Evaluation of the performance of different cleaning treatments in reducing microbial contamination of poultry transport crates

1. The present systems for cleaning the plastic crates (drawers) used to transport live poultry to the processing plant are known to be inadequate for removing microbial contamination. 2. To investigate possible improvements, a mobile experimental rig was constructed and operated in the lairage of a poultry processing plant. The cleaning rig could simulate the conditions of commercial cleaning systems and utilise freshly emptied crates from the processing plant. 3. The aim of the study was to improve cleaning by enhancing the removal of adherent organic material on the crates and by reducing microbial contamination by at least 4 log(10) units. 4. Trials showed that the most effective treatments against Campylobacter were either (a) the combination of soaking at 55 degrees C, brushing for 90 s, washing for 15 s at 60 degrees C, followed by the application of disinfectant (Virkon S in this study) or (b) the use of ultrasound (4 kW) at 65 degrees C for 3 to 6 min, with or without mechanical brushing of crates. 5. Both of these treatments also achieved a 4 log(10) reduction or more in the counts of Enterobacteriaceae but were less effective in reducing aerobic plate counts. 6. It was noted that there was little correlation between the visual assessment of crate cleanliness and microbiological counts. 7. It was concluded that the demonstrated enhanced cleaning could contribute significantly to overall hygiene control in poultry meat production.     

Effect of boiling water carcass immersion on aerobic bacteria counts of poultry skin and processed ground poultry meat

This study was conducted to determine the relationship between bacteria destruction on poultry carcass skin and bacteria in raw ground poultry meat from the same carcasses. Immersion time in boiling water of broiler chicken whole carcasses required for maximum reduction of naturally occurring aerobic bacterial count on skin was measured. Treatments for chicken carcasses consisted of immersion in boiling water (approximately 95 degrees C) for 0, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, and 4 min. Four skin samples taken following treatment and three taken from subsequently ground carcass meat were analyzed for total aerobic plate counts (APC). Analysis of the data indicated a linear increase in bacterial destruction on skin with increased boiling water immersion time from 0 to 4 min. Reduction of skin bacteria to less than 1 log10 occurred at 3 min carcass immersion or longer. The analysis also indicated that treatment with boiling water and removal of skin was effective in reducing bacterial counts in ground meat to similar levels at all treatment times from 0.5 to 4.0 min. Findings from this study indicated that a boiling water immersion intervention and removal of skin could reduce subsequent bacteria contamination of ground meat. This intervention could minimize the risk of pathogen-contaminated primary processed poultry carcasses used in further processing.     

Antimicrobial efficacy of AvGard carcase wash under industrial processing conditions

1. The efficacy of the AvGard Trisodium Phosphate (TSP) immersion carcase wash process was evaluated during 5 industrial trials against Salmonella , Enterobacteriaceae , thermotolerant coliforms and total aerobic count. The effect against Pseudomonas was also studied in the first 3 trials. 2. Dramatic reductions in Salmonella incidence were seen using a whole carcase rinse method. In 4 of the 5 trial sites, only one positive sample was found after AvGard of an average control incidence of 57.7%. In the 5th site, a water-chilled broiler plant, an average control incidence of 74.0% was reduced to 9.4% after AvGard 3. In the latter case, Most Probable Number (MPN) analyses were performed on some of the Salmonella positive samples taken from the control and post-treatment series; the average MPN count per carcase on controls was 115, whereas for AvGard treated birds the figure was only 0.6 per carcase, a greater than 2 log reduction. 4. In addition, AvGard treatment gave average log reductions for all trials of: Enterobacteriaceae ; 2.5 log; Coliforms; 2.7 log, and Total Aerobic Count; 1.1 log, leading to carcases substantially free of Gram negative pathogens. 5. Pseudomonas was reduced by an average of 1.7 log in the first 3 trials, dramatically reducing the carcase loading of this important spoilage organism. treatment (average 0.5% incidence), in spite treatment.     

