Spray chilling of lamb carcasses

Two spray-chilling treatments were developed to improve appearance and reduce weight loss during lamb chilling. Rates of cooling and weight loss and meat quality were compared to conventionally chilled carcasses.

The first treatment was an intermittent spray during the first 3 h of chilling. The second consisted of only two sprays at 2 h and 10 h post mortem. The conventional control was a two-stage process, with air at 10°C and 1 m/s up to 10 h post mortem, followed by air at 0°C and 1 m/s for a further 14 h.

Both treatments significantly reduced weight loss at 24 h post mortem compared to conventional, from 2·20% to 0·86% and 1·20%, respectively. During a further 4 days storage, the savings were maintained, with weight losses being 3·97%, 2·97% and 3·19%, respectively.

There were small (<1 h) but significantly reductions in the cooling times of spray-chilled loins and legs, attributed to sustained evaporative cooling of the continually wetted surfaces.

No effects on texture or drip loss and only slight effects on surface lean and fat colour were found. Variation in texture between animals within treatments was far greater than between treatments and could not be accounted for by variations in cooling rates.     

Weight loss caused by development of Sitophilus zeamais Motsch. in maize

Seventy single maize kernels were exposed to oviposition by Sitophilus zeamais. Weevils developed in 50 kernels, 16 yielding one adult, 24 two, 7 three, 2 four and 1 five adults. Weight loss of the kernels was observed throughout the developmental period, at 27°C 70% r.h. Development took a mean of 37 days resulting in adults with a mean weight of 3.1 mg. The overall mean loss in weight per grain was 18.3% or 52.1 mg and on average 2.0 insects emerged per kernel. The total consumption by an insect was 35.1 mg in grains with one emerging adult and approximately 25 mg for those with more than one. Half the total loss occurred between 13–24 days. An estimate of percentage weight loss was obtained by multiplying the percentage of damaged kernels by 0.12, 0.18 or 0.29 for kernels with 1, 2 or 3 emergence holes respectively. Frass weight was found to be of no use in estimating weight loss.     

Rabbit growth, feed efficiency and body composition: Effects of recombinant porcine somatotropin

The effects of recombinant porcine somatotropin (rpST) were studied on rabbits from INRA 1077 strain, between the ages of 70 and 90 days. Ten rabbits received a daily intramuscular rpST injection (100 mg per day per kg of live weight) and were compared with ten control rabbits. Growth rate and feed efficiency were not affected by treatment. Perirenal fat deposits were smaller in rpST-treated than in the control rabbits (2·01 vs 2·72%) as were reference carcass lipid content (9·4 vs 10·8) and energy value (0·84 vs 0·88 MJ /100 g). The ratio between polyunsaturated fatty acids (FA) and saturated and monounsaturated FA was higher (0·32 vs 0·28). Reference carcass protein content was increased (20·5 vs 19·9%), as was the percentage of skin in slaughter weight (14·3 vs 13·4%). Muscular ultimate pH (24 h post mortem) was lower in the semimembranosus accessorius (5·67 vs 5·78) and in the biceps femmoris (5·65 vs 5·74) of treated rabbits. In conclusion, rpST, as a heterologous hormone, develops protein-rich tissues whilst lowering fat content and appears to affect the balance of muscular energy metabolism.     

The effects of residual oxygen concentration and temperature on the degradation of the colour of beef packaged under oxygen-depleted atmospheres

Samples of beef longissimus dorsi (LD), approximately 5 × 5 × 1 cm, were packaged in pairs under 10 litre volumes of N₂ or CO₂ containing O₂ at concentrations between 100 and 1000 ppm. The packaged samples were stored at temperatures of 5, 1, 0 or −1·5°C, for times between 4 and 48 h. Samples of beef psoas major (PM) were packaged under N₂ or CO₂ containing O₂ at between 100 and 600 ppm, and stored at −1·5°C for 24 or 48 h. After storage, each sample was assessed for colour deterioration and discoloration, and for the fraction of metmyoglobin in the surface pigment.

