Effects of Dietary Lactose on Incidence and Levels of Salmonellae on Carcasses of Broiler Chickens Grown to Market Age12

Effects of Dietary Lactose on Incidence and Levels of Salmonellae on Carcasses of Broiler Chickens Grown to Market Age 1 2 AMY L. WALDROUP, WAKAKO YAMAGUCHI, JAMES T. SKINNER, and PARK W. WALDROUP Animal and Poultry Sciences Department, University of Arkansas, Fayetteville, Arkansas 72701

ABSTRACT Two trials were conducted to evaluate the effects of lactose in the diet of broilers grown to market weights on incidence and levels of salmonellae on the carcass. Lactose was substituted for sand in otherwise nutritionally complete diets at levels of 0,2.5,5, and 7.5% and fed from day-old to 49 days of age. Birds were reared on used (Trial 1) or new (Trial 2) litter and inoculated via the drinking water on Days 2, 7, and 14 with 108 cfu/mL Salmonella typhimurium (ATCC 14028). At 50 days, 12 (Trial 1) or 24 (Trial 2) birds per treatment were processed and prechill carcasses were evaluated for salmonellae incidence and level by the most probable number (MPN) method. Body weight of male broilers was significantly reduced by feeding diets containing up to 7.5% lactose. Feed intake of broilers fed diets containing lactose was significantly reduced and feed utilization improved, suggesting that lactose provided some metabolizable energy. The degree of litter caking was significantly increased, and cecal pH was significantly decreased as dietary lactose increased. Prechill carcasses of broilers fed diets with 7.5% lactose had significantly higher levels of salmonellae than did prechill carcasses of broilers fed 0% lactose. The results of the present study suggest that supplementing poultry diets with lactose is not a viable means in itself of reducing or eliminating salmonellae incidence or levels on processed broiler carcasses. (Key words: Salmonella, lactose, carcasses, processing, food safety) 1992 Poultry Science 71288-295

tissues are carbohydrate in nature, and treatment with an appropriate carbohyNumerous studies have been conducted drate may prevent effective attachment by in efforts to decrease salmonellae contami- obstructing adhesion or the attachment nation of broiler carcasses during produc- site (Bitton and Marshall, 1980; Ofek and tion and processing. One approach is Beachey, 1980; Abraham et ah, 1983). preventing attachment of salmonellae in Recent in vitro studies suggest that adherthe intestine and cecae or on the surface of ence of Salmonella typhimurium to the the carcass by various physical or chemical means. Most bacterial attachment intestine of day-old chicks and to the cecae mechanisms and receptor sites on animal of 7- to 10-day-old broilers is inhibited by d-mannose (McHan et ah, 1989; Oyofo et ah, 1989a,b,c) or lactose (Corrier et ah, 1990a,b; Hinton et ah, 1990; Ziprin et ah, •'Published with the approval of the director, Ar- 1990). kansas Agricultural Experiment Station. Salmonellae colonization of the chick is Supported through a USDA Cooperative State Research Service Special Research Grants Program most likely to occur during the first few weeks of life (Smith and Tucker, 1980; (8902384). INTRODUCTION

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(Received for publication August 13, 1991)

