Veterinary Parasitology, 35 (1990) 29-42 Elsevier Science Publishers B.V., Amsterdam - - Printed in The Netherlands
29
The Relationship B e t w e e n Dietary Energy Levels and the Severity of Trypanosoma brucei Infection in Growing Pigs B.O. F A G B E M I ' , E.B. O T E S I L E 2, M.O. M A K I N D E 3 and O.A. A K I N B O A D E 1
Departments of 1Veterinary Microbiology and Parasitology, 2Veterinary Medicine, and 3Veterinary Physiology and Pharmacology, University of Ibadan, Ibadan (Nigeria) (Accepted for publication 31 May 1989)
ABSTRACT Fagbemi, B.O., 0tesile, E.B., Makinde, M.O. and Akinboade, O.A., 1990. The relationship between dietary energy levels and the severity of Trypanosoma brucei infection in growing pigs. Vet. Parasitol., 35: 29-42. Growing pigs were placed on high, medium and low planes of dietary energy and were infected with a virulent strain of Trypanosoma brucei. During an 8-week period post-infection (p.i.), the respective liveweight gains by infected pigs on high, medium and low energy levels were 52.1, 21.2 and 38.5%, respectively, of the corresponding gains by non-infected control pigs. There was a fall in red blood cell values p.i. which worsened with decreasing energy levels. Leucocytosis was observed in all infected pig groups and was mainly due to lymphocytosis. By 6 weeks p.i., the lyrephocyte count had returned to near normal values in pigs on high and medium energy levels, but was persistently high in those on a low energy level. Neutropaenia was observed in all infected pig groups and persisted until 8 weeks p.i. The results indicated that nutrition modulates the host response to infection with trypanosomes.
INTRODUCTION
Parasitism is often modulated by interacting factors within and outside the host (Trager, 1986). In the tropics, parasitic diseases are usually aggravated by malnutrition during the months of the dry season when feeds and feedstuffs are in short supply [Akerejola, 1980; International Livestock Centre for Africa (I.L.C.A.), 1980 ]. During such periods, nutritional deficiencies, especially those of energy and protein, are common (I.L.C.A., 1980). In Nigeria, the incidence of parasitic infections, such as trypanosomiasis, is high in pigs and is often associated with stunting (Dipeolu et al., 1982) and mortality (Agu and Bajeh, 1986). It is therefore necessary to investigate the exact manner in which the level of nutrition influences the severity of parasitic diseases in a tropical environment. This paper describes the effects of dietary 0304-4017/90/$03.50
© 1990 Elsevier Science Publishers B.V.
30
B.0. FAGBEMIET AL.
energy levels on the growth rate and haematological parameters of growing pigs experimentally infected with a virulent strain of Trypanosoma brucei. M A T E R I A L S AND M E T H O D S
Experimental animals Eighteen 3-month-old Large White pigs were obtained from a commercial farm in Ibadan, Nigeria. They were housed in fly-proof pens with concrete floors. The blood of the animals was examined and confirmed to be free from blood parasites. The pigs were dewormed with piperazine citrate (Pfizer, Lagos, Nigeria) at a dosage of 400 mg kg -1 body weight. The animals were allowed 2 weeks to adjust to the new environment, during which they were fed a standard commercial growers' ration (Pfizer Livestock Feeds, Lagos, Nigeria).
Experimental rations After the adaptation period, the pigs were placed on three different experimental rations (A, B and C ) containing high, medium and low energy planes, respectively. The crude protein levels in the three rations were similar (isonitrogenous). The compositions and proximate analyses of the feeds are given in Tables 1 and 2, respectively. Feed and water were provided ad libitum. TABLE 1
Composition of rations offered to pigs Feed ingredient
Percentage in ration A
Maize Rice bran
70.0
Peanut cake Palm kernel cake Blood meal Oyster shell Vitamin pre-mix ~
20.0 4.0 4.25 1.0 0.5 0.25
NaC1
Total ~Pfizer Livestock Feeds, Lagos, Nigeria.
