Samples from the left muscle were collected from 20 (2 to 3 y) camels and 24 cattle (1 to 3 y). For chemical composition, muscle samples were dried in a freeze dryer, and then ground to determine moisture, protein, fat, and ash. Macro- and micro-minerals were determined using an Inductively Coupled Plasma Emission Spectrometer. Quality characteristics of the meat were evaluated using shear force value, pH, sarcomere, myofibrillar fragmentation index, expressed juice, cooking loss percent, and CIE L *, a *, b * color values. Electrical stimulation resulted in a significantly ( P < 0.05) more rapid pH fall in the muscle during the first 24 h after slaughter in both species. Muscles from electrically stimulated carcasses had significantly ( P < 0.05) lower ultimate pH, longer sarcomere, and lower shear force values than those from nonstimulated carcasses. Lightness ( L *), myofibrillar fragmentation, and expressed juice were significantly ( P < 0.05) higher for stimulated than for nonstimulated muscles. Muscles of camels had significantly ( P < 0.05) higher expressed juice, cooking loss percent, redness color ( a *), and lower fat, Mg, K, and P than those from cattle. Electrical stimulation improved quality characteristics of meat from both species. This indicates that meat quality of local camel and cattle can be improved by electrical stimulation and consequently improves their acceptability to consumers and better marketability.     

Quality of beef loin steaks as influenced by animal age, electrical stimulation and ageing

The tenderness of beef M. longissimus dorsi muscles from cattle about 1 8 months (0-2 tooth) and 54 months (8 tooth) old at the time of slaughter was investigated. The influence of electrical stimulation on the mechanical and sensory panel assessments obtained for loin steaks was examined at 24 h post slaughter and also after ageing three weeks. Effective electrical stimulation of the carcasses produced, at 24 h from slaughter, steaks from both age groups which were uniform, acceptable and predictable in tenderness. The colour of loin steaks from the younger animals was lighter than loin steaks from older animals, while the weep in the vacuum packages was less for meat from the older animals than that from the younger ones.     

Low voltage electrical stimulation and post-mortem energy metabolism in beef

In the present study, the influence of low voltage electrical stimulation on glycolysis, concentrations of creatine phosphate and adenine nucleotides, as well as the relationship between metabolic activity and tenderness, was examined in bovine M. longissimus dorsi. During stimulation, about 50% of the creatine phosphate was consumed and the immediate pH drop was, on average, 0·21 units. The increased energy consumption resulted in a decrease in the halftime of ATP from 10 h in non-stimulated muscles to 5 h in electrically stimulated muscles. The total high energy phosphate turnover was found to be 2400 μmol/h/g during stimulation and 18 μmol/h/g immediately following stimulation compared with 9 μmol/h/g for the non-stimulated counterpart. No obvious abnormalities were found in the course of changes during energy metabolism following stimulation, besides the increased metabolic rate. Significant relationships were found between the degradation of several of the energy metabolites during stimulation and improvements in tenderness. It is concluded that, within the variation found in this study, the better the effect of electrical stimulation in increasing the metabolic rate, the better the resulting meat tenderness. Results also showed that the higher the shear force in the non-stimulated part, the better was the effect of electrical stimulation in improving the meat tenderness.     

Effect of electrical stimulation on post mortem biochemical characteristics and quality of Longissimus dorsi thoracis muscle from buffalo (Bubalus bubalis)

High voltage electrical stimulation (700 V, 1400 V peak, pulses 1 s on/1 s off, 60 Hz, 2 A) on buffalo carcasses resulted in a significantly more rapid pH fall in Longissimus dorsi thoracis muscle when compared to non stimulated controls (p < 0.01), during the first 24 h after slaughter. The IMP/ATP ratio on the same period showed a much more rapid increase for the stimulated muscles (1.07 and 1.16 at times 1 and 2.5 h post mortem vs control values of 0.77 and 0.83, respectively). Sensory and instrumental evaluation of texture of meat cooled by two distinct processes showed that tenderness at 24 h post mortem was higher in the stimulated muscles compared to non-stimulated controls, irrespective of the cooling process adopted. High voltage stimulation significantly decreases cohesiveness, increases myofibril fragmentation; and SDS polyacrylamide gel electrophoresis of the myofibrillar proteins showed a weakening of Troponin T band during 6 days of ageing in non-stimulated control muscles, whereas electrical stimulation accelerated the process of ageing over 3 days. This is the first report on acceleration of conditioning in buffalo muscle and the conditions described here have a high potential for application in meat industry for buffalo slaughter.     