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was assumed that lactose 4 provided no energy to the diet (Atkinson et al., 1957; Moran, 1985) and was nutritionally inert; therefore the energy content of the diet was reduced slightly below that normally observed in commercial United States broiler diets so as not to require excessive levels of supplemental fats. The ratio of energy to essential nutrients suggested by Thomas et al. (1986) was maintained. Complete vitamin and trace mineral mixtures that met the requirements suggested by the National Research Council (1984) were used to supplement all diets. Diets were formulated for starter (0 to 21 days), grower (21 to 42 days), and finisher (42 to 49 day) periods. Salinomycin 5 (66 m g / k g ) MATERIALS AND METHODS was added to starter and grower diets as an anticoccidial. Composition of the diets In two consecutive trials, sexed day-old is shown in Table 1. chicks of a commercial broiler strain 3 were A large batch of each feed was mixed obtained from a local hatchery and 60 chicks (30 males and 30 females) were for each feeding period and aliquots used randomly allocated into each of 16 pens for mixing test diets. Lactose was included (5.2 m 2 ) in an insulated broiler house with in test diets at 0, 2.5, 5.0, or 7.5%; washed concrete floors. In the first trial the pens builder's sand was used as an inert filler contained previously used oak shavings as needed. Diets were fed in meal form. Each diet was assigned to four replicate with a top dressing of new oak shavings; pens of chickens in each trial in a randomin the second trial the pens contained an ized block design; diets and tap water equal mixture of new rice hulls and new were given for ad libitum consumption. pine shavings. Each pen was equipped Samples of diets were subjected to Kjelwith two hanging feeders and an auto- dahl assay for crude protein (Association matic waterer; during the first 7 days of Official Agricultural Chemists, 1970) to supplemental feeders and waterers were verify proper mixing; all diets were found used. Whole-house brooding was used to be within expected values for crude with minimum temperatures set at 30 C protein. for the 1st wk, with a reduction of 2.8 C / On Days 2, 7, and 14, birds were wk to a minimum of 19.2 C. ThermostatiSalmonella typhimurium cally controlled gas stoves, ventilation inoculated with 6 (ATCC 14028) via the drinking fountains fans, and sidewall curtains were used to as described by Izat et al. (1990a,b,c). This maintain proper temperature and ventilaprocedure, utilizing this organism, has tion rates. Incandescent lights were used been shown to result in a high percentage 23 h daily (0100 to 2400 h). of colonized birds (Izat et al, 1990a,c). Diets were formulated to meet a miniAt 21, 42, and 49 days of age, the mum of 105% of the amino acid needs chickens in each pen were group-weighed suggested for the broiler male by Thomas by sex and pen feed consumption was et al. (1986). For formulation purposes it determined. Feed utilization was calculated as feed consumed divided by body weight. Deaths were noted as they oc3 Cobb 500, Cobb-Vantress, Inc., Siloam Springs, curred; all birds that died were weighed and the weight of dead birds used in AR 72761. 4 Lactose provided by Milk Specialties Co., Dun- determining feed utilization. dee, IL 60118. Samples of birds were taken at 21 (Trial ^io-Cox, Agri-Bio Corp., Gainesville, GA 30503. American Type Culture Collection, Rockville, 2) and 49 (both trials) days of age for determination of cecal weight and p H of MD 20852. DeLoach, 1989; Ziprin et al, 1989). Intervention during this time may reduce salmonellae contamination of processed broiler carcasses at market age. However, chickens are continually exposed to salmonellae from many sources throughout their growing period and interference with intestinal colonization per se may not necessarily reduce the incidence of salmonellae contamination of the carcass. Therefore, the objective of the present study was to evaluate the effects of feeding lactose to broilers from day-old to market weight on performance and salmonellae incidence and levels of processed broiler carcasses.

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WALDROUP ET AL. TABLE 1. Composition and calculated nutrient content of experimental diets

Ingredients and calculated nutrient content

Grower (21 to 42 days)

Finisher (42 to 49 days)

