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Elevated sperm morphological abnormalities of Yankasa rams consequent to Trypanosoma vivax infection
Animal Reproduction Science, 31 ( 1993 ) 2 4 3 - 2 4 8
243
Elsevier Science Publishers B.V., A m s t e r d a m
Elevated sperm morphological abnormalities of Yankasa rams consequent to Trypanosoma vivax infection V.O. Sekoni National Animal Production Research Institute, Ahmadu Bello University, P.M.B. 1096, Shika, Zaria, Nigeria (Accepted 25 June 1992)
ABSTRACT Sekoni, V.O., 1993. Elevated sperm morphological abnormalities of Yankasa rams consequent to Trypanosoma vivax infection: Anita. Reprod. Sci., 31: 243-248. Twelve Yankasa rams from 2.5 to 3 years of age were divided into two groups of six for a study which lasted 15 weeks. All the rams initially had low sperm morphological abnormalities in their semen before the six animals in the treatment group were infected with Trypanosoma vivax. All of the infected rams developed chronic trypanosomiasis. Detailed studies of sperm morphological abnormalities were carried out for a period of 9 weeks post infection (p.i.). There was a rapid and progressive elevation of all abnormalities in the semen of the infected rams. Typical spermatozoa of infected rams were highly deformed with multiple morphological abnormalities. At 9 weeks p.i. the control group of rams had a mean of 3.9% for total sperm morphological abnormalities which differed ( P < 0.001 ) from the mean value of 99.80% for the infected group. Most rams were unfit for breeding at 3 weeks p.i. The result shows that T. vivax infection can render rams unfit for breeding within a short period of time.
INTRODUCTION
Ruminants are of great economic importance in the Livestock Industry in Africa. Small ruminants, especially sheep play an important role in the socioeconomic life of the people in Nigeria. They also make a significant contribution to the national economy (Adu and Ngere, 1979 ). It has been reported that the reproductive capacity of ruminants is variable in different parts of the country (Lamorde and Weinman, 1972 ). Trypanosomiases are among the important diseases of ruminants which cause various reproductive problems in both male and female animals. GenCorrespondence to: V.O. Sekoni, N a t i o n a l A n i m a l P r o d u c t i o n Research Institute, A h m a d u Bello University, P.M.B. 1096, Shika, Zaria, Nigeria.
© 1993 Elsevier Science Publishers B.V. All rights reserved 0 3 7 8 - 4 3 2 0 / 9 3 / $ 0 6 . 0 0
244
v.o. SEKONI
ital lesions have been reported in unspecified breeds of bucks and rams infected with Trypanosoma vivax or Trypanosoma brucei (Isoun and Anosa, 1974; Ikede, 1979; Anosa and Isoun, 1980). Deterioration of semen characteristics has also been reported (Isoun and Anosa, 1974; Agu et al., 1986; Akpavie et al., 1987). No detailed study has been reported on the effect of trypanosomiasis on the various spermatozoa morphological abnormalities in r a m semen. Therefore, the aim of this study was to investigate the effect of T. vivax infection on the incidence of the various sperm morphological abnormalities in the semen of Yankasa rams and the possible influence on their fertility. MATERIALS AND METHODS
Twelve healthy rams aged between 2.5 and 3 years, which were negative for blood parasites, were used for the investigation which lasted 15 weeks. The rams were randomly selected and had good semen characteristics. They were housed in a fly-proof building. Baseline data for the various sperm morphological abnormalities were collected during the first 6 weeks when the rams were randomly divided into two groups of six. Each group was housed in a separate fly-proof room in a fly-proof building and were fed concentrates, fresh pasture, hay, silage, salt licks and water ad libitum. This precaution was taken to prevent the spread of the infection by haematophagous flies to the control group and other animals in the neighbourhood. Six animals were infected with the Y-58 strain of T. vivax isolated from a case of natural infection of cattle in Northern Nigeria. Stabilates were preserved in 5% DMSO (dimethylsulphoxide) and stored in liquid nitrogen. This stabilate was first