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Resistance Potential of Certain Breeds of Domestic Fowl Exposed to Raillietina tetragona Infections
Resistance Potential of Certain Breeds of Domestic Fowl Exposed to Raillietina tetragona Infections 6. EFFECTS OF STARVATION OF THE HOST CHICKEN ON THE TAPEWORM RAILLIETINA TETRAGONA* A. M. NADAKAL, A. MOHANDAS, K. 0 . JOHN AND K\ MURALEEDHARAN Department of Zoology, Mar Ivanios College, Trivandrum, Kerala—India (Received for publication October 13, 1971) ABSTRACT Effects of short periods of starvation on the fowl cestode, Raillietina tetragona, developed in four breeds of chickens, White Leghorn, White Rock, Desi and Hybrid (White LeghornXDesi) are reported. The data based on 40 birds revealed significant reduction in segment discharge, depletion of glycogen reserve of the worms, elimination of entire worms and reduction in worm weight, almost correlated with the duration of starvation. POULTRY SCIENCE 5 1 : 1027-1031,
INTRODUCTION
F
ACTORS such as nature of diet, feeding time, feeding habits, sickness and starvation of the host are known to exert profound influence on the physiology of intestinal helminths. Chandler (1943), Chandler et al. (1950), Read (1959), Roberts and Platzer (1967) among others, have shown the sensitivity of cestodes to carbohydrate deficiency of the host diet and that suboptimal carbohydrate, in quantity or quality, deleteriously affects their development. Studies made by Levine (1938) and Reid (1940, 1942a, b, 1944, 1945) revealed that host starvation caused decreased segment production and glycogen depletion of the worms, Davainea proglottina and Raillietina cesticillus, respectively. Reid (1942 a, b) also reported that the scolex was unaffected by starvation and was able to regenerate new strobila upon resumption of normal feeding of the host bird. However, little is known in this connection about R. tetragona, one of the most important of the fowl cestodes. An attempt was, therefore, made to study the effects of short periods of starvation
1972
on this tapeworm developed in four breeds of domestic fowl. MATERIALS AND METHODS Day-old chickens of the four breeds, White Leghorn, White Rock, Desi and Hybrid (White LeghornXDesi) were procured and maintained in brooders on adequate diet. When 21-days old, 10 birds of each breed were selected and each of them received 10 cysticercoids recovered from three species of ants, Tetramorium simillimum, Tetramorium sp.2 and Pheidole sp. The cysticercoids were administered to the birds following the method of Nadakal et al. (1970a). Infected chickens were kept individually in wire-mesh cages. Thirty five days post-infection, two birds of each breed were subjected to 6, 12, 18 and 24 hours of starvation and an equal number, properly fed, kept as controls. Birds which shed larger number of segments were selected for longer periods of starvation. The starvation schedule and time of autopsy of birds are shown below:
* This research has been financed by a grant, FG-In-387 by the United States Department of Agriculture under PL.480.
1027
Duration of starvation Ohrs. 6 hrs. 12 hrs. 18 hrs. 24 hrs.
Starvationtime
— 9 9 3 9
A.M.-3 P.M.-9 P.M.-9 A.M.-9
P.M. A.M. A.M. A.M.
Time of autopsy 9 A.M. 3 P.M. 9 A.M. 9 A.M. 9 A.M.
1028
A. M. NADAKAL, A. MOHANDAS, K. O. JOHN AND K. MURALEEDHARAN TABLE 1.—Data on the discharge of segments Duration of starvation Breed
White Leghorn White Rock Desi Hybrid
6 hrs.
12 hrs.
18 hrs.
24 hrs.
St
USt
St
USt
St
USt
St
USt
101 127 92 114
148 145 113 159
95 89 95 80
152 113 175 92
192 218 223 53
255 263 285 76
35 398 22 154
287 589 175 283
St. Number of segments discharged during starvation period. USt. Number of segments discharged during corresponding pre-starvation period.