The results obtained with N₂ and CO₂ atmospheres were similar. The colours of all LD samples had deteriorated after 4 h storage at 5 or 1°C, although the degree of deterioration increased with increasing O₂ concentration. All LD samples stored for 12 h at 5 or 1°C were extensively discoloured, with metmyoglobin fractions generally exceeding 60%, but those stored at −1·5°C for 48 h or less, under O₂ concentrations ≤ 400 ppm had undergraded colours. The colours of some LD samples stored at −1·5°C under about 600 ppm of O₂ were also undergraded, but the colours of samples stored under 800 or 1000 ppm had deteriorated by 24 h. The colours of LD samples stored at 0°C under > 200 ppm had deteriorated after 24 h storage, and the colours of samples stored under 100 ppm O₂ had deteriorated after 48 h storage. All PM samples were wholly discoloured after storage at −1·5°C. Evidently, the colour of beef muscle of high colour stability is resistant to degradation by atmospheres containing < 600 ppm of O₂ when the meat is stored at sub-zero temperatures, but not when the storage temperature is at or above 0°C. Beef muscle of low colour stability, such as the PM, will discolour at all low concentrations of O₂ irrespective of the storage temperature.     

Influence of food withdrawal at various times preslaughter on carcass yield and meat quality in sheep

Castrated male crossbred lambs were fed a complete pelleted diet ad libitum for 4 weeks prior to slaughter at a liveweight of about 32 kg. Forty lambs were killed directly off feed and forty each after 24, 48 and 72 h from food withdrawal. They had access to water at all times. Fasting had a significant effect on the weights of all body components examined except the combined fleece and feet. Liveweight was lost slightly more rapidly over the initial 24 h after food withdrawal, and this was attributable mainly to a 20% decrease in the weight of the gut contents. The overall rate of liveweight loss between 0 and 72 h was 0.14% h^?1. The corresponding loss of carcass weight was 0.085% h^?1, some reduction in yield being evident by 24 h of fast although a significant effect was seen only after 48 h. Liver weight was lost most rapidly (0.69% h^?1) over the initial 24 h but continued to be lost throughout fasting. Associated with the initial decrease in liver weight was a rapid loss of glycogen to very low levels by 24 h after food withdrawal. Fasting also reduced muscle glycogen concentrations but had no large or consistent effects on ultimate pH, reflectance or water-holding capacity.     

Improving pork quality by electricalstimulation or pelvic suspension ofcarcasses

This investigation compared the separate and combined effects on meat quality of electrical stimulation (ES) and pelvic suspension of pig carcasses chilled rapidly or conventionally. Sides from 80 pigs, 80–90 kg live weight, were allocated to one of four treatments followed by either conventional chilling (1°C for 24 h) or rapid chilling (-20°C for 2–3 h, before 1°C until 24 h post-slaughter). The four treatments were: Achilles suspended, with and without high voltage ES, and pelvic suspended, with and without ES.

The quality attributes: pH, colour and opacity, drip loss, instrumental and sensory texture were measured in M. longissimus thoracis et lumborum, at 10 days post-slaughter. Rapid chilling reduced the evaporative weight loss by 0·5% There were no significant effects of treatment on colour or opacity, although ES samples were slightly paler. Drip loss was also slightly greater with ES, particularly when combined with pelvic suspension, but in no case was the meat classified as PSE. Instrumental measurements of 'texture showed improved tenderness from both ES and pelvic suspension, even after 10 days ageing. The improvement was less pronounced when ES and pelvic suspension were combined Taste panelling confirmed that samples treated by ES or pelvic suspension, separately or combined, were significantly more tender than samples from non-ES, Achilles hung sides. ES and pelvic suspension were equally effective in improving the tenderness of pork loin. Pelvic suspension did not suffer the disadvantage of increased drip loss that occurred with ES in this study.     

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.     