100
B
60.0 20.0 13.25 5.0 1.0 0.5 0.25 100
C
70.0 20.0 3.75 5.0 1.0 0.5 0.25 100
DIETARYENERGYAND TRYPANOSOMA BRUCEI IN PIGS
31
TABLE 2 Proximate analyses of rations fed to pigs Component
Dry matter (%) Crude protein (%) Ether extract (%) Crude fibre (%) Nitrogen-free extract (%) Total ash (%) Gross energy (kcal g - l ) Calculated digestible energy (kcal g - l )
Ration A
B
C
91.1 20.4 5.2 4.8 64.6 3.8 4.4 3.7
90.6 20.1 6.2 5.3 56.5 10.6 4.7 2.2
91.0 19.8 2.0 7.6 47.8 14.8 4.8 1.8
Parasite material, infection procedure and measurement of parasitaemia The parasite used was a strain of T. brucei originally isolated from naturally infected pigs in Nigeria and stored in liquid nitrogen at the National Veterinary Research Institute, Vom, Nigeria. Prior to infection of the experimental pigs, the trypanosomes were passaged in rats and a pig. The experimental pigs were infected by injecting pig blood containing 107 trypanosomes into the cranial vena cava. Parasitaemia in the ear vein blood of the pigs were assessed daily by the method of Herbert and Lumsden (1976).
Haematological parameters Approximately 5 ml of blood were collected at weekly intervals from the cranial vena cava of each pig into sterile containers with heparin. Packed cell volume (PCV) was determined by the micro-haematocrit method. Haemoglobin (Hb) concentration was measured by the cyanomethaemoglobin method. Total red blood cell (RBC) and total white blood cell (WBC) counts were determined with an electronic cell counter (Coulter Counter Model ZF, Coulter Electronics, Gt. Britain). Differential WBC counts were determined from thin blood smears fixed with methanol and stained with Giemsa.
Experimental plan After the adaptation period, the pigs were divided into three experimental groups (A, B and C ). Each group contained six pigs. The animals were on these diets for 5 weeks before experimental infections were carried out. This was to create the desired differences in the nutritional status of the animals before
32
B.O. FAGBEM1 ET AL.
experimental infection. In each group, four pigs were infected with trypanosomes while the remaining two pigs served as non-infected controls. Live weights of pigs were recorded at weekly intervals throughout the period of the experiment with a trade spring balance (Salter, Gt. Britain). Similarly, haematological parameters were monitored weekly pre- and post-infection for the whole duration of the experiment. RESULTS
Parasitaemia The mean period to detection of trypanosomes in the peripheral blood of pigs following experimental infection was 4.8 + 1.0, 4.3 + 0.5 and 3.8 _+0.5 days for pigs on high, medium and low energy rations, respectively. Thereafter, the pigs exhibited fluctuating parasitaemia with peaks of 107s-10 s7 trypanosomes m l - 1, occurring at intervals of ~ 6 day (Table 3 ).
Liveweight gains The mean liveweight gains of pigs both before and after infection with T.
brucei are shown in Fig. 1. During the 5-week period before infection, there TABLE 3
T. brucei mean parasitaemia in pigs on diets w i t h different energy levels Days p.i.
4 7 10 13 16 19 22 25 28 31 34 :~7 40 43 46 49
Parasitaemia (log,o trypanosomes ml 1 blood) H i g h plane
Medium plane
Low plane
1.7 3.2 1.8 1.4 2.7 5.4 6.5 6.2 7.8 5.9 7.2 6.3 7.6 6.0 7.8 5.8
1.9 3.6 1.5 1.2 3.0 6.0 6.8 6.3 8.1 6.2 7.0 6.1 7,9 7.1 8.3 6.5
2.2 3.9 1.8 1.8 2.9 6.2 7.2 6.8 8.3 6.3 8.7 6.5 8.0 6.9 8.5 7.3
DIETARY ENERGYAND TRYPANOSOMA BRUCEI IN PIGS
~3
50
4O
A
3O
20
~0
~E
0
L~
40
o
30. o_
20.
