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Pastures for Chickens and Their Relation to the Parasitic Fauna
Pastures for Chickens and Their Relation to the Parasitic Fauna A. C. TODD AND B. J. MCSPADDEN Tennessee Agricultural Experiment Station, Knoxville
W
ARTIME shortages of certain feedstuffs that have come to be recognized as highly nutritious for poultry led to intensified investigation of supplements for the complete rations previously available as prepared products. Parker and McSpadden (1944) published the results of work at the Tennessee Experiment Station with pastures for growing pullets. Their studies extended over a 3-year period and covered the performance of 740 Barred Rock pullets, divided into 4 groups. All received the same starting mash, as a basal ration, plus whole yellow corn as a grain feed from 8 weeks, amd were raised, respectively, on bare range, and on ranges seeded to spring oats, a ryegrass-lespedeza mixture, and alfalfa. It was found that pullets raised on pastures were heavier, had lower mortality rates, consumed less feed, and utilized their feed more efficiently than those on bare range. The present paper is written to present the preliminary findings of two years of a projected 5-year investigation to determine what part of the difference between birds raised on the bare range and those raised on pastures can be ascribed to infection by parasites. The investigation also presents an opportunity to observe the annual development of the parasitic fauna in the 4 lots, because flocks of mature chickens are maintained within 120 feet of the pastures under study. The parasitic infections undoubtedly have more than one place of
origin. It is possible that some infections of preceding years survive within each brooder house despite rigorous cleaning between broods. Infections may survive on the ranges. A series of samplings have disclosed the following 15 species of parasites that were present in the other flocks: 4 coccidia, Eimeria maxima, E. mitis, E. necatrix, and E. tenella; 6 roundworms, Ascaridia galli, Capillaria annulata, C. caudinflata, C. columbae, Heterakis gallinae, and Tetrameres americana; and 5 tapeworms, Choanotaenia infundibulum, Davainea proglottina, Hymenolepis carioca, Raillietina cesticillus, and R. tetragona. These infections could be carried to the 4 lots by vectors, or by intermediate hosts, or both. MATERIALS AND PROCEDURE
The experiment is being conducted on 4 adjacent ranges, the dimensions of each being approximately 50X140 feet. A 10 X 12-foot colony brooder house is located on each range. In the 2-year period which this paper covers the lots have been arranged as follows: Lot Lot Lot Lot
1—Bare range, vegetation removed. 2—Seeded with clover and ryegrass. 3—Seeded with lespedeza. 4—Seeded with alfalfa.
In March, 1945, from 118 to 120 unsexed Rhode Island Red chicks were placed in each brooder house, where they were maintained until released from confinement and admitted to the ranges, at 8 weeks of age. In 1946, the same pro576
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(Received for publication April 30, 1947)
RELATION OF PASTURES TO PARASITIC FAUNA IN CHICKENS
Parasitic fauna, 1945 At 24 weeks, 89 cockerels were available for examination in the 4 lots (table 1). Of
were infected by A. galli; all 23 (100.0 percent) by H. gallinae; 7 (30.4 percent) by C. infundibulum; and 9 (39.1 percent) by H. carioca. The greatest number of worms found in any one infected bird was 309, consisting of 13 specimens of H. gallinae, 12 C. infundibulum, and 284 H. carioca. The average number of worms in an infected bird was 56.0; the aggregate species present, 1.9. The range of specimens of A. galli in infected birds in lot 2 was 1 to 2; for H. gallinae, 2 to 160; for C. infundibulum, 2 to 37; and for H. carioca, 1 to 284.