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

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

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

Drip loss of case-ready meat and of premium cuts and their associations with earlier measured sample drip loss, meat quality and carcass traits in pigs

Drip loss of 374 samples taken from porcine M. longissimus dorsi and M. semimembranosus was measured by using the “bag method” (BM), EZ-DripLoss (EZ-DL) from premium cuts (PC) and in retail tray (case-ready meat; CRM). This provided a comparison between these methods and their relationships to other meat quality and carcass traits. Samples were prepared at 24 h post-mortem (pm) and were measured 24 and 48 h after preparation (at 48 and 72 h pm) using the BM and after 48 h (at 72 h pm) with the EZ-DL and PC. Drip loss of meat kept in retail trays was measured after 7 days (CRM₇) and daily within a week (CRM_1–7). Average drip loss was 1.80% and 3.10% using the BM after 24 and 48 h, respectively. EZ-DL and CRM₇ showed higher drip losses of 4.71% and 4.00%. Daily loss of CRM_1–7 showed a concavely shaped curve and increased from 1.57% to 5.64% after 7 days. High correlations were obtained between drip loss of CRM₇ and BM (r = 0.88) or the EZ-DL (r = 0.91). The development of drip loss in case-ready meat fitted by linear-quadratic regression (y = 0.439 + 1.245x − 0.072x²) showed that high drip loss measured earlier by bag and EZ-DripLoss methods was highly associated with a high intercept (r = 0.63–0.72), a high linear increase (r = 0.77–0.81), but larger decrease in increments (r = −0.82 to −0.86) during weekly stored meat in retail trays as supplied at consumer level. Because the positive linear regression coefficient was substantially higher than the negative quadratic regression coefficient, the development of drip loss is mainly dependent on the initial drip loss. Therefore, animals with high drip loss within 72 h post-mortem also showed undesirable high drip loss curves over the entire retail period. Relationships between drip loss and other meat quality traits were similar for BM, EZ-DL and CRM₇. Of these the correlation between pH₂₄ and drip loss was highest with r = −0.54, −0.49 and −0.47 for BM, EZ-DL and CRMH₇, respectively. Interestingly, a correlation of r = −0.35 between blood pH value and CRML₇ was obtained. Carcass traits such as loin, ham, shoulder, belly weight or loin eye area showed only marginal correlations to drip loss. In conclusion, EZ-DL was the most appropriate method to predict drip loss of case-ready meat in retail trays and its development during a 7 day storage period.     

Weight loss and metabolic profiles in obese individuals using two different approaches

Intentional weight loss with a reduction in adipose tissue is associated with an improvement in medical complications linked to obesity. The aim of this study was to compare the effect of two different weight loss diets on obese individuals (BMI 30-40 kg m(-2)) for improvements in anthropometric measurements and blood biomarkers. Study 1 comprised a low energy diet (LED) of 5000-6000 kJ d(-1) for a slow but steady weight loss over 12 weeks. Study 2 comprised a very low energy diet (VLED) of 3000 kJ d(-1) using meal replacements for rapid weight loss over a shorter period of 4 weeks followed by 10 weeks of weight stabilisation to prevent rebound after rapid weight loss. Nutrition information sessions were given to both groups. Fasting blood samples, anthropometric measurements and 3-day food diaries were collected at baseline and again at completion of weight loss, at 12 weeks for LED group and 4 weeks for VLED group. Mean weight loss in the LED group (n = 18) was -3.17 kg (-3.7%) compared to a -6.54 kg (-7%) loss in the VLED group (n = 14) (p < 0.001). The VLED group experienced significantly greater reductions in fat mass, -13.9% compared to -8.9% for the LED group (p < 0.05). Significantly greater reductions in blood glucose (p < 0.05), cholesterol and LDL-C (p < 0.01 for both), and waist circumference (p≤ 0.05) were noted in VLED compared to those for LED diet. Short-term, rapid weight loss produced the desired ≥5% weight loss suggested to substantially reduce metabolic abnormalities associated with obesity, and to reduce health risks.     

