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Effect of Antibiotic Agents upon Experimental Ascaridia galli Infections in Chickens1
Effect of Antibiotic Agents upon Experimental Ascaridia galli Infections in Chickens1 (Received for publication January 25, 1951)
T
acute infections caused by bacteria and viruses. These present experiments were undertaken to determine effects of three antibiotic agents, penicillin, streptomycin, and neomycin, upon experimental infections in chickens with the large intestinal roundworm, Ascaridia galli. The data indicate that these agents in the diet of chicks can restrict the size (in terms of length) and percentage of development of the parasite, and in so doing may enable the parasitized animals to achieve greater weight gains.
WO main avenues of investigation are employed by agricultural parasitologists to aid domestic animals in attaining maximum efficient production. The first of these, medication, is directed most properly at infections carried by members of the breeding flocks because their infections are reservoirs for the exposure of new generations of animals. Secondarily, medicated feeds have come into use to protect against and minimize the effects of parasitic infections in animals constituting an individual generation. Control of parasitism appears to rest upon proper and efficient use of medication. The other basis of investigation is in connection with determining relationships of nutrient materials in the diet of animals to the ability of the animals to withstand, or tolerate, effects of infection. Both types of investigation are based upon modern and efficient methods of sanitation and management.
MATERIALS AND METHODS
While present antibiotic agents perhaps have been developed primarily to combat infections caused by bacteria, the later establishment of their effectiveness against certain viral and rickettsial forms indicates that possible action against animal parasites should be determined as well. Worm parasite infections undoubtedly occur in domestic animals more universally than do the relatively virulent and 1 The investigation reported in this paper is in connection with a project of the Kentucky Agricultural Experiment Station and is published by permission of the Director.
Chicks used in these tests were straightrun New Hampshires obtained from a commercial hatchery in Richmond, Kentucky. The day-old chicks were started in electric battery brooders and transferred to growing batteries after they feathered. The chicks were vaccinated against Newcastle disease by intranasal instillation at two days of age. They were wingbanded at one week of age. Chicks in the first two experiments were fed a commercial starting and growing ration. Chicks in the third experiment were fed a starting and growing ration which served as the basal ration, compounded according to a formula previously published, Todd (1948). In the first two experiments, where penicillin alone was tested, the antibiotic was added to the basal ration at the rate of 6.8 mg./lb. feed. This rate was the result of an unfortunate error in calcula-
763
Downloaded from http://ps.oxfordjournals.org/ at Frankfurt University Library, Section Stadt- und Universitaetsbibliothek on April 12, 2015
A. C. T O D D
Department of Animal Pathology, Kentucky Agricultural Experiment Station, Lexington, Kentucky
764
A. C. TODD
In each experiment each bird exposed to Ascaridia galli infection received 50 + infective A. galli eggs by means of a pipette inserted directly into its esophagus. The infective A. galli eggs were obtained from prepared cultures. The trials were designed so that the antibiotics tested would be continuously available in the feed, and presumably present in the digestive tracts of the exposed birds, during the interval after exposure when the immature worms would first hatch from the worm eggs and attempt to establish themselves and mature in the anterior portion of the small intestine of the test chicks. The data collected were the weight gains of the chicks in the three-week period after exposure, the number of worms present at postmortem three weeks after exposure, and the size attained by the worms (in terms of length) during the test period. EXPERIMENTAL RESULTS