TABLE 1.—Mortalities and helminth infections of birds raised on bare range (lot 1) and on pastures (lots 2, 3, 4), 1945 Mortality record
Helminth fauna of birds examined Number birds infected by parasites
No. No. No. PerLot chicks chicks birds Percent cent survivbirds started mortal- exam(March) ing (Ocined infected ity tober)
1 2 3 4
120 119 119 118
33 49 55 60
72.5 58.8 53.8 49.2
17 23 24 25
100.0 100.0 100.0 100.0
the 17 birds in lot 1, 5 (29.4 percent) were infected by Ascaridia galli; all 17 (100.0 percent) by Heterakis gallinae; 4 (23.5 percent) by Choanotaenia infundibulum; and 1 (5.9 percent) by Hymenolepis carioca. The greatest number of worms found in any one bird was 83. These consisted of 16 specimens of H. gallinae, 15 C. infundibulum, and 52 E. carioca. The average number of worms in an infected bird was 14.0 and the average number of species in the aggregate infection was 1.6. In the 5 birds infected by .4. galli, the number of this species ranged from 1 to 4; H. gallinae ranged from 2 to 31; C. infundibulum, from 2 to 15; and the single bird with H. carioca had 52 specimens. Of the 23 birds in lot 2, 5 (21.7 percent)
Avg. Avg. no. no. worms species Choanoper Hetera- taenia Hymeno- per bird bird kis lepis infundigallinae bulum carioca
Roundworms Ascaridia galli 5 5 4 12
17 23 24 25
Tapeworms
4 7 0 6
1 9 8 12
14 56 44 40
1.6 1.9 1.5 2.2
From lot 3, 24 birds were examined, and of this number, 4 (16.0 percent), were infected by A. galli; all 24 (100.0 percent) by H. gallinae; none by C. infundibulum; and 8 (33.3 percent) by H. carioca. The greatest number of worms present in any one bird was 205:100 specimens of H. gallinae and 105 H. carioca. The average number of worms in an infected bird was 44, and the infection consisted, on the average, of 1.5 species. The 4 birds infected by A. galli each had one specimen; the range for H. gallinae was 2 to 100; and for H. carioca, 2 to 105. Of the 25 birds in lot 4, 12 (48.0 per cent) were infected by A. galli; all 25 (100.0 percent) by H. gallinae; 6 (24.0 percent) by C. infundibulum; and 12
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cedure was followed, except that Barred Rock chicks were used and from 81 to 92 chicks were started in each brooder house. In 1945, all the surviving cockerels in each lot were removed and examined for parasitic infections at 24 weeks of age. In 1946, 4 samplings, of 5 cockerels each, were taken from each lot and examined for parasitic infections at monthly intervals, starting at 8 weeks.
577
578
A. C. TODD AND B. J. MCSPADDEN
.BLE 2.—Egg TABLE 2
were placed in each brooder house in April. They were released from confinement in the brooder houses and given access to the prepared ranges in May. From June 27 to July 1, 5 cockerels were removed from each lot and examined for parasites; similar samplings were taken July 31-Aug. 1, Sept. 11-13, and Oct. 30-Nov. 4. The findings of these 4 examinations are summarized in Table 3. In 1946, the following six species of parasites were recovered from birds in the 4 lots: Eimeria tenella, the causative agent
production {percent performance) of 108 pullets, survivors of chronic coccidiosis infections
Lot
April
May
June
July
Aug.
Sept.
Oct.
Nov.
Dec.
Jan.
Feb.
Summary
1 2 3 4
60.5 56.2 59.3 62.2
59.1 63.2 64.4 65.0
36.6 51.7 50.1 54.4
25.8 33.9 28.8 32.4
26.3 31.8 29.3 29.0
22.8 22.7 16.5 16.8
11.6 8.8 7.9 5.6
5.3 4.6 6.5 2.6
15.0 9.2 16.8 14.1
40.9 13.8 20.1 22.4
36.3 16.0 18.1 19.3
30.5 27.3 28.1 28.8
of cecal coccidiosis; Ascaridia galli, a large roundworm from the small intestine; Heterakis gallinae, a cecal roundworm; Tetrameres americana, a roundworm from the proventriculus; Hymenolepis carioca, a tapeworm from the duodenum; and Raillietina cesticillus, a tapeworm from the jejunum. These parasites are species which had been found in the other flocks of university chickens. While the number of birds in each sampling is small, it may still appear from the data in Table 3 that the apparent order of development of the parasitic infections in 1946 has been established. It might be assumed that a parasite with the greatest incidence had appeared in the flock first; e.g., in the June 27-July 1 sampling, 19 of the 20 birds examined were infected by Eimeria tenella and only 5 by Heterakis gallinae. When such data are combined with the date of first apParasitic fauna, 1946 pearance of other parasites, the order of In 1946, unsexed Barred Rock chickss development of the infections probably
early May and finally subsided in July. Of the original number, 17 cockerels andL 16 pullets survived in lot 1, 23 cockerels; and 26 pullets in lot 2, 24 cockerels and 31 pullets in lot 3, and 25 cockerels and[ 35 pullets in lot 4. The pullets were maintained in the brooder houses and on the: ranges until April, 1946, when they were: placed in batteries in laying houses. The! 108 pullets then were examined for coccidia and were found to be passing oocysts, 9 months after the outbreak. The: species of coccidian most generally present; in these birds at that time was Eimeriai mitis; whereas, the causative agent ofE chronic coccidiosis 9 months previouslyT was Eimeria necatrix. The egg production rates of the abovej pullets, expressed as percentages of possible performance, are recorded in Table5 2.
