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Transmission of Salmonella Through an Integrated Poultry Organisation
Transmission of Salmonella Through an Integrated Poultry Organisation B . S. BAINS AND MARGARET A. M A C K E N Z I E
Provincial Traders Pry. Ltd., Box 10, P.O., Morningside, 4170 Brisbane, Queensland,
Australia
(Received for publication September 19, 1973)
ABSTRACT High mortality in infected broiler flocks was correlated with increased incidence of Salmonella in the grain constituents of the breeder rations. The Salmonella chain of infection was traced through the grain to breeder feed, breeder carrier birds, breeder farm litter and nest box materials, hatchery dead-in-shell embryos, day-old broilers and subsequently to the dressed broilers. Regular monitoring of these aspects of poultry production is suggested as a useful means of reducing Salmonella contamination levels in the integrated industry to a minimum. INTRODUCTION
P
ARATYPHOID is one of the most important bacterial diseases of poultry. Since salmonellosis is also an important public health disease, procedures in the poultry industry have recently been oriented towards the reduction, control, and eventual eradication of Salmonella from poultry flocks (Morris et al, 1969; Jackson et al., 1971). There are five major sources of Salmonella contamination in the industry—feed, carrier birds, litter, nest boxes and environment; a breakdown in any one source may lead to the reestablishment of the Salmonella chain of infection. The purpose of the present study was to determine the source, persistence and dissemination of Salmonella in an outbreak of salmonellosis in a commercial integrated poultry organization. EXPERIMENTAL PROCEDURE The poultry facility studied consisted of breeder and broiler farms located within an area approximately 80 km. in diameter. The feed mill, hatcheries and processing plant were located within the area but were well separated from each other to prevent crosscontamination between plants. Hatchery sanitation procedures were designed to minimize the possibility of multiplication and spread of contamination within the hatchery buildings. Regular microbiologi-
cal swabbing and sampling of fluff in the hatcheries ensured the maintenance of high standards of hygiene. Eggs for hatching were collected four times per day on the breeding farm; soiled eggs were not used for hatching. The eggs were fumigated on the farm within 1/2 hour of collection in a sealed room at 21° C. and 65% humidity for 20 minutes, using a mixture of formalin and potassium permanganate in a ratio of 140 ml. and 85 g. per 9 m.2 of fumigation room, respectively. The eggs were transported to the hatchery twice daily in a closed, fumigated vehicle. On receival at the hatchery the eggs were stored at 13-16° C. and 75-80% humidity. Prior to setting, the eggs were transferred into a preheating room and fumigated, as before, at an egg temperature of 24° C. The eggs were then set in the incubator. On transfer to the hatchers the eggs were again fumigated; henceforth until hatching, a continuous fumigation with formaldehyde in a 520 cm. 2 surface area pan was carried out. The hatcheries were washed and disinfected daily on all surfaces including belts, trolleys, tables, walls and floors. Disinfectant foot baths were provided at all entries to the building. Samples of litter from the breeding farm were obtained by collecting 5 kg. of litter from all sections of the shed weekly, using a sterile scoop. At the end of the month the
1114
Downloaded from http://ps.oxfordjournals.org/ at UCSF Library on April 11, 2015
POULTRY SCIENCE 53: 1114-1118, 1974
1115
SALMONELLA TRANSMISSION
Grains (Meals)"
Breeder Feed
