Longer journeys to processing plants are associated with higher mortality in broiler chickens.

1. The number of broilers recorded as dead on arrival (DOA) in 1113 journeys to a poultry processing plant was related to the length of the journeys. The average journey time was 3.3 h and the maximum recorded was 9 h. 2. Overall, 0.194% of 3.2 million birds were DOA. Mortality was higher for journeys which took longer. For journeys lasting less than 4 h the incidence of dead birds was 0.156%; for longer journeys the incidence was 0.283%. 3. There was some evidence that it was time of journey, rather than distance travelled, that was more important in determining mortality.

Effect of the angle of slope on the ease with which pigs negotiate loading ramps.

In experiments to investigate the time taken by pigs to negotiate ramps with different slopes it was found that they ascended with greater facility than they descended. Between 0 degrees and 20 degrees, the slope appeared to have little effect on the time taken to ascend or descend. Above 20 degrees the time taken to ascend increased linearly. The relationship between the time taken to descend and the slope above 20 degrees was biphasic with times increasing substantially above 35 degrees. There were also differences between the times taken on different days but no evidence of habituation. Pigs took longer to climb steeper ramps with wider spaces between cleats but there was no significant effect on the time taken to descend.

Time spent by broiler chickens in transit to processing plants.

The minimum distance transported, the journey time and the total marketing time were estimated for 5819 journeys in which 19.3 million broilers were transported to four processing plants. The average distance travelled was 33.5 km, the average journey plus unloading time was 2.7 hours and the average total marketing time, from the start of loading to the completion of unloading, was 3.6 hours. The maximum recorded journey plus unloading time was 12.1 hours and the maximum recorded total marketing time was 12.8 hours. There was considerable variation between plants, those with smaller annual throughputs tending to have longer average times. In 46 per cent of journeys the birds were unloaded within three hours of the start of loading, in 78 per cent within five hours and in 94 per cent within seven hours of the start of loading.

Transport and lairage times of lambs slaughtered commercially in the south of England.

The times spent in transport and lairage by 124,036 lambs slaughtered in two plants in the south of England were recorded. About half of them travelled for up to 120 km, taking up to four hours, and three-quarters travelled not more than 300 km, the journeys taking up to about six hours. Bimodal frequency distributions of lairage time were apparent; overall one third of the lambs spent up to four hours in lairage but more than 40 per cent were kept for longer than 14 hours, while they were held overnight. Early season lambs tended to travel shorter distances to slaughter and spent less time in lairage than late season lambs. The average total times spent in transit and lairage were 22.3 hours and 13.3 hours at the two plants.

An estimate of the incidence of dark cutting beef in the United Kingdom.

Eight slaughterplants with throughputs ranging from 20 to 300 animals per day were examined to estimate the incidence of dark cutting beef in the United Kingdom. Four thousand, eight hundred and sixteen animals were surveyed and information concerning animal category, source, season and preslaughter handling conditions recorded. Muscle samples were removed to estimate glycogen concentration and after incubation, ultimate pH. The overall incidence of dark cutting (pHu ≥ 6·0) was 4·1%. Increased incidence was associated with short (≤ 20 miles) and long (≥ 150 miles) transport distances. Slaughter on the day of arrival rather than overnight lairage also increased the incidence. Plants were classified into small (killing ≤ 50 animals per day) or large (killing ≥ 100 per day). Eighty per cent of the animals slaughtered passed through the large plants, and a higher incidence was also associated with these plants. Bulls had the highest incidence and heifers the lowest. A seasonal effect was recorded with the highest incidence found between July and October. The results, however, indicate that factors in addition to those examined are also important.

The relationships between glycogen stores and muscle ultimate pH in commercially slaughtered pigs.

Small samples of liver and m. adductor (AD) were collected within 45 minutes of death from the carcasses of a total of 604 pigs killed at three bacon factories. Glycogen concentrations were measured and part of the muscle sample allowed to complete post-mortem glycolysis in order to estimate ultimate pH (pHu) values. Liver glycogen levels were also used to predict overall food withdrawal times. Muscle glycogen concentrations ranged from 2.2 to 15.3 mg/g, liver glycogen from 0.01 to 50.7 mg/g and pHu in the AD from 5.51 t 6.76. The overall average predicted fasting time was 16.5 +/- 0.54 (SEM) hours and 22% of pigs had pHu values in the AD greater than 6.2 indicative of potentially dark, firm, dry meat. Muscle glycogen concentration was positively correlated with liver glycogen (r = 0.27, P less than 0.01) and negatively correlated with predicted fasting time (r = -0.30, P less than 0.001). The pHu in the AD was negatively correlated with liver glycogen (r = -0.34, P less than 0.001) and positively correlated with predicted fasting time (r = 0.37, P less than 0.001). Therefore, pigs which had reduced concentrations of glycogen in their livers, indicative of longer food withdrawal times before slaughter, tended to have less glycogen in their muscles and a higher pHu in the meat.

An examination of potential indices of fasting time in commercially slaughtered sheep.

A total of 215 market lambs was slaughtered either directly off grass or after 12, 24, 36, 48 or 72 h from food withdrawal. They had access to water at all times. Half the animals were given a moderate exercise and were subjected to venepuncture about 0.5 h before slaughter. Samples of blood were collected at exsanguination and samples of liver and muscle subsequently removed during carcass dressing. Blood packed cell volume and the concentrations of plasma glucose, lactate, free fatty acids, beta-hydroxybutyrate and total protein, and glycogen in liver and muscle, were examined as potential indices of fasting time. Fasting caused significant changes in all parameters but only beta-hydroxybutyrate increased progressively with longer food-withdrawal times and was unaffected by exercise or the stress of venepuncture. The pattern of response to fasting could be described by an equation of the Gompertz form. Sex of animal did not affect fasting responses but origin of blood (venepuncture or at exsanguination) influenced absolute levels of all the measured blood components except total plasma protein.

Evaluation of lean meat quality in pigs using two electronic probes.

The Danish Fat-O-Meater grading probe (FOM) and the Fibre Optic Probe (FOP) developed at IFR, Bristol, were evaluated for their potential ability to predict lean meat quality in a sample of 76 pig carcasses showing a wide range of quality in the M. longissimus dorsi. When probings were made after chilling at about 20 h post mortem the correlations between probe value (FOP(u) and FOM(u)) and reflectance (EEL value), drip loss during storage and subjective assessment score for colour-structure were high (FOP(u) and reflectance, r = 0·89; drip loss, r = 0·78; subjective assessment, r = 0·90. FOM(u) and reflectance, r = 0·88; drip loss, r = 0·73; subjective assessment r = 0·81). Nevertheless, probe values could not be used to unambiguously group samples into normal, pale, soft, exudative (PSE) or dark, firm, dry (DFD) classes. Correlations between probe values at 45 min post mortem and measures of ultimate meat quality were much lower. Neither probe could potentially differentiate between normal and DFD meat at this time and differentiation between normal and PSE meat was also poorer.

Depletion of glycogen reserves in fasting broiler chickens.

1. Male broiler chickens were killed at various times up to 36 h after withdrawal of food; hepatic and muscle glycogen concentrations and pH were compared with those of control birds given continuous access to food and water. 2. Liver glycogen was reduced to negligible concentrations (less than 1 mg/g) within 6 h of food deprivation and the initial pH was elevated. 3. Withdrawal of food had no effect on glycogen concentrations in the m. pectoralis superficialis (PS) but reduced them in the m. biceps femoris (BF); the reduction was significant after 12 h. Ultimate pH was elevated by fasting in the BF, but not the PS.