50.62 30.12 6.69 2.33 1.45 .40 .09 .20 .50 .10 7.50 100.00

51.16 29.23 7.45 2.14 1.35 .40 .00 .17 .50 .10 7.50 100.00

59.77 21.36 7.00 1.99 1.27 .40 .00 .11 .50 .10 750 100.00

2,975 19.57 1.12 56 1.32 1.15 .52 .85 .75

3,030 19.09 1.04 .52 1.29 1.05 .48 .81 .74

3,085 16.11 .97 .48 1.05 .83 .39 .68 .62

Provides per kilogram of diet: vitamin A, 9,900 IU; cholecalciferol, 3,300 ICU; vitamin E, 13 IU; menadione, 1.1 mg; riboflavin, 6.6 mg; niacin, 66 mg; pantothenic acid, 16.5 mg; choline, 660 mg; thiamin, 1.1 mg; pyridoxine, 3.3 mg; vitamin Bj2, -013 mg; biotin, .11 mg; folic acid, 1.1 mg; ethoxyquin, 125 mg; selenium, .2mg. 2 Provides per kilogram of diet: Fe, 100 mg; Mn, 100 mg; Zn, 100 mg; Cu, 10 mg; I, 1 mg. 3 Consists of variable amounts of lactose or washed builder's sand.

cecal contents. At each age period, three females from each pen were randomly selected with the proviso that they were within one half standard deviation of the sexed mean weight. The birds were killed by cervical dislocation, and the cecae were removed and weighed. The contents of the cecae were removed, placed in an equal part by weight of distilled water, shaken with glass beads, and the p H determined. At 50 days of age the birds were removed from the pens and a subjective Utter score was assigned to each pen; the scores were based upon percentage of the surface area of the pen that was caked over. Three (Trial 1) or six (Trial 2) males from each replicate pen (12 or 24 per

'Cervin Automated Systems, Inc., Minneapolis, MN 55410. Pickwick Co., Cedar Rapids, 1A 52402.

treatment for Trials 1 and 2, respectively) that were within one-half standard deviation of the sexed mean weight were processed in a pilot processing plant. Eight hours prior to processing, feed (but not water) was withdrawn. Birds were placed in clean coops and transported 4 k m to the processing plant where they were processed within 1 h. Birds were stunned by an electric knife/ killed by severing the jugular vein, allowed to bleed for 90 s, scalded for 2 min in clean hot water at 60 C, and picked in a rotary d r u m picker. 8 The carcasses were manually eviscerated, taking care not to contaminate the carcass with intestinal material. All birds within a single treatment were processed as a group, with the treatments processed in random order, determined by lot. The processing equipment and the evisceration area were cleaned and disinfected between treatments, and fresh scald water was used for each treatment group.

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Ground yellow corn Dehulled soybean meal Animal-vegetable fat Dicalcium phosphate Ground limestone Iodized salt Lysine HC1 DL-methionine Vitamin premix 1 Trace mineral mix 2 Variable3 Total Calculated nutrient content ME, kcal/kg Crude protein, % Calcium, % Nonphytate phosphorus, % Arginine, % Lysine, % Methionine, % TSAA, % Threonine, %

Starter (0 to 21 days)

LACTOSE AND SALMONELLA CONTAMINATION

9

Difco Laboratories, Detroit, MI 48201.

were used as the error mean square. There were no interactions of trial by lactose for microbiological data, so data from the two trials were combined for presentation. Where applicable, treatment means were separated using the Least Squares Means option of base SAS® software, which uses repeated t tests. Statements of statistical significance in all instances is based upon P<.05.

RESULTS AND DISCUSSION The inclusion of lactose in the diet resulted in a significant (P<.05) reduction in body weight of male broiler chickens at 21 and 49 days of age (Table 2). At 21 days the response was best fit by a linear expression and at 49 days by a quadratic expression. Body weight of female broiler chickens was not significantly influenced by dietary lactose. These data are in contrast to those of Rutter et al. (1953), who reported that the inclusion of lactose in the ration at levels u p to 20% did not impair the growth rate of chicks, and of Corrier et al. (1990b), who reported that inclusion of 7% lactose had no adverse effect on weight of broilers at 40 days of age. However, Scott (1952) reported that inclusion of 3.25% lactose in the diet of turkeys had a deleterious effect on growth and on the increase of enlarged hocks. Feed intake during all age periods was significantly (P<.05) reduced in a linear manner (Table 2). Feed utilization was significantly (P<.05) improved at 21, 42, and 49 days of age by inclusion of lactose in the diet; at 21 and 42 days the response was best fit by a linear equation, and at 49 days by a quadratic equation. These data indicate that lactose may be utilized for energy by the chick, as suggested by Vohra (1967), who reported that the ME value for lactose is highly variable and dependent upon usage level; ME values ranging from 730 to 1,430 kcal/kg dry matter were indicated. There was no significant (P>.05) effect of dietary lactose levels on mortality rate (Table 2). Litter caking was significantly (P<.05) affected by dietary lactose; there was a linear increase in percentage of caked-over litter as lactose levels increased. Rutter et al. (1953) observed

