The shelf‐life of uneviscerated and eviscerated chicken carcasses stored at 10°C and 4°C

1. Uneviscerated and eviscerated chicken carcasses were processed together and stored in groups of 10 at 10°C and 4°C; a further 10 eviscerated carcasses were wrapped in “polythene” bags and stored at 4°C.

2. The bacteriological condition of the uneviscerated and eviscerated carcasses prior to storage was very similar.

3. At 10 °C the eviscerated carcasses developed a slight “off” odour in 3 to 4 d (average 3.5 d) whilst the first signs of greening in the uneviscerated carcasses occurred in 4 to 6 d (average 5 d).

4. At 4 °C wrapped eviscerated carcasses developed slight “off” odour in 5 to 6 d (average 5.6 d) whilst the unwrapped eviscerated carcasses varied considerably in their shelf‐life from 5 to 11 d (average 7.9 d). After 18 d the uneviscerated carcasses were still quite acceptable and no bacteria were found in the breast muscle (i.e. < 150/g).

5. Bacteriological examinations made of the skin of the three groups of chickens stored at 4 °C confirmed the differences obtained in shelf‐life; Pseudomonas spp. were found to be the predominant spoilage organisms in each case.     

Prevalence and characterisation of Cryptosporidium species in cattle faeces and on beef carcases at slaughter

Cattle are known reservoirs and asymptomatic excretors of Cryptosporidium, a protozoan parasite that causes severe and protracted diarrhoea in people. The incidence of Cryptosporidium was investigated in 288 matched samples taken from beef carcases of 1 g samples of faeces retrieved immediately after de-legging, 25 cm2 samples of beef excised from the rump of uneviscerated carcases, and 25 cm2 samples of beef excised from the brisket area of eviscerated carcases. Cryptosporidium species were detected in 21 of the faecal samples after salt flotation and immunofluorescent microscopy. The species isolated from the positive samples were identified by restriction fragment length polymorphism and PCR as Cryptosporidium andersoni (54.5 per cent) and Cryptosporidium parvum genotype 2 (45.5 per cent). In the faecal samples, there was a significantly higher prevalence of the parasite in samples taken in summer (May to July) and winter (November to January) than in spring or autumn. No Cryptosporidium species were recovered from any of the beef samples.     

Relation between loss of fluid from thawing chicken carcasses and uptake of water during processing

The fluid which is released from frozen eviscerated chicken carcasses during thawing has been studied. Variation has been observed in the amounts of fluid lost by different carcasses thawed under standardised conditions and this has not been adequately‐explained by variations in pre‐slaughter treatment (a long or a short journey between farm and factory) or by variations in processing after slaughter (long or short cuts before evisceration, mechanical or static water chilling or, in static chilling, different ratios of ice: water: chicken).

A preliminary study of the composition of the exudate formed during thawing and subsequent holding at 1° C. has indicated a progressive increase in the amounts of blood pigment, total nitrogen and total solids during a period of 6 days. Under similar conditions the amounts of blood pigments and solids were greater in the exudate from carcasses that had not been chilled before freezing. When comparable carcasses were thawed at ambient temperatures between 1° C. and 30° C., the times for the temperature of the deep muscle to rise from ‐20° to + 1° C. ranged from 96 hr to 4 hr and the corresponding amounts of fluid lost were 2.91 and 1.25 per cent of the frozen wrapped weight.     

The incidence of clostridia in poultry carcasses and poultry processing plants

An investigation of the incidence and types of clostridia was carried out as part of a bacteriological examination of poultry carcasses and plant swabs. From 19 per cent to 35 per cent of chicken carcasses from four processing plants were contaminated with clostridia in the “total” differential reinforced clostridial medium count whereas 27–5 per cent to 83–5 per cent were contaminated with clostridial spores. Swabs of equipment and personnel (hands and aprons) in three of the plants showed that from 15 per cent to 75 per cent of the samples were positive for “ total” clostridia, and from 33 per cent to 85 per cent positive for clostridial spores. Clostridium welchii was recovered from all poultry plants but the incidence varied widely between the four plants sampled. The organisms isolated were Cl. bifermentans, Cl. histolyticum, Cl. butyricum, Cl. sporogenes and Cl. welchii. The majority of Cl. welchii isolates were from spore counts.     