inoculated into a goat which developed clinical trypanosomiasis. Each ram was inoculated through the jugular vein with 1 ml of blood containing approximately 1 × 106 trypanosomes. Parameters monitored post infection (p.i.) were parasitaemia, rectal temperature, packed cell volume and haemoglobin concentration according to techniques described by Coles ( 1967 ) and Woo ( 1969 ). Blood smears were also used to detect and identify trypanosomes. All the parameters were estimated thrice weekly. Palpation of the scrotal contents was done weekly. Semen collection was by the electro-ejaculator technique. Sperm morphological abnormalities of the acrosome, detached heads, cytoplasmic droplets, midpiece, and sperm tail were estimated after the semen was diluted with buffered formal saline and counting at least 500 sperm per slide, using a phase contrast microscope (Hancock, 1957; Rao et al., 1980; Sekoni et al., 1981 ). Semen smears stained with eosin-nigrosin were used to determine the morphological abnormalities of the sperm head (Lagerlof, 1934; Rao et al., 1980; Sekoni et al., 1981 ). Five h u n d r e d spermatozoa were counted. Analysis of variance was used to compare differences between animals in
T. VIVAX1NFECTION IN YANKASARAMS
245
the T. vivax-infected group and the control group. The degree of significance is denoted by superscripts a, b, c where a denotes P < 0.05, b denotes P < 0.01 and c denotes P < 0.001. RESULTS
Clinical findings Trypanosomes were present in the peripheral circulation of all the infected rams at 3 days p.i. There were fluctuating levels of parasitaemia during the study period. All the infected rams developed a chronic type of trypanosomiasis which was characterised by intermittent pyrexia, rapid weight loss, progressive anaemia, weakness, lethargy, dullness, pale mucous membranes, scrotal enlargement and oedema, enlarged superficial lymph nodes and some other clinical signs. Rectal temperatures of the control group ranged between means of 38.8 and 39.5 ° C compared with 38.9-41.6 ° C in the infected group ( P < 0.001 ). Packed cell volumes ranged between 29.7% and 30.5% in the control group compared with a range of 19.3-29.6% in the infected animals ( P < 0.001 ). Haemoglobin (gl d1-1 ) of the control group ranged from 10.1 to 11, but were lower in the infected group (6.8-10.2 gl dl-1; P < 0 . 0 0 1 ). The rams in the control group remained healthy throughout the investigation.
Sperm morphological abnormalities The pre-infection baseline data of sperm morphological abnormalities for all the rams were within normal ranges (Table 1 ) and in agreement with values reported for Yankasa rams (Osinowo et al., 1982, 1988; Kumi-Diaka et al., 1985b). Following infection, there was a progressive elevation of all the various sperm morphological abnormalities in the infected group of rams. Mean values for acrosomal abnormalities for the control group differed ( P < 0.001 ) from those for the infected group. The acrosomal abnormalities were mainly those of the rough, thickened, and detached varieties. Detailed results are presented in Table 1. Mean percentage values of sperm head morphological abnormalities for the control group differed ( P < 0 . 0 0 1 ) from the infected group (Table 1 ). The abnormalities were mainly those of the pyriform, narrow at the base and abnormal contour varieties. Mean percentage values for detached heads for the control group were less than those for the infected group ( P < 0.001 ). The detached heads in the latter group were highly deformed and of abnormal morphology. Elevation of proximal cytoplasmic droplets in the semen of infected rams was very marked (Table 1 ). There was also a marked increase in
246
v.o. SEKONI
TABLE 1 M e a n percentage values o f s p e r m morphological a b n o r m a l i t i e s in t h e s e m e n o f t h e infected a n d control g r o u p s o f r a m s . Values for t h e control group are g i v e n in parentheses. Pre-infection n u m b e r o f r a m s , 12; n u m b e r o f r a m s p e r g r o u p post infection, six Weeks p.i.i
Acrosome
Sperm head
Detached heads
Proximal droplets
Distal droplets
Middle piece
Sperm tail
Total
0 1