The effect of commercial steam pasteurization on the levels of Enterobacteriaceae and Escherichia coli on naturally contaminated beef carcasses

The aim of the study was to assess the reduction achieved by steam pasteurization of beef carcasses of Escherichia coli, Enterobacteriaceae and total aerobic mesophilic plate counts (APCs). In total, 30 carcass halves were exposed to steam pasteurization (90 degrees C, 10 s exposure time) and the 30 corresponding carcass halves remained as untreated controls. The neck, midline and rump were sampled on each carcass half. Significant reductions in E. coli incidence (P < 0.05) and counts, 0.5 log10 CFU 1000 cm(-2) (P < 0.05), were observed on rump sites only. Significant reductions (>0.8 log10 CFU 1000 cm(-2)) of Enterobacteriaceae were observed at all carcass sites sampled (P < 0.05). Enterobacteriaceae reductions (>2 log10 CFU 1000 cm(-2)) were highly significant at the more contaminated sites (P < 0.001). Reductions in total APCs were inconsistent. Steam pasteurization significantly reduced the level of E. coli and Enterobacteriaceae at more contaminated sites, but did not result in complete decontamination. Therefore, steam pasteurization should be classed as an aid to hygienic beef processing, but not as a critical control point.     

Effects of chlorination of chill water on the bacteriologic profile of raw chicken carcasses and giblets.

In March 1989, the USDA Food Safety and Inspection Service sampled raw chicken carcasses and giblets at a federally inspected slaughter establishment in Puerto Rico to determine the effects of adding chlorine to carcass and giblet chill water on bacterial contents of raw poultry products. Over four 8-hour workdays, 200 carcass rinse samples were collected at 3 sites in the establishment; 39 giblet rinse samples were collected at 1 site. Analyses of the carcass rinse samples indicated that carcasses had average aerobe plate counts of log10 3.20 before chilling and 2.51 after chilling; Enterobacteriaceae counts of log10 2.57 before chilling and 1.75 after chilling; and Escherichia coli counts of log10 2.04 before chilling and 1.20 after chilling. Salmonellae were found on 43% of the carcasses before chilling and on 46% after chilling. Analyses of the giblet and neck rinse samples indicated that raw giblets and necks after chilling had average aerobe plate count of log10 3.49, Enterobacteriaceae count of log10 2.57, and E coli count of log10 1.06. Salmonellae were found on 12% of the giblets and necks sampled. Results compared favorably with giblet and neck rinse sample results obtained during a baseline sampling study in November and December 1987. The baseline results indicated aerobe plate count of log10 3.72; Enterobacteriaceae count of log10 2.90; E coli count of log10 1.14; and salmonellae on 69% of the giblets and necks sampled. Placing raw chicken carcasses in chlorinated chill water reduced aerobe, Enterobacteriaceae, and E coli plate counts. Prevalence of carcasses with salmonellae remained nearly the same.(ABSTRACT TRUNCATED AT 250 WORDS)     

Profile of selected bacterial counts and Salmonella prevalence on raw poultry in a poultry slaughter establishment.

The USDA Food Safety and Inspection Service determined populations of bacteria on poultry during processing at a slaughter plant in Puerto Rico in November and December 1987. The plant was selected because of its management's willingness to support important changes in equipment and processing procedures. The plant was representative of modern slaughter facilities. Eight-hundred samples were collected over 20 consecutive 8-hour days of operation from 5 sites in the processing plant. Results indicated that slaughter, dressing, and chilling practices significantly decreased the bacterial contamination on poultry carcasses, as determined by counts of aerobic bacteria, Enterobacteriaceae, and Escherichia coli. Salmonella was not enumerated; rather, it was determined to be present or absent by culturing almost the entire rinse. The prevalence of Salmonella in the study decreased during evisceration, then increased during immersion chilling.     

