Effects of electrical stimulation, followed by moderate cooling, on meat quality characteristics of veal Longissimus dorsi

Three groups of male Friesian veal calves (in total, 92) were slaughtered in separate series. Within each group, a subgroup (selected on the basis of blood characteristics determined 1 week ante mortem) was electrically stimulated immediately after bleeding (64 s-Mitab® Low voltage unit). Carcasses were transferred ca. 25 min post mortem (pm) to a cooler at 6°C and ca 2 h pm to a cooler at 3°C.

Electrical stimulation (ES) increased brightness and, to a lesser extent, yellowness, of the freshly cut surface (6th rib Longissimus dorsi, 24 h pm) but resulted also in a diminished water-holding capacity (WHC) of the veal meat. The effect of ES on tenderness (Warner-Bratzler shear force, 48 h pm) is positive for two of the three groups but negative for the third. This indicates that ES probably results in two opposite effects on tenderness—‘toughening’, as a result of the sarcomere shortening which occurred in all three groups, and ‘tenderizing’, as a result of microscopical fibre disruption. Our data indicate that disadvantages of ES may outweigh advantages when followed by moderate cooling.     

Short communication: Effect of replacing corn with beet pulp in a high concentrate diet fed to weaned Holstein calves on diet digestibility and growth

Using soluble fiber sources in starter and grower feeds for dairy calves less than 4 mo of age is common to reduce costs compared with including traditional cereal grains. Beet pulp (BP) contains relatively high concentrations of pectin compared with other fibrous feed ingredients and has been shown to be an acceptable replacement for corn in adult cow diets. However, limited information is available on BP digestibility and growth performance for young calves fed diets with BP. In this study, 48 male Holstein calves (59 ± 2 d of age, 77 ± 2.2 kg of initial body weight) were fed 95% concentrate, 5% chopped grass hay diets in groups with 4 calves/pen for 56 d. Pens were randomly assigned to 1 of 3 dietary treatments containing 0, 15, or 30% BP on an as-fed basis. Body weights, hip widths, and body condition scores were assessed at 56 (start of trial), 84, and 112 d of age. Dry matter intakes and refusals were recorded daily by pen. Digestion coefficients (dC) of the diets and microbial protein flows were estimated when calves were approximately 84 d of age. Fecal samples were collected daily from pen floors over a 7-d period, and urine samples were collected from 2 calves/pen over a 2-d period and analyzed for purine derivatives. Calf average daily gain and hip width change decreased linearly (from 1.09 to 1.04 kg/d and 5.4 to 4.8 cm over 56 d, respectively) with increasing BP. Dry matter, organic matter (from 79.7 to 75.6%), crude protein (75.7 to 70.1%), and starch (97.1 to 93.1%) dC decreased with increasing inclusion rates of BP. Conversely, neutral detergent fiber (from 47.1 to 52.7%) and acid detergent fiber (44.1 to 53.0%) dC increased with increasing BP. Estimates of urine output and microbial protein flow using purine derivatives did not differ among treatments. Under the conditions of this study, BP reduced growth largely by reducing diet digestibility in dairy calves from 56 to 112 d of age.     

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.     

Proteome changes in the insoluble protein fraction of bovine Longissimus dorsi muscle as a result of low-voltage electrical stimulation

Changes induced by low-voltage electrical stimulation (ES; 0-95 V for 8 s; 95 V for 32 s) in the insoluble protein fraction of bovine longissimus dorsi (LD) muscle at 1 and 24h post-ES were investigated by proteomics. Protein abundance patterns from ten Norwegian Red (NRF) young bulls were compared, and significant changes due to ES were found by rotation test and partial least square (PLS) regression analyses. Five protein spots showed lower abundance in ES samples at both sampling times, and in addition, 10 proteins at 1 h post-ES and 13 proteins at 24 h post-ES changed significantly in abundance due to ES. Reduced abundance of full-length structural proteins in ES samples indicates an accelerated proteolysis due to ES. Moreover, increased abundance of small heat shock proteins indicates earlier initiation of stress responses due to ES. These findings provide a better understanding of the biochemical processes taking place as a result of ES during post mortem storage of meat.     