Data obtained in the three experiments are shown in Table 1. In the first experiment the parasitized
birds on the basal ration had a mean weight gain of 310.4 gm. in the threeweek test period and 4.38 worms were recovered from them, on average, at postmortem. The exposed birds on the penicillin ration had a mean gain of 298.3 gm. and had an average of 4.43 worms. The differences in weight gains of the two groups of birds were not significant when submitted to statistical analysis, nor were the slight differences in mean worm numbers. The control birds of both groups were significantly heavier than the parasitized birds. One hundred and sixty whole worms from the basal group and 167 whole worms from the penicillin group had mean lengths of 21.41 mm. and 20.09 mm., respectively. This difference in length exceeded the five percent level of significance and is, therefore, the first indication in this present work, that an antibiotic can inhibit the development of a worm parasite. In the second experiment another hatch of chickens was used and the ration was a new supply of the same .commercial chick starter. In this test the parasitized birds on the basal ration gained 33.7 gm. less weight than did the parasitized birds on the penicillin ration. While fewer worms were recovered from birds fed penicillin, 5.03 versus 6.40 worms, the difference was not significant when submitted to an analysis of variance. Two hundred and thirty-eight whole worms recovered from the birds fed the basal ration averaged 2.75 mm. longer than the 176 whole worms recovered from birds fed the penicillin ration. This difference exceeded the one percent level of significance and is, therefore, a highly significant demonstration of the ability of the antibiotic to inhibit the development of the worm parasite. In this second experiment the advantage in weight gain held by birds fed the penicillin ration exceeded the five percent level of significance and
Downloaded from http://ps.oxfordjournals.org/ at Frankfurt University Library, Section Stadt- und Universitaetsbibliothek on April 12, 2015
tion, the intended rate having been 15 mg./lb. feed. In the third experiment the three antibiotics tested were added to the basal ration at the rate of 15 mg./lb. feed. In the latter experiment vitamin B12 was added to the basal ration itself, and to the streptomycin (Merck) and neomycin (Upjohn) rations in order to equalize the amount of Bl2 added to the penicillin ration. The penicillin (Merck) employed in all three experiments was contained in a base with 15 mg. B12 per pound of the mixture. In the first two experiments the penicillin ration was fed for three days before the chickens on that diet were exposed to the worm infection. In the third experiment the four groups of chicks had access to their prepared rations for one day before exposure to the worm infections.
765
ANTHELMINTIC ACTION OF ANTIBIOTICS
TABLE 1.—Effects
Test
Number birds
Age birds at exposure (days)
10 40 10 40
19 19 19 19
10 40 10 40
10 40 10 40 10 40 10 40
third experiment are based on the individual lengths of the 1,293 whole worms in a total of 1,405 worms recovered from the four groups of exposed birds at postmortem. Four hundred and twentyeight whole worms recovered from birds fed the basal ration had an average
of antibiotics on experimental A. galli injections
Nature of group
Mean weight gajn in test (grams)
Basal ration Basal ration Penicillin ration Penicillin ration
Nonexposed controls Exposed birds Nonexposed controls Exposed birds
350.0 310.4 385.1 298.3
19 19 19 19
Basal ration Basal ration Penicillin ration Penicillin ration
Nonexposed controls Exposed birds Nonexposed controls Exposed birds
354.7* 302.7* 377.4* 336.4*
16 16 16 16 16 16 16 16
Basal ration Basal ration Penicillin ra,tion Penicillin ration Streptomycin ration Streptomycin ration Neomycin ration Neomycin ration
Nonexposed controls Exposed birds Nonexposed controls Exposed birds Nonexposed controls Exposed birds Nonexposed controls Exposed birds
360.9 339.4 379.1 364.8 357.1 364.3 339.2 342.5
Diet
Mean number worms recovered
Mean worm length (mm.)
4.38
21.41*
4.43
20.09*
.—:— 6.40
21.13**
5.03
18.38**
11.48*
27.79**
7.05*
23.37**
8.15*
24.56**
8.45*
25.78**
•
* Exceeds 5 percent level of significance. ** Exceeds 1 percent level of significance.