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Prechill carcasses were sampled using the whole carcass rinse technique (Cox et al, 1983) with a mechanical shaker (Dickens et al., 1985). The carcass rinse samples were evaluated for incidence and levels of salmonellae using a three-tube, most probable number (MPN) technique (Oblinger and Koburger, 1984). No attempt was made to distinguish between inoculated serotype (ATCC 14028) and other indigenous species. Isolation and identification of salmonellae was accomplished using the methods described by the Food and Drug Administration (1984). All bacteriological media were prepared according to directions provided by the manufacturer. 9 Lactose preenrichment of samples was not utilized because the authors (Izat et al., 1989) and numerous others have demonstrated that salmonellae on the surface of prechill broiler carcasses are not stressed and that preenrichment in lactose broth is not beneficial for recovery. Data were statistically analyzed using the General Linear Model (GLM) procedure of the SAS Institute (1982). Orthogonal polynomials for linear, quadratic, and cubic responses to lactose levels were calculated as described by Steel and Torrie (1980). For performance data, the statistical unit was the pen or sex within pen as appropriate. The statistical model included trial and block effects and interaction of these two main effects. Residual effects were used as the error mean square. Mortality data were transformed using square root transformation; other percentage data were transformed to arc sine prior to statistical analysis. All performance data are presented in the tables as natural numbers. There were no interactions of trial by lactose on performance data, so the two trials were combined for presentation. Microbiological data were also analyzed using the GLM procedure. The statistical unit was the carcass rinse sample. All MPN salmonellae values were analyzed using the logio transformations. The MPN salmonellae values were analyzed by trial, treatment, and interaction of these two main effects; residual effects

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WALDROUP ET AL. TABLE 2. Effects of dietary lactose levels on live performance of broiler chickens (means of two trial with four replicate pens of 30 males and 30 females per trial) Percentage dietary lactose

Parameter

7.5

SEM 4 4 3

Significance 1 L NS L L L,Q L L

598 576 913 1.54 6.69 5.31 .78

604 580 899 1.52 6.13 5.50 .82

589 581 879 1.50 5.48 6.52 .99

568 554 864 1.48 5.46 7.05 1.06

1,952 1,728 2,688 1.94

1,985 1,716 2,654 1.90

1,902 1,707 2,571 1.89

1,910 1,702 2,559 1.87

12 7 12 .01

NS NS L L

2,421 2,099 1,110 4,711 2.08 4.79 11.25 6.59 14 .68

2,470 2,056 1,091 4,644 2.02 5.21 22.50 6.24 18 .84

2,363 2,086 1,058 4,508 2.02 4.38 33.75 6.04 19 .93

2,219 1,911 1,005 4,428 2.01 5.42 50.00 5.82 22 1.12

16 40 8 17 .01 .36 4.14 .02 .2 .01

L,Q NS L L L,Q NS L L L L

.01 .04 .10 .02

L and Q are significant (P<.05) linear or quadratic orthogonal effects, respectively. Percentage of litter caked over.