宰后僵直及成熟过程中羊背最长肌理化性质的变化

动物宰后从肌肉到肉品经过僵直、成熟等一系列复杂的生理生化反应。僵直及成熟过程的研究可为肉品质改善及肉制品加工提供理论依据。选取杂交公羊(小尾寒羊×北京本地羊)双侧背最长肌在4℃成熟0.5、2.0、6.0、12.0、24.0、48.0、72.0、120.0、168.0 h,测定不同时间的pH值、剪切力、肌节长度、ATP含量、肌原纤维小片化指数(myofibril fragmentation index,MFI)、钙蛋白酶活力。结果表明:宰后成熟过程中,pH值先下降后逐渐趋于稳定,从第24小时后变化不显著(P0.05);剪切力先上升后下降,在第24小时达到最大值;肌节长度在宰后先缩短后逐渐变长,且在第48小时缩至最短;ATP含量先上升后下降,48 h后趋于稳定;μ-钙蛋白酶80 kD大亚基在宰后24 h基本降解完全,其降解的78 kD大亚基在第48小时降解完全;肌间线蛋白和肌钙蛋白T作为μ-钙蛋白酶的降解底物,在成熟过程中发生降解,第168小时几乎观察不到完整的蛋白条带;随着宰后时间的延长,羊背最长肌从第2小时开始僵直,到第24小时程度达到最大,从第48小时开始解僵,解僵后肉的嫩度逐渐改善。     

Effect of low voltage electrical stimulation of pig carcasses and ageing on sensory attributes of fresh pork

The effect of electrically stimulating pig carcasses and ageing on sensory attributes of pork was evaluated in this study. A total of 48 female pigs [Duroc×Large White/Landrace (A; n=24) and Large White/Landrace (B; n=24)] were randomly allocated immediately prior to slaughter to one of two low voltage stimulation treatments; no stimulation or 150 mA applied for 30 s at 2 min post-exsanguination. Each side of the carcass was then randomly allocated to an ageing treatment of either 2 or 7 days post-slaughter. Muscle pH of the M. longissimus lumborum was lower (P<0.001) in electrically stimulated carcasses when measured from 40 min to 8 h post-slaughter compared with non-stimulated carcasses. Percentage drip loss, muscle lightness and PSE incidence were not influenced (P>0.05) by electrical stimulation. Electrical stimulation of pig carcasses and ageing pork for 7 days post-slaughter both improved (P<0.001) consumer scores for tenderness, juiciness, overall liking and quality category, however the interaction term of electrical stimulation and ageing was not significant for any of the sensory attributes. Pork from non-stimulated carcasses that was aged for 2 day post-slaughter was less tender (P<0.01) compared with pork in all other treatments. These results indicate that electrical stimulation (150 mA applied for 30 sec at 2 min post-exsanguination) was effective in improving eating quality attributes of pork, particularly when pork was aged for only 2 days post-slaughter, without detrimentally affecting colour or drip loss.     

Effect of electrical stimulation, hip suspension and ageing on quality of chilled pig meat

Carcasses from 60 Large white pigs, weighing 62-85 kg, were split and half were stimulated (700 V, 12·5 Hz for 90 s) 20 min after slaughter. Half of the stimulated (ES) and half of the non-stimulated sides were suspended from the Obturator foramen at 40 min after slaughter and resuspended from the Achilles tendon after 6 h. The sides were then subjected to one of two chilling treatments: (a) air at -15°C until M. longissimus dorsi (LD) in the lumbar region was below 10°C (approx. 3 h from slaughter), followed by air at 1°C for the remainder of chilling; (b) air at 1°C throughout. Rapid chilling increased toughness of LD but not M. semimembranosus (Sm). Stimulation improved tenderness in both muscles, increased drip loss in Sm and increased paleness in LD which could be reversed by rapid chilling. Pelvic suspension reduced drip and improved tenderness with similar magnitude to ES. Ageing improved tenderness in all except pelvic suspended sides but ES produced the most tender pork at 7 days.     