In the third experiment a third hatch of chickens was used and these birds were fed the custom prepared ration. The apparent differences in amounts of weight gained by the four groups of exposed birds (Table 1) were not statistically significant. The average 25.4 gm. greater gain of exposed birds fed the penicillin ration over exposed birds fed the basal ration did approach significance at the five percent level. An F value of 3.61 was obtained and significance at the five percent level, in an analysis of variance was 3.96. Significant differences were found in numbers of worms recovered at postmortem and in the mean lengths of the worms. The mean worm lengths shown for the
length of 27.79. mm. Three hundred and seven whole worms from birds fed neomycin, 293 whole worms from birds fed streptomycin and 265 whole worms from birds fed penicillin averaged 2.01 mm., 3.23 mm., and 4.42 mm. shorter in length, respectively. These differences again exceeded the one percent level in an analysis of variance and are, therefore, highly significant. The first data to indicate that antibiotics could reduce worm numbers significantly were obtained in the third experiment. An average of 11.48 worms were recovered from the forty exposed birds on the basal ration. Exposed birds on the neomycin, streptomycin, and penicillin diets were found to be parasi-
Downloaded from http://ps.oxfordjournals.org/ at Frankfurt University Library, Section Stadt- und Universitaetsbibliothek on April 12, 2015
approached the one percent level. It must be assumed, probably, that the advantage is most largely derived from the level of nutrition and not from reduction of worm development. The nonexposed control birds again significantly outgained the parasitized birds.
766
A. C. TODD
DISCUSSION These present experiments are now being used as points of departure for further investigations concerned with establishing levels of administration for greatest anthelmintic action of a given antibiotic agent. Anthelmintic actions of the antibiotic agents in the experiments here reported were inhibition of growth of the test parasite and reductions of worm numbers. The experiments are being conducted with chickens because of generally circulated, but largely nonspecific, reports of unfavorable action of antibiotics upon the normal bacterial flora of ruminants. The apparent action of penicillin upon an ascarid parasite is of potential importance from a parasitological standpoint. Present ascaricides for poultry have a narrow safety margin between host tolerance and effective anthelmintic action. Inhibition of parasite development can be assumed, perhaps, to delay sexual maturity of the parasite and resultant worm egg production. In these experiments inhibition of development of the parasite and reduction in worm numbers, in two of the three tests, were accompanied by significantly greater weight gains in birds on the penicillin ration. Superior weight gains in birds fed the penicillin rations in the second test apparently were not due to reduction of worm numbers but rather to the B12 added from the penicillin base or from the penicillin, or from another growth-prompting factor inherent in the
penicillin itself. The third test may demonstrate that properly supplemented rations can enable chicks to overcome effects of infection. Weight gains of each group of exposed birds were not significantly different from their own nonexposed controls, except possibly in the birds fed the basal ration (Table 1). But because B i2 was contained in each of the four rations in test three, it can be assumed as a basis for further study that the greater weight gains of birds fed penicillin were due in part to an extra growthpromoting factor in the B12 or to reduction in numbers of parasites present. SUMMARY Three separate tests have been conducted in an effort to determine possible anthelmintic action of antibiotic agents in the diet of chicks. The tests indicate that penicillin fed at the rate of 6.8 mg./lb. feed can inhibit development of the test parasite, Ascaridia galli, in the intestine of chicks. At the rate of 15 mg./lb. feed anthelmintic action of penicillin is considerably enhanced and significant reductions were found to occur in numbers of worms developing from controlled exposures. In a single comparison of penicillin, streptomycin, and neomycin, each fed at the rate of 15 mg./lb. feed, the anthelmintic action of penicillin was somewhat superior to the other two antibiotic agents. The tests were not conducted in such a manner that the superior weight gains found to occur in birds fed the penicillin rations in two of the tests could be identified as due to the anthelmintic action of the antibiotic. REFERENCE Todd, A. C , 1948. Thyroactive iodocasein and thiouracil in the diet, and growth of parasitized chicks. Poultry Sci. 27: 818-821.
Downloaded from http://ps.oxfordjournals.org/ at Frankfurt University Library, Section Stadt- und Universitaetsbibliothek on April 12, 2015
tized at postmortem by an average of 8.45, 8.15, and 7.05 worms, respectively. These differences exceeded the five percent level of significance in an analysis of variance. In the third experiment the antibiotics were fed at the rate of 15 mg./lb. feed.