Tissue growth patterns in the carcasses of water buffalo and Friesian crossbred cattle-part 1: Individual muscles and anatomical muscle groups

The left sides of the carcasses of twelve Egyptian buffalo, nine half Friesian (♂ Friesian x ♀ Egyptian Baladi) and nine three-quarter Friesian (♂ x ♀ half-Friesian) bulls, serially slaughtered between 161 and 560 kg for buffaloes and between 176 and 448 kg for cattle, were used to describe the growth and distribution of individual muscles and muscle groups.

Genotype-group differences in the relative rate of growth were not significant in 85 of 89 muscles and in 8 of 9 muscle groups. The pooled within-group growth coefficients of individual muscles revealed different increasing growth gradients, i.e. disto-proximal in both limbs, mediolateral in the proximal pelvic limb, from elbow flexors to shoulder flexors in the proximal thoracic limb, caudo-cranial in the trunk and from hypaxial to epaxial muscles around the spinal column. The relative growth was lowest in the distal part of the limbs and highest in the anterior part of the carcass (SMG 7 and 8), with the loin and abdominal muscle groups growing at a rate similar to that of the total muscle. The neck and thorax muscle group grew at a higher rate in Friesian crosses than in buffaloes.

Genotype-group differences in the weight of each muscle relative to total side muscle (TSM) were significant in 50 of 89 muscles. Of the 50 muscles (constituting around 59% of TSM), 24 (approximately 44% of TSM) were from the expensive muscle groups. As compared with the most different Friesian cross (base = 100) at equal TSM, buffaloes had higher weight of muscle in the hindlimb (107·5% proximally; 106·3% distally) and forelimb (120·0% proximally: 104·6% distally) and significantly less weight of the muscle groups forming the abdominal wall (79·8%) and connecting the forelimb to the thorax (89·1%) and to the neck (90·7%). The weight of the combined expensive groups was significantly greater in buffaloes than in cattle (maximum difference = 1·8 kg) with a tendency for buffaloes to have relatively less of the tender muscles surrounding the spinal column.     

The desert camel as a meat animal

Fifty-two mature, fattened male camels were used for determining live animal and carcase measurements, carcase yield and characteristics. The average slaughter weight of mature, fattened desert camels was 456 kg, while the mean empty body weight was 404·8 kg. The camel carcase dressed out as 55·8% and 63·6% of live and empty body weight, respectively.

The mean carcase composition was 56% meat,19% bone and 13·7% fat. Of the body components of the camel, the head, hide and liver represented 3·5, 8·6 and 2·0% of the empty body weight, respectively.

The correlations between heart girth and liveweight were high and positive. The depth of the camel hump was significantly highly correlated with carcase fat and the hump fat weight had a positive high correlation (r = 0·97, P < 0·001) with carcase fat.     

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.     

Effects of stage of lactation and level of feed intake on energy utilization by Alpine dairy goats