into sterile jars containing 80 ml. of selenite broth. The flocks were examined on processing by collecting 300 caecae aseptically into separate sterile containers on the processing line, and selecting 30 random samples for slicing aseptically into 80 ml. of selenite broth in a sterile jar. Two kg. samples of all batches of breeder feed were taken with a sterile scoop into a sterile bag immediately upon production at the feed mill, and despatched to the laboratory. At the end of the month all samples were pooled, mixed thoroughly, and 144 replicate 20 g. samples taken at random with a sterile spatula for incubation in 80 ml. of selenite broth containing 6 ml. of a 10% Tergitol No. 7 detergent solution. Similarly, 2 kg. samples of all batches of grains were collected aseptically with a sterile scoop as the closed grain truck arrived at the feed mill, prior to unloading, to avoid any possibility of cross-contamination. The samples of grain were combined monthly, and twelve replicate 20 g. samples taken at random from each grain type into jars containing 80 ml. of selenite broth and 6 ml. of Tergitol No. 7 solution. The selenite broth samples were processed for Salmonella by incubating at 43° C. for 48 hours, plating onto brilliant green sulfapyridine (BGS) agar and incubating at 37° C. for 24 hours. Suspect Salmonella colonies were transferred to fresh plates of BGS
\ Breeder ' Carrier Birds^v»_
. Litter ' Nest Boxes
Caecae in /_ Processed Broilers FIG. 1. Salmonella chain of infection
>
Eg
• —T
\ Dead-In-Shells Day-old Chicks
Downloaded from http://ps.oxfordjournals.org/ at UCSF Library on April 11, 2015
samples were pooled and mixed thoroughly, and twelve 20 g. samples taken at random with a sterile spatula into sterile jars, each containing 80 ml. of selenite broth. Similarly, 1 kg. of nest box material was collected from the nest boxes weekly, the samples combined at the end of the month, and six 20 g. samples taken at random into sterile jars containing 80 ml. of selenite broth. Breeder carrier birds were examined for Salmonella by autopsying two cull birds collected on the farm during the month, and pooling samples of a) heart, liver, spleen and kidney, and b) intestine and caecum, taken aseptically from each bird into sterile jars containing 80 ml. of selenite broth. Samples of dead-in-shell embryos were taken by collecting 300 unhatched embryos from the hatchery once per month and selecting 30 embryos at random for bacteriological examination. The eggs were swabbed with 70% alcohol, and the embryo extracted aseptically into a sterile jar, homogenized in 10 ml. selenite broth, and incubated in 80 ml. of selentite broth. Samples of all day-old broiler flocks placed were examined routinely for Salmonella at 4 days of age in the laboratory. Fifty culls from each flock were autopsied, pooling the hearts, livers, spleens and kidneys, and the intestine and caecae, into separate sterile containers. The specimens were homogenized in 10 ml. selenite broth, and three 20 ml. replicates of each homogenate inoculated
10 S.t. 4 S.t.
0
June
August
0
0
0
rtrt. 1 S.s.
9 S.s. 4
2 S.s. 5 S.s.
rh.
2 S.t.
0 0
0 W = Wheat S = Sorghum M = Maize S.t. = Salmonella typhimurium S.s. = Salmonella Singapore S.a. = Salmonella anatum S.d. = Salmonella derby S.o. = Salmonella oranienberg S.se. = Salmonella senftenberg
November
October
September
July
1 S.t. 1 S.t. 0
9 S.t.
May
April
March
0 1 S.t. 4 S.t. 8 S.t.
w
January February
Grain (12 samples) S
0
0
1 S.t. 0
9 S.s. 3 S.s.
9 S.s.
3 S.s. 7 S.s.
0 0
3 S.t.
39 (36 S.t. ( 1 S.a. ( 1 S.d. ( 1 S.se. 12(11 S.t. (1 S.o. 12(11 S.t. (1 S.o. 2 ( 1 S.t. (1 S.o. 0 1 S.t.
1 S.t.
1 S.t.
5 S.t.
50 S.t.
5 (3 S.t. (2 S.s.
50 S.t.
7 S.t.
1 S.t.
36 S.t.
60 S.t.
1 S.t. 1 S.t.
Breeder litter (12 samples)
10 S.t. 12 S.t.
Breeder rations (144 samples)
3 S.t.
2 S.t.
0
0
1 S.t.
0
0
0
1 S.t.
7 S.t.
5 S.t.
0
9 S.t.
2 S.t.
2 S.t.
0 0
Breeder carrier birds (10 samples)
3 (2 S.t. (1 S.s.