Effects of evisceration and storage temperature on changes in meat quality of traditional farm‐fresh Turkeys

1. Conditions affecting the keeping quality of traditional farm‐fresh turkeys were investigated.

2. Storage of uneviscerated Wrolstad turkeys at 4 °C for 10 days caused no statistically significant changes in meat flavour or texture.

3. During further storage at —2 °C, however, there was a slight but significant change in flavour, which became more marked with time in birds which had been eviscerated after the initial period at 4 °C.

4. Both eviscerated and uneviscerated birds became slightly tougher during storage.

5. Initial holding at 4 °C increased the numbers of psychrotrophic bacteria on the skin by about 10³ but subsequent changes at — 2 °C were slight for uneviscerated birds.

6. Eviscerated carcases had higher counts than uneviscerated birds after storage at — 2 °C and, although ‘off’ odours were not detected, spoilage appeared to be imminent at the end of the 20‐d period.     

The bacteriological condition of eviscerated chickens processed under controlled conditions in a spin-chilling system and sampled by two different methods

Quantitative changes have been determined in the flora of chicken carcasses after passage through a series of three separate spin‐chillers. The majority of organisms were eliminated from the chill‐water during processing by using 1.7 1 of water per carcass and 45 to 50 ppm of total residual chlorine in the first two chillers and 1.0 1 of water per carcass and 25 to 30 ppm of residual chlorine in the third chiller.

Total viable counts at 20 and 37 °C and levels of coli‐aerogenes bacteria obtained from the rinsing of whole carcasses were reduced by more than 90% during chilling. Results obtained both with and without the use of chlorination compared favourably with those claimed for other chilling systems. It was concluded that the main effect of chlorination in the chillers was to destroy organisms washed from the carcasses, thus avoiding recontamination.

A comparison of two different sampling methods showed that maceration of neck‐skin usually gave higher counts of both faecal and spoilage bacteria after chilling than the rinsing of whole carcasses.     

Bacteriological Quality of Ready-Mixed Mink Feed in Finland

Frozen samples of Finnish ready-mixed mink feed were analyzed for total bacterial count, the number of faecal streptococci, the coliform count, the number of haemolytic bacteria and the number of sulphite-reducing bacteria. The investigation comprised 242 feed samples from 38 central kitchens and larger private farm kitchens, the combined feed production of which is about 85 % of the yearly feed production of Finland.Of all samples 48.3 % had a total bacterial count of 10⁶ … 6} × 106 bacteria per g of feed. The total bacterial count was relatively constant during the first four production periods of the year (December-August) and was elevated during the last period (September-November). The percentage of samples containing less than 2.5 × 10⁴ faecal streptococci per g of feed was 49.8 %; 62 % of the samples contained less than 2.5 × 10⁴ coliform bacteria per g. The content of coliform bacteria was lowest during the third production period (May); 48.5 % of the samples contained 5 × 10³ … 10⁵ haemolytic bacteria per g, and 4.6 % were negative. The content of haemolytic bacteria was relatively constant during the whole production year; 52.6 % of the feed samples contained 5 × 10³ … 10⁵ sulphite-reducing bacteria per g, and 17.2 % were negative. The mean content of sulphite-reducing bacteria was lowest during the second production period (March-April).The results are discussed and compared with corresponding results from Norway and Denmark.     

The effect of post‐mortem storage on the water‐soluble proteins of breast muscles of uneviscerated pheasant and chicken carcasses

Electropherograms, obtained by polyacrylamide gel electrophoresis, of water‐soluble proteins extracted from the breast muscles of uneviscerated pheasant and chicken carcasses which had been stored at 10 °C were compared. The results indicated that chicken muscle proteins remained largely unchanged, while marked changes occurred in pheasant muscle proteins especially after 10 d post‐mortem.     

Chlorination of water used for poultry processing

The effect on bacterial numbers in the spin‐chillers and on the processed carcasses in a large broiler processing plant of increasing the amount of free residual chlorine by stages from 0 to 20 p.p.m. has been studied. The count at 22° C. on nutrient agar in the chillers and on the birds was lowest at the 18–20 p.p.m. level of chlorine. This effect was less at the 5–8 and 10–13 P‐P‐m. levels. Faecal streptococci, and Staphylococcus aureus on the carcasses were not significantly affected by increasing the chlorine concentration. Coli‐aerogenes numbers were significantly reduced in the spin‐chillers at the highest chlorine level. It is concluded that 18–20 p.p.m. of free chlorine in a suitable water supply is of value in broiler processing but that lower levels of chlorine may not be effective.     