Thirty-six lactating Alpine does were used to determine effects of stage of lactation and level of feed intake on energy utilization. Twelve does were assigned to measurement periods in early, mid, and late lactation (wk 5, 13, and 27, respectively). For 6 does of each group, after ad libitum consumption of a 60% concentrate diet, feed intake was restricted to near the metabolizable energy (ME) requirement for maintenance (ME_m) for 8 d followed by fasting for 4 d. For other does, fasting immediately followed ad libitum consumption. Intake of ME was similar among stages of lactation with ad libitum intake (22.1, 22.1, and 19.8 kJ/d in early, mid, and late lactation, respectively). The efficiency of ME use for maintenance determined with does fed near ME_m averaged 81%. Fasting heat energy was greater for ad libitum consumption than for near ME_m consumption [368 vs. 326 kJ/kg of body weight (BW)^0.75] and was numerically lowest among stages in late lactation with near ME_m intake (334, 350, and 295 kJ/kg of BW^0.75 in early, mid, and late lactation, respectively) and ad libitum consumption (386, 384, and 333 kJ/kg of BW^0.75 in early, mid, and late lactation, respectively). The efficiency of use of dietary ME for lactation was greater for consumption near ME_m than for consumption ad libitum (67.9 vs. 58.6%) and with ad libitum consumption tended to decrease with advancing stage of lactation (63.9, 57.3, and 54.5% for early, mid, and late lactation, respectively). Estimated ME_m was greater for ad libitum intake than for near ME_m intake and was lowest during late lactation (429, 432, and 358 kJ/kg of BW^0.75 for near ME_m intake and 494, 471, and 399 kJ/kg of BW^0.75 for ad libitum intake in early, mid, and late lactation, respectively). However, because of increasing BW as the experiment progressed, ME_m (MJ/d) was similar among stages of lactation with both levels of intake. The efficiency of ME use for maintenance and lactation was similar among stages of lactation and greater with near ME_m intake than ad libitum intake (77.1 vs. 67.7%). In conclusion, the ME_m requirement (kJ/kg of BW^0.75) of does in late lactation was less than in early and mid lactation. A marked effect of restricted feed intake subsequent to ad libitum consumption on estimates of efficiency of energy use for maintenance and lactation was observed compared with use of nonlactating animals. Level of feed intake can have substantial effect on estimates of energy utilization by lactating dairy goats.     

The effect of feed withdrawal during lairage on meat quality characteristics in ostriches

Commercially reared ostriches (n = 84) were randomly allocated to one of two groups. The first group (stressed: n = 38) was deprived of food for a period of 2.5 days prior to slaughter, to simulate the stress experienced by slaughter ostriches held in holding pens (lairage) at a commercial ostrich abattoir over a weekend. The second group (control: n = 46) was fed normally until 24 h prior to slaughter. Initial live weight as well as hot and cold drumstick weight were independent (P > 0.05) of treatment. Stressed birds lost on average (±SE) approximately three times more weight than control birds over the experimental period (−3.2 ± 0.6 vs. −1.0 ± 0.5 kg, respectively). Full stomach and alimentary tract weights did not differ between treatments although there was a tendency for that derived from stressed birds to have lower stomach contents. The intra-muscular (Muscularis iliofibularis) pH_f of stressed birds was 0.22 units higher (P < 0.01) than that of contemporaries in the control group 1 h post-slaughter (6.03 ± 0.06 vs. 5.81 ± 0.05, respectively). After 26.5 h in a refrigerated room, this difference still remained at 0.25 units (6.46 ± 0.07 vs. 6.21 ± 0.07, respectively; P < 0.05). Post-slaughter changes in intra-muscular pH followed approximately the same trend in stressed and control birds. Intra-muscular temperature was largely independent of treatment, although there was a suggestion of a slightly higher (P = 0.18) temperature in stressed birds immediately post-slaughter. Cooking loss, drip loss and shearing values were not affected (P > 0.05) by the withholding of food for 2.5 days. It can thus be concluded that withholding feed from ostriches on lairage over a period of 2.5 days does not have any negative influence on the meat yield or physical quality traits thereof.     

Thermal death kinetics and heating rate effects for fifth-instar Cydia pomonella (L.) (Lepidoptera: Tortricidae)

Thermal death kinetic parameters of fifth-instar codling moths (Cydia pomonella (L.)) and the effect of three heating rates (1°C min⁻¹, 10°C min⁻¹, and 18°C min⁻¹) on larval mortality were determined by a heating block system. The insects were heated to four temperatures (46°C, 48°C, 50°C, and 52°C) held for predetermined periods followed by 24 h storage at 4°C before mortality evaluation. Thermal death kinetics for fifth-instar codling moths followed a 0.5th order of kinetic reaction. Minimum time required to achieve 100% mortality of a given population decreased with temperature in a semi-logarithmic manner. No larval survival was observed in samples of 600 insects after exposure to 46°C, 48°C, 50°C, and 52°C for 50, 15, 5, and 2 min, respectively. Activation energy for thermal kill of fifth-instar codling moths at the heating rate of 18°C min⁻¹ was estimated to be about 472 kJ mol⁻¹. The lethal time accumulated during the ramp period was about 1.8, 0.2, and 0.1 min for the heating rates of 1°C min⁻¹, 10°C min⁻¹, and 18°C min⁻¹, respectively.     