Changes of the fatty acid composition and malondialdehyde concentration in rabbit Longissimus dorsi muscle after regular electrical stimulation

The experiment was carried out to investigate, whether in vivo transcutaneous electrical nerve stimulation (TENS) affects the fatty acid composition and antioxidant status of rabbit Longissimus dorsi muscle. Altogether 20 Pannon White meat type rabbits were divided into two groups, from which one was routinely exposed to TENS treatment with the following settings: 2 events (each 20 min) a day/50 days, 1 channel (2 electrodes)/animal, 30 Hz, 20 μs impulse length and 10 mA. The control group was not treated. After slaughtering gas chromatography analysis of the muscle showed significantly decreased stearic, arachidonic and docosahexaenoic acid proportions, while the estimated activity of the elongase enzyme decreased. The malondialdehyde concentration decreased insignificantly in the treated group, however, it followed the changes of the total highly unsaturated fatty acid amount (three or more double bonds), which decreased from 9.16% to 7.81%. The adaptation to the in vivo electrical treatment may significantly influence the meat fatty acid profile, especially PUFA proportion.     

Effect of a low chloride diet on lactating Holstein cows.

Twenty primiparous lactating Holstein cows were fed diets supplemented with either .5% sodium chloride or .75% sodium bicarbonate. Those fed the latter diet conserved chloride by reducing the chloride concentration in urine, feces, and, to a small but nonsignificant amount, in milk. The low chloride diet did not affect consumption of feed dry matter and water or milk production and composition. There was no indication of pica or other aberrant taste behavior. One half of the cows in each diet group was given free choice salt block of trace elements. Those fed the low chloride diet consumed more salt (337 versus 149 g/cow per wk). When chloride requirements have been established and data on chloride composition become more widely available, it will be possible to include both sodium and chloride in diet formulations and omit salt. This will reduce the amount of salt needed as either a sodium or chloride supplement.     

Effects of feeding corn or barley on composition of milk and diet digestibility

Complete mixed, cubed diets containing corn or barley as the cereal component were fed to eight cows, four first lactation and four second or later lactation. Diets were fed for ad libitum intake in two periods of 21 d each. Percentages of milk fat, protein, lactose, and solids were not affected by corn or barley. Percentages of casein, whey, and nonprotein nitrogen were not different nor was proportion of total nitrogen represented as casein, whey, or nonprotein nitrogen for corn or barley diets. Production status, first lactation versus older cows, did not affect milk composition of casein, whey, and nonprotein nitrogen. Apparent digestibility of dry matter and energy was not different, but fiber digestibility was significantly lower for the barley diet. Intake of dry matter and digestible energy and yield of milk and milk constituents were not different. When diets were fed to rumen fistulated heifers, molar percentages of volatile fatty acids, total volatile fatty acid concentration, and pH of rumen fluid were not different for corn or barley diets.     

低压电刺激对不同部位宰后牦牛肉肌原纤维蛋白水解的影响

研究电刺激对不同部位牦牛肉宰后成熟过程中微观结构及肌原纤维蛋白水解的影响。将牦牛宰后5min内进行低压电刺激(21V,50Hz,90s)并冷却排酸,于宰后0、1、3、5d取前部肱三头肌(TB)中部背最长肌(ML)和后部半膜肌(SM),分析其肌节长度、肌纤维直径、MFI指数、肌原纤维超微结构和全肌肉蛋白电泳图谱。结果表明:电刺激使不同部位牦牛肉肌节长度显著变化(p0.05),肌纤维直径平均缩小6%、5%和9%;TB、ML和SM宰后0~5d MFI值分别上升54%、55%和92%,SM嫩度显著增大(p0.01);不同部位牦牛肉肌原纤维超微结构中挛缩带占有率分别为23.9%、26.3%和31.2%,肌原纤维结构形变溶解;SDS-PAGE电泳图谱显示,TB、ML和SM部肌原纤维蛋白均在48~75ku之间降解彻底。本研究证实了电刺激缩短牦牛肉宰后成熟时间,对不同部位牦牛肉嫩度改善,特别是对肉质较差的SM效果显著。     