T
acute infections caused by bacteria and viruses. These present experiments were undertaken to determine effects of three antibiotic agents, penicillin, streptomycin, and neomycin, upon experimental infections in chickens with the large intestinal roundworm, Ascaridia galli. The data indicate that these agents in the diet of chicks can restrict the size (in terms of length) and percentage of development of the parasite, and in so doing may enable the parasitized animals to achieve greater weight gains.
WO main avenues of investigation are employed by agricultural parasitologists to aid domestic animals in attaining maximum efficient production. The first of these, medication, is directed most properly at infections carried by members of the breeding flocks because their infections are reservoirs for the exposure of new generations of animals. Secondarily, medicated feeds have come into use to protect against and minimize the effects of parasitic infections in animals constituting an individual generation. Control of parasitism appears to rest upon proper and efficient use of medication. The other basis of investigation is in connection with determining relationships of nutrient materials in the diet of animals to the ability of the animals to withstand, or tolerate, effects of infection. Both types of investigation are based upon modern and efficient methods of sanitation and management.
MATERIALS AND METHODS
While present antibiotic agents perhaps have been developed primarily to combat infections caused by bacteria, the later establishment of their effectiveness against certain viral and rickettsial forms indicates that possible action against animal parasites should be determined as well. Worm parasite infections undoubtedly occur in domestic animals more universally than do the relatively virulent and 1 The investigation reported in this paper is in connection with a project of the Kentucky Agricultural Experiment Station and is published by permission of the Director.
Chicks used in these tests were straightrun New Hampshires obtained from a commercial hatchery in Richmond, Kentucky. The day-old chicks were started in electric battery brooders and transferred to growing batteries after they feathered. The chicks were vaccinated against Newcastle disease by intranasal instillation at two days of age. They were wingbanded at one week of age. Chicks in the first two experiments were fed a commercial starting and growing ration. Chicks in the third experiment were fed a starting and growing ration which served as the basal ration, compounded according to a formula previously published, Todd (1948). In the first two experiments, where penicillin alone was tested, the antibiotic was added to the basal ration at the rate of 6.8 mg./lb. feed. This rate was the result of an unfortunate error in calcula-
763
Downloaded from http://ps.oxfordjournals.org/ at Frankfurt University Library, Section Stadt- und Universitaetsbibliothek on April 12, 2015
A. C. T O D D
Department of Animal Pathology, Kentucky Agricultural Experiment Station, Lexington, Kentucky
764
A. C. TODD
In each experiment each bird exposed to Ascaridia galli infection received 50 + infective A. galli eggs by means of a pipette inserted directly into its esophagus. The infective A. galli eggs were obtained from prepared cultures. The trials were designed so that the antibiotics tested would be continuously available in the feed, and presumably present in the digestive tracts of the exposed birds, during the interval after exposure when the immature worms would first hatch from the worm eggs and attempt to establish themselves and mature in the anterior portion of the small intestine of the test chicks. The data collected were the weight gains of the chicks in the three-week period after exposure, the number of worms present at postmortem three weeks after exposure, and the size attained by the worms (in terms of length) during the test period. EXPERIMENTAL RESULTS
Data obtained in the three experiments are shown in Table 1. In the first experiment the parasitized