The spoilage flora and shelf‐life of duck carcasses stored at 2 or ‐ 1°c in oxygen‐permeable or oxygen‐impermeable film

1. A comparison was made of” oven ready “ duck carcasses stored at 2 or — 1 °C and wrapped in either a low‐density oxygen‐permeable polyethylene film or a heat‐shrunk oxygen‐impermeable film.

2. At spoilage the main organisms at 2 and — 1 °C on the carcasses wrapped in the oxygen‐permeable film were pseudomonads, producing unacceptable “off odours” when their numbers were >10⁸/cm². This occurred in about 10 d at 2 °C but in about 19 d at ‐ 1° C.

3. The effect of wrapping in the heat‐shrunk oxygen‐impermeable film was to delay or inhibit the growth of pseudomonads and thus extend the shelf‐life by more than 50% at either temperature. The predominant organisms isolated from the spoiling carcasses were atypical lactobacilli and enterobacteria.

4. Sensory assessment of the carcasses stored at — 1 °C by a trained panel indicated that, although less obvious “ off odours “ were produced by the micro‐organisms growing on the carcasses wrapped in the impermeable film, differences were detected at 33 d when the numbers of bacteria reached about 10⁷/cm² whilst at 41 d the meat was described as rancid.     

Factors affecting the use of chlorine in the spin‐chilling of eviscerated poultry

Conditions have been determined under which chlorination can be used to eliminate both faecal and spoilage bacteria from the water used for chilling eviscerated poultry carcasses, thus avoiding any hazard from cross‐contamination.

All combinations of three rates of water usage (2.5, 5 or 8 1 per carcass) and three concentrations of total residual chlorine (10 to 15, 25 to 30 or 45 to 50 ppm), obtained by the addition of sodium hypochlorite, were compared. It was found that the majority of bacteria present were destroyed by the use of 45 to 50 ppm of total chlorine in conjunction with 5 1 of water per carcass. When the rate of water usage was increased to 8 1 per carcass it was found that 25 to 30 ppm of residual chlorine in the chill‐water gave comparable results.

The effect of water usage on the concentrations of free residual chlorine present in the chill‐water during processing is discussed. When chlorine gas was added continuously at a fixed concentration to the input water the concentration of total residual chlorine decreased in each chiller. This method of chlorination was found to be less effective in destroying bacteria than the hypochlorite method which could be used to vary the amount of added chlorine in order to maintain the required total residual concentration during processing.     

Chlorination in poultry processing

The effect of relatively high concentrations of available chlorine in the tanks used for chilling freshly eviscerated chickens on their shelf‐life at 1° C. and on their appearance, taste and odour has been studied.

The nominal initial concentrations of available chlorine that were used were (in p.p.m.): 50, 100, 200, 400, 1000, 2000, 4000 and 8000. The carcasses were immersed in the slush ice for 4 hr. and after this time 20–30 per cent of the initial level, up to 200 p.p.m., was detected as combined chlorine when the contents of the tanks had been stirred between the 2nd and 3rd hr.

Under these conditions and with an initial nominal concentration of available chlorine of 200 p.p.m. shelf‐life at 1° C. was extended by about 20 per cent. Panels of observers detected no significant effect on appearance, taste or odour and the results of a small‐scale consumer trial supported these findings. Initial concentrations of available chlorine of 500 p.p.m. and more resulted in tainted carcasses.     

Microbiological aspects of poultry processing

The microbiological condition of poultry carcasses is shown to be influenced by the general hygiene in the processing plant which is largely determined by (i) the quality of the raw materials, (ii) the design of plant and buildings, (iii) personal hygiene and (iv) cleaning efficiency. The standard of hygiene is dealt with under (i) assessment of contamination on surfaces, (ii) estimation of contamination on carcasses, including bacteria of public health significance and (iii) other measurements of value. Microbiological sampling of surfaces and carcasses is discussed and standards are suggested for water supplies, surfaces and carcasses. Data are presented from 430 frozen eviscerated carcasses sampled over the period of 12 months from a large processing plant.     