0.8 0.33 (0.17) 1.1(P (0.42) 1.92 c (0.17) 1.58 ~ (0.25) 1.83 ¢ (0.25) 3.00 ¢ (0.08) 3.29 ¢ (0.04) 4.67 ~ (0.08) 4.92 c (0.33)
1.22 1.23 (1.22) 4.75 b (1.62) 6.77 c (1.35) 7.42 c (1.60) 7.15 c (1.68) 9.68 c (1.18) 15.12 ¢ (1.07) 13.67 ~ (0.90) 18.75 ¢ (1.23)
0.17 1.33 a (0.17) 1.58 b (0.83) 3.42 c (0.50) 4.71 c (0.17) 5.42 c (0.18) 6.42 c (0.25) 5.50 ~ (0.08) 6.92 ¢ (0.21) 8.67 ¢ (0.42)
0.50 1.33 (0.58) 6.67 c (0.42) 12.67 ¢ (0.44) 23.58 ~ (0.67) 29.42 c (0.17) 33.08 c (0.25) 27.38 ¢ (0.17) 28.79 c (0.21) 29.21 ¢ (0.67)
0.08 0.08 (0.08) 2.08 c (0.25) 0.75 a (0.0) 0.70 a (0.0) 3.50 a (0.25) 0.63 a (0.21) 1.50 a (0.38) 1.63 a (0.54) 1.17 ~ (0.33)
0.42 0.33 (0.42) 1.54 c (0.50) 1.79 a (0.67) 3.50 ° (0.08) 2.38 ~ (0.46) 6.58 c (0.21) 4.83 ~ (0.13) 8.46 ¢ (0.13) 8.25 ¢ (0.33)
1.33 0.75 (1.33) 8.58 ¢ (0.83) 16.42 ~ (0.92) 22.54 ¢ (0.17) 43.25 ° (1.13) 38.08 ~ (1.25) 42.33 ~ (0.96) 38.7Y (1.17) 28.83 ~ (0.75)
3.97 5.38 (3.97) 26.29 c (4.87) 43.50 c (4.02) 63.50 ~ (2.93) 88.96 c (3.97) 97.42 ~ (3.43) 98.95 ¢ (2.82) 98.96 ~ (3.23) 99.80 ¢ (3.90)
2 3 4 5 6 7 8 9
Differences b e t w e e n t h e infected g r o u p a n d c o r r e s p o n d i n g controls in t h e s a m e c o l u m n are d e n o t e d by superscripts a, b, c ( a P < 0.05; b P < 0.01; c P < 0.001 ). ~Weeks p.i., weeks post infection; W e e k 0, pre-infection baseline data.
the mean values for midpiece abnormalities in semen from the infected group ( P < 0.001 ). The midpiece abnormalities were mainly of the rough, swollen, coiled, and coiled round-the-head varieties. Sperm-tail abnormalities were also elevated in the semen of the infected rams ( P < 0.001 ) (Table 1 ). There was remarkable elevation of total sperm morphological abnormalities in the semen of the infected rams which differed significantly from the value for the control group from the second week p.i. till the end of the investigation ( P < 0 . 0 0 1 ) (Table 1 ). DISCUSSION
The results from this study have shown that trypanosomiasis due to T. viv a x infection caused a very rapid elevation in all of the various sperm morphological abnormalities in the semen of infected rams. Significant elevation of sperm morphological abnormalities in the semen of the infected rams were recorded as early as the second week p.i. The mean values of the various sperm
T. FIVAXINFECTIONIN YANKASARAMS
247
morphological abnormalities recorded in the semen of the rams far exceeded the normal range reported in the semen of fertile Yankasa rams (Osinowo et al., 1982, 1988; Kumi-Diaka et al., 1985a,b). All the infected rams were unfit for breeding due to the elevation of spermatozoa morphological abnormalities from the third week p.i. until the end of the investigation when most of them had sperm abnormalities totalling 100%. This result shows that T. vivax infection has a more severe effect on ovine sperm morphology than previously reported. The earliest significant noticeable elevation of sperm morphological abnormalities which were recorded between the second and third week p.i. were those of the proximal cytoplasmic droplets and the sperm tail. These were later followed by the elevation of all the other sperm morphological abnormalities during the subsequent weeks of the investigation. Genital lesions have been demonstrated in rams and bucks infected with pathogenic trypanosomes (Isoun and Anosa, 1974; Ikede, 1979; Anosa and Isoun, 1980). In this study the infection might have caused degenerative changes or damage to the male genitalia which subsequently resulted in the elevation of the various sperm morphological abnormalities. Numerous hypotheses have been proposed as to how the trypanosomes might have caused the degenerative changes in the male genitalia. Some of these hypotheses include those of damage done by the invasion of genital organs by the trypanosomes, toxin.s produced by the parasite and the chronic fluctuating pyrexia that eharacterised the disease (Isoun and Anosa, 1974; Ikede, 1979; Anosa and Isoun, 1980). It is concluded from the results obtained in this study that trypanosomiasis caused by T. vivax infection may be an important causative agent of infertility in rams in areas such as sub-Saharan Africa where pathogenic trypanosomes and their vectors (tsetse flies) are prevalent.