Regular fecal examination was carried out during the patent period to ensure destrobilization and/or elimination of entire worms, if any. The number of segments discharged was noted during pre-starvation and starvation periods. Starved birds were given water as needed. At the end of each starvation period, the experimental birds were sacrificed and the number of recovered worms recorded. After taking weight of worms, they were immediately processed for glycogen determination following the method of Seifter et al. (1950) using Spectronic-20 at 620 xa/x. A simple analysis of variance method was carried out taking variety and period as two treatments and the treatment effects and the effect due to the interaction of variety and period were tested. RESULTS AND DISCUSSION
The data on segment discharge, weight and glycogen content of the worms recovered from birds starved for different periods as well as those from control birds and worm expulsion and recovery of worms at autopsy are presented in Tables 1 to 4. Our data indicate that longer periods of starvation adversely affect the cestode, R. tetragona. One of the effects was reduction in the production of segments by worms in all breeds of chickens (Table 1). Similar observations were also made in the case of worms, Davainea proglottina in
chickens (Levine, 1938), Hymenolepis diminuta in rats (Chandler, 1943; Roberts and Platzer, 1967) and Cotugnia digonopora in chickens (Nadakal et al., 1970b). Of all the nutritional requirements of cestodes, the vital importance of carbohydrate has been well established (Read, 1959; von Brand, 1966). The deficiency or lack of carbohydrates in the host diet adversely affects the segment production and the weight gain of worms (Chandler, 1943; Read, 1959; and Roberts and Platzer, 1967). In starved birds the worms are literally deprived of their nutritional requirements, especially carbohydrates, needed for normal metabolism. Roberts (1966) reported that there is a threshold concentration of carbohydrates, below which formation of segments is inhibited. It is also possible that host starvation brings about certain changes in the intestinal milieu which are not compatible with the worms. For instance, we noticed an increased production of mucosal exudate and bile secretion in the gut of host birds starved for longer periods. The average weight of worms obtained in different starvation periods as well as from different breeds showed significant differences. Reduction in weight of worms was not very consistent; however it was well-marked during 18 and 24 hours of starvation. It is difficult to explain the increase in the weight of worms recovered
1029
STARVATION AND TAPEWORM RESISTANCE
from one of the White Leghorns and another of the White Rocks starved for 24 hours (Table 2). In each case there were only two worms. One might argue, therefore, that there was no competition and hence the weight of worms was not much affected due to starvation. I t seems that this situation is partly due to inherent metabolic variations of both the host and the parasite. Our results on the weight and segment production of worms are in agreement with the observations made by Read and Rothman (1957) and Roberts (1961) that shedding of segments is not a direct function of growth rate using weight as a criterion. We noted progressive reduction in the rate of segment discharge during starvation periods despite the fluctuations in the worm weight. The general tendency for the weight loss of worms in birds starved for longer periods might also be due to water loss as reported by Overturf and Dryer (1968). It is known that host starvation causes drastic depletion of polysaccharide reserve of worms (von Brand, 1966). In the present investigation we have observed significant differences between periods in the rate of depletion of worm glycogen (Table 3). There were, however, minor fluctuations, which might be due to metabolic variations of individual worms. About 62% and 55% of glycogen contents were depleted in worms obtained from White Leghorns and White Rocks, respectively, starved for 24 hours. In Desi, by 18 hours of starvation, about 67% of the worm glycogen disappeared. Reid (1940, 1942 a, b) and Reid and Ackert (1941) reported that after 24 hours of starvation, the glycogen content of R. cesticilliis was reduced by 92%. Similar observations have also been made by Overturf and Dryer (1968) in the case of H. diminuta in rats. The rapid depletion of worm glycogen in starved hosts suggests
T A B L E 2.—Average worm weight in grams per bird at different periods of starvation (Two birds of each breed as controls and experimentals) Breed
Control
White Leghorn
Experimental 6 hrs.
12 hrs. 18 hrs. 24 hrs.
204.4 182.5
178.0 114.2
145.6 181.9
105.6 99.4
180.0
White Rock
260.0 221.3
155.0 207.9
210.0 227.0
168.3 196.2
153.0 225.0
Desi
131.3 158.1
250.7 115.0
163.0 101.4
123.0 88.5
Hybrid
115.0 138.1
150.0 126.9
120.0 101.9
—
— —
The value of the variance ratio obtained for the treatment namely, variety, period and interaction effect are 15.4, 9.2 and 1.2 respectively. From tables the value of variance ratio for F(»,3)=3.10, F(2o,4)=2.87 and F(io.i2) =2.28 at 5% level of significance. There is no interaction between variety and period.