低压电刺激对不同部位宰后牦牛肉肌原纤维蛋白水解的影响

研究电刺激对不同部位牦牛肉宰后成熟过程中微观结构及肌原纤维蛋白水解的影响。将牦牛宰后5min内进行低压电刺激（21V,50Hz,90s）并冷却排酸,于宰后0、1、3、5d取前部肱三头肌（TB）中部背最长肌（ML）和后部半膜肌（SM）,分析其肌节长度、肌纤维直径、MFI指数、肌原纤维超微结构和全肌肉蛋白电泳图谱。结果表明:电刺激使不同部位牦牛肉肌节长度显著变化（p<0.05）,肌纤维直径平均缩小6%、5%和9%;TB、ML和SM宰后0⁵d MFI值分别上升54%、55%和92%,SM嫩度显著增大（p<0.01）;不同部位牦牛肉肌原纤维超微结构中挛缩带占有率分别为23.9%、26.3%和31.2%,肌原纤维结构形变溶解;SDS-PAGE电泳图谱显示,TB、ML和SM部肌原纤维蛋白均在48⁷5ku之间降解彻底。本研究证实了电刺激缩短牦牛肉宰后成熟时间,对不同部位牦牛肉嫩度改善,特别是对肉质较差的SM效果显著。      

The effect of high and low voltage electrical stimulation on beef quality

Meat bulls were assigned to three treatment groups—high voltage intermittent electrical stimulation, low voltage electrical stimulation and no stimulation.Both stimulation methods resulted in a significantly more rapid pH fall in the longissimus and adductor muscles during the first 8 h post mortem. Carcass cooling rates were relatively slow, since temperatures of the longissimus and adductor muscles were 15°C, respectively, at 8 h post mortem.Samples of stimulated longissimus, cut at 24h post mortem and vacuum stored at 3°C for 6 days, had a brighter red colour, higher drip and heating loss, lower shear force values and scored better in taste panels, compared with samples from control carcasses. No significant differences were observed between high and low voltage electrical stimulation in quality traits measured.Although the combined result of pH and temperature measurements during the first 8 h post mortem suggest an absence of cold shortening conditions in control carcasses, a lower sarcomere length was found in samples of the longissimus muscle taken from these carcasses at 24 h post mortem.     

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.     

The effect of electrical stimulation, time of boning and high temperature conditioning on sensory quality traits of porcine Longissimus dorsi muscle

The effects of electrical stimulation (300 V, 1 A, 50 Hz, AC, 30 s) and high temperature conditioning (4h/15°C) on sensory quality traits of hot- and cold-boned, vacuum-packaged longissimus dorsi muscle of halothanenegative pigs were assessed at 12 days post mortem. Electrical stimulation accelerated the pH fall significantly, but had negligible effects on all quality traits measured, i.e. shear force, drip formation, fresh meat colour, cooking loss and degree of sarcoplasmic protein denaturation (p > 0·05). As compared with cold boning, hot boning significantly lowered drip losses (p < 0·05). Shear forces, which increased as a result of hot boning (p < 0·05), were reduced again through a 4 h/15°C conditioning period before chilling at 1 ±1°C. In addition, high temperature conditioning resulted in significantly lower drip losses (p < 0·05). It is suggested that prevention of cold-induced reduction of proteolytic enzyme activity is primarily responsible for both these findings.     