3 S.t.
1 S.t. 1 S.t.
Breeder nest boxes (6 samples)
4
3
3
2
(3
De fr
No. of samples positive for Salmonella
TABLE 1.—Salmonella isolations during a 9-month breeding cy
loaded from http://ps.oxfordjournals.org/ at UCSF Library on April 11, 2015
SALMONELLA TRANSMISSION
medium at 37° C. for 24 hours, and tested for Salmonella polyvalent " 0 " and " H " serum agglutination, hydrogen sulphide, urease, lysine decarboxylase and indole production and glucose, sucrose, lactose, mannitol, maltose and salicin fermentation. Cultures identified as salmonellae were sent to the Salmonella Reference Laboratory, Adelaide, for typing. RESULTS AND DISCUSSION
the time the infected eggs were laid revealed a sudden increase in Salmonella isolation rate in litter and nest box material and carrier birds during the same months. This corresponded with an abnormally high isolation rate of Salmonella from the breeder feed, and from grain samples arriving at the feed mill. Subsequent investigation revealed a plague of rodents in the grain-growing area during the months March to August, the period in which heavy grain contamination was recorded. This indicated that the rodents were the most likely source of Salmonella contamination in the grain; this was supported by several isolations of Salmonella typhimurium cultures from rat faeces obtained from the grain farms during the period. As the microbiological quality of the grains improved from August onwards, with a suppression of the rodent menace, a significant decrease was noted in isolations of Salmonella from breeder feed, litter and nest box samples, carrier birds, dead-in-shell embryos and day-old broiler flocks, indicating a direct correlation between Salmonella levels in the poultry organisation and contamination of the grains with Samonella. The results of bacteriologic examination of caecae from broiler flocks on processing 8-9 weeks after hatch indicated a similar correlation between contaminated grains fed to breeder hens and the Salmonella carrier status of broiler caecae at processing. The predominant serotype isolated from breeder rations, carrier birds, litter and nest box samples, dead-in-shell embryos, day-old flocks and carcase caecae was S. typhimurium; S. Singapore also occurred frequently, but to a lesser extent. These were also the serotypes detected consistently in the grain samples during the problem period. A number of other serotypes including S. oranienberg, S. anatum, S. senftenberg and S. derby were also detected during this period, and probably originated from the meal constituents of the breeder feed.
Downloaded from http://ps.oxfordjournals.org/ at UCSF Library on April 11, 2015
The Salmonella status in a poultry organization was monitored regularly throughout the 9-month laying cycle of a breeder flock by examination of breeder farm litter and nest box samples, breeder carrier birds, dead-in-shell embryos, 4 day-old broiler flocks, caecae from processed broilers, breeder rations and grains, to determine the level of Salmonella in the infection chain (see Figure 1). Initial examination of samples during January and February for Salmonella revealed low levels of Salmonella in the grains, breeder feed, litter and nest boxes; no salmonellae were detected in breeder culled hens, deadin-shell embryos or chicks from 4 day-old broiler flocks (Table 1). In March, a significant increase occurred in the isolation rate of Salmonella from the grain constituents of the breeder feed, wheat, sorghum and maize; this was accompanied by a corresponding increase in isolation of Salmonella from the breeder feed, carrier birds and 4 day-old broiler flocks hatching from eggs laid during that period. During the months April to August, high mortalities occurred during the first week in a considerable number of broiler flocks. Results of bacteriologic examination of the flocks indicated that specimens collected from the flocks contained Salmonella typhimurium. Samples of dead-in-shell embryos from the hatches of the flocks were similarly found to be infected with Salmonella. An examination of the breeding farm status at
1117
1118
B. S. BAINS AND M. A. MAC KENZIE
From the results of this study it appears that salmonellae may be transmitted continuously through the grains to the breeder feed, to breeder parent stock, to day-old chicks, and thence to the finished product. The rapid dissemination of Salmonella through the infection chain may be controlled by routine monitoring of all aspects of the industry, allowing early detection of a problem area and thus preventing costly and undesirable hatching, day-old and product contamination losses.
to Mrs. H. Adam for able technical assistance throughout this work. REFERENCES Jackson, C. A. W., M. J. Lindsay and F. Shiel, 1971. A study of the epizootiology and control of Salmonella typhimurium infection in a commercial poultry organisation. Am. Vet. J. 47: 485-491. Morris, G. K., B. L. McMurray, M. M. Gatton and J. G. Wells, 1969. A study of the dissemination of Salmonellosis in a commercial broiler chicken operation. Am. J. Vet. Res. 30: 1413-1421.