REFERENCES Adu, I.F. and Ngere, L.O., 1979. The indigenous sheep of Nigeria. World Rev. Anim. Prod., 15 (3): 51-62. Agu, W.E., Ige, K. and Olatunde, D.S., 1986. Evaluation of semen quality of rams infected with Trypanosoma vivax. Anim. Reprod. Sci., 11: 123-127. Akpavie, S.O., Ikede, B.O. and Egbunike, G.N., 1987. Ejaculate characteristics of sheep infected with Trypanosoma brucei and T. vivax: Changes caused by treatment with diminazene aceturate. Res. Vet. Sci., 42: 1-6. Anosa, V.O. and Isoun, T.T., 1980. Further observations on the testicular pathology in Trypanosoma vivax infection of sheep and goats. Res. Vet. Sci., 28:151-160. Coles, H.E., 1967. Veterinary Clinical Pathology. W.B. Saunders, Philadelphia and London, pp. 72-165. Hancock, J.L., 1957. The morphology of boar spermatozoa. J. R. Micro. Soc., 76: 84-97. Ikede, B.O., 1979. Genital lesions in experimental chronic Trypanosoma brucei infection in rams. Res. Vet. Sci., 26: 145-151.
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Isoun, T.T. and Anosa, V.O., 1974. Lesions in the reproductive organs of sheep and goats experimentally infected with Trypanosoma vivax. Tropenmed. Parasitol., 25: 469-476. Kumi-Diaka, J., Djang-Fordjour, T.K., Sekoni, V.O. and Ogwu, D., 1985a. Effect of different husbandry systems on the reproductive development of post weaning ram lambs under tropical conditions. Theriogenology, 23 (4): 583- 591. Kumi-Diaka, J., Adesiyun, A.A., Sekoni, V.O. and Ezeokoli, C.D., 1985b. Scrotal dimensions and ejaculate characteristics of three breeds of sheep in tropical Nigeria. Theriogenology, 23 (4): 671-677. Lagerlof, N., 1934. Researchers concerning the morphologic changes in the spermatozoa and in the testicles of sterile or subnormally fertile bulls. Acta. Pathol. Microbiol. Scand., 19 (Supplement): 254. Lamorde, A.G. and Weinman, D.E., 1972. A comparison of reproductive performances of Northern Nigeria cattle with those of government farms. Niger. Vet. J., 1:19-22. Osinowo, O.A., Bale, J.O. and Eduvie, L.O., 1982. Semen quality of Yankasa rams. Trop. Anim. Health Prod., 14: 189. Osinowo, O.A., Ahmed, M.S. and Ekpe, G.A., 1988. Semen quality and sperm output of Yankasa rams at different ages. Theriogenology, 29 (2): 381-386. Rao, A.R., Bane, A. and Gustafsson, B.K., 1980. Changes in the morphology of spermatozoa during their passage through the genital tract in dairy bulls with normal and impaired spermatogenesis. Theriogenology, 14 ( 1 ): 1-11. Sekoni, V.O., Gustafsson, B.K. and Mather, E.C., 1981. Influence of wet fixation, staining techniques and storage time on bulls sperm morphology. Nord. Vet. Med., 33: 161-166. Woo, P.T.K., 1969. The haematocrit centrifuge technique for the detection oftrypanosomes in blood. Can. J. Zool., 47: 921-923.