Enhancement of lean characteristics of veal carcasses by electrical stimulation

Forty Holstein vealers (approximately 16 weeks of age) were slaughtered, skinned, split longitudinally and one side was electrically stimulated (700 V, 2 A and seventeen impulses) for 1 min. Internal temperatures of the rib and round were recorded at 1 h and 24 h post mortem. Approximately 24 h post mortem, lean colour scores were assigned to the cross-section of the longissimus muscle at the 11th-12th rib interface, to the outside surface of the biceps femoris muscle and to the rectus abdominis and transverse abdominis muscles of the flank; lean texture and firmness scores were also assigned to the cut surface of the longissimus muscle. 'House grades' were assigned to each side of each carcass by plant personnel. Initial (1 h) rib and round temperatures were significantly higher for the electrically stimulated sides; however, at 24 h, neither round nor rib temperatures differed between control and electrically stimulated sides. Lean colour, firmness and texture scores for longissimus muscles were significantly (P < 0·0001) improved by electrical stimulation. Electrically stimulated sides also had lighter lean colour scores in the rectus and transverse abdominis and biceps femoris muscles. Electrical stimulation increased the number of carcasses receiving the top 'house grade' and reduced the number of carcasses in the lowest 'house grade'. These data indicate that electrical stimulation will improve lean colour, firmness and texture of veal carcasses when ribbed and evaluated after a 24 h chill.     

Investigation of methods to detect mechanically recovered meat in meat products - III: Microscopy

Carcasses from 36 Large White gilts, 70–80 kg live weight, were randomly allocated to three experimental groups. Pigs in the first group were electrically stimulated with low voltage during bleeding (85v, 14Hz for 64 s) and split before cooling. The left sides were rapidly chilled in air at -15°C for 75 min and then at 1°C until 24 h post-slaughter; right sides were chilled conventionally in air at 1°C for 24 h. In the second group, two different treatments were used 20 min post-slaughter: left sides were stimulated with low voltage, and right sides with high voltage (700 v, 12·5 Hz for 90 s). Both sets of sides were chilled rapidly. Carcasses from the third group were not stimulated, and sides chilled either rapidly or conventionally. Drip loss, colour and texture were measured in M. longissimus thoracis et lumborum at 3 and 10 days post-slaughter.

At 3 days post-slaughter the high voltage, treatment gave meat which was the most tender, was not pale and lost no more drip than unstimulated controls. Low voltage stimulation during bleeding gave meat which was 18% more tender than the unstimulated controls, but the improvement in tenderness was not as great as the 28% achieved with high voltage. Unexpectedly, low voltage stimulation applied 20 min after slaughter, was almost as effective in improving tenderness (by 17%) as low voltage applied during bleeding.

Tenderness improved from 3 days to 10 days in all stimulated samples, but not in unstimulated controls. The results suggest a degree of coldtoughening in the latter, even with conventional chilling, and a positive effect of electrical stimulation on tenderness, independent of its protective action against cold-shortening.     

Electrical stimulation during exsanguination: Effects on the prevalence of blood splash and on sensory quality characteristics in veal

Twenty-four veal calves were stunned with a captive bolt. Twelve calves were shackled by the left, the other twelve by the right hindleg. Approximately 1 min after sticking, six carcasses of each of these subgroups were stimulated electrically with equipment relying on a combined high (3000 V, 0·83 pulses s(-1), 1·5 ms duration) and low 35 V, 14 pulsess(-1)) voltage action. The remaining carcasses were left unharmed. At 24 h post-mortem hindquarters were boned to commercial primal cuts. Surrounding connective tissue and cut-up surfaces of primals as well as certain locations vulnerable for blood splash were further dissected. Neither electrical stimulation nor shackling by either of the hindlegs significantly affected the prevalence and severity of blood splash. Post-mortem factors promoting blood splash and possibly related to electrical stimulation and shackling are discussed. At 7 days post-mortem the sensory meat quality was assessed. In general, electrical stimulation did not significantly affect waterbinding and colour characteristics in longissimus (M. longissimus dorsi) and semimembranosus samples. Sarcomere lengths were similar in stimulated and control groups in longissimus but not in semimembranosus muscle. In both muscles shear force values were lower after electrical stimulation. In general, neither longissimus nor semimembranosus samples excised ipsilaterally from the shackled leg side exhibited differences in tenderness and sarcomere length. It is concluded that shackling by one leg or the other does not interfere with the tenderising effect of electrical stimulation.     

