Studies in Hatchery Sanitation

Studies in Hatchery Sanitation 3. THE EFFECT OF AIR-BORNE BACTERIAL POPULATIONS ON CONTAMINATION OF EGG AND EMBRYO SURFACES S. E. MAGWOOD 1 Canada, Department of Agriculture, Hull, Quebec (Received for publication May 22, 1964)

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ARGE air-borne bacterial populations J have been revealed in hatcheries through the use of air sampling equipment and these have been regarded as indicators of the sanitary status of the operation; Anonymous (1960), Chute and Gershman (1961) and Gentry et al. (1962). Little is known, however, of the ecology of these airborne microorganisms; what is their role in initiating contamination of eggs and embryos; where are the reservoirs of contamination; where does multiplication occur? Magwood and Marr (1964) in describing a simplified bacteriological-statistical technique for assessing bacterial populations on surfaces in hatcheries, observed that air-borne bacterial counts were proportional to those of horizontal surfaces such as floors and table tops. Because of their relatively large area these surfaces were believed to harbor the major reservoir of contamination. They speculated that the organisms became air-borne from employee activity and were drawn into the hatchers where they multiplied during hatching. They were expelled from the hatching machines on dust and fluff and again settled on horizontal surfaces. This cycle would then be repeated during successive hatches. This hypothesis is supported by the results of a detailed investigation, herein

1 Animal Pathology Division, Health of Animals Branch, Canada Department of Agriculture, Animal Diseases Reserach Institute, Hull, P. Q.

reported, of the effect of small and of large air-borne bacterial populations on the amount of contamination of the setting and hatching machines, eggs and birds through a series of hatches. MATERIALS AND METHODS Hatcheries. Two hatcheries whose sanitary state was known were selected for this study. One had low bacterial counts of the air and the other regularly had high counts. They are termed respectively the "clean" and the "contaminated" hatchery or air as indicated by the context. The clean hatchery comprised a Brower Humidaire 300-A setter and 300-A hatcher together with two Leahy Favorite Model 624 hatchers of 500-egg capacity each. All were housed in a single room. The contaminated hatchery was in an upstairs room of a building which was used for growing chickens to laying age. The incubators were two single-stage Jamesway machines, one Model 1080 and one Model 252. Egg supply. Chicken eggs were received from one of the laboratory flocks which supplied eggs for virus studies. Turkey eggs were received from other laboratory flocks. The chicken eggs were gathered several times daily and the turkey eggs usually once daily. They were maintained in an egg cooler at approximately 15°C. until setting time. No fumigation or washing was practiced on any of the eight ex-

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perimental hatches; three of these were turkeys and five were chickens. Air sampling. The air sampling technique described previously by Magwood (1964) employed a Technical Development Laboratory slit sampler which on calibration passed 1.07 cubic feet of air per minute. The air-borne populations were graded 0, 1, 2 and 3 according to the system of Gentry et al. (1962). Bacteriological-statistical technique. The method for estimating bacterial counts of surfaces has been described by Magwood and Marr (1964) and, in brief consisted of the following steps. A square inch of a selected surface, as demarcated by a wire template, was wiped with a buffer-moistened cotton swab. The soiled portion of the swab was then applied over a quadrant of a plate of trypticase glucose extract agar (Baltimore Biological Laboratories). A total of 8 or 12 areas representative of the surface were sampled. The dry surface of concrete floors was lightly sprayed with a buffer solution before the swabbing and the individual areas examined on floors was smaller, being only one-quarter inch square. After incubation of the plates in air at 37°C. for 24 hours the mean counts and 95% confidence limits were determined employing specially constructed nomograms as described by Magwood and Marr (1964). The mean colony counts per square inch of surface (0.06 square inch on floors) were the values plotted on the charts in Figure 1, except in three instances as illustrated by the following example. A mean count of 98 and upper and lower limits of 65 and 143 were considered to represent a mean count in excess of 100 and were plotted on the 100-300 line. Setting and hatching environments. The two hatcheries were utilized to provide