its importance in cestode metabolism. Another consequence of host starvation was the elimination of the entire worms, especially during 24 hours of starvation (Table 4). In White Leghorns and White Rocks, however, a few worms could survive 24 hours of starvation, but from Desi and Hybrid birds all the worms were eliminated by this time. The discharge of plentiful yellowish-white mucosal exudate was characteristically noticed in birds starved for longer periods. Unlike R. echinobothrida and R. cesticillus, R. tetragona is only superficially attached to the intestinal wall and so it was easy for the worms to get expelled along with the mucosal exudate. Levine (1938) and Reid (1940, 1942 a, b) never observed the elimination of entire worms in their starvation studies with D. proglottina and R. cesticillus respectively. Reid noted regeneration of scolices which remained attached to the intestinal wall when the host birds were brought back to normal feeding. Free from intestinal food contents, we have been able to make a thorough examination of the gut epithelia of starved hosts at autopsy but failed to recover any scolex. Reid (1944, 1945) attributed elimination of the worm, As-
1030
A. M. NADAKAL, A. MOHANDAS, K. O. JOHN AND K. MURALEEDHARAN TABLE 3.—Average glycogen content, in gram percent, per worm (Two birds of each breed as controls and experimentals) Experimental Breed
Control 6 hrs.
12 hrs.
18 hrs.
24 hrs.
White Leghorn
6.53 7.11
3.99 4.12
2.78 3.08
1.63 3.67
2.54
White Rock
5.91 8.97
5.94 4.77
5.40 5.85
3.64 3.30
3.41 3.20
Desi
6.93 6.23
4.60 8.80
5.40 3.36
3.89 2.80
—
Hybrid
7.43 5.03
4.55 7.33
6.89 3.76
—
—
The value of the variance ratio obtained for the treatment namely, variety, period and interaction effect are 3.0, 24.5 and 1.5 respectively. From tables the value of F(2o,s)=3.10, F (20,4) = 2.87 and F(2o,i2) = 2.28, at 5 % level of significance. I t is seen that there is significant difference between periods at 5 % level of significance. Between varieties there is no significant difference and there is no interaction.
caridia galli during starvation to carbohydrate deficiency leading to enfeeblement of worms to cope up with the peristaltic contraction of the intestine. It is likely that in the starved host, the worms themselves are starved almost to moribund state and become easily expelled along with the intestinal mucus. We have also noticed elimination of entire worms in the apparently normal host. This may be due to voluntary partial starvation of the host resulting from factors including change of diet and fear as suggested by Reid (1942a, b). From a few birds starved for 24 hours,
no worm could be recovered despite regular segment discharge even a few hours before autopsy. There was no elimination of the entire worms either. It is likely that the worms might have been digested by the host birds. Reid (1945) also suggested the phenomenon of worm digestion in starved hosts in his studies with A. galli. It is generally held that living helminths escape from being digested by the host because of the presence of anti-enzymes or enzyme inhibitors (Watson, 1960). The expelled worms as well as those recovered from birds starved for 24 hours, were fragmented, degenerate and knotted with
TABLE 4.—Data on the recovery of worms at autopsy and elimination of worms during the starvation periods Duration of starvation Breed
White Leghorn White Rock Desi Hybrid R—Worms recovered. E—Worms eliminated.