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(48.0 percent) by H. carioca. The greatest number of worms present in any one bird was 254, comprised of 25 specimens of H. gallinae and 229 H. carioca. The average number of worms in an infected bird was 40 and the average number of species present was 2.2. The range of specimens of A. galli present was 1 to 6; H. gallinae 3 to 36; C. infundibulum, 1 to 6; and H. carioca, 1 to 229. In 1945, the number of birds available for study was reduced by an outbreak of chronic coccidiosis, which developed in
579
RELATION OF PASTURES TO PARASITIC FAUNA IN CHICKENS
was as follows: 1) Eimeria tenella, 2) Heterakis gallinae, 3) Ascaridia galli, 4) Hymenolepis carioca, 5) Raillietina cesticillus, 6) Tetrameres americana. The first 3 parasites found in the lots in 1946 were species which have a direct
determine whether the parasitic faunae of birds on bare range and birds raised on pastures can account for the difference in performance observed by Parker and McSpadden. From 2 years' investigation, it appears that the amount of helminth
Mortality record No. chicks PerNo. Lot chicks surcent started viving mor(April) (Oc- tality tober)
Parasitic fauna--number infected Date Birds Birds exam- exam- inined ined fected
Avg. Avg. no. no. Tapeworms worms species per per H. E. R. T. bird galli- A. E. ameri- cari- cesti- bird tenella nae galli cana oca cillus Coccidia
Roundworms
1
91
71
22.0
6-27 7-31 9-11 10-30
5 5 5 S
5 4 5 5
5 1 5 4
1 2 2 5
0 2 2 2
0 0 0 0
0 0 0 4
0 0 0 0
1.0 1.2 12.6 167.0
1.0 1.0 1.3 2.2
2
81
73
10.0
6-27 7-31 9-12 10-31
5 5 5 5
4 4 3 5
4 3 1 2
2 2 2 4
0 0 3 2
0 0 0 0
0 0 2 2
0 0 • 1 0
1.0 1.5 84.0 38.2
1.0 1.0 2.6 1.6
3
92
88
4.0
7- 1 8- 1 9-13 11- 1
5 5 5 5
5 5 5 5
5 5 3 3
1 4 5 5
0 3 4 4
0 0 0 1
0 2 5 5
0 0 0 0
1.0 47.0 218.fr 215.0
1.0 2.2 2.8 3.0
4
84
80
5.0
7- 1 8- 1 9-13 11- 4
5 S 5 5
5 5 5 5
5 S 4 4
1 0 3 5
0 1 5 3
0 0 0 0
0 0 4 1
0 0 0 0
1.0 1.0 26.0 80.5
1.0 1.0 2.4 1.8
•
life cycle; i.e., the oocysts of E. tenella and the eggs of H. gallinae and A. galli are eliminated from the body of the host in the droppings, and a new host becomes infected by ingesting these forms after they have embryonated to an infective stage. The fourth parasite to appear, Hymenolepis carioca, has an indirect life cycle requiring flies or certain species of beetles as intermediate hosts. For Raillietina cesticillus, the housefly and various beetles serve as intermediate hosts, while Tetrameres americana is said to be carried by grasshoppers and cockroaches. DISCUSSION
The purpose of this investigation is to
infections found in 1945 and 1946 were not the major factor responsible for the inferior performance of birds raised on bare range. Certainly, however, the higher mortality rates of birds on bare range during the outbreak of chronic coccidiosis (Table 1) indicate that coccidial infections have been an important cause of mortality. When the average worm burden and the average number of parasite species in birds from the bare lot are compared with those in birds on pasture, it is clearly shown in the data from 1945 (Table 1), and indicated in the data from 1946 (Table 3), that the heaviest helminth infections were sustained by birds on the pastures. The bare range is maintained
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TABLE 3.—Mortalities and parasitic infections of birds raised on bare range (lot 1) and on pastures (lots 2, 3,4), 1946
580
A. C. TODD AND B. J. MCSPADDEN
A contrast has been observed in the order of development of the parasitic infections in the 4 lots under study with the order of development of infections found by Horsfall (1936), who studied the spread of helminths, in one year, from infected to uninfected poultry yards. Working with 10-month chickens, which had been demonstrated to be free of helminth infections, on ground where no chickens had ranged previously, and at a distance of 300 feet from other flocks, she found that: 1) four helminths, common to other flocks nearby, appeared in birds