Effects of Feed Withdrawal Time on the Incidence of Fecal Spillage and Contamination of Broiler Carcasses at Processing

Carcass contamination during processing is an expensive problem for poultry processors. Feed withdrawal (FW) is commonly used to reduce the amount of gut contents prior to slaughter, thereby reducing the probability of contamination. The present study used market aged mixedsex broilers to evaluate the effect of FW time on the incidence of fecal spillage and contamination of broiler carcasses at processing. In order to develop a more simple research protocol for FW, the effects of live haul and holding in stationary crates were compared. Broilers were subjected to 1 of 4 FW times (4, 8, 12, and 16 h) prior to slaughter at a commercial processing plant, in which the incidence of carcass contamination was recorded. Carcass yield and clearance of contents from 8 gut sections were determined. Moisture content of the pooled gut contents was assessed.Shrink increased from 2.1 to 3.3% of pre-FW BW after 4 and 16 h, respectively. Gut weights decreased significantly with every additional 4 h of FW. The incidence of processing plant inefficiencies decreased with increasing FW time. Gut moisture was not correlated with FW time, although moisture of the gut contents was reduced in birds subjected to live haul. Twelve hours of FW resulted in an optimal combination of gut clearance and carcass yield.     

Presence of inoculated Campylobacter and Salmonella in unabsorbed yolks of male breeders raised as broilers

Day-old male broiler breeder chicks were obtained from a commercial hatchery and raised as broilers. For Experiment 1, at 5 wk of age, the broilers were orally inoculated with a 10(6) cfu/ml of a characterized strain of Campylobacter jejuni and a cocktail (three naladixic acid-resistant strains) of Salmonella serovars. One week after inoculation, the birds were euthanatized and defeathered. The abdominal cavity was examined and any unabsorbed yolk material (and remaining yolk stalk) and ceca were aseptically removed for microbiological analyses. For each pooled sample (two birds per pool), an aerobic plate count (APC), an Enterobacteriaceae (ENT) count, and a test for the presence of Campylobacter and Salmonella was performed. For Experiment 2, at 5 wk of age, the broilers were orally inoculated with 10(5) cfu/ml of a characterized strain of Campylobacter jejuni. One week after inoculation, the birds (n = 20) were killed, defeathered, and the yolk stalk, attached yolk, or free-floating yolk and ceca were individually analyzed for presence of Campylobacter. For Experiment 1, the Salmonella-inoculated birds had 2/12 ceca and 0/12 unabsorbed yolk samples positive for Salmonella. The average yolk APC was log10 3.4 cfu/g and the average ENT was log10 1.9 cfu/g. For the Campylobacter-inoculated birds, 12/12 ceca and 9/12 unabsorbed yolk samples were positive for Campylobacter. The average yolk APC was log10 3.5 cfu/g and the average ENT was log10 3.1 cfu/g. For Experiment 2, the inoculated Campylobacter birds had 19/20 ceca, 5/20 free floating yolks, and 19/20 yolk stalks positive. In Experiment 1, the inoculated Campylobacter colonized the ceca in every instance and were present in 75% of the unabsorbed yolks. Alternatively, the inoculated Salmonella were not found in any of the unabsorbed yolks and only rarely in the ceca. In Experiment 2, the inoculated Campylobacter was found in very high numbers in the yolk and internal body samples. Determining to what extent these internal bodies and unabsorbed yolks play in bacterial colonization and contamination of the birds at processing has not been determined. The next step will be to determine the incidence of unabsorbed yolks and presence of Campylobacter and Salmonella in these bodies of commercial broilers at processing.     

Treatment of fresh poultry carcases with emulsions of glycerol monocaprate (monocaprin) to reduce contamination with Campylobacter and psychrotrophic bacteria

1. A previous study has shown that emulsions of monocaprin in citrate lactate buffer at pH 4·1-4·3 are highly active in killing Campylobacter in water, where they reduce viable bacterial counts by more than 6 log(10) colony forming units (cfu) in 1 min at a concentration of 1·25 mM (0·03%). 2. The present study was carried out to evaluate whether monocaprin emulsions could be used to kill Campylobacter on raw poultry. 3. It was shown that immersion of naturally contaminated chicken legs in 20 mM (0·5%) monocaprin emulsion at pH 4·1 for 1 min at 20°C reduced the number of Campylobacter by 2·0 to 2·7 log(10) cfu. Pre-chill dipping of whole carcases into 20 mM monocaprin emulsion in the slaughterhouse also caused a significant reduction in Campylobacter contamination. 4. Immersion in monocaprin emulsions at pH 4·1 was also assessed as a means to reduce the number of psychrotrophic spoilage bacteria. There were lower psychrotrophic bacteria counts on treated chicken parts than on untreated controls after storage at 3°C for up to 14 d. 5. Immersion in emulsions of monocaprin, which is a natural lipid classified as GRAS, may be a feasible method to reduce the number of Campylobacter and spoilage bacteria on raw poultry. This method could reduce the risk of human exposure to Campylobacter, and at the same time increase the shelf-life of poultry products.     