Unstarved normal control
6 hours
12 hours
18 hours
24 hours
R
E
R
E
R
E
R
E
R
E
13 9 13 9
— — — —
15 9 9 12
— — — —
17 10 12 14
— — — —
17 14 15
— — —
2 7
2 .3 5 4
—
3
— —
STARVATION AND TAPEWORM RESISTANCE
mucosal exudate. Structural changes in the cuticle of worms caused by starvation stress, particularly those associated with molecular organization of glycoproteins, might have made them amenable to the attack of digestive enzymes of the host. In conclusion, our observations indicate that host starvation is definitely deleterious to these worms since it tends to retard growth and expel them from the host. As the attachment of these worms to the intestinal epithelium is only superficial, they may readily be discharged by the birds along with mucosal exudate during longer periods of starvation. Hence periodic starvation of the birds may be helpful in controlling this tapeworm infection, particularly in Desi and Hybrids. ACKNOWLEDGEMENT
Grateful acknowledgement is made to Mr. S. Ramalinga Iyer of the Bureau of Economics and Statistics, Kerala for the statistical analysis of the data. The authors are thankful to Dr. Poulose John B.V.Sc. for technical assistance and to the authorities of Mar Ivanios College for providing space and facilities. REFERENCES Chandler, A. C , 1943. Studies on the nutrition of tapeworms. Amer. J. Hyg. 37: 121-129. Chandler, A. C , C. P. Read and H. O. Nicholas., 1950. Observations on certain phases of nutrition and host-parasite relations of Hymenolepis diminuta in white rats. J. Parasit. 36: 523-535. Levine, P. P., 1938. Observations on the biology of the poultry cestode Davainea proglottina in the intestine of the host. J. Parasit. 24: 423-431. Nadakal, A. M., K. O. John, K. Muraleedharan and A. Mohandas, 1970a. Resistance potential of certain breeds of domestic fowl exposed to Raillietina tetragona infections. I—Contributions to the biology of Raillielina tetragona (Molin, 1858). Proc. Helminth. Soc. Wash. 37: 141-143. Nadakal, A. M., K. Muraleedharan, A. Mohandas and K. O. John, 1970b. Observations on certain aspects of the biology of the tapeworm Cotugnia digonopora (Pasquale, 1890) Diamare, 1893. Jap. J. Parasit. 19: 196-198.
1031
Overturf, M., and R. L. Dryer, 1968. Lipid metabolism in the adult cestode Hymenolepis diminuta. Comp. Biochem. Physiol. 27: 145-175. Read, C. P., 1959. The role of carbohydrates in the biology of cestodes. VIII—Some conclusions and hypothesis. Exptl. Parasitol. 8: 365-382. Read, C. P., and A. H. Rothman, 1957. The role of carbohydrates in the biology of cestodes. IV— Some effects of the host dietary carbohydrate on growth and reproduction of Hymenolepis. Exptl. Parasitol. 6: 294-305. Reid, W. M., 1940. Some effects of short starvation periods upon the fowl cestode Raillielina cesticillus (Molin). J. Parasit. 26 (suppl): 16. Reid, W. M., 1942a. Removal of the tapeworm Raillietina cesticillus by short periods of starvation. Poultry Sci. 21:220-229. Reid, W. M., 1942b. Certain nutritional requirements of the fowl cestode Raillielina cesticillus (Molin) as demonstrated by short periods of starvation of the host. J. Parasit. 28: 319-340. Reid, W. M., 1944. The effects of host starvation on worm elimination and glycogen depletion with nematode Ascaridia galli. J. Parasit. 30 (Suppl): 12. Reid, W. M., 1945. The relationship between glycogen depletion in the nematode Ascaridia galli (Schrank) and elimination of the parasite by the host. Amer. J. Hyg. 41: 150-155. Reid, W. M., and J. E. Ackert, 1941. The removal of chicken tapeworms by forced starvation and some effects of such treatment on tapeworm metabolism. J. Parasit. 27 (suppl): 35. Roberts, L. S., 1961. The influence of population density on patterns and physiology of growth in Hymenolepis diminuta (Cestoda: Cyclophyllidea) in the definitive host. Exptl. Parasitol. 11: 332371. Roberts, L. S., 1966. Developmental physiology of cestodes. I—Host dietary carbohydrate and the 'crowding effect' in Hymenolepis diminuta. Exptl. Parasitol. 18: 305-310. Roberts, L. S., and E. G. Platzer, 1967. Developmental physiology of cestodes. II—Effects of changes in host dietary carbohydrate and roughage on previously established Hymenolepis diminuta. J. Parasit. 53: 85-93. Seifter, S., S. Dayton, B. Novic and E. Muntwyler, 1950. The estimation of glycogen with anthrone reagent. Arch. Biochem. 25: 191-200. Von Brand T., 1966. Biochemistry of Parasites. Academic Press, New York and London. Watson, J. M., 1960. Medical Helminthology. Balliere, Tindall and Cox. 7 & 8 Henrietta street, London (First edition) p. 42.