10" _P_ LU i
J Z
29
The Relationship B e t w e e n Dietary Energy Levels and the Severity of Trypanosoma brucei Infection in Growing Pigs B.O. F A G B E M I ' , E.B. O T E S I L E 2, M.O. M A K I N D E 3 and O.A. A K I N B O A D E 1
Departments of 1Veterinary Microbiology and Parasitology, 2Veterinary Medicine, and 3Veterinary Physiology and Pharmacology, University of Ibadan, Ibadan (Nigeria) (Accepted for publication 31 May 1989)
ABSTRACT Fagbemi, B.O., 0tesile, E.B., Makinde, M.O. and Akinboade, O.A., 1990. The relationship between dietary energy levels and the severity of Trypanosoma brucei infection in growing pigs. Vet. Parasitol., 35: 29-42. Growing pigs were placed on high, medium and low planes of dietary energy and were infected with a virulent strain of Trypanosoma brucei. During an 8-week period post-infection (p.i.), the respective liveweight gains by infected pigs on high, medium and low energy levels were 52.1, 21.2 and 38.5%, respectively, of the corresponding gains by non-infected control pigs. There was a fall in red blood cell values p.i. which worsened with decreasing energy levels. Leucocytosis was observed in all infected pig groups and was mainly due to lymphocytosis. By 6 weeks p.i., the lyrephocyte count had returned to near normal values in pigs on high and medium energy levels, but was persistently high in those on a low energy level. Neutropaenia was observed in all infected pig groups and persisted until 8 weeks p.i. The results indicated that nutrition modulates the host response to infection with trypanosomes.
INTRODUCTION
Parasitism is often modulated by interacting factors within and outside the host (Trager, 1986). In the tropics, parasitic diseases are usually aggravated by malnutrition during the months of the dry season when feeds and feedstuffs are in short supply [Akerejola, 1980; International Livestock Centre for Africa (I.L.C.A.), 1980 ]. During such periods, nutritional deficiencies, especially those of energy and protein, are common (I.L.C.A., 1980). In Nigeria, the incidence of parasitic infections, such as trypanosomiasis, is high in pigs and is often associated with stunting (Dipeolu et al., 1982) and mortality (Agu and Bajeh, 1986). It is therefore necessary to investigate the exact manner in which the level of nutrition influences the severity of parasitic diseases in a tropical environment. This paper describes the effects of dietary 0304-4017/90/$03.50
© 1990 Elsevier Science Publishers B.V.
30
B.0. FAGBEMIET AL.
energy levels on the growth rate and haematological parameters of growing pigs experimentally infected with a virulent strain of Trypanosoma brucei. M A T E R I A L S AND M E T H O D S
Experimental animals Eighteen 3-month-old Large White pigs were obtained from a commercial farm in Ibadan, Nigeria. They were housed in fly-proof pens with concrete floors. The blood of the animals was examined and confirmed to be free from blood parasites. The pigs were dewormed with piperazine citrate (Pfizer, Lagos, Nigeria) at a dosage of 400 mg kg -1 body weight. The animals were allowed 2 weeks to adjust to the new environment, during which they were fed a standard commercial growers' ration (Pfizer Livestock Feeds, Lagos, Nigeria).
Experimental rations After the adaptation period, the pigs were placed on three different experimental rations (A, B and C ) containing high, medium and low energy planes, respectively. The crude protein levels in the three rations were similar (isonitrogenous). The compositions and proximate analyses of the feeds are given in Tables 1 and 2, respectively. Feed and water were provided ad libitum. TABLE 1
Composition of rations offered to pigs Feed ingredient
Percentage in ration A
Maize Rice bran
70.0
Peanut cake Palm kernel cake Blood meal Oyster shell Vitamin pre-mix ~
20.0 4.0 4.25 1.0 0.5 0.25
NaC1
Total ~Pfizer Livestock Feeds, Lagos, Nigeria.