243
Elsevier Science Publishers B.V., A m s t e r d a m
Elevated sperm morphological abnormalities of Yankasa rams consequent to Trypanosoma vivax infection V.O. Sekoni National Animal Production Research Institute, Ahmadu Bello University, P.M.B. 1096, Shika, Zaria, Nigeria (Accepted 25 June 1992)
ABSTRACT Sekoni, V.O., 1993. Elevated sperm morphological abnormalities of Yankasa rams consequent to Trypanosoma vivax infection: Anita. Reprod. Sci., 31: 243-248. Twelve Yankasa rams from 2.5 to 3 years of age were divided into two groups of six for a study which lasted 15 weeks. All the rams initially had low sperm morphological abnormalities in their semen before the six animals in the treatment group were infected with Trypanosoma vivax. All of the infected rams developed chronic trypanosomiasis. Detailed studies of sperm morphological abnormalities were carried out for a period of 9 weeks post infection (p.i.). There was a rapid and progressive elevation of all abnormalities in the semen of the infected rams. Typical spermatozoa of infected rams were highly deformed with multiple morphological abnormalities. At 9 weeks p.i. the control group of rams had a mean of 3.9% for total sperm morphological abnormalities which differed ( P < 0.001 ) from the mean value of 99.80% for the infected group. Most rams were unfit for breeding at 3 weeks p.i. The result shows that T. vivax infection can render rams unfit for breeding within a short period of time.
INTRODUCTION
Ruminants are of great economic importance in the Livestock Industry in Africa. Small ruminants, especially sheep play an important role in the socioeconomic life of the people in Nigeria. They also make a significant contribution to the national economy (Adu and Ngere, 1979 ). It has been reported that the reproductive capacity of ruminants is variable in different parts of the country (Lamorde and Weinman, 1972 ). Trypanosomiases are among the important diseases of ruminants which cause various reproductive problems in both male and female animals. GenCorrespondence to: V.O. Sekoni, N a t i o n a l A n i m a l P r o d u c t i o n Research Institute, A h m a d u Bello University, P.M.B. 1096, Shika, Zaria, Nigeria.
© 1993 Elsevier Science Publishers B.V. All rights reserved 0 3 7 8 - 4 3 2 0 / 9 3 / $ 0 6 . 0 0
244
v.o. SEKONI
ital lesions have been reported in unspecified breeds of bucks and rams infected with Trypanosoma vivax or Trypanosoma brucei (Isoun and Anosa, 1974; Ikede, 1979; Anosa and Isoun, 1980). Deterioration of semen characteristics has also been reported (Isoun and Anosa, 1974; Agu et al., 1986; Akpavie et al., 1987). No detailed study has been reported on the effect of trypanosomiasis on the various spermatozoa morphological abnormalities in r a m semen. Therefore, the aim of this study was to investigate the effect of T. vivax infection on the incidence of the various sperm morphological abnormalities in the semen of Yankasa rams and the possible influence on their fertility. MATERIALS AND METHODS
Twelve healthy rams aged between 2.5 and 3 years, which were negative for blood parasites, were used for the investigation which lasted 15 weeks. The rams were randomly selected and had good semen characteristics. They were housed in a fly-proof building. Baseline data for the various sperm morphological abnormalities were collected during the first 6 weeks when the rams were randomly divided into two groups of six. Each group was housed in a separate fly-proof room in a fly-proof building and were fed concentrates, fresh pasture, hay, silage, salt licks and water ad libitum. This precaution was taken to prevent the spread of the infection by haematophagous flies to the control group and other animals in the neighbourhood. Six animals were infected with the Y-58 strain of T. vivax isolated from a case of natural infection of cattle in Northern Nigeria. Stabilates were preserved in 5% DMSO (dimethylsulphoxide) and stored in liquid nitrogen. This stabilate was first inoculated into a goat which developed clinical trypanosomiasis. Each ram was inoculated through the jugular vein with 1 ml of blood containing approximately 1 × 106 