ranged on uninfected ground within 3 months; 2) two tapeworms, Hymenolepis carioca and Raillietina cesticillus, appeared first; and 3) two roundworms, Heterakis gallinae and Ascaridia lineata, appeared just at the end of the 3-month period. Horsfall concluded that migratory habits of the intermediate hosts enabled the tapeworms to cross the 300-foot space barrier more quickly than the two roundworms which have direct life cycles, and which, therefore, were transferred mechanically. In the lots studied at Tennessee in 1946, which are separated from other flocks of chickens by a distance of 120 feet, the first three parasites to appear were those with direct life cycles. Mayhew (1934) demonstrated that pullets which survived cecal coccidiosis never became profitable because of retarded growth, which in turn was reflected in delayed and lower egg production. The egg production of the Rhode Island Red pullets in laying batteries, after being maintained on the 4 lots for 12 months, appeared to be conditioned more by their previous diet than by their concurrent status as carriers of coccidia and other parasitic infections. The superior performance of birds given access to green pastures as a supplement to an adequate basal ration, when compared with that of birds given only the basal ration, has been clearly evident during the first two years of this investigation. The supplementary green food has not prevented infection; on the contrary, it has indirectly promoted heavier parasitic burdens than those sustained by birds on bare ranges. Despite the fact that little exact knowledge exists concerning losses caused by the 5 helminths found in birds on the 4 lots, a rather general agreement may be said to have been established that the cumulative effect of these parasites is deleterious. The performance of birds on pastures probably
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without vegetation, so that stages of parasites which need to embryonate to the infective stage, and intermediate hosts which might feed on droppings, are subjected to a much more unfavorable environment than exists in the pasture lots, where some protection is afforded from direct sunlight, adverse temperatures, and loss of moisture. The theory that the better the diet, the more resistant an animal is to infection by parasites, is too loose. Similarly, the fact that the threshold of infection of uninfected birds is easily surmounted by parasites—combined with the fact that strains of parasites exist which possess greater, or less, virulence—is too often overlooked. Parasites are perfectly adapted to enter, and infect, healthy, "normal" chickens. The birds raised on pastures have been shown to carry the heaviest helminth infections. This is true at least for the two years of this study. It seems 'more accurate, therefore, to say that chickens with better diets are better able to withstand the effects of helminth infections. While birds raised on pastures can withstand heavier infections, sanitary precautions for such flocks should not be abandoned, since it appears that vegetated areas are more favorable environments for the development and maintenance of parasitic infections.
RELATION OF PASTURES TO PARASITIC FAUNA IN CHICKENS
SUMMARY
1. In a group of 4 lots, similar in size but different in the type of pasture, or lack of it, an investigation has been initiated to determine the total effect of parasitic infections upon chickens ranged on the lots. Two years' investigations are presented.
2. Greater mortality rates due to coccidial infections have been found in birds ranged on the bare lot than in birds ranged on pastures. 3. Birds ranged on pastures have been found to carry the heavier burdens of helminth infections. 4. The Supplemental green food obtained by birds ranged on pastures does not, per se, prevent parasitic infections. It does, apparently, enable birds to withstand greater parasitic burdens. 5. Vegetation appears to furnish a better environment than bare range for the development and survival of infective stages of parasites, regardless of whether the life cycle of a parasite is direct or indirect. REFERENCES
. Horsfall, M. W. 1936. Notes on the spread, in one year, of helminths from infected to uninfected poultry yards. Proc. Helm. Soc. Wash. 3 (2): 66. Mayhew, R. L. 1934. Studies of coccidiosis. VI. Effect of early attack on egg production. Poultry Sci. 23(3): 148-154. Parker, J. E. and McSpadden, B. J. 1944. Pastures for growing pullets. Tenn. Agric. Expt. Sta. Bui. 188,14p.
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could be improved by different management. Under the present arrangement, the birds on pastures range freely in the early morning and late afternoon, and are driven to seek the only sources of shade on each lot, inside or in the shelter of the brooder houses, during the warmer part of the day. Accumulation of droppings in the vegetation in the shade of the brooder houses furnishes a perfect environment for development and survival of infective stages of parasites with either direct or indirect life cycles. Because the brooder houses on the 4 lots are stationary, it would appear that a porous surface, such as that afforded by a layer of cinders, would reduce the number of parasites available to infect the birds.