birds on the basal ration had a mean weight gain of 310.4 gm. in the threeweek test period and 4.38 worms were recovered from them, on average, at postmortem. The exposed birds on the penicillin ration had a mean gain of 298.3 gm. and had an average of 4.43 worms. The differences in weight gains of the two groups of birds were not significant when submitted to statistical analysis, nor were the slight differences in mean worm numbers. The control birds of both groups were significantly heavier than the parasitized birds. One hundred and sixty whole worms from the basal group and 167 whole worms from the penicillin group had mean lengths of 21.41 mm. and 20.09 mm., respectively. This difference in length exceeded the five percent level of significance and is, therefore, the first indication in this present work, that an antibiotic can inhibit the development of a worm parasite. In the second experiment another hatch of chickens was used and the ration was a new supply of the same .commercial chick starter. In this test the parasitized birds on the basal ration gained 33.7 gm. less weight than did the parasitized birds on the penicillin ration. While fewer worms were recovered from birds fed penicillin, 5.03 versus 6.40 worms, the difference was not significant when submitted to an analysis of variance. Two hundred and thirty-eight whole worms recovered from the birds fed the basal ration averaged 2.75 mm. longer than the 176 whole worms recovered from birds fed the penicillin ration. This difference exceeded the one percent level of significance and is, therefore, a highly significant demonstration of the ability of the antibiotic to inhibit the development of the worm parasite. In this second experiment the advantage in weight gain held by birds fed the penicillin ration exceeded the five percent level of significance and
Downloaded from http://ps.oxfordjournals.org/ at Frankfurt University Library, Section Stadt- und Universitaetsbibliothek on April 12, 2015
tion, the intended rate having been 15 mg./lb. feed. In the third experiment the three antibiotics tested were added to the basal ration at the rate of 15 mg./lb. feed. In the latter experiment vitamin B12 was added to the basal ration itself, and to the streptomycin (Merck) and neomycin (Upjohn) rations in order to equalize the amount of Bl2 added to the penicillin ration. The penicillin (Merck) employed in all three experiments was contained in a base with 15 mg. B12 per pound of the mixture. In the first two experiments the penicillin ration was fed for three days before the chickens on that diet were exposed to the worm infection. In the third experiment the four groups of chicks had access to their prepared rations for one day before exposure to the worm infections.
765
ANTHELMINTIC ACTION OF ANTIBIOTICS
TABLE 1.—Effects
Test
Number birds
Age birds at exposure (days)
10 40 10 40
19 19 19 19
10 40 10 40
10 40 10 40 10 40 10 40
third experiment are based on the individual lengths of the 1,293 whole worms in a total of 1,405 worms recovered from the four groups of exposed birds at postmortem. Four hundred and twentyeight whole worms recovered from birds fed the basal ration had an average
of antibiotics on experimental A. galli injections
Nature of group
Mean weight gajn in test (grams)
Basal ration Basal ration Penicillin ration Penicillin ration
Nonexposed controls Exposed birds Nonexposed controls Exposed birds
350.0 310.4 385.1 298.3
19 19 19 19
Basal ration Basal ration Penicillin ration Penicillin ration
Nonexposed controls Exposed birds Nonexposed controls Exposed birds
354.7* 302.7* 377.4* 336.4*
16 16 16 16 16 16 16 16
Basal ration Basal ration Penicillin ra,tion Penicillin ration Streptomycin ration Streptomycin ration Neomycin ration Neomycin ration
Nonexposed controls Exposed birds Nonexposed controls Exposed birds Nonexposed controls Exposed birds Nonexposed controls Exposed birds
360.9 339.4 379.1 364.8 357.1 364.3 339.2 342.5
Diet
Mean number worms recovered
Mean worm length (mm.)
4.38
21.41*
4.43
20.09*
.—:— 6.40
21.13**
5.03
18.38**
11.48*
27.79**
7.05*
23.37**
8.15*
24.56**
8.45*
25.78**
•
* Exceeds 5 percent level of significance. ** Exceeds 1 percent level of significance.