the following environments or sequence of environments for setting and hatching: Exp. 1. set and hatched in clean air; Exp. 2. set and hatched in contaminated air; Exp. 3. set in clean air, hatched in contaminated air; Exp. 4. set in contaminated air and hatched in clean air. Two separate settings were incubated and hatched in each combination of environments. The chicken and turkey eggs were allotted to the experiments in order to aid in defining the effects of the environmental contamination. For example, chicken eggs which were known to have fewer bacteria on the surface than the turkey eggs, were used in Experiments 1 and 3 to minimize the addition of bacteria on the eggs to the clean surroundings. Any "build-up" which might be observed could be attributed to the environment. Conversely, in measuring the effect of successive contaminated then clean environments in Experiment 4, turkey eggs were employed to ensure that the bacterial counts on the eggs would be sufficiently high that either a decline in the counts or the failure of a "build-up" to occur during hatching could be more readily observed. Eggs were transferred from one hatchery to another, when this was required, on the 18th day of incubation and they were then placed in the hatchers. An exception was in the case of Exp. 4 when it was necessary to move the eggs to the clean hatchery before the mid-term examination period. Surfaces swabbed. Surfaces were swabbed at the following periods: at the time of setting (S); at the 10th day which was approximately mid-way in the setting period (M); at the time of transfer to the hatchers (T); early in the hatch when approximately 20% of the chicks were hatched (EH); and, late in the hatch (LH) immediately preceding removal of the birds from the hatchers. The following

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i M T EH LH EGG SHELL SURFACE

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S M T EH LH SHELL MEMBRANE OUTER SURFACE

S M T EH LH SHELL MEMBRANE INNER SURFACE

»' • M T EH LH CHICK BACKS

HATCHING: CLEAN AIR

HATCHING: CONTAMINATED AIR

SETTING: CONTAMINATED AIR

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SETTING: CLEAN AIR

SETTING AND HATCHING: CONTAMINATED AIR

SETTING AND HATCHING: CLEAN AIR

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S M T EH LH INCUBATOR WALLS AND TRAY SIDES

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rt=T:

M T R FL

FIG. 1. Bacterial populations at intervals during setting and hatching in four different hatchery environm set in the incubators (S), ten days later mid-way through the incubation period (M), on the eighteenth day w early in the hatching period (EH) and late in the hatching period (LH). The air-borne bacterial population tem of Gentry el al. (1962).

0-2

30-100 10-30 3-9

300-1000 100-300

1000 +

PIPPED UNHATCHED EGGS WERE EXAMINED TURKEY EGGS

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surfaces were examined: egg shell surfaces, outer and inner surfaces of the shell membrane, chick backs, incubator and hatcher trays and walls, and, the room floors. Most of these hatches were involved in other studies and large numbers of eggs could not be sacrificed. For this reason sampling of egg membranes was conducted only at essential periods. Bacterial counts were made of the air in the room and in the incubator or hatcher at each sampling period. RESULTS AND DISCUSSION

The counts of all the surfaces were markedly influenced by each environment as shown by the series of graphs in Figure 1. When the complete cycle of setting and hatching (Exp. 1) was in clean air the counts on the chicken egg shells which were low at setting time continued low. Reading the row of graphs from left to right it is striking that all the surfaces remained nearly sterile throughout the setting and hatching cycle except that the concrete floor had moderate counts. In contrast, in contaminated air (Exp. 2) the separate chicken and turkey hatches gave results which differed from one another at some periods. The initial counts on the chicken eggs were higher than in Exp. 1, probably due to air-borne dust collecting on them, prior to setting, while preparations were being made for the swabbing. These counts fell from the 100-300 range to 30-100 and then to the 10-30 range at the transfer (T) and early hatch (EH) samplings respectively. During hatching they rose abruptly on all surfaces. A comparable dip and rise is evident in the air sample counts at these periods. In explanation, the weather was very warm at this time and the room doors and windows were opened wide in an attempt to maintain proper temperatures. The free flow of clean outdoors air through the room likely was the reason for the tem-