Investigation of hygiene aspects during air chilling of poultry carcases using a model rig

1. An experimental rig, designed and built to simulate conditions found in commercial poultry chilling systems, was used to investigate the effects of varying air temperature and chilling duration, and the effect of chlorinated water sprays, on the microbial load present on the skin and in the body cavity of freshly eviscerated poultry carcases; deep muscle and skin temperatures were monitored during chilling at three different temperatures. 2. During dry chilling for 2 h, total viable microbe counts (TVC) and counts of coliforms and pseudomonads from the body cavity fell by between half and one log unit; smaller reductions were observed in samples from the breast skin. 3. The situation changed when chlorinated water sprays (50, 100 or 250 ppm available chlorine) were applied for the first hour of chilling; spraying carcases enhanced the reduction in numbers on the skin; the effect was most pronounced with 250 ppm chlorine; conversely in the body cavity, the general effects of sprays was to increase contamination by up to one log unit. 4. There was no evidence that sprays increased the rate of chilling. 5. When carcases were held overnight in the rig at 11 degrees C after chilling, microbe counts on dry-chilled carcases remained stable, but increased on carcases that had been sprayed with chlorinated water.     

Elimination of Salmonella spp. by lactic acid

The aim of the present study was to determine the elimination of Salmonella by different lactic acid concentrations in microbiological media and on turkey carcass elements. The average bacteria counts in the control samples without lactic acid were: 1.8 x 10(8), 1.1 x 10(8) and 2.3 x 10(8), for S. Enteritidis, S. Anatum and S. Typhimurium, respectively. The concentration of lactic acid of 0.1% in the agar media completely inhibited the growth of all Salmonella strains. At 0.05% lactic acid concentration, the bacteria count was 2 log cycles lower and at a 0.03% solution it was 1 log cycle lower than that in the respective control samples. However, the examined bacteria developed in the presence of 0.02% and 0.01% lactic acid concentrations and their counts fell into the same log brackets. An analysis of the experimental results obtained from turkey carcass elements immersed in the lactic acid solution showed that the Salmonella identification rate was determined by the bacteria inoculum spread over the turkey carcass surface. The contamination of 10(1) CFU of Salmonella spread onto the turkey carcass was completely eliminated by immersing the carcasses in 1% or 2% lactic acid solutions. The contamination of turkey carcass elements with 10(2) CFU of S. Enteritidis and their immersion in 2% lactic acid solution for 15 min resulted in the reduction of the number of samples with Salmonella compared to the number of control samples with Salmonella. At contaminations of 10(3) CFU on the carcass surfaces, the immersions in 1% and 2% lactic acid solutions did not reduce Salmonella counts.     

Sources of salmonellae in an uninfected commercially-processed broiler flock.

Cultural monitoring was used to study the incidence and sources of salmonellae in a 4160 bird broiler flock during the growing period, transport and processing in a commercial plant. No salmonellae were isolated from any of 132 litter samples of 189 chickens cultured during the seven-week growing period, even though nest litter samples from four of the eight parent flocks yielded salmonellae and Salmonella worthington was isolated from the meat meal component of the grower ration. On arrival at the plant, 2/23 birds sampled carried S. infantis on their feathers, although intestinal cultures failed to yield salmonellae. Three of 18 processed carcasses samples yielded salmonellae (S. infantis, S. heidelberg, S. typhimurium var copenhagen). The most likely source of these salmonellae was the plastic transport crates, since 15/107 sampled before the birds were loaded yielded salmonellae (S. infantis, S. typhimurium). The crate washer at the plant did not reduce the incidence of Salmonella-contaminated crates, since 16/116 sampled after washing yielded salmonellae (S. infantis, S. typhimurium, S. heidelberg, S. schwarzengrund, S. albany).     