pronounced diarrhea as lactose levels in the diet increased. DeLoach et al. (1990) reported that inclusion of lactose in the water or inclusion of whey (as a source of lactose) in the feed significantly increased water consumption. N o attempt was made in the present study to determine whether the increase in litter caking was associated with either diarrhea, increased water consumption, or both. Cecal p H was significantly (P<.05) reduced at 21 and 49 days of age by the inclusion of lactose in the diet (Table 2). At 21 days the response was best fit by a linear equation and at 49 days by a quadratic equation. This is in agreement with the reports of Beach (1925), Beach and Davis (1925), Kline et al. (1932), and Ashcraft (1933). Cecal p H values in the present study for control and 7.5% lactosetreated birds were similar to those reported by Corrier et al. (1990b) for birds fed the control and 7% lactose diets. Weight of the cecae at 21 and 49 days of

age, expressed either as total weight or as percentage of body weight, was significantly (P<.05) increased in a linear manner as the amount of lactose in the diet increased, with a great deal of gaseous material present in the cecae of birds fed diets with the higher levels of lactose. This is in agreement with the report of Bilgili and Moran (1990). At least 75% of the prechill carcasses were salmonellae-positive, regardless of dietary treatment (Table 3). There were no significant (P>.05) differences in incidence levels of salmonellae on prechill carcasses. Significantly higher numbers of salmonellae were observed on prechill carcasses of birds fed 7.5% lactose as compared with the positive control birds fed diets with no lactose or birds fed diets with 2.5 or 5% lactose. This may have been related to the increased incidence of litter caking in these pens, although Reiber et al. (1990) found no relationship to salmonellae levels on carcasses of broilers produced on new versus previously used litter.

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21 days of age Male weight, g Female weight, g Feed intake, g per bird Feed:gain ratio, g:g Ceca pH Ceca weight, g Ceca, % of BW 42 days of age Male weight, g Female weight, g Feed intake, 21 to 42 days, g Feed:gain ratio, 0 to 42 days, g:g 49 days of age Male weight, g Female weight, g Feed intake, 42 to 49 days, g Feed intake, 0 to 49 days, g Feed:gain ratio, 0 to 49 days, g:g Mortality, % Litter caking, % Ceca pH Ceca weight, g Ceca, % of BW

5.0

2.5

0

LACTOSE AND SALMONELLA CONTAMINATION TABLE 3. The effects of dietary lactose on logio most probable number (MFN) per milliliter of salmonellae present in the rinse fluid of prechill broiler carcasses

Corrier et al. (1990b) and Ziprin et al. (1990) reported that 7% dietary lactose, in combination with inoculation with anaerobic cultures of cecal microflora from adult chickens, significantly reduced salmonellae colonization in the cecae of young chickens. In neither of these studies was lactose fed in the absence of the anaerobic culture, as was done in the present study. The interdependence of dietary lactose and anaerobic cecal cultures in the inhibition of salmonellae colonization is not completely clear. Hinton et al. (1990) reported that chickens given either lactose (2.5% in drinking water) or anaerobic cecal cultures alone had significantly fewer S. typhimurium recovered from their cecae than did the controls; those given a combination of lactose and the anaerobic culture had significantly fewer S. typhimurium recovered than those given either lactose or the culture alone. Corrier et al. (1991b) found that protection against Salmonella senftenberg colonization in young turkey poults was similar for groups inoculated with an anaerobic cecal culture or those provided with dietary lactose (5% in the feed); a combination of the anaerobic culture and dietary lactose resulted in a level of protection against colonization equal to or higher than either treatment administered separately. Hinton et al. (1991) reported that