In the third experiment a third hatch of chickens was used and these birds were fed the custom prepared ration. The apparent differences in amounts of weight gained by the four groups of exposed birds (Table 1) were not statistically significant. The average 25.4 gm. greater gain of exposed birds fed the penicillin ration over exposed birds fed the basal ration did approach significance at the five percent level. An F value of 3.61 was obtained and significance at the five percent level, in an analysis of variance was 3.96. Significant differences were found in numbers of worms recovered at postmortem and in the mean lengths of the worms. The mean worm lengths shown for the
length of 27.79. mm. Three hundred and seven whole worms from birds fed neomycin, 293 whole worms from birds fed streptomycin and 265 whole worms from birds fed penicillin averaged 2.01 mm., 3.23 mm., and 4.42 mm. shorter in length, respectively. These differences again exceeded the one percent level in an analysis of variance and are, therefore, highly significant. The first data to indicate that antibiotics could reduce worm numbers significantly were obtained in the third experiment. An average of 11.48 worms were recovered from the forty exposed birds on the basal ration. Exposed birds on the neomycin, streptomycin, and penicillin diets were found to be parasi-
Downloaded from http://ps.oxfordjournals.org/ at Frankfurt University Library, Section Stadt- und Universitaetsbibliothek on April 12, 2015
approached the one percent level. It must be assumed, probably, that the advantage is most largely derived from the level of nutrition and not from reduction of worm development. The nonexposed control birds again significantly outgained the parasitized birds.
766
A. C. TODD
DISCUSSION These present experiments are now being used as points of departure for further investigations concerned with establishing levels of administration for greatest anthelmintic action of a given antibiotic agent. Anthelmintic actions of the antibiotic agents in the experiments here reported were inhibition of growth of the test parasite and reductions of worm numbers. The experiments are being conducted with chickens because of generally circulated, but largely nonspecific, reports of unfavorable action of antibiotics upon the normal bacterial flora of ruminants. The apparent action of penicillin upon an ascarid parasite is of potential importance from a parasitological standpoint. Present ascaricides for poultry have a narrow safety margin between host tolerance and effective anthelmintic action. Inhibition of parasite development can be assumed, perhaps, to delay sexual maturity of the parasite and resultant worm egg production. In these experiments inhibition of development of the parasite and reduction in worm numbers, in two of the three tests, were accompanied by significantly greater weight gains in birds on the penicillin ration. Superior weight gains in birds fed the penicillin rations in the second test apparently were not due to reduction of worm numbers but rather to the B12 added from the penicillin base or from the penicillin, or from another growth-prompting factor inherent in the
penicillin itself. The third test may demonstrate that properly supplemented rations can enable chicks to overcome effects of infection. Weight gains of each group of exposed birds were not significantly different from their own nonexposed controls, except possibly in the birds fed the basal ration (Table 1). But because B i2 was contained in each of the four rations in test three, it can be assumed as a basis for further study that the greater weight gains of birds fed penicillin were due in part to an extra growthpromoting factor in the B12 or to reduction in numbers of parasites present. SUMMARY Three separate tests have been conducted in an effort to determine possible anthelmintic action of antibiotic agents in the diet of chicks. The tests indicate that penicillin fed at the rate of 6.8 mg./lb. feed can inhibit development of the test parasite, Ascaridia galli, in the intestine of chicks. At the rate of 15 mg./lb. feed anthelmintic action of penicillin is considerably enhanced and significant reductions were found to occur in numbers of worms developing from controlled exposures. In a single comparison of penicillin, streptomycin, and neomycin, each fed at the rate of 15 mg./lb. feed, the anthelmintic action of penicillin was somewhat superior to the other two antibiotic agents. The tests were not conducted in such a manner that the superior weight gains found to occur in birds fed the penicillin rations in two of the tests could be identified as due to the anthelmintic action of the antibiotic. REFERENCE Todd, A. C , 1948. Thyroactive iodocasein and thiouracil in the diet, and growth of parasitized chicks. Poultry Sci. 27: 818-821.
Downloaded from http://ps.oxfordjournals.org/ at Frankfurt University Library, Section Stadt- und Universitaetsbibliothek on April 12, 2015
tized at postmortem by an average of 8.45, 8.15, and 7.05 worms, respectively. These differences exceeded the five percent level of significance in an analysis of variance. In the third experiment the antibiotics were fed at the rate of 15 mg./lb. feed.