porary reduction in the counts. The turkey eggs in Exp. 2 were incubated at a different time and, not being exposed to the "clean air-wash," maintained high counts throughout the cycle after a slight initial decline. This seemingly anomalous decline in the chicken egg counts actually demonstrates the effect of a large volume of clean air which has temporarily driven out the contaminated air. The duration of the "airing" was probably insufficient to reduce the counts of the incubator walls and tray sides as these persisted at their usual levels. When the cycle was divided as shown in Exp. 3 and eggs which had been set in clean air and had low counts, were transferred to hatch in contaminated air, high counts were observed on all of the surfaces subsequent to the transfer. On the other hand, in Exp. 4, when the eggs were set in contaminated air and hatched in clean air, the high counts on the shell surfaces which were observed during the setting period dropped markedly after transfer to the clean hatchery and low counts then prevailed on all of the surfaces. The probable fate of the bacteria on eggs was also investigated. That these counts of egg shell surfaces rose or fell according to the counts of the environmental air is apparent from the graphs. The persistence of high counts in a contaminated hatchery was not surprising and attention can be focussed on the conditions under which low counts were achieved. The counts on chicken eggs when set in clean air were very low for new-laid eggs and reflected the special care they received. However, when set in or transferred to contaminated air as in Exps. 2 and 3 the counts rose quickly and persisted at high levels. The opposite effect was shown on the turkey eggs in Exp. 4. These eggs had counts in the 300-1000 range which are comparable to those found by Magwood (1964) on chicken

CONTAMINATION BY AIR-BORNE BACTERIA

eggs at commercial hatcheries. After one week's incubation in the contaminated air, the turkey eggs were moved to clean air. The counts determined three days later were very low, indicating that the bacteria perished quickly. If some penetrated the shell membrane they failed to multiply in the eggs because under the conditions of these trials bacteria were not recovered from the inner surfaces of the membranes adhering to the shell at any time before hatching. Therefore the fate of the bacteria on the turkey eggs, both on the shell and on the outer surface of the shell membrane, was failure to survive in clean setters. That setters provide an adverse environment for bacterial survival on egg shells has been reported by Magwood and Marr (1964) and is supported by the observation of Lancaster and Crabb (1953) who found that experimental Salmonella contamination disappeared rapidly from the surface of eggs under normal incubator conditions. Thus, eggs which are sufficiently clean to be generally acceptable to hatcheries, and this does not include very dirty or improperly washed eggs, are "automatically" almost freed of bacteria during incubation in a clean setter. At the time of hatching, air-borne bacteria have easy access to a generous, if temporary, food supply in the nutritious fluids which surround the hatching birds. If these bacteria are few in number, and the hatching period is not unduly prolonged, the resulting build-up in numbers of bacteria is relatively small. On the other hand, if the air-borne inoculum is large as in Exps. 2 and 3 the bacterial populations rise abruptly while the food and moisture is adequate on the shell membranes and associated structures. As the birds dry off the organisms become air-borne on dust and fluff particles leading to increased counts of the environmental air and subsequently of the hori-

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zontal surfaces. The key factor is simple cleanliness and the size of the air-borne inoculum is directly related to it. These findings have been applied experimentally in reducing the bacterial exposure of hatching embryos under commercial conditions. The air-borne pollution arising from floors was reduced by regular washings with a disinfectant solution. The effects of this measure on minimizing the bacterial exposure of newlyhatched birds will be reported separately. The efficacy of sanitation programs may be increased by recognizing that airborne bacteria carried on dust particles are directly related to the degree of contamination of hatches; that these particles spread rapidly from to room in a hatchery and when left to accumulate on horizontal surfaces provide a major source of contamination for future hatches. Adequate clean-up and sanitation programs must include the rapid, timely and regular elimination of these dust particles throughout the hatchery. SUMMARY