dietary lactose (2.5% in the drinking water) significantly reduced the cecal colonization by S. typhimurium in young chickens. A combination of dietary lactose with a 10-mo-old anaerobic cecal culture was no more effective than lactose alone; however, a combination of dietary lactose with a 1-mo-old anaerobic cecal culture was more effective in reducing cecal colonization than either treatment alone. In contrast to these reports, Corrier et al. (1991a) reported that lactose (5% in the feed), in the absence of inoculation with an anaerobic cecal culture, failed to provide protection against cecal colonization of Salmonella enteritidis in newly hatched chicks but enhanced the colonization resistance in chicks inoculated with anaerobic cultures of cecal flora. In all of the reports cited above the numbers of salmonellae in the cecae were decreased by dietary lactose; however, they were not totally eliminated, thus allowing the possibility of continual shedding into the litter and subsequent contamination of the external surface of the bird. In virtually all of the reports cited above, chicks or poults were not grown to market ages and the carcass or external surface was not evaluated for incidence or level of salmonellae. In one trial where broilers were grown to market weights (Corrier et al., 1990b) continual application of dietary lactose in combination with a cecal anaerobic culture significantly reduced, but did not totally eliminate, the number of broilers whose cecal culture tested positive for S. typhimurium; there was no indication of the extent of external contamination. A similar parallel may be drawn to the studies on the use of dmannose in broiler diets. McHan et al. (1989) and Oyofo et al. (1989c) reported that adherance of S. typhimurium to the cecae of 7-day-old chicks was inhibited by d-mannose, but Izat et al. (1990b) found that feeding broilers d-mannose to market weights had no consistent influence on levels of salmonellae on prechill carcasses. Numerous studies indicate that current production practices involving breeding flocks, grow-out conditions, and transport of live birds to the processing plant result in birds that are contaminated with salmonellae and other pathogens prior to pro-

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Positive/total log™ MPN/mL Dietary carcasses salmonellae lactose, % (percentage) ±SEM 2 35/36 (972%)* .0 .078 ± .W1* a 2.5 27/36 (75.0%) .478 ± .17b 5.0 33/36 (91.7%)a .019 ± .16c 75 33/36 (91.7%)a 1.195 ± .18a a_c Means within column with no common superscripts differ significantly (P<.05). dumber of salmonellae positive carcasses out of total number of carcasses sampled; lower detection level = logio -1.52 MPN salmonellae/mL. ^Levels of salmonellae recovered from the rinse fluid of prechill broiler carcasses found salmonellaepositive using the whole carcass rinse procedure (Cox et al, 1983).