The effectiveness of in‐plant chlorination in poultry processing

1. Sampling carcasses after plucking or after the post‐evisceration spray‐wash showed that 10 or 20 ppm available chlorine in the processing‐plant water supply caused little reduction in carcass contamination.

2. When 20 ppm chlorine was used in the water supply to parts of the processing‐plant other than the mechanical immersion chilling system, counts of faecal and spoilage bacteria from carcasses were reduced approximately 10‐fold after passage through the chilling system; bacterial numbers were correspondingly decreased in the chiller water due to a carry‐over of chlorine from the final spray‐washer.

3. Artificial contamination of carcasses with a readily identifiable strain of Escherichia coli confirmed the occurrence of cross‐contamination during plucking and evisceration; in‐plant chlorination reduced neither the proportion of carcasses contaminated nor the numbers of organisms transferred at these stages.

4. In most cases the chlorine‐resistance of poultry spoilage pseudo‐monads was greater than that of E. coli; hence in‐plant chlorination is to be recommended for processing‐plant water supplies which carry such spoilage organisms.     

Effect of nipple drinker water flow rate and season on performance of lactating swine.

A cooperative study involving six experiment stations and 236 crossbred litters was conducted to determine the effect of nominal nipple drinker water flows of 700 mL/min and 70 mL/min (actual = 701 and 76 mL/min, respectively) during winter (November through February; 124 litters) and summer (June through August; 112 litters) seasons on performance of lactating sows and their litters. Within a season, sows were paired according to expected farrowing date and assigned at random to crates. Water flow rate treatments were assigned at random to sows within pairs. Sows were housed in farrowing crates from d 109 of gestation until either d 21 (two stations) or d 28 of lactation (four stations). Within 24 h after farrowing, litters were adjusted to contain 8 to 12 piglets. Sow feed intake (SFI) and litter weight (LW) were recorded weekly. Sow weights were recorded at d 109 of gestation, d 0, and d 21 of lactation. Sows lactating beyond 21 d were also weighed on d 28. Analysis of covariance was applied to sow weight change, average daily SFI, and LW data where litter size after crossfostering was the covariate. Average ambient temperature 30 cm above the floor at 0830 and 1600 was 24.6 +/- 0.15 degrees C and 29.4 +/- 0.14 degrees C, respectively, during summer and 20.7 +/-0.13 degrees C and 21.8 +/- 0.11 degrees C during winter trials. Restricted drinker water flow rate decreased SFI (P < 0.01; 4.59 vs. 3.94 kg/d, respectively, for 700 and 70 mL/min) and increased BW loss (P < 0.01; 0.56 vs 0.89 kg/d, respectively for 700 and 70 mL/min) but did not affect litter size (P > 0.87) or LW (P > 0.89) during the first 21 d of lactation. During d 22 to 28, the 70 mL/min flow decreased SFI (P < 0.01; 5.02 vs. 4.47 kg/d respectively, for 700 and 70 mL/min). Over the 21-d lactation period, the 70 mL/min treatment depressed (P < 0.01) SFI more during the winter (5.12 vs. 4.24 kg/d for 700 and 70 mL/ min, respectively) than during the summer (4.05 vs 3.65 kg/d for 700 and 70 mL/min, respectively). Season affected SFI (P < 0.01; 4.68 vs. 3.85 kg/d, respectively, for winter and summer), sow weight loss (P < 0.001; 0.46 vs 0.83 kg/d, respectively, for winter and summer), and LW at 21 d (P < 0.05; 52.8 vs. 49.6 kg, respectively, for winter and summer) but not (P > 0.96) the number of pigs per litter. Results of this study suggest that ample access to drinking water and controlling ambient temperature during summer months are essential for sow and litter performance.     