Effect of low voltage electrical stimulation on protein and quality changes in bovine muscles during postmortem aging

This experiment was conducted to determine the influence of low voltage electrical stimulation (ES) on the tenderness development of beef round muscles. Eight steers were slaughtered, and ES applied to one side of each carcass within 90 min of exsanguination. Steaks from M. longissimus dorsi, semimembranosus, adductor, and gracilis were vacuum packaged and aged at 4 °C for 9 d. Star probe, sensory evaluation, Western blot assays of troponin-T and μ-calpain autolysis and 2D-DIGE were conducted. ES resulted in accelerated (P < 0.05) pH decline of the longissimus in the first 24 h postmortem. ES did not influence (P > 0.05) proteolysis and tenderness, but did alter the predominance of metabolic proteins in the soluble fraction of muscle. Aging for 9 d improved tenderness (P < 0.05). The data confirmed that low voltage ES at 90 min of exsanguination had no effect on proteolysis and tenderness development in the longissimus dorsi, semimembranosus, adductor or gracilis in beef.     

Effect of a mixture of steam-flaked corn and soybeans on health, growth, and selected blood metabolism of Holstein calves

The objective of the experiment was to evaluate the effects of steam-flaked corn grains and soybeans on calf health, growth, and selected blood parameters. Holstein bull calves (n = 30, approximately 7 ± 3 d of age) were purchased from local dairy farms and offered milk, starter diets, and hay, and were then assigned to the experiment at 21 ± 3 d of age. Calves were blocked into 3 treatments by birth date and body weight and randomly assigned to receive fresh milk and a commercial pelleted starter containing extruded corn and soybeans (ECS), steam-flaked corn and soybeans (SFCS), or ground corn and soybeans (GCS). The experiment was conducted with calves from 3 to 13 wk of age. Body weight, calf starter intake, milk intake, total dry matter intake, and body structural growth were not significantly influenced by corn and soybean processing during the study; however, feed efficiency was significantly improved by the SFCS treatment. Average daily gain generally decreased during the weaning week for all treatments, but did not differ significantly among treatments. Health incidences for calves fed the SFCS starter were lower than those fed the other 2 treatments. The blood hematocrit was higher for calves fed the SFCS starter than for those fed the GCS and ECS starters during wk 6 to 11. The concentration of plasma β-hydroxybutyrate was higher for the calves fed the GCS and SFCS treatments than for those fed the ECS treatment during wk 6 to 13, but lower during wk 4 and 5. Plasma glucose concentrations decreased remarkably with increasing calf age but were not affected by corn and soybean processing. Plasma nonesterified fatty acids were influenced by calf age, and higher NEFA concentration was observed in the SFCS treatment than in the other 2 treatments during wk 5 to 9. Calves consuming the SFCS starter had similar average daily gain, milk intake, starter intake, total dry matter intake, and body structure, but had improved feed efficiency when compared with animals consuming the GCS and ECS starters. The SFCS starter decreased incidence of diarrhea during the postweaning period and required less veterinary treatment. These data suggest that the steam-flaking of corn and soybeans can influence the growth performance and the selected blood parameters of calves and that, in this study, the extrusion of corn and soybeans had no beneficial effect on the growth performance of calves.     

Effect of dietary fat supplementation on methane emissions from dairy cows fed wheat or corn

Diets that contain high proportions of either wheat or supplementary fat have been individually reported to reduce enteric methane production. The objective of this research was to determine the effect of dietary fat supplementation on methane emissions and milk yield from cows fed diets containing either corn or wheat grains. It was hypothesized that cows fed a diet containing wheat would produce less methane and have lower methane yield (methane per kg of dry matter intake; MY) than cows fed a diet containing corn and that methane mitigation from fat supplementation would occur irrespective of the type of grain in the basal diet. The experiment involved 32 Holstein-Friesian dairy cows allocated to 1 of 4 treatment groups (n = 8) and individually fed different diets restricted to approximately 90% of their mean ad libitum intake measured during a covariate period. All animals were offered 11.5 kg of dry matter/d of alfalfa hay, 1.8 kg of dry matter/d of solvent-extracted canola meal, and 1 of 4 dietary supplements. Dietary supplements were 8 kg of dry matter/d of either corn or wheat, or these same treatments with the addition of 0.8 kg of canola oil. In this 5-wk experiment, d 1 to 7 served as the covariate period, d 8 to 14 as the transition period, d 15 to 28 as the adaptation period, and d 29 to 35 as the experimental period. Cows were fed their full treatment diets from d 15 to 35 during which time milk production and feed intake were measured daily. During d 29 to 35, methane production was measured for individual cows daily using the sulfur hexafluoride tracer method. The resulting averages for milk production and feed intake were analyzed by analysis of covariance with factorial grain by fat as treatment structure, animal as the unit within blocks, and the corresponding milk production or feed intake covariate averages as principal covariate. Data on milk fatty acids, ruminal fluid data on pH, ammonia, volatile fatty acids, protozoa, and methane were analyzed by ANOVA using the same treatment and blocking structures excluding the principal covariate. Cows fed a diet containing wheat had greater MY than cows fed a diet containing corn. Irrespective of the type of grain in the diet, increasing the fat concentration from 2 to 6% dry matter reduced MY. It is concluded that the grain component in the basal diet does not affect the mitigating effects of dietary fat supplements on MY.     