The effect of small and of large airborne bacterial populations on the degree of contamination of eggs, shell membranes and other surfaces was studied during incubation and hatching. A direct relationship was observed between the air-borne population and the degree of contamination of the various surfaces. In clean air the bacterial counts of egg shells dropped quickly and low counts persisted on all surfaces to the completion of hatching. When this procedure was reversed the counts on eggs at transfer, which previously had been high, decreased quickly enough that low counts prevailed to the completion of hatching. These findings indicate that, in order to minimize bacterial contamination of eggs and hatching birds, the hatchery premises must be kept free of reservoirs of con-

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tamination which readily become airborne. ACKNOWLEDGMENTS

The author is indebted to: Mr. M. S. Mitchell, Chief, Production Section, Poultry Division, Canada Department of Agriculture and his officers for assistance; Drs. K. Malkin and A. I. Swann for conducting some of the work and Messrs. E. Moreau, U. St-Jacques and E. Sally for technical assistance. The bio-Graphic unit of the Department prepared the chart. REFERENCES Anonymous, 1960. Report on the Animal Health Services in Great Britain, 1958. London, Her

Majesty's Stationery Office, 76-77. Chute, H. L., and M. Gershman, 1961. A new approach to hatchery sanitation. Poultry Sci. 40: 568-571. Gentry, R. F., M. Mitrovic and G. R. Bubash, 1962. Application of Andersen sampler in hatchery sanitation. Poultry Sci. 41: 794-804. Lancaster, J. E., and W. E. Crabb, 1953. Studies on disinfection of eggs and incubators I. The survival of Salmonella pullorum, thompson and typhimurium on the surface of the hen's egg and on incubator debris. Brit. Vet. J. 109:139-148. Magwood, S. E., 1964. Studies in hatchery sanitation. 1. Fluctuation in microbial counts of air in poultry hatcheries. Poultry Sci. 43: 441-449. Magwood, S. E., and H. Marr, 1964. Studies in hatchery sanitation. 2. A simplified method for assessing bacterial populations on surfaces within hatcheries. Poultry Sci. 43: 1558-1566.

A Comparison of Cooking Methods for Boneless Turkey Rolls and Bars1 JACK L. FRY, 2 GRAYCE E. GOERTZ, M. HAL TAYLOR AND ANNA S. HOOPER Kansas State University, Manhattan (Received for publication May 28, 1964)

INTRODUCTION

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ARGE scale processing of ready-toJ cook, whole turkeys into turkey rolls and other convenient forms is developing rapidly. Providing convenient foods is a way to increase per capita consumption of turkey and offers lower transportation costs, less storage space, shorter cooking time, and better portion control. Turkey rolls are available in most areas either raw frozen or pre-cooked. Turkey rolls also may be prepared from ready-to-cook, whole turkeys.

1 Contribution No. 281, Department of Poultry Science and Contribution No. 264, Department of Home Economics (Foods and Nutrition), Kansas Agricultural Experiment Station, Manhattan. 2 Present address: Poultry Science Dept., Univ. of Florida, Gainesville, Florida.

For turkey rolls to be acceptable, they must be competitively priced and be satisfactory in organoleptic qualities. Palatability of roasted light meat turkey rolls was reported by Augustine el al. (1962) as similar to roasted whole turkeys. In a study of end point temperature and oven temperatures (250°, 300° and 350°F.) Marquess el al. (1963) found that cooking losses of light meat rolls dry roasted to either 176° or 185°F. increased with increasing end point temperature and oven temperature. Cooking time of dark meat rolls dry roasted to either 185° or 194°F. increased with increased end point temperature, but cooking losses or yields were not significantly affected. Light meat rolls cooked at 250°F. were scored higher in flavor than those cooked at other temperatures; otherwise no significant dif-