Microflora of two different types of poultry litter

1. The microbiological composition of litter (straw and wood shavings) was sampled, prior to placing 1-d-old chicks, during housing of the birds and after depopulation. Two independent trials were conducted. 2. The total aerobic plate count (APC) was determined and the predominant microflora of the samples was identified using flow charts. 3. Before chick placement, the APC of wood shavings (about 4.0 log/g) was lower than the APC of straw (about log 7.5/g). With stocking, in both types of litter the APC increased to about log 9.76/g straw-litter and log 9.89/g wood shavings, respectively. After depopulation, the APC remained high (> log 9 in both types of litter) within the period of observation. 4. From both experiments, 1981 isolates were collected and identified, most of them were Gram-positive. During stocking the birds, the number of Gram-positive isolates (in particular Gram-positive irregular rods and Micrococcaceae) increased; after depopulation it stayed at that high value, whereas the number of Gram-negative isolates remained low. In both types of litter the isolates were obtained in a comparable proportion.     

Natural Occurrence of Campylobacter Species,Salmonella Serovars,and Other Bacteria in Unabsorbed Yolks of Market-Age Commercial Broilers

In the developing avian embryo, the main energy source is the yolk. Toward the end of the incubation period, the remaining yolk sac is internalized into the abdominal cavity. At hatch, the remaining yolk comprises 20% of the chick's BW and provides the nutrients needed for maintenance. Posthatch, chicks rapidly initiate the transition from yolk dependence to the utilization of exogenous feed. However, at present, it is not known what types of bacteria are found to be associated with unabsorbed yolk sacs from market-age broilers. For Experiment 1, one hundred 6-wk-old defeathered broiler carcasses were obtained from a commercial processing facility during each of 3 visits. In the second experiment, one hundred 8-wk-old defeathered broiler carcasses were obtained from a different commercial processing plant on 4 separate occasions. For both experiments, each carcass was aseptically opened and inspected for the presence of an unabsorbed yolk sac. Three to 5 carcasses containing a free-floating yolk sac (within the abdominal cavity) and the yolk stalk (without a yolk sac) and 3 to 5 carcasses containing an attached yolk and yolk stalk from each repetition were randomly selected and analyzed for levels and types of total aerobic bacteria (APC), Enterobacteriaceae (ENT), and for the presence of Campylobacter spp. and Salmonella serovars. The APC ranged from log 3.3 to >log 6.0, and the ENT ranged from log 2.8 to >log 6.0. Staphylococcus spp. and Streptococcus spp. were the predominant organisms in APC, whereas Escherichia coli and Hafnia alvei were found to comprise the ENT. Campylobacter spp. was found in 29% of the yolk stalks, 32% of the attached yolk sacs, and 13% of the free-floating yolk sacs. All Campylobacter isolates were determined to be Campylobacter jejuni, except for 1 attached yolk and yolk stalk, which was Campylobacter coli. Salmonella serovars were found in 26% of the yolk stalks, 48% of the attached yolk sacs, and 23% of the free-floating yolk sacs, and the majority of Salmonella isolates were Salmonella Typhimurium. The significance of these bacterial reservoirs and carcass contamination during processing is yet to be determined.     

Shedding of foodborne pathogens and microbial carcass contamination of hunted wild ruminants

To assess the shedding of selected bacterial foodborne pathogens, fecal samples from 239 hunted wild red deer, roe deer, chamois, and ibex were examined. All samples tested negative for Salmonella spp. and L. monocytogenes, but other Listeria species were occasionally found. Of the 239 fecal samples, 32.6% tested positive for stx (Shiga toxins), 6.7% for eae (intimin) and 13.8% for both stx and eae genes. Among the 56 isolated Shiga toxin-producing Escherichia coli (STEC) strains, 44.6% harbored genes for the Stx2 group, 30.4% for the Stx1 group, and 21.4% for both Stx1 and Stx2. Only two of these strains harbored eae. Hence, wild ruminants constitute a reservoir for STEC, but further characterization data of the isolated strains are required to assess their actual human pathogenicity. In addition, 328 carcasses from hunted wild red deer, roe deer, and chamois were examined for total viable counts (TVC) and Enterobacteriaceae by swabbing. For the examined animal species, average TVC (4.0-4.2 log CFU cm(-2)) and average Enterobacteriaceae counts/detection rates (2.3-2.6 log CFU cm(-2); 87.5-90%) were at comparable levels. On the other hand, the microbial status of carcasses differed between certain abattoirs by several orders of magnitude. Strict compliance with good hunting and hygiene practices during any step from shooting, through evisceration in the field, to dehiding, cooling, and processing is therefore of central importance to avoid contaminations and to prevent foodborne pathogens carried by the animals from entering the food chain.     