581
W
ARTIME shortages of certain feedstuffs that have come to be recognized as highly nutritious for poultry led to intensified investigation of supplements for the complete rations previously available as prepared products. Parker and McSpadden (1944) published the results of work at the Tennessee Experiment Station with pastures for growing pullets. Their studies extended over a 3-year period and covered the performance of 740 Barred Rock pullets, divided into 4 groups. All received the same starting mash, as a basal ration, plus whole yellow corn as a grain feed from 8 weeks, amd were raised, respectively, on bare range, and on ranges seeded to spring oats, a ryegrass-lespedeza mixture, and alfalfa. It was found that pullets raised on pastures were heavier, had lower mortality rates, consumed less feed, and utilized their feed more efficiently than those on bare range. The present paper is written to present the preliminary findings of two years of a projected 5-year investigation to determine what part of the difference between birds raised on the bare range and those raised on pastures can be ascribed to infection by parasites. The investigation also presents an opportunity to observe the annual development of the parasitic fauna in the 4 lots, because flocks of mature chickens are maintained within 120 feet of the pastures under study. The parasitic infections undoubtedly have more than one place of
origin. It is possible that some infections of preceding years survive within each brooder house despite rigorous cleaning between broods. Infections may survive on the ranges. A series of samplings have disclosed the following 15 species of parasites that were present in the other flocks: 4 coccidia, Eimeria maxima, E. mitis, E. necatrix, and E. tenella; 6 roundworms, Ascaridia galli, Capillaria annulata, C. caudinflata, C. columbae, Heterakis gallinae, and Tetrameres americana; and 5 tapeworms, Choanotaenia infundibulum, Davainea proglottina, Hymenolepis carioca, Raillietina cesticillus, and R. tetragona. These infections could be carried to the 4 lots by vectors, or by intermediate hosts, or both. MATERIALS AND PROCEDURE
The experiment is being conducted on 4 adjacent ranges, the dimensions of each being approximately 50X140 feet. A 10 X 12-foot colony brooder house is located on each range. In the 2-year period which this paper covers the lots have been arranged as follows: Lot Lot Lot Lot
1—Bare range, vegetation removed. 2—Seeded with clover and ryegrass. 3—Seeded with lespedeza. 4—Seeded with alfalfa.
In March, 1945, from 118 to 120 unsexed Rhode Island Red chicks were placed in each brooder house, where they were maintained until released from confinement and admitted to the ranges, at 8 weeks of age. In 1946, the same pro576
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(Received for publication April 30, 1947)
RELATION OF PASTURES TO PARASITIC FAUNA IN CHICKENS
Parasitic fauna, 1945 At 24 weeks, 89 cockerels were available for examination in the 4 lots (table 1). Of
were infected by A. galli; all 23 (100.0 percent) by H. gallinae; 7 (30.4 percent) by C. infundibulum; and 9 (39.1 percent) by H. carioca. The greatest number of worms found in any one infected bird was 309, consisting of 13 specimens of H. gallinae, 12 C. infundibulum, and 284 H. carioca. The average number of worms in an infected bird was 56.0; the aggregate species present, 1.9. The range of specimens of A. galli in infected birds in lot 2 was 1 to 2; for H. gallinae, 2 to 160; for C. infundibulum, 2 to 37; and for H. carioca, 1 to 284.