trypanosomes. Parameters monitored post infection (p.i.) were parasitaemia, rectal temperature, packed cell volume and haemoglobin concentration according to techniques described by Coles ( 1967 ) and Woo ( 1969 ). Blood smears were also used to detect and identify trypanosomes. All the parameters were estimated thrice weekly. Palpation of the scrotal contents was done weekly. Semen collection was by the electro-ejaculator technique. Sperm morphological abnormalities of the acrosome, detached heads, cytoplasmic droplets, midpiece, and sperm tail were estimated after the semen was diluted with buffered formal saline and counting at least 500 sperm per slide, using a phase contrast microscope (Hancock, 1957; Rao et al., 1980; Sekoni et al., 1981 ). Semen smears stained with eosin-nigrosin were used to determine the morphological abnormalities of the sperm head (Lagerlof, 1934; Rao et al., 1980; Sekoni et al., 1981 ). Five h u n d r e d spermatozoa were counted. Analysis of variance was used to compare differences between animals in
T. VIVAX1NFECTION IN YANKASARAMS
245
the T. vivax-infected group and the control group. The degree of significance is denoted by superscripts a, b, c where a denotes P < 0.05, b denotes P < 0.01 and c denotes P < 0.001. RESULTS
Clinical findings Trypanosomes were present in the peripheral circulation of all the infected rams at 3 days p.i. There were fluctuating levels of parasitaemia during the study period. All the infected rams developed a chronic type of trypanosomiasis which was characterised by intermittent pyrexia, rapid weight loss, progressive anaemia, weakness, lethargy, dullness, pale mucous membranes, scrotal enlargement and oedema, enlarged superficial lymph nodes and some other clinical signs. Rectal temperatures of the control group ranged between means of 38.8 and 39.5 ° C compared with 38.9-41.6 ° C in the infected group ( P < 0.001 ). Packed cell volumes ranged between 29.7% and 30.5% in the control group compared with a range of 19.3-29.6% in the infected animals ( P < 0.001 ). Haemoglobin (gl d1-1 ) of the control group ranged from 10.1 to 11, but were lower in the infected group (6.8-10.2 gl dl-1; P < 0 . 0 0 1 ). The rams in the control group remained healthy throughout the investigation.
Sperm morphological abnormalities The pre-infection baseline data of sperm morphological abnormalities for all the rams were within normal ranges (Table 1 ) and in agreement with values reported for Yankasa rams (Osinowo et al., 1982, 1988; Kumi-Diaka et al., 1985b). Following infection, there was a progressive elevation of all the various sperm morphological abnormalities in the infected group of rams. Mean values for acrosomal abnormalities for the control group differed ( P < 0.001 ) from those for the infected group. The acrosomal abnormalities were mainly those of the rough, thickened, and detached varieties. Detailed results are presented in Table 1. Mean percentage values of sperm head morphological abnormalities for the control group differed ( P < 0 . 0 0 1 ) from the infected group (Table 1 ). The abnormalities were mainly those of the pyriform, narrow at the base and abnormal contour varieties. Mean percentage values for detached heads for the control group were less than those for the infected group ( P < 0.001 ). The detached heads in the latter group were highly deformed and of abnormal morphology. Elevation of proximal cytoplasmic droplets in the semen of infected rams was very marked (Table 1 ). There was also a marked increase in
246
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TABLE 1 M e a n percentage values o f s p e r m morphological a b n o r m a l i t i e s in t h e s e m e n o f t h e infected a n d control g r o u p s o f r a m s . Values for t h e control group are g i v e n in parentheses. Pre-infection n u m b e r o f r a m s , 12; n u m b e r o f r a m s p e r g r o u p post infection, six Weeks p.i.i
Acrosome
Sperm head
Detached heads
Proximal droplets
Distal droplets
Middle piece
Sperm tail
Total
0 1
0.8 0.33 (0.17) 1.1(P (0.42) 1.92 c (0.17) 1.58 ~ (0.25) 1.83 ¢ (0.25) 3.00 ¢ (0.08) 3.29 ¢ (0.04) 4.67 ~ (0.08) 4.92 c (0.33)