INTRODUCTION
F
ACTORS such as nature of diet, feeding time, feeding habits, sickness and starvation of the host are known to exert profound influence on the physiology of intestinal helminths. Chandler (1943), Chandler et al. (1950), Read (1959), Roberts and Platzer (1967) among others, have shown the sensitivity of cestodes to carbohydrate deficiency of the host diet and that suboptimal carbohydrate, in quantity or quality, deleteriously affects their development. Studies made by Levine (1938) and Reid (1940, 1942a, b, 1944, 1945) revealed that host starvation caused decreased segment production and glycogen depletion of the worms, Davainea proglottina and Raillietina cesticillus, respectively. Reid (1942 a, b) also reported that the scolex was unaffected by starvation and was able to regenerate new strobila upon resumption of normal feeding of the host bird. However, little is known in this connection about R. tetragona, one of the most important of the fowl cestodes. An attempt was, therefore, made to study the effects of short periods of starvation
1972
on this tapeworm developed in four breeds of domestic fowl. MATERIALS AND METHODS Day-old chickens of the four breeds, White Leghorn, White Rock, Desi and Hybrid (White LeghornXDesi) were procured and maintained in brooders on adequate diet. When 21-days old, 10 birds of each breed were selected and each of them received 10 cysticercoids recovered from three species of ants, Tetramorium simillimum, Tetramorium sp.2 and Pheidole sp. The cysticercoids were administered to the birds following the method of Nadakal et al. (1970a). Infected chickens were kept individually in wire-mesh cages. Thirty five days post-infection, two birds of each breed were subjected to 6, 12, 18 and 24 hours of starvation and an equal number, properly fed, kept as controls. Birds which shed larger number of segments were selected for longer periods of starvation. The starvation schedule and time of autopsy of birds are shown below:
* This research has been financed by a grant, FG-In-387 by the United States Department of Agriculture under PL.480.
1027
Duration of starvation Ohrs. 6 hrs. 12 hrs. 18 hrs. 24 hrs.
Starvationtime
— 9 9 3 9
A.M.-3 P.M.-9 P.M.-9 A.M.-9
P.M. A.M. A.M. A.M.
Time of autopsy 9 A.M. 3 P.M. 9 A.M. 9 A.M. 9 A.M.
1028
A. M. NADAKAL, A. MOHANDAS, K. O. JOHN AND K. MURALEEDHARAN TABLE 1.—Data on the discharge of segments Duration of starvation Breed
White Leghorn White Rock Desi Hybrid
6 hrs.
12 hrs.
18 hrs.
24 hrs.
St
USt
St
USt
St
USt
St
USt
101 127 92 114
148 145 113 159
95 89 95 80
152 113 175 92
192 218 223 53
255 263 285 76
35 398 22 154
287 589 175 283
St. Number of segments discharged during starvation period. USt. Number of segments discharged during corresponding pre-starvation period.
Regular fecal examination was carried out during the patent period to ensure destrobilization and/or elimination of entire worms, if any. The number of segments discharged was noted during pre-starvation and starvation periods. Starved birds were given water as needed. At the end of each starvation period, the experimental birds were sacrificed and the number of recovered worms recorded. After taking weight of worms, they were immediately processed for glycogen determination following the method of Seifter et al. (1950) using Spectronic-20 at 620 xa/x. A simple analysis of variance method was carried out taking variety and period as two treatments and the treatment effects and the effect due to the interaction of variety and period were tested. RESULTS AND DISCUSSION
The data on segment discharge, weight and glycogen content of the worms recovered from birds starved for different periods as well as those from control birds and worm expulsion and recovery of worms at autopsy are presented in Tables 1 to 4. Our data indicate that longer periods of starvation adversely affect the cestode, R. tetragona. One of the effects was reduction in the production of segments by worms in all breeds of chickens (Table 1). Similar observations were also made in the case of worms, Davainea proglottina in