The authors wish to express appreciation
A Rapid Technique for Extraction of Yolk Cholesterol K. W. WASHBURN ANDD. F. NIX 1
Department of Poultry Science, University of Georgia, Athens, Georgia 30602 (Received for publication September 20, 1973) ABSTRACT Modifications were made in the Folch (1956) procedure of extraction of cholesterol to obtain a simpler, more rapid extraction of egg yolk cholesterol with no loss of accuracy and repeatability. In the modified extraction procedure 15 ml. of 2:1 chloroformmethanol was added to 1 gm. egg yolk, the sample shaken by hand, 5 ml. of H 2 0 added and the sample again shaken by hand. After centrifugation, the removal of the aqueous-methanol layer and filteration of the chloroform layer, the cholesterol content of samples was determined. The amount of cholesterol extracted and recovered by the modified technique was significantly higher than when the original extraction procedure was used. The increased extraction was due both to the smaller volume of chloroform-methanol used in emulsification and to the method of shaking. Substitution of KC1 solution for water, or addition of sodium sulfate appeared to have no effect on the cholesterol extracted. The coefficient of variability for extractions obtained by the modified method was 9.8% compared to 29.9% for extractions obtained by the original procedure. POULTRY SCIENCE 53: 1118-1122, 1974
T
HE cholesterol content of egg yolk can be affected by a number of factors including temperature, season and dietary supplements. For example, Clarenburg et al. (1971) reported that yolk cholesterol could be lowered 35% by feeding a plant sterol, sitosterol. However, the genetic influence on the deposition of cholesterol in the egg may 1. Present address: Wayne Poultry, Georgia 30501.
Gainesville,
set the limits within which environmental manipulations can change it. A number of methods have been used for the extraction of yolk cholesterol. The fat extraction method of Folch et al. (1956) with the Zlatkis et al. (1953) colorimetric method for cholesterol determination has been used in a number of studies and has been found to provide reliable yolk cholesterol determinations. However, the time required in current methods of extraction of egg yolk makes
Downloaded from http://ps.oxfordjournals.org/ at UCSF Library on April 11, 2015
ACKNOWLEDGMENT
Provincial Traders Pry. Ltd., Box 10, P.O., Morningside, 4170 Brisbane, Queensland,
Australia
(Received for publication September 19, 1973)
ABSTRACT High mortality in infected broiler flocks was correlated with increased incidence of Salmonella in the grain constituents of the breeder rations. The Salmonella chain of infection was traced through the grain to breeder feed, breeder carrier birds, breeder farm litter and nest box materials, hatchery dead-in-shell embryos, day-old broilers and subsequently to the dressed broilers. Regular monitoring of these aspects of poultry production is suggested as a useful means of reducing Salmonella contamination levels in the integrated industry to a minimum. INTRODUCTION
P
ARATYPHOID is one of the most important bacterial diseases of poultry. Since salmonellosis is also an important public health disease, procedures in the poultry industry have recently been oriented towards the reduction, control, and eventual eradication of Salmonella from poultry flocks (Morris et al, 1969; Jackson et al., 1971). There are five major sources of Salmonella contamination in the industry—feed, carrier birds, litter, nest boxes and environment; a breakdown in any one source may lead to the reestablishment of the Salmonella chain of infection. The purpose of the present study was to determine the source, persistence and dissemination of Salmonella in an outbreak of salmonellosis in a commercial integrated poultry organization. EXPERIMENTAL PROCEDURE The poultry facility studied consisted of breeder and broiler farms located within an area approximately 80 km. in diameter. The feed mill, hatcheries and processing plant were located within the area but were well separated from each other to prevent crosscontamination between plants. Hatchery sanitation procedures were designed to minimize the possibility of multiplication and spread of contamination within the hatchery buildings. Regular microbiologi-