Effect of different types and locations of the electrode source of an extra low voltage electrical stimulation system on beef quality

An extra low voltage (45V) electrical stimulation (ES) system was used to determine the effects of using different types and locations of the positive electrode and negative ground of the ES system on beef carcass quality. Thirty-three Angus heifers (22 months of age) were assigned at slaughter to one of six ES treatments (trt): (1) rectal probe with a ground inserted in the incision made below the brisket during exsanguination, (2) rectal probe with ground inserted in the neck above the atlas joint, (3) rectal probe with a ground attached to the lower mandible, (4) muzzle clamp with a ground inserted in the shackled leg, (5) nasal clamp with a ground inserted in the shackled leg and (6) non-stimulated controls. Stimulation was generated using a full wave rectified pulsating direct current of 16 Hz for a duration of 90s within 3 min of exsanguination. Carcasses were chilled at 2°C and evaluated at 24h post mortem. Regardless of type or where the electrodes were placed within the carcass, all ES trt produced a more rapid drop in pH than the control group. Differences in the effectiveness of the various ES trt on improving meat tenderness were observed. For four selected muscles of the carcass (longissimus, semimembranosus, biceps femoris and triceps brachii) the most consistent and uniform improvement in tenderness was found using ES trt 1 or trt 3. The only drawback associated with trt 1 was the ineffectiveness in eliminating the formation of heat-ring. The other ES trt were successful in alleviating this problem. This study indicates that type and locations of electrode source in an extra voltage ES system are important factors to consider in developing an efficacious low voltage ES system. This work also suggests successful implementation of extra low voltage carcass ES for commercial use if specific types of rectal probe electrode systems are used.     

Effects of photoperiod and pair-feeding on lactation of cows fed corn or barley grain in total mixed rations

Effects of photoperiod and type of grain were assessed using 47 cows (wk 1; 59.5 d of lactation) exposed daily to 16 h of light (long day) and fed randomly one of two diets containing an equal amount of cracked corn or rolled barley. During wk 5, cows were assigned within each diet to long day and ad libitum feeding, short day (8 h of light: 2 h of dark: 2 h of light: 12 h of dark) and ad libitum feeding, or long day and ad libitum feeding (wk 5 to 8) followed by pair feeding with short day cows between wk 9 and 16. Milk composition was not affected by treatments. Between wk 9 and 16, long day cows fed for ad libitum consumption or pair fed produced 5 to 11% more milk than cows exposed to short day; feed intake of long day cows fed for ad libitum consumption was greater than short short day and long day cows pair fed cows. Milk yield and total feed intake were not affected by type of grain in the diet. In conclusion, long day photoperiod increased milk yield and feed intake.     