chickens (Levine, 1938), Hymenolepis diminuta in rats (Chandler, 1943; Roberts and Platzer, 1967) and Cotugnia digonopora in chickens (Nadakal et al., 1970b). Of all the nutritional requirements of cestodes, the vital importance of carbohydrate has been well established (Read, 1959; von Brand, 1966). The deficiency or lack of carbohydrates in the host diet adversely affects the segment production and the weight gain of worms (Chandler, 1943; Read, 1959; and Roberts and Platzer, 1967). In starved birds the worms are literally deprived of their nutritional requirements, especially carbohydrates, needed for normal metabolism. Roberts (1966) reported that there is a threshold concentration of carbohydrates, below which formation of segments is inhibited. It is also possible that host starvation brings about certain changes in the intestinal milieu which are not compatible with the worms. For instance, we noticed an increased production of mucosal exudate and bile secretion in the gut of host birds starved for longer periods. The average weight of worms obtained in different starvation periods as well as from different breeds showed significant differences. Reduction in weight of worms was not very consistent; however it was well-marked during 18 and 24 hours of starvation. It is difficult to explain the increase in the weight of worms recovered
1029
STARVATION AND TAPEWORM RESISTANCE
from one of the White Leghorns and another of the White Rocks starved for 24 hours (Table 2). In each case there were only two worms. One might argue, therefore, that there was no competition and hence the weight of worms was not much affected due to starvation. I t seems that this situation is partly due to inherent metabolic variations of both the host and the parasite. Our results on the weight and segment production of worms are in agreement with the observations made by Read and Rothman (1957) and Roberts (1961) that shedding of segments is not a direct function of growth rate using weight as a criterion. We noted progressive reduction in the rate of segment discharge during starvation periods despite the fluctuations in the worm weight. The general tendency for the weight loss of worms in birds starved for longer periods might also be due to water loss as reported by Overturf and Dryer (1968). It is known that host starvation causes drastic depletion of polysaccharide reserve of worms (von Brand, 1966). In the present investigation we have observed significant differences between periods in the rate of depletion of worm glycogen (Table 3). There were, however, minor fluctuations, which might be due to metabolic variations of individual worms. About 62% and 55% of glycogen contents were depleted in worms obtained from White Leghorns and White Rocks, respectively, starved for 24 hours. In Desi, by 18 hours of starvation, about 67% of the worm glycogen disappeared. Reid (1940, 1942 a, b) and Reid and Ackert (1941) reported that after 24 hours of starvation, the glycogen content of R. cesticilliis was reduced by 92%. Similar observations have also been made by Overturf and Dryer (1968) in the case of H. diminuta in rats. The rapid depletion of worm glycogen in starved hosts suggests
T A B L E 2.—Average worm weight in grams per bird at different periods of starvation (Two birds of each breed as controls and experimentals) Breed
Control
White Leghorn
Experimental 6 hrs.
12 hrs. 18 hrs. 24 hrs.
204.4 182.5
178.0 114.2
145.6 181.9
105.6 99.4
180.0
White Rock
260.0 221.3
155.0 207.9
210.0 227.0
168.3 196.2
153.0 225.0
Desi
131.3 158.1
250.7 115.0
163.0 101.4
123.0 88.5
Hybrid
115.0 138.1
150.0 126.9
120.0 101.9
—
— —
The value of the variance ratio obtained for the treatment namely, variety, period and interaction effect are 15.4, 9.2 and 1.2 respectively. From tables the value of variance ratio for F(»,3)=3.10, F(2o,4)=2.87 and F(io.i2) =2.28 at 5% level of significance. There is no interaction between variety and period.
its importance in cestode metabolism. Another consequence of host starvation was the elimination of the entire worms, especially during 24 hours of starvation (Table 4). In White Leghorns and White Rocks, however, a few worms could survive 24 hours of starvation, but from Desi and Hybrid birds all the worms were eliminated by this time. The discharge of plentiful yellowish-white mucosal exudate was characteristically noticed in birds starved for longer periods. Unlike R. echinobothrida and R. cesticillus, R. tetragona is only superficially attached to the intestinal wall and so it was easy for the worms to get expelled along with the mucosal exudate. Levine (1938) and Reid (1940, 1942 a, b) never observed the elimination of entire worms in their starvation studies with D. proglottina and R. cesticillus respectively. Reid noted regeneration of scolices which remained attached to the intestinal wall when the host birds were brought back to normal feeding. Free from intestinal food contents, we have been able to make a thorough examination of the gut epithelia of starved hosts at autopsy but failed to recover any scolex. Reid (1944, 1945) attributed elimination of the worm, As-
1030
A. M. NADAKAL, A. MOHANDAS, K. O. JOHN AND K. MURALEEDHARAN TABLE 3.—Average glycogen content, in gram percent, per worm (Two birds of each breed as controls and experimentals) Experimental Breed
Control 6 hrs.
12 hrs.
18 hrs.
24 hrs.