cal swabbing and sampling of fluff in the hatcheries ensured the maintenance of high standards of hygiene. Eggs for hatching were collected four times per day on the breeding farm; soiled eggs were not used for hatching. The eggs were fumigated on the farm within 1/2 hour of collection in a sealed room at 21° C. and 65% humidity for 20 minutes, using a mixture of formalin and potassium permanganate in a ratio of 140 ml. and 85 g. per 9 m.2 of fumigation room, respectively. The eggs were transported to the hatchery twice daily in a closed, fumigated vehicle. On receival at the hatchery the eggs were stored at 13-16° C. and 75-80% humidity. Prior to setting, the eggs were transferred into a preheating room and fumigated, as before, at an egg temperature of 24° C. The eggs were then set in the incubator. On transfer to the hatchers the eggs were again fumigated; henceforth until hatching, a continuous fumigation with formaldehyde in a 520 cm. 2 surface area pan was carried out. The hatcheries were washed and disinfected daily on all surfaces including belts, trolleys, tables, walls and floors. Disinfectant foot baths were provided at all entries to the building. Samples of litter from the breeding farm were obtained by collecting 5 kg. of litter from all sections of the shed weekly, using a sterile scoop. At the end of the month the
1114
Downloaded from http://ps.oxfordjournals.org/ at UCSF Library on April 11, 2015
POULTRY SCIENCE 53: 1114-1118, 1974
1115
SALMONELLA TRANSMISSION
Grains (Meals)"
Breeder Feed
into sterile jars containing 80 ml. of selenite broth. The flocks were examined on processing by collecting 300 caecae aseptically into separate sterile containers on the processing line, and selecting 30 random samples for slicing aseptically into 80 ml. of selenite broth in a sterile jar. Two kg. samples of all batches of breeder feed were taken with a sterile scoop into a sterile bag immediately upon production at the feed mill, and despatched to the laboratory. At the end of the month all samples were pooled, mixed thoroughly, and 144 replicate 20 g. samples taken at random with a sterile spatula for incubation in 80 ml. of selenite broth containing 6 ml. of a 10% Tergitol No. 7 detergent solution. Similarly, 2 kg. samples of all batches of grains were collected aseptically with a sterile scoop as the closed grain truck arrived at the feed mill, prior to unloading, to avoid any possibility of cross-contamination. The samples of grain were combined monthly, and twelve replicate 20 g. samples taken at random from each grain type into jars containing 80 ml. of selenite broth and 6 ml. of Tergitol No. 7 solution. The selenite broth samples were processed for Salmonella by incubating at 43° C. for 48 hours, plating onto brilliant green sulfapyridine (BGS) agar and incubating at 37° C. for 24 hours. Suspect Salmonella colonies were transferred to fresh plates of BGS
\ Breeder ' Carrier Birds^v»_
. Litter ' Nest Boxes
Caecae in /_ Processed Broilers FIG. 1. Salmonella chain of infection
>
Eg
• —T
\ Dead-In-Shells Day-old Chicks
Downloaded from http://ps.oxfordjournals.org/ at UCSF Library on April 11, 2015
samples were pooled and mixed thoroughly, and twelve 20 g. samples taken at random with a sterile spatula into sterile jars, each containing 80 ml. of selenite broth. Similarly, 1 kg. of nest box material was collected from the nest boxes weekly, the samples combined at the end of the month, and six 20 g. samples taken at random into sterile jars containing 80 ml. of selenite broth. Breeder carrier birds were examined for Salmonella by autopsying two cull birds collected on the farm during the month, and pooling samples of a) heart, liver, spleen and kidney, and b) intestine and caecum, taken aseptically from each bird into sterile jars containing 80 ml. of selenite broth. Samples of dead-in-shell embryos were taken by collecting 300 unhatched embryos from the hatchery once per month and selecting 30 embryos at random for bacteriological examination. The eggs were swabbed with 70% alcohol, and the embryo extracted aseptically into a sterile jar, homogenized in 10 ml. selenite broth, and incubated in 80 ml. of selentite broth. Samples of all day-old broiler flocks placed were examined routinely for Salmonella at 4 days of age in the laboratory. Fifty culls from each flock were autopsied, pooling the hearts, livers, spleens and kidneys, and the intestine and caecae, into separate sterile containers. The specimens were homogenized in 10 ml. selenite broth, and three 20 ml. replicates of each homogenate inoculated
10 S.t. 4 S.t.
0
June
August
0
0
0
rtrt. 1 S.s.