The effects of withholding feed and water on carcass shrinkage and meat quality in beef cattle

Eighty beef crossbred steers with an average weight of 493 kg (4·66 kg SD) were allocated at random to one of five treatments to assess the effects of withholding feed and water on carcass shrinkage and meat quality. The five treatments were: slaughter from the feedlot (T1); and 12, 24, 36 and 48 h periods without feed and water prior to slaughter (T2-5).Weights were taken of the live animal and the carcass to monitor shrinkage along with relevant meat quality measurements. There were no treatment differences (P > 0·05) in initial farm weight, but plant weight shrinkage increased from 31gkg(-1) for T1 to 106 g kg(-1) for T5. Warm carcass weight decreased (P < 0·05) from 278·8 kg for T1, to 270·7 kg for T3 and 261·9 kg for T5. Liver, alimentary tract components, hide and head decreased as a proportion of farm weight as time without feed and water increased. Muscle pH at 6 days post mortem was increased (P < 0·05) in T3-5 compared to T1, with the result that muscle colour became darker, and steaks had less drip loss. Shear values increased (P < 0·05) from 6·3 kg in T1 to 7·7 kg in T4 and T5 indicating an increase in muscle toughness as time without feed and water increased. It was concluded that steers lose live weight rapidly within the first 24 h without feed and water, and that these relatively short periods of time (24 h) can have detrimental effects on carcass shrinkage and muscle quality.     

Chemical and Physical Characteristics of Chicken Livers Following Adrenocorticotropic Hormone-induced Stress

Commercial chickens were implanted with a micro-osmotic pump which released 1 IU/kg BW/day of adrenocorticotropic hormone (ACTH) and were sacrificed after 24 and 48h. The weight of liver increased from 3.36% for the untreated controls to 4.56 and 5.40% of ready-to-cook carcass weight for 24 and 48h after implantation, respectively. The fat content increased from 4.44% for the untreated group to 9.97 and 12.17% for 24 and 48h treated group, respectively. However, the pH and moisture content of liver decreased with the ACTH treatment and the livers were more pale. The ATCH treatment decreased the percentages of 14:0 and 18:2 fatty acids and increased that of 18:1 fatty acid in the liver.     

Variation among beef breeds in carcass retail value at constant carcass saleable meat content and percentage of higher priced cuts

Data from the single slaughter point trials of the Meat and Livestock Commission's (MLC) beef breed evaluation programme were used to examine the importance of retail value (RV) calculation in breed evaluation trials.

The analysis involved a total of 2010 carcasses comprising four production system groups. Sire breeds included Aberdeen-Angus, British Friesian, Charolais, Devon, Hereford, Galloway, Limousin, Lincoln Red, Luing, Simmental, South Devon, Sussex and Welsh Black.

RV was computed as the sum of the values of trimmed deboned primal joints expressed as pence per kilogram of carcass weight. 1981 prices from MLC's Retail Prices Survey for England and Wales were used.

A model was fitted to the RV data for each of the production system groups with effects for sire breed, year and sire breed × year interaction, and with regression on saleable meat percentage in carcass (SM). The largest difference recorded between sire breeds was 2·1 pence/kg (0·85% of overall mean RV). The pooled within-system residual standard deviation after fitting the model was 1·4 pence/kg. When regression on the percentage of total saleable meat in the higher priced cuts (SMD) was added to the model, the corresponding range and residual standard deviation were reduced to 1·0 and 0·8 pence/kg, respectively. In the circumstances, the calculation of RV would, therefore, make only a minor refinement to the results.     

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

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

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

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