The effect of processing and marketing procedures on the bacteriological condition and shelf life of eviscerated turkeys

Experiments carried out in a turkey processing plant showed that there was a fivefold increase in the number of psychrophilic bacteria present after holding eviscerated carcasses in static slush ice tanks for 24 hr. The predominant bacteria in the 24 hr chill tanks were strains of Flavobacterium, Cytophaga and Pseudomonas.

The carcasses were wrapped in heat‐shrunk‐oxygen‐impermeable film and after freezing packed in individual boxes and held at ‐20° C. The storage life at 1°, 10° and 20° C. was determined together with the time taken for the frozen carcasses to equilibrate to these temperatures. It was found that at 1° C. the carcasses kept for about 3 weeks, but at 10° C. they spoiled within 7 days and at 20° G. within 3 days.

An analysis of the spoilage flora showed that although Pseudomonas strains predominated on the turkeys stored at 1° C. fewer were isolated from turkeys stored at 10° C. and 20° C. At these two temperatures an organism identified as Enterobacter liquefaciens predominated together with atypical lactobacilli resembling unidentified strains previously described by Thornley and Sharpe (1959).     

Bovine serum albumin and cell counts in the diagnosis of subclinical udder infection

Summary

Puncture of the milk cisterns was performed in 120 bacteriologically positive quarters of forty‐seven lactating dairy cows on three farms. This method was used to determine whether the existing infection was an infection of the teat canal or one of the udder. The results were related to the concentration of bovine serum albumin (BSA) and the cell count in the milk. Of the bacteriologically negative quarters, both BSA levels (in 91 per cent of the quarters the BSA concentration was 0.20 mg. per ml. of milk or less) and cell counts (92 per cent contained less than 500,000 cells per ml. of milk) were low. In cases of udder infection with primary pathogenic bacteria there was a marked increase in cell count (90 per cent more than 500,000 cells per ml. of milk), whereas the increase in BSA was rather small (51 per cent still contained 0.20 mg. BSA per ml. of milk or less). While the difference in cell counts of milk from quarters with udder infections and teat canal infections with primary pathogenic bacteria was significant, the difference between the BSA levels of these two groups was not. Therefore, the cell count supplies more reliable information than does the BSA level of the milk. Of all infections, 23 per cent were found to be infections of the teat canal.     

The distribution of clostridia in poultry processing plants

An investigation was made of the contamination of poultry carcasses with clostridia during processing. In both chickens and turkeys clostridia were present initially on the feet and breast feathers (geometric mean counts of 10²‐10³/g) and were frequently isolated from the vent area immediately after evisceration. Mean counts from the breast surface just before packaging were < I‐3/10 cm² and there were 31–467/g in samples of neck skin at the same stage. Counts were progressively lower in water samples taken from scald‐tanks, wash‐tanks, spin‐chillers and chill‐tanks.

A large proportion of the isolates obtained from both chicken and turkey plants were haemolytic Clostridium welchii, but a significant number of strains from the turkey plants could not be identified with recognised species.     

Hatchery hygiene evaluation as measured by microbiological examination of samples of fluff

The microbial content of 1,180 samples of fluff from hatchers at 18 chick and 6 turkey hatcheries has been determined. The samples were taken (a) 12–15 hr before removal of birds from the hatchers, (b) just before or after theremoval of chicks orpoults, (c) after fumigation and (d) inreplicate from the same hatcher.

Fifty‐eight per cent of the samples of chick fluff contained one million or more bacteria but only 24 per cent contained more than 100,000 coli‐aerogenes bacteria. Moulds were not found in 68 per cent of the samples. Some samples of fluff were examined for coagulase positive staphylococci and fluorescent pseudomonads but these organisms were generally not detected. Bacillus cereus was recovered in very large numbers from a few samples. Bacterial and coli‐aerogenes counts from poult fluff were generally higher than those from chick fluff but the numbers of pseudomonads and coagulase positive staphylococci recovered were generally negligible.

In an intensive study of samples of fluff from one turkey hatchery, it was found that the level of contamination of fluff increased during hatching and the laying season and was accompanied by a decrease in poult quality. Sampling from any location in the hatcher appears to provide a representative indication of overall contamination at that time. Fumigation of fluff and debris generally caused a reduction in the level of contamination in the fluff.