9 S.s. 4
2 S.s. 5 S.s.
rh.
2 S.t.
0 0
0 W = Wheat S = Sorghum M = Maize S.t. = Salmonella typhimurium S.s. = Salmonella Singapore S.a. = Salmonella anatum S.d. = Salmonella derby S.o. = Salmonella oranienberg S.se. = Salmonella senftenberg
November
October
September
July
1 S.t. 1 S.t. 0
9 S.t.
May
April
March
0 1 S.t. 4 S.t. 8 S.t.
w
January February
Grain (12 samples) S
0
0
1 S.t. 0
9 S.s. 3 S.s.
9 S.s.
3 S.s. 7 S.s.
0 0
3 S.t.
39 (36 S.t. ( 1 S.a. ( 1 S.d. ( 1 S.se. 12(11 S.t. (1 S.o. 12(11 S.t. (1 S.o. 2 ( 1 S.t. (1 S.o. 0 1 S.t.
1 S.t.
1 S.t.
5 S.t.
50 S.t.
5 (3 S.t. (2 S.s.
50 S.t.
7 S.t.
1 S.t.
36 S.t.
60 S.t.
1 S.t. 1 S.t.
Breeder litter (12 samples)
10 S.t. 12 S.t.
Breeder rations (144 samples)
3 S.t.
2 S.t.
0
0
1 S.t.
0
0
0
1 S.t.
7 S.t.
5 S.t.
0
9 S.t.
2 S.t.
2 S.t.
0 0
Breeder carrier birds (10 samples)
3 (2 S.t. (1 S.s.
3 S.t.
1 S.t. 1 S.t.
Breeder nest boxes (6 samples)
4
3
3
2
(3
De fr
No. of samples positive for Salmonella
TABLE 1.—Salmonella isolations during a 9-month breeding cy
loaded from http://ps.oxfordjournals.org/ at UCSF Library on April 11, 2015
SALMONELLA TRANSMISSION
medium at 37° C. for 24 hours, and tested for Salmonella polyvalent " 0 " and " H " serum agglutination, hydrogen sulphide, urease, lysine decarboxylase and indole production and glucose, sucrose, lactose, mannitol, maltose and salicin fermentation. Cultures identified as salmonellae were sent to the Salmonella Reference Laboratory, Adelaide, for typing. RESULTS AND DISCUSSION
the time the infected eggs were laid revealed a sudden increase in Salmonella isolation rate in litter and nest box material and carrier birds during the same months. This corresponded with an abnormally high isolation rate of Salmonella from the breeder feed, and from grain samples arriving at the feed mill. Subsequent investigation revealed a plague of rodents in the grain-growing area during the months March to August, the period in which heavy grain contamination was recorded. This indicated that the rodents were the most likely source of Salmonella contamination in the grain; this was supported by several isolations of Salmonella typhimurium cultures from rat faeces obtained from the grain farms during the period. As the microbiological quality of the grains improved from August onwards, with a suppression of the rodent menace, a significant decrease was noted in isolations of Salmonella from breeder feed, litter and nest box samples, carrier birds, dead-in-shell embryos and day-old broiler flocks, indicating a direct correlation between Salmonella levels in the poultry organisation and contamination of the grains with Samonella. The results of bacteriologic examination of caecae from broiler flocks on processing 8-9 weeks after hatch indicated a similar correlation between contaminated grains fed to breeder hens and the Salmonella carrier status of broiler caecae at processing. The predominant serotype isolated from breeder rations, carrier birds, litter and nest box samples, dead-in-shell embryos, day-old flocks and carcase caecae was S. typhimurium; S. Singapore also occurred frequently, but to a lesser extent. These were also the serotypes detected consistently in the grain samples during the problem period. A number of other serotypes including S. oranienberg, S. anatum, S. senftenberg and S. derby were also detected during this period, and probably originated from the meal constituents of the breeder feed.