TABLE 1.—Mortalities and helminth infections of birds raised on bare range (lot 1) and on pastures (lots 2, 3, 4), 1945 Mortality record
Helminth fauna of birds examined Number birds infected by parasites
No. No. No. PerLot chicks chicks birds Percent cent survivbirds started mortal- exam(March) ing (Ocined infected ity tober)
1 2 3 4
120 119 119 118
33 49 55 60
72.5 58.8 53.8 49.2
17 23 24 25
100.0 100.0 100.0 100.0
the 17 birds in lot 1, 5 (29.4 percent) were infected by Ascaridia galli; all 17 (100.0 percent) by Heterakis gallinae; 4 (23.5 percent) by Choanotaenia infundibulum; and 1 (5.9 percent) by Hymenolepis carioca. The greatest number of worms found in any one bird was 83. These consisted of 16 specimens of H. gallinae, 15 C. infundibulum, and 52 E. carioca. The average number of worms in an infected bird was 14.0 and the average number of species in the aggregate infection was 1.6. In the 5 birds infected by .4. galli, the number of this species ranged from 1 to 4; H. gallinae ranged from 2 to 31; C. infundibulum, from 2 to 15; and the single bird with H. carioca had 52 specimens. Of the 23 birds in lot 2, 5 (21.7 percent)
Avg. Avg. no. no. worms species Choanoper Hetera- taenia Hymeno- per bird bird kis lepis infundigallinae bulum carioca
Roundworms Ascaridia galli 5 5 4 12
17 23 24 25
Tapeworms
4 7 0 6
1 9 8 12
14 56 44 40
1.6 1.9 1.5 2.2
From lot 3, 24 birds were examined, and of this number, 4 (16.0 percent), were infected by A. galli; all 24 (100.0 percent) by H. gallinae; none by C. infundibulum; and 8 (33.3 percent) by H. carioca. The greatest number of worms present in any one bird was 205:100 specimens of H. gallinae and 105 H. carioca. The average number of worms in an infected bird was 44, and the infection consisted, on the average, of 1.5 species. The 4 birds infected by A. galli each had one specimen; the range for H. gallinae was 2 to 100; and for H. carioca, 2 to 105. Of the 25 birds in lot 4, 12 (48.0 per cent) were infected by A. galli; all 25 (100.0 percent) by H. gallinae; 6 (24.0 percent) by C. infundibulum; and 12
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cedure was followed, except that Barred Rock chicks were used and from 81 to 92 chicks were started in each brooder house. In 1945, all the surviving cockerels in each lot were removed and examined for parasitic infections at 24 weeks of age. In 1946, 4 samplings, of 5 cockerels each, were taken from each lot and examined for parasitic infections at monthly intervals, starting at 8 weeks.
577
578
A. C. TODD AND B. J. MCSPADDEN
.BLE 2.—Egg TABLE 2
were placed in each brooder house in April. They were released from confinement in the brooder houses and given access to the prepared ranges in May. From June 27 to July 1, 5 cockerels were removed from each lot and examined for parasites; similar samplings were taken July 31-Aug. 1, Sept. 11-13, and Oct. 30-Nov. 4. The findings of these 4 examinations are summarized in Table 3. In 1946, the following six species of parasites were recovered from birds in the 4 lots: Eimeria tenella, the causative agent
production {percent performance) of 108 pullets, survivors of chronic coccidiosis infections
Lot
April
May
June
July
Aug.
Sept.
Oct.
Nov.
Dec.
Jan.
Feb.
Summary
1 2 3 4
60.5 56.2 59.3 62.2
59.1 63.2 64.4 65.0
36.6 51.7 50.1 54.4
25.8 33.9 28.8 32.4
26.3 31.8 29.3 29.0
22.8 22.7 16.5 16.8
11.6 8.8 7.9 5.6
5.3 4.6 6.5 2.6
15.0 9.2 16.8 14.1
40.9 13.8 20.1 22.4
36.3 16.0 18.1 19.3
30.5 27.3 28.1 28.8
of cecal coccidiosis; Ascaridia galli, a large roundworm from the small intestine; Heterakis gallinae, a cecal roundworm; Tetrameres americana, a roundworm from the proventriculus; Hymenolepis carioca, a tapeworm from the duodenum; and Raillietina cesticillus, a tapeworm from the jejunum. These parasites are species which had been found in the other flocks of university chickens. While the number of birds in each sampling is small, it may still appear from the data in Table 3 that the apparent order of development of the parasitic infections in 1946 has been established. It might be assumed that a parasite with the greatest incidence had appeared in the flock first; e.g., in the June 27-July 1 sampling, 19 of the 20 birds examined were infected by Eimeria tenella and only 5 by Heterakis gallinae. When such data are combined with the date of first apParasitic fauna, 1946 pearance of other parasites, the order of In 1946, unsexed Barred Rock chickss development of the infections probably
early May and finally subsided in July. Of the original number, 17 cockerels andL 16 pullets survived in lot 1, 23 cockerels; and 26 pullets in lot 2, 24 cockerels and 31 pullets in lot 3, and 25 cockerels and[ 35 pullets in lot 4. The pullets were maintained in the brooder houses and on the: ranges until April, 1946, when they were: placed in batteries in laying houses. The! 108 pullets then were examined for coccidia and were found to be passing oocysts, 9 months after the outbreak. The: species of coccidian most generally present; in these birds at that time was Eimeriai mitis; whereas, the causative agent ofE chronic coccidiosis 9 months previouslyT was Eimeria necatrix. The egg production rates of the abovej pullets, expressed as percentages of possible performance, are recorded in Table5 2.