A suggested assessment of hatchery hygiene based on the microbial examination of fluff is given and the advantages and disadvantages of this method are discussed.     

Errata

Summary

Netobimin was tested for efficacy against Haemonchus contortus using 7 groups of 5 parasite‐free lambs of six month age. The lambs in group 1 and 2 were infected with 10,000 larvae of a benzimidazole susceptible strain and those in groups 3–7 with the same dose of a resistant strain. The following treatment scheme was applied 21 days after infection: lambs in groups 2 and 4 ‐ 7.5 mg kg^‐1 netobimin, in group 5 ‐ 20 mg kg^‐1 netobimin, in group 6 ‐ 5 mg kg^‐1 oxfendazole and in group 7 ‐ 3.8 mg kg^‐1 albendazole. The lambs in groups 1 and 3 remained untreated. All lambs were slaughtered 28 days after infection. Egg counts decreased in all lambs after treatment, but increased again in lambs in groups 4, 6 and 7. There was a slight increase in lambs in group 5, while those in group 2 remained negative. Post‐mortem worm counts showed a reduction of 99.8 per cent in lambs in group 2 compared to those in group 1. In lambs in group 4–7 the reduction of worm counts was respectively 40.9, 89.5, 24.7 and 40.7 per cent compared to those in group 3. Egg development assays carried out 20 days after infection showed an average LD₅₀ of 0.46 mg ml^‐1 thiabendazole for the resistant strain. After treatment (day 27) the LD₅₀ was 0.53, 0.48, 0.58, 0.56 and 0.47 in lambs in the groups 3–7. It is concluded that netobimin and other (pro) ‐benzimidazoles should not be used in cases of benzimidazole resistance and that levamisole, pyrantel tartrate or ivermectin are preferable.     

Effect of forage legumes containing condensed tannins on lungworm (Dictyocaulus sp.) and gastrointestinal parasitism in young red deer (Cervus elaphus)

To investigate the effect of feeding forage legumes containing condensed tannins ( ) on internal parasitism, red deer calves were fed either lucerne (Medicago sativa; 0.1 per cent ), birdsfoot trefoil (Lotus corniculatus; 1.9 per cent ) or sulla (Hedysarum coronarium; 3.5 per cent ) and trickle-infected with deer-origin gastrointestinal nematode and lungworm (Dictyocaulus sp.) larvae for 5 weeks, then slaughtered at 7 weeks. There was a significant negative linear relationship between dietary concentration and abomasal nematode burdens. No significant differences in faecal egg counts, lungworm burdens or voluntary feed intake were found. Deer fed sulla had higher liveweight gain, carcass weight and carcass dressing-out percentage, higher serum total protein and albumin concentration and lower serum gastrin concentration and faecal lungworm larval count, compared with lucerne-fed deer. Inclusion of sulla in diets for young red deer may reduce the impact of internal parasites and/or reduce the dependence on anthelmintic treatment.     

Congenital cataracts in an Ayrshire herd: a herd case report

Background

Microbiological standards within pork slaughter processing plants in the European Union are currently governed by Commission Regulation (EC) 2073/2005, which describes detailed performance criteria at specific stages of the procedure (following carcass dressing and before chilling) for total viable counts (TVC), Enterobacteriaceae (EB) and Salmonella spp. In this study, 95 carcasses from an Irish pork slaughter plant were sampled by swabbing 100 cm² of surface at three sites (belly, ham, jowl) to examine the effects of eight processing stages (stunning, bleeding, scalding, singeing, polishing, evisceration, final inspection and chilling) on contamination levels.

Results

TVC ranged from approximately 1.7–6.3 log cfu cm² during sampling. There were significant reductions in TVC for all sites after scalding and singeing (p < 0.05), whilst there was a significant increase in counts after polishing and evisceration (p < 0.05) compared with preceding stages. EB counts indicated hygienic weak points in the examined slaughter plant leading to faecal (cross)-contamination, with elevated counts after stunning, bleeding and evisceration (p < 0.05), compared with final counts after chilling.

Conclusions

Although the bacterial numbers reported in this study may reflect specific plant practices and temporal influences, results show that contamination can be introduced at various steps in the process and highlight the importance of monitoring locations other than those required by legislation within the process. Monitoring can be used to establish baseline levels for high-risk stages specific to each plant and to assess the effectiveness of additional interventions.