100
B
60.0 20.0 13.25 5.0 1.0 0.5 0.25 100
C
70.0 20.0 3.75 5.0 1.0 0.5 0.25 100
DIETARYENERGYAND TRYPANOSOMA BRUCEI IN PIGS
31
TABLE 2 Proximate analyses of rations fed to pigs Component
Dry matter (%) Crude protein (%) Ether extract (%) Crude fibre (%) Nitrogen-free extract (%) Total ash (%) Gross energy (kcal g - l ) Calculated digestible energy (kcal g - l )
Ration A
B
C
91.1 20.4 5.2 4.8 64.6 3.8 4.4 3.7
90.6 20.1 6.2 5.3 56.5 10.6 4.7 2.2
91.0 19.8 2.0 7.6 47.8 14.8 4.8 1.8
Parasite material, infection procedure and measurement of parasitaemia The parasite used was a strain of T. brucei originally isolated from naturally infected pigs in Nigeria and stored in liquid nitrogen at the National Veterinary Research Institute, Vom, Nigeria. Prior to infection of the experimental pigs, the trypanosomes were passaged in rats and a pig. The experimental pigs were infected by injecting pig blood containing 107 trypanosomes into the cranial vena cava. Parasitaemia in the ear vein blood of the pigs were assessed daily by the method of Herbert and Lumsden (1976).
Haematological parameters Approximately 5 ml of blood were collected at weekly intervals from the cranial vena cava of each pig into sterile containers with heparin. Packed cell volume (PCV) was determined by the micro-haematocrit method. Haemoglobin (Hb) concentration was measured by the cyanomethaemoglobin method. Total red blood cell (RBC) and total white blood cell (WBC) counts were determined with an electronic cell counter (Coulter Counter Model ZF, Coulter Electronics, Gt. Britain). Differential WBC counts were determined from thin blood smears fixed with methanol and stained with Giemsa.
Experimental plan After the adaptation period, the pigs were divided into three experimental groups (A, B and C ). Each group contained six pigs. The animals were on these diets for 5 weeks before experimental infections were carried out. This was to create the desired differences in the nutritional status of the animals before
32
B.O. FAGBEM1 ET AL.
experimental infection. In each group, four pigs were infected with trypanosomes while the remaining two pigs served as non-infected controls. Live weights of pigs were recorded at weekly intervals throughout the period of the experiment with a trade spring balance (Salter, Gt. Britain). Similarly, haematological parameters were monitored weekly pre- and post-infection for the whole duration of the experiment. RESULTS
Parasitaemia The mean period to detection of trypanosomes in the peripheral blood of pigs following experimental infection was 4.8 + 1.0, 4.3 + 0.5 and 3.8 _+0.5 days for pigs on high, medium and low energy rations, respectively. Thereafter, the pigs exhibited fluctuating parasitaemia with peaks of 107s-10 s7 trypanosomes m l - 1, occurring at intervals of ~ 6 day (Table 3 ).
Liveweight gains The mean liveweight gains of pigs both before and after infection with T.
brucei are shown in Fig. 1. During the 5-week period before infection, there TABLE 3
T. brucei mean parasitaemia in pigs on diets w i t h different energy levels Days p.i.
4 7 10 13 16 19 22 25 28 31 34 :~7 40 43 46 49
Parasitaemia (log,o trypanosomes ml 1 blood) H i g h plane
Medium plane
Low plane
1.7 3.2 1.8 1.4 2.7 5.4 6.5 6.2 7.8 5.9 7.2 6.3 7.6 6.0 7.8 5.8
1.9 3.6 1.5 1.2 3.0 6.0 6.8 6.3 8.1 6.2 7.0 6.1 7,9 7.1 8.3 6.5
2.2 3.9 1.8 1.8 2.9 6.2 7.2 6.8 8.3 6.3 8.7 6.5 8.0 6.9 8.5 7.3
DIETARY ENERGYAND TRYPANOSOMA BRUCEI IN PIGS
~3
50
4O
A
3O
20
~0
~E
0
L~
40
o
30. o_
20.
10" _P_ LU i
J Z