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into market age broilers. Poultry Sci. 69: 1670-1674. Bitton, G., and K. C. Marshall, 1980. Absorption of Microorganisms to Surface. John Wiley and Sons, New York, NY. Corrier, D. E., B. Hargis, A. Hinton, Jr., D. Lindsey, D. Caldwell, J. Manning, and J. DeLoach, 1991a. Effect of anaerobic cecal microflora and dietary lactose on colonization resistance of layer chicks to invasive Salmonella enteritidis. Avian Dis. 35: 337-343. Corrier, D. E., A. Hinton, Jr., L. F. Kubena, R. L. Ziprin, and J. R. DeLoach, 1991b. Decreased Salmonella colonization in turkey poults inoculated with anaerobic cecal microflora and provided dietary lactose. Poultry Sci. 70:1345-1350. Corrier, D. E., A. Hinton, Jr., R. L. Ziprin, R. C. Beier, and J. R. DeLoach, 1990a. Effect of dietary lactose on cecal pH, bacteriostatic volatile fatty acids, and Salmonella typhimurium colonization of broiler chicks. Avian Dis. 34:617-625. Corrier, D. E., A. Hinton, Jr., R. L. Ziprin, and J. R. DeLoach, 1990b. Effect of dietary lactose on Salmonella colonization of market-age broiler ACKNOWLEDGMENTS chickens. Avian Dis. 34:668-676. Cox, N. A., J. E. Thomson, and J. S. Bailey, 1983. The lactose used in this study was Procedure for isolation and identification of Salmonella from poultry carcass. Agriculture provided through the courtesy of Trevor Handbook No. 603. USDA, Agricultural ReTomkins, Milk Specialties Co., Dundee, IL search Service, Washington, DC. 60118. The assistance of R. E. Hierholzer, J. DeLoach, J. R., 1989. Salmonella prevention with M. Kopek, J. P. McGinnis, S. Kaniawati, S. carbohydrates. Broiler Jnd. 52:8-10. Raymond, V. Jindal, M. H. Adams, and S. DeLoach, J. R., B. A. Oyofo, D. E. Corrier, L. F. Kubena, R. L. Ziprin, and J. O. Norman, 1990. E. Watkins in care of the birds and Reduction of Salmonella typhimurium concentramicrobiological assay is greatly appreciattion in broiler chickens by milk or whey. Avian ed. Dis. 34:389-392. Dickens, J. A., N. A. Cox, J. S. Bailey, and J. E. Thomson, 1985. Automated microbiological REFERENCES sampling of broiler carcasses. Poultry Sci. 64: 1116-1120. Abraham, S. N., E. H. Beachey, and A. W. Simpson, 1983. Adherence of Streptococcus pyogens, Escher-Food and Drug Administration, 1984. Bacteriological ichia coli, and Pseudomonas aeruginosa to fibronec- Analytical Manual. 6th ed. Food and Drug Administration. Association of Official Analyttin-coated and uncoated epithelial cells. Infect. ical Chemists, Arlington, VA. Immun. 41:1261-1268. Ashcraft, D. W., 1933. Effect of milk products on pH Hinton, A., Jr., D. E. Corrier, G. E. Spates, J. O. Norman, R. L. Ziprin, R. C. Beier, and J. R. of intestinal contents of domestic fowl. Poultry DeLoach, 1990. Biological control of Salmonella Sci. 12:292-298. typhimurium in young chickens. Avian Dis. 34: Association of Official Agricultural Chemists, 1970. 626-633. Official Methods of Analysis. 11th ed. Associa- Hinton, A., Jr., D. E. Corrier, R. L. Ziprin, G. E. tion of Official Agricultural Chemists, WashingSpates, and J. R. DeLoach, 1991. Comparison of ton, DC. the efficacy of cultures of cecal anaerobes as Atkinson, R. L., F. H. Kratzer, and G. F. Stewart, inocula to reduce Salmonella typhimurium coloni1957. Lactose in animal and human feeding: A zation in chicks with or without dietary lactose. review. J. Dairy Sci. 50:1114-1132. Poultry Sci. 70:67-73. Beach, J. R., 1925. The effect of feeding Bacillus Izat, A. L., M. Colberg, R. A. Thomas, M. H. Adams, acidophillus, lactose, dry skim milk, or whole and C. D. Driggers, 1990a. Effects of lactic acid milk on the hydrogen-ion concentration of the in processing waters on the incidence of salmocontents of the ceca of chickens. Hilgardia 1(8): nellae on broilers. J. Food Qual. 13:295-306. 145-165. Izat, A. L., C. D. Driggers, M. Colberg, M. A. Reiber, Beach, J. R., and D. E. Davis, 1925. The influence of and M. H. Adams, 1989. Comparison of the feeding lactose or dry skim milk on artificial DNA probe to culture methods for the detection infection of chicks with Eimeria avium. Hilgardia of Salmonella on poultry carcasses and proces1(8):167-181. sing waters. J. Food Prot. 52:564-570. Bilgili, S. F., and E. T. Moran, Jr., 1990. Influence of Izat, A. L., R. E. Hierholzer, J. M. Kopek, M. H. whey and probiotic-supplemented withdrawal Adams, M. A. Reiber, and J. P. McGinnis, 1990b. feed on the retention of Salmonella intubated Research note: Effects of D-mannose on inci-

cessing (Matthes, 1981; Mayer et al., 1984; Reiber et al., 1990). Whether or not the organism colonizes in the cecae may have little relevance to the incidence of salmonellae contamination of the carcass if the organism is continually introduced into the environment from one or more sources. Results of the present study suggest that supplementing poultry diets with lactose is not a viable means in itself of reducing or eliminating salmonellae incidence or levels on processed broiler carcasses. Whether or not a combination of lactose supplementation coupled with inoculation with an anaerobic cecal culture would be effective in this regard has yet to be demonstrated.

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