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(48.0 percent) by H. carioca. The greatest number of worms present in any one bird was 254, comprised of 25 specimens of H. gallinae and 229 H. carioca. The average number of worms in an infected bird was 40 and the average number of species present was 2.2. The range of specimens of A. galli present was 1 to 6; H. gallinae 3 to 36; C. infundibulum, 1 to 6; and H. carioca, 1 to 229. In 1945, the number of birds available for study was reduced by an outbreak of chronic coccidiosis, which developed in
579
RELATION OF PASTURES TO PARASITIC FAUNA IN CHICKENS
was as follows: 1) Eimeria tenella, 2) Heterakis gallinae, 3) Ascaridia galli, 4) Hymenolepis carioca, 5) Raillietina cesticillus, 6) Tetrameres americana. The first 3 parasites found in the lots in 1946 were species which have a direct
determine whether the parasitic faunae of birds on bare range and birds raised on pastures can account for the difference in performance observed by Parker and McSpadden. From 2 years' investigation, it appears that the amount of helminth
Mortality record No. chicks PerNo. Lot chicks surcent started viving mor(April) (Oc- tality tober)
Parasitic fauna--number infected Date Birds Birds exam- exam- inined ined fected
Avg. Avg. no. no. Tapeworms worms species per per H. E. R. T. bird galli- A. E. ameri- cari- cesti- bird tenella nae galli cana oca cillus Coccidia
Roundworms
1
91
71
22.0
6-27 7-31 9-11 10-30
5 5 5 S
5 4 5 5
5 1 5 4
1 2 2 5
0 2 2 2
0 0 0 0
0 0 0 4
0 0 0 0
1.0 1.2 12.6 167.0
1.0 1.0 1.3 2.2
2
81
73
10.0
6-27 7-31 9-12 10-31
5 5 5 5
4 4 3 5
4 3 1 2
2 2 2 4
0 0 3 2
0 0 0 0
0 0 2 2
0 0 • 1 0
1.0 1.5 84.0 38.2
1.0 1.0 2.6 1.6
3
92
88
4.0
7- 1 8- 1 9-13 11- 1
5 5 5 5
5 5 5 5
5 5 3 3
1 4 5 5
0 3 4 4
0 0 0 1
0 2 5 5
0 0 0 0
1.0 47.0 218.fr 215.0
1.0 2.2 2.8 3.0
4
84
80
5.0
7- 1 8- 1 9-13 11- 4
5 S 5 5
5 5 5 5
5 S 4 4
1 0 3 5
0 1 5 3
0 0 0 0
0 0 4 1
0 0 0 0
1.0 1.0 26.0 80.5
1.0 1.0 2.4 1.8
•
life cycle; i.e., the oocysts of E. tenella and the eggs of H. gallinae and A. galli are eliminated from the body of the host in the droppings, and a new host becomes infected by ingesting these forms after they have embryonated to an infective stage. The fourth parasite to appear, Hymenolepis carioca, has an indirect life cycle requiring flies or certain species of beetles as intermediate hosts. For Raillietina cesticillus, the housefly and various beetles serve as intermediate hosts, while Tetrameres americana is said to be carried by grasshoppers and cockroaches. DISCUSSION
The purpose of this investigation is to
infections found in 1945 and 1946 were not the major factor responsible for the inferior performance of birds raised on bare range. Certainly, however, the higher mortality rates of birds on bare range during the outbreak of chronic coccidiosis (Table 1) indicate that coccidial infections have been an important cause of mortality. When the average worm burden and the average number of parasite species in birds from the bare lot are compared with those in birds on pasture, it is clearly shown in the data from 1945 (Table 1), and indicated in the data from 1946 (Table 3), that the heaviest helminth infections were sustained by birds on the pastures. The bare range is maintained
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TABLE 3.—Mortalities and parasitic infections of birds raised on bare range (lot 1) and on pastures (lots 2, 3,4), 1946
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A. C. TODD AND B. J. MCSPADDEN
A contrast has been observed in the order of development of the parasitic infections in the 4 lots under study with the order of development of infections found by Horsfall (1936), who studied the spread of helminths, in one year, from infected to uninfected poultry yards. Working with 10-month chickens, which had been demonstrated to be free of helminth infections, on ground where no chickens had ranged previously, and at a distance of 300 feet from other flocks, she found that: 1) four helminths, common to other flocks nearby, appeared in birds