Downloaded from http://ps.oxfordjournals.org/ at UCSF Library on April 11, 2015
The Salmonella status in a poultry organization was monitored regularly throughout the 9-month laying cycle of a breeder flock by examination of breeder farm litter and nest box samples, breeder carrier birds, dead-in-shell embryos, 4 day-old broiler flocks, caecae from processed broilers, breeder rations and grains, to determine the level of Salmonella in the infection chain (see Figure 1). Initial examination of samples during January and February for Salmonella revealed low levels of Salmonella in the grains, breeder feed, litter and nest boxes; no salmonellae were detected in breeder culled hens, deadin-shell embryos or chicks from 4 day-old broiler flocks (Table 1). In March, a significant increase occurred in the isolation rate of Salmonella from the grain constituents of the breeder feed, wheat, sorghum and maize; this was accompanied by a corresponding increase in isolation of Salmonella from the breeder feed, carrier birds and 4 day-old broiler flocks hatching from eggs laid during that period. During the months April to August, high mortalities occurred during the first week in a considerable number of broiler flocks. Results of bacteriologic examination of the flocks indicated that specimens collected from the flocks contained Salmonella typhimurium. Samples of dead-in-shell embryos from the hatches of the flocks were similarly found to be infected with Salmonella. An examination of the breeding farm status at
1117
1118
B. S. BAINS AND M. A. MAC KENZIE
From the results of this study it appears that salmonellae may be transmitted continuously through the grains to the breeder feed, to breeder parent stock, to day-old chicks, and thence to the finished product. The rapid dissemination of Salmonella through the infection chain may be controlled by routine monitoring of all aspects of the industry, allowing early detection of a problem area and thus preventing costly and undesirable hatching, day-old and product contamination losses.
to Mrs. H. Adam for able technical assistance throughout this work. REFERENCES Jackson, C. A. W., M. J. Lindsay and F. Shiel, 1971. A study of the epizootiology and control of Salmonella typhimurium infection in a commercial poultry organisation. Am. Vet. J. 47: 485-491. Morris, G. K., B. L. McMurray, M. M. Gatton and J. G. Wells, 1969. A study of the dissemination of Salmonellosis in a commercial broiler chicken operation. Am. J. Vet. Res. 30: 1413-1421.
The authors wish to express appreciation
A Rapid Technique for Extraction of Yolk Cholesterol K. W. WASHBURN ANDD. F. NIX 1
Department of Poultry Science, University of Georgia, Athens, Georgia 30602 (Received for publication September 20, 1973) ABSTRACT Modifications were made in the Folch (1956) procedure of extraction of cholesterol to obtain a simpler, more rapid extraction of egg yolk cholesterol with no loss of accuracy and repeatability. In the modified extraction procedure 15 ml. of 2:1 chloroformmethanol was added to 1 gm. egg yolk, the sample shaken by hand, 5 ml. of H 2 0 added and the sample again shaken by hand. After centrifugation, the removal of the aqueous-methanol layer and filteration of the chloroform layer, the cholesterol content of samples was determined. The amount of cholesterol extracted and recovered by the modified technique was significantly higher than when the original extraction procedure was used. The increased extraction was due both to the smaller volume of chloroform-methanol used in emulsification and to the method of shaking. Substitution of KC1 solution for water, or addition of sodium sulfate appeared to have no effect on the cholesterol extracted. The coefficient of variability for extractions obtained by the modified method was 9.8% compared to 29.9% for extractions obtained by the original procedure. POULTRY SCIENCE 53: 1118-1122, 1974
T
HE cholesterol content of egg yolk can be affected by a number of factors including temperature, season and dietary supplements. For example, Clarenburg et al. (1971) reported that yolk cholesterol could be lowered 35% by feeding a plant sterol, sitosterol. However, the genetic influence on the deposition of cholesterol in the egg may 1. Present address: Wayne Poultry, Georgia 30501.
Gainesville,
set the limits within which environmental manipulations can change it. A number of methods have been used for the extraction of yolk cholesterol. The fat extraction method of Folch et al. (1956) with the Zlatkis et al. (1953) colorimetric method for cholesterol determination has been used in a number of studies and has been found to provide reliable yolk cholesterol determinations. However, the time required in current methods of extraction of egg yolk makes
Downloaded from http://ps.oxfordjournals.org/ at UCSF Library on April 11, 2015
ACKNOWLEDGMENT