Low voltage electrical stimulation of lamb carcasses: effects on meat quality

The effects of an early post mortem low voltage electrical stimulation (28 V, 60 Hz) on biochemical changes and on final tenderness in muscles Longissimus thoracis et lumborum and Semimembranosus from lamb carcasses were studied. It was shown that electrical stimulation accelerated the glycolytic process resulting in a significant fall in pH during the first 6 h post mortem in both muscles examined and in a significant reduction in adenosine triphosphate (ATP) content in muscle Longissimus thoracis et lumborum. The effect of electrical stimulation on tenderness was recorded by measuring shear force values 2 and 7 days post mortem. Tenderness was significantly improved by electrical stimulation for the Longissimus thoracis et lumborum both at 2 and at 7 days post mortem, while for Semimembranosus electrical stimulation significantly increased tenderness just at 7 days post mortem.     

COMBINED EFFECTS OF ELECTRICAL STIMULATION, CARCASS POSTURE AND INSULATED BAGS ON RAM LAMB TENDERNESS

Thirty-six ram lambs fed a high roughage diet from weaning to 6 months of age and 48 kg body weight at slaughter were assigned randomly to six postmortem (PM) treatments: (1) control; (2) carcasses placed in insulated bags (B) for 24h PM; (3) carcasses suspended via the coccygeal vertebrae (P); (4) electrical stimulation (ES); (5) ES combined with B for 24 h PM; and (6) ES combined with P for 1.5 h poststimulation then suspended via the achilles tendon. Stimulation improved shear values for the longissimus and rectus femoris muscles. Method B without ES reduced shear values for the Longissimus, Semimembranosus, biceps femoris and rectus femoris. Use of method P without ES reduced shear values for the longissimus and semimembranosus. Combining ES with method B reduced shear values for all the muscles evaluated. Similar results were found when combining ES with method P.     

The influence of the rate of pH decline on the rate of ageing for pork. II: Interaction with chilling temperature

The influence of the rate of pH decline post slaughter on the rate of ageing of pork m. longissimus thoracis et lomborum was investigated. The rate of pH decline on 24 finisher pigs was manipulated by altering the method of stunning (carbon dioxide or electrical head to heart) and by the use of electrical stimulation (none or low voltage electrical stimulation (LVES) at 4 min post slaughter for either 15 s or 60 s). The rate of temperature decline was altered by chilling at 2 or 14?°C until rigor. The pH and temperature decline rates generated were designed to induce cold shortening at one extreme and protein denaturation at the other. The research results showed that the rate of pH decline was increased by electrical stimulation which in turn reduced cold shortening and improved tenderness. Chilling at 14?°C reduced the time to reach rigor by 1.3 h and resulted in a faster aging rate as indicated by a larger percentage change in WBSF from rigor to 4 days postmortem relative to carcases chilled at 2?°C. The greater tenderising effect appeared to be due to a combination of prevention of cold shortening and increased proteolysis. However, chilling slowly at 14?°C or the use of LVES for 60 s or any combination of these treatments did not induce protein denaturation.     

Mechanical Tensioning of Electrically Stimulated Carcasses for Improved Tenderness

The combined effect of electrical stimulation and tensioning on tenderness was studied with cows and lambs. Each carcass was split into sides: both sides were electrically stimulated (300V.a.c., 60Hz, 120sec) within 30 min after bleeding, one side was then tensioned. At 48 hr post-stimulation, samples were taken from the semimembranosus and longissimus dorsi for shear test, sarcomere length and fiber diameter. Tensioning produced 9% and 15% decreases in shear force in the semimembranosus and longissimus dorsi respectively. Longer sarcomeres and narrower fiber diameter were also observed in tensioned muscles. All differences were significant at P < 0.05. Tensioning may be used to further improve tenderness of electrically stimulated carcasses.     

Electrical stimulation of beef sides

Sides of beef were stimulated with one of three different systems of stimulation-a high voltage system (1100 V), a low voltage system (110 V) and an extra low voltage system (45 V). Warner-Bratzler shear measurements indicated that for muscles removed at 1 or 2 h post slaughter and then subjected to conditions which induce cold shortening, the high voltage system was superior to the other two. Warner-Bratzler shear values and taste panel tenderness scores indicated that, for all stimulation treatments, muscles removed from stimulated sides at 22 h post slaughter were more tender than those removed from control sides at the same time. Muscles from sides which had received the high voltage treatment, but not those from sides which had received the other stimulation treatments, were judged by the taste panel to be less juicy than muscles from the control sides. Lower shear values for individual muscles from stimulated sides were usually accompanied by longer sarcomeres and it is suggested that the major effect of electrical stimulation is the prevention of cold shortening.