ranged on uninfected ground within 3 months; 2) two tapeworms, Hymenolepis carioca and Raillietina cesticillus, appeared first; and 3) two roundworms, Heterakis gallinae and Ascaridia lineata, appeared just at the end of the 3-month period. Horsfall concluded that migratory habits of the intermediate hosts enabled the tapeworms to cross the 300-foot space barrier more quickly than the two roundworms which have direct life cycles, and which, therefore, were transferred mechanically. In the lots studied at Tennessee in 1946, which are separated from other flocks of chickens by a distance of 120 feet, the first three parasites to appear were those with direct life cycles. Mayhew (1934) demonstrated that pullets which survived cecal coccidiosis never became profitable because of retarded growth, which in turn was reflected in delayed and lower egg production. The egg production of the Rhode Island Red pullets in laying batteries, after being maintained on the 4 lots for 12 months, appeared to be conditioned more by their previous diet than by their concurrent status as carriers of coccidia and other parasitic infections. The superior performance of birds given access to green pastures as a supplement to an adequate basal ration, when compared with that of birds given only the basal ration, has been clearly evident during the first two years of this investigation. The supplementary green food has not prevented infection; on the contrary, it has indirectly promoted heavier parasitic burdens than those sustained by birds on bare ranges. Despite the fact that little exact knowledge exists concerning losses caused by the 5 helminths found in birds on the 4 lots, a rather general agreement may be said to have been established that the cumulative effect of these parasites is deleterious. The performance of birds on pastures probably
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without vegetation, so that stages of parasites which need to embryonate to the infective stage, and intermediate hosts which might feed on droppings, are subjected to a much more unfavorable environment than exists in the pasture lots, where some protection is afforded from direct sunlight, adverse temperatures, and loss of moisture. The theory that the better the diet, the more resistant an animal is to infection by parasites, is too loose. Similarly, the fact that the threshold of infection of uninfected birds is easily surmounted by parasites—combined with the fact that strains of parasites exist which possess greater, or less, virulence—is too often overlooked. Parasites are perfectly adapted to enter, and infect, healthy, "normal" chickens. The birds raised on pastures have been shown to carry the heaviest helminth infections. This is true at least for the two years of this study. It seems 'more accurate, therefore, to say that chickens with better diets are better able to withstand the effects of helminth infections. While birds raised on pastures can withstand heavier infections, sanitary precautions for such flocks should not be abandoned, since it appears that vegetated areas are more favorable environments for the development and maintenance of parasitic infections.
RELATION OF PASTURES TO PARASITIC FAUNA IN CHICKENS
SUMMARY
1. In a group of 4 lots, similar in size but different in the type of pasture, or lack of it, an investigation has been initiated to determine the total effect of parasitic infections upon chickens ranged on the lots. Two years' investigations are presented.
2. Greater mortality rates due to coccidial infections have been found in birds ranged on the bare lot than in birds ranged on pastures. 3. Birds ranged on pastures have been found to carry the heavier burdens of helminth infections. 4. The Supplemental green food obtained by birds ranged on pastures does not, per se, prevent parasitic infections. It does, apparently, enable birds to withstand greater parasitic burdens. 5. Vegetation appears to furnish a better environment than bare range for the development and survival of infective stages of parasites, regardless of whether the life cycle of a parasite is direct or indirect. REFERENCES
. Horsfall, M. W. 1936. Notes on the spread, in one year, of helminths from infected to uninfected poultry yards. Proc. Helm. Soc. Wash. 3 (2): 66. Mayhew, R. L. 1934. Studies of coccidiosis. VI. Effect of early attack on egg production. Poultry Sci. 23(3): 148-154. Parker, J. E. and McSpadden, B. J. 1944. Pastures for growing pullets. Tenn. Agric. Expt. Sta. Bui. 188,14p.
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could be improved by different management. Under the present arrangement, the birds on pastures range freely in the early morning and late afternoon, and are driven to seek the only sources of shade on each lot, inside or in the shelter of the brooder houses, during the warmer part of the day. Accumulation of droppings in the vegetation in the shade of the brooder houses furnishes a perfect environment for development and survival of infective stages of parasites with either direct or indirect life cycles. Because the brooder houses on the 4 lots are stationary, it would appear that a porous surface, such as that afforded by a layer of cinders, would reduce the number of parasites available to infect the birds.
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