Effect of low voltage electrical stimulation on biochemical and quality characteristics of Longissimus thoracis muscle from one-humped Camel (Camelus dromedaries)

The effects of electrical stimulation (90 V) 20 min post mortem on meat quality and muscle fibre types of four age group camels (1–3, 4–6, 7–9, 10–12 years) camels were assessed. Quality of the Longissimus thoracis at 1 and 7 days post mortem ageing was evaluated using shear force, pH, sarcomere length, myofibrillar fragmentation index, expressed juice, cooking loss and L^∗, a^∗, b^∗ colour values. Age of camel and electrical stimulation had a significant effect on meat quality of L. thoracis. Electrical stimulation resulted in a significantly (P < 0.05) more rapid pH fall in muscle during the first 24 h after slaughter. Muscles from electrically-stimulated carcasses had significantly (P < 0.05) lower pH values, longer sarcomeres, lower shear force value, higher expressed juice and myofibrillar fragmentation index than those from non-stimulated ones. Electrically-stimulated meat was significantly (P < 0.05) lighter in colour than non-stimulated based on L^∗ value. Muscles of 1–3 year camels had a significantly (P < 0.05) lower shear force value, and pH, but longer sarcomere, and higher myofibrillar fragmentation index, expressed juice, and lightness colour (L^∗) than those of the 10–12 years camels. The proportions of Type I, Type IIA and Type IIB were 25.0, 41.1 and 33.6%, respectively were found in camel meat. Muscle samples from 1–3 year camels had significantly (P < 0.05) higher Type I and lower Type IIB fibres compared to those from 10–12 year camel samples. These results indicated that age and ES had a significant effect on camel meat quality.     

Effects of stress from electrical dehorning on feed intake, growth, and blood constituents of Holstein heifer calves

Eighteen Holstein heifer calves were allotted to two groups. Calves in one group were dehorned electrically at 8 wk of age whereas the control group remained horned through 12 wk of age. Feed intake and growth rate did not differ between the two groups. Blood constituents varied with age, nutrition of calf, and dehorning. Dehorning influenced cortisol in blood plasma with high concentrations (25 versus 6 ng/ml) measured for 1 h after dehorning. Electrical dehorning at 8 wk of age presents no long-term stress to calves.     

Alternating frequency to increase the response to stimulation from medium voltage electrical stimulation and the effect on objective meat quality

The use of alternating frequencies during stimulation can increase stimulation response of a medium voltage electrical stimulation unit (MVS) by increasing the rate of pH decline. Various combinations of frequency modulation were tested in experiment 1 to determine the treatment resulting in the greatest stimulation response; the lowest initial pH, fastest rate of pH decline, highest temperature at pH 6 and the highest number of carcasses with a pH of 6 by 25(o)C and the treatment achieving the highest number of carcasses in the pH temp window (temperature at pH 6 between 18-25(o)C). The objective meat quality of these treatments compared to an unstimulated treatment was tested in experiment 2. Modulating the frequency (Hz) across the 6 segmented electrodes of the MVS by 10, 15, 25, 10, 15, 25Hz (Treatment 6, using a pulse width: 2.5ms, current: 1A) resulted in the greatest stimulation response. This treatment may be suitable for abattoirs that hot bone sheepmeat and require fast pH declines to ensure minimal cold shortening of meat. However, this treatment did not result in the tenderer meat despite the higher stimulation response. This treatment may have induced a greater number of contractions overall and therefore a greater pH decline response but resulted in less myofibrillar disruption compared to the other treatments due to a concomitant decreased force of contraction thus reducing potential tenderisation. Maintaining a constant frequency of 15Hz (Treatment 1; pulse width: 2.5ms, current: 1A) resulted in a higher number of carcasses in the pH temp window required (temperature at pH 6 between 18-25(o)C) in part A (P<0.05) and in addition to the higher tenderness levels this treatment may be more appropriate to satisfy the overall demands of abattoirs using these systems. This paper has also demonstrated electrical stimulation results in tenderer meat compared to unstimulated meat even after 30d of ageing (2.53±0.4 compared to 2.85±0.1 for the loin (M. longissimus thoracis et lumborum) (P<0.01) possibly due to a protective benefit of stimulation on meat tenderness. Overall, no detrimental effects of modulating frequency were observed on drip loss or retail colour display despite a greater rate of colour change observed with the modulated frequency treatment and the longer aged product.