White Leghorn
6.53 7.11
3.99 4.12
2.78 3.08
1.63 3.67
2.54
White Rock
5.91 8.97
5.94 4.77
5.40 5.85
3.64 3.30
3.41 3.20
Desi
6.93 6.23
4.60 8.80
5.40 3.36
3.89 2.80
—
Hybrid
7.43 5.03
4.55 7.33
6.89 3.76
—
—
The value of the variance ratio obtained for the treatment namely, variety, period and interaction effect are 3.0, 24.5 and 1.5 respectively. From tables the value of F(2o,s)=3.10, F (20,4) = 2.87 and F(2o,i2) = 2.28, at 5 % level of significance. I t is seen that there is significant difference between periods at 5 % level of significance. Between varieties there is no significant difference and there is no interaction.
caridia galli during starvation to carbohydrate deficiency leading to enfeeblement of worms to cope up with the peristaltic contraction of the intestine. It is likely that in the starved host, the worms themselves are starved almost to moribund state and become easily expelled along with the intestinal mucus. We have also noticed elimination of entire worms in the apparently normal host. This may be due to voluntary partial starvation of the host resulting from factors including change of diet and fear as suggested by Reid (1942a, b). From a few birds starved for 24 hours,
no worm could be recovered despite regular segment discharge even a few hours before autopsy. There was no elimination of the entire worms either. It is likely that the worms might have been digested by the host birds. Reid (1945) also suggested the phenomenon of worm digestion in starved hosts in his studies with A. galli. It is generally held that living helminths escape from being digested by the host because of the presence of anti-enzymes or enzyme inhibitors (Watson, 1960). The expelled worms as well as those recovered from birds starved for 24 hours, were fragmented, degenerate and knotted with
TABLE 4.—Data on the recovery of worms at autopsy and elimination of worms during the starvation periods Duration of starvation Breed
White Leghorn White Rock Desi Hybrid R—Worms recovered. E—Worms eliminated.
Unstarved normal control
6 hours
12 hours
18 hours
24 hours
R
E
R
E
R
E
R
E
R
E
13 9 13 9
— — — —
15 9 9 12
— — — —
17 10 12 14
— — — —
17 14 15
— — —
2 7
2 .3 5 4
—
3
— —
STARVATION AND TAPEWORM RESISTANCE
mucosal exudate. Structural changes in the cuticle of worms caused by starvation stress, particularly those associated with molecular organization of glycoproteins, might have made them amenable to the attack of digestive enzymes of the host. In conclusion, our observations indicate that host starvation is definitely deleterious to these worms since it tends to retard growth and expel them from the host. As the attachment of these worms to the intestinal epithelium is only superficial, they may readily be discharged by the birds along with mucosal exudate during longer periods of starvation. Hence periodic starvation of the birds may be helpful in controlling this tapeworm infection, particularly in Desi and Hybrids. ACKNOWLEDGEMENT
Grateful acknowledgement is made to Mr. S. Ramalinga Iyer of the Bureau of Economics and Statistics, Kerala for the statistical analysis of the data. The authors are thankful to Dr. Poulose John B.V.Sc. for technical assistance and to the authorities of Mar Ivanios College for providing space and facilities. REFERENCES Chandler, A. C , 1943. Studies on the nutrition of tapeworms. Amer. J. Hyg. 37: 121-129. Chandler, A. C , C. P. Read and H. O. Nicholas., 1950. Observations on certain phases of nutrition and host-parasite relations of Hymenolepis diminuta in white rats. J. Parasit. 36: 523-535. Levine, P. P., 1938. Observations on the biology of the poultry cestode Davainea proglottina in the intestine of the host. J. Parasit. 24: 423-431. Nadakal, A. M., K. O. John, K. Muraleedharan and A. Mohandas, 1970a. Resistance potential of certain breeds of domestic fowl exposed to Raillietina tetragona infections. I—Contributions to the biology of Raillielina tetragona (Molin, 1858). Proc. Helminth. Soc. Wash. 37: 141-143. Nadakal, A. M., K. Muraleedharan, A. Mohandas and K. O. John, 1970b. Observations on certain aspects of the biology of the tapeworm Cotugnia digonopora (Pasquale, 1890) Diamare, 1893. Jap. J. Parasit. 19: 196-198.
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