Estimation of platelet counts on feline blood smears

Blood samples were obtained from 50 cats admitted for hematologic evaluation at the Royal (Dick) School of Veterinary Studies. Manual platelet counts were done using a hemacytometer, and the average number of platelets per oil immersion field (1,000X magnification) was determined on stained blood smears. A hemacytometer count was not obtained for one sample because of a failure in erythrocyte lysing. In nine samples, obvious platelet clumps in the blood smear prevented accurate determination of the number of platelets per oil immersion field. Hemacytometer counts on these nine samples ranged from 260-587 X 10 (3) platelets/microliter, suggesting that platelet clumps on a blood smear were usually associated with adequate platelet numbers. Simple regression analysis of hemacytometer counts and the average umber of platelets per oil immersion field for the remaining 40 samples yielded correlation coefficients (r) of 0.776 on untransformed data, and 0.892 on log10-transformed data. Each platelet per oil immersion field represented a circulating platelet count of approximately 20 X 10(3)/microliter, similar to conversion factors reported for dogs and human beings. It was concluded that estimation of platelet number on stained blood smears is a simple and quick method that appears to be reliable over a wide range of platelet counts in cats.     

Bacteriological quality of raw cow's milk from four dairy farms and a milk collection centre in and around Addis Ababa

Bacteriological quality of raw cow's milk taken at different sampling points from four dairy farms and a milk collection centre in and around Addis Ababa was evaluated. Milk samples were aseptically collected from udder, bucket, storage container before and after cooling and upon arrival at the processing plant. A high increase in the mean total aerobic plate count was observed in milk samples taken from the bucket (1.1 x 10(5) cfu/ml), storage container before cooling (4 x 10(6) cfu/ml) and upon arrival at the processing plant (1.9 x 10(8) cfu/ml). The mean coliform counts ranged from 1.3 x 10(4) cfu/ml (storage container before cooling) to 7.1 x 10(4) cfu/ml (upon arrival at the processing plant). The hygienic quality of raw milk from the collection centre was poor with a mean total bacterial count of 1.3 x 10(7) cfu/ml. Milk sampled from the udder contained mainly staphylococci and micrococci as udder-specific bacteria, while samples taken at later stages were additionally contaminated with bacteria of environmental origin (especially Enterobacteriaceae). Lack of knowledge about clean milk production, use of unclean milking equipment and lack of potable water for cleaning purposes were some of the factors which contributed to the poor hygienic quality of raw milk in the study farms.     

Effects of countercurrent scalding and postscald spray on the bacteriologic profile of raw chicken carcasses.

In June and September 1988, the USDA Food Safety and Inspection Service sampled raw chicken carcasses at a federally inspected slaughter establishment in Puerto Rico to determine the effects of changing the scalding equipment on bacterial contents of raw poultry products. The scalding equipment was changed to a countercurrent configuration, with a postscald hot-water rinse cabinet that sprayed carcasses as they exited the scalder. Analysis of 250 carcass-rinse samples collected at preevisceration, prechill, and postchill sites over 7 days indicated that carcasses had mean aerobe plate counts of log(10)3.73 before evisceration, 3.18 before chilling, and 2.87 after chilling; Enterobacteriaceae counts of log(10)2.70 before evisceration, 2.25 before chilling, and 1.56 after chilling; and Escherichia coli counts of log(10)2.09 before evisceration, 1.61 before chilling, and 0.89 after chilling. Salmonellae were found on 24% of the carcasses before evisceration, on 28% before chilling, and on 49% after chilling. Although bacterial count reductions were significant at all 3 sites, the proportion of carcasses contaminated with salmonellae in this study was higher at the postchill than prechill site (49 vs 28%). This no doubt was caused by cross-contamination in the chiller. These percentages indicated that although simple scalder changes contributed substantially to the improvement of the bacterial quality of chicken carcasses, additional interventions in the chilling process (such as chlorination of chill water) are important to control cross-contamination and to preserve the positive effects obtained by the scalder changes.