1.22 1.23 (1.22) 4.75 b (1.62) 6.77 c (1.35) 7.42 c (1.60) 7.15 c (1.68) 9.68 c (1.18) 15.12 ¢ (1.07) 13.67 ~ (0.90) 18.75 ¢ (1.23)
0.17 1.33 a (0.17) 1.58 b (0.83) 3.42 c (0.50) 4.71 c (0.17) 5.42 c (0.18) 6.42 c (0.25) 5.50 ~ (0.08) 6.92 ¢ (0.21) 8.67 ¢ (0.42)
0.50 1.33 (0.58) 6.67 c (0.42) 12.67 ¢ (0.44) 23.58 ~ (0.67) 29.42 c (0.17) 33.08 c (0.25) 27.38 ¢ (0.17) 28.79 c (0.21) 29.21 ¢ (0.67)
0.08 0.08 (0.08) 2.08 c (0.25) 0.75 a (0.0) 0.70 a (0.0) 3.50 a (0.25) 0.63 a (0.21) 1.50 a (0.38) 1.63 a (0.54) 1.17 ~ (0.33)
0.42 0.33 (0.42) 1.54 c (0.50) 1.79 a (0.67) 3.50 ° (0.08) 2.38 ~ (0.46) 6.58 c (0.21) 4.83 ~ (0.13) 8.46 ¢ (0.13) 8.25 ¢ (0.33)
1.33 0.75 (1.33) 8.58 ¢ (0.83) 16.42 ~ (0.92) 22.54 ¢ (0.17) 43.25 ° (1.13) 38.08 ~ (1.25) 42.33 ~ (0.96) 38.7Y (1.17) 28.83 ~ (0.75)
3.97 5.38 (3.97) 26.29 c (4.87) 43.50 c (4.02) 63.50 ~ (2.93) 88.96 c (3.97) 97.42 ~ (3.43) 98.95 ¢ (2.82) 98.96 ~ (3.23) 99.80 ¢ (3.90)
2 3 4 5 6 7 8 9
Differences b e t w e e n t h e infected g r o u p a n d c o r r e s p o n d i n g controls in t h e s a m e c o l u m n are d e n o t e d by superscripts a, b, c ( a P < 0.05; b P < 0.01; c P < 0.001 ). ~Weeks p.i., weeks post infection; W e e k 0, pre-infection baseline data.
the mean values for midpiece abnormalities in semen from the infected group ( P < 0.001 ). The midpiece abnormalities were mainly of the rough, swollen, coiled, and coiled round-the-head varieties. Sperm-tail abnormalities were also elevated in the semen of the infected rams ( P < 0.001 ) (Table 1 ). There was remarkable elevation of total sperm morphological abnormalities in the semen of the infected rams which differed significantly from the value for the control group from the second week p.i. till the end of the investigation ( P < 0 . 0 0 1 ) (Table 1 ). DISCUSSION
The results from this study have shown that trypanosomiasis due to T. viv a x infection caused a very rapid elevation in all of the various sperm morphological abnormalities in the semen of infected rams. Significant elevation of sperm morphological abnormalities in the semen of the infected rams were recorded as early as the second week p.i. The mean values of the various sperm
T. FIVAXINFECTIONIN YANKASARAMS
247
morphological abnormalities recorded in the semen of the rams far exceeded the normal range reported in the semen of fertile Yankasa rams (Osinowo et al., 1982, 1988; Kumi-Diaka et al., 1985a,b). All the infected rams were unfit for breeding due to the elevation of spermatozoa morphological abnormalities from the third week p.i. until the end of the investigation when most of them had sperm abnormalities totalling 100%. This result shows that T. vivax infection has a more severe effect on ovine sperm morphology than previously reported. The earliest significant noticeable elevation of sperm morphological abnormalities which were recorded between the second and third week p.i. were those of the proximal cytoplasmic droplets and the sperm tail. These were later followed by the elevation of all the other sperm morphological abnormalities during the subsequent weeks of the investigation. Genital lesions have been demonstrated in rams and bucks infected with pathogenic trypanosomes (Isoun and Anosa, 1974; Ikede, 1979; Anosa and Isoun, 1980). In this study the infection might have caused degenerative changes or damage to the male genitalia which subsequently resulted in the elevation of the various sperm morphological abnormalities. Numerous hypotheses have been proposed as to how the trypanosomes might have caused the degenerative changes in the male genitalia. Some of these hypotheses include those of damage done by the invasion of genital organs by the trypanosomes, toxin.s produced by the parasite and the chronic fluctuating pyrexia that eharacterised the disease (Isoun and Anosa, 1974; Ikede, 1979; Anosa and Isoun, 1980). It is concluded from the results obtained in this study that trypanosomiasis caused by T. vivax infection may be an important causative agent of infertility in rams in areas such as sub-Saharan Africa where pathogenic trypanosomes and their vectors (tsetse flies) are prevalent.
REFERENCES Adu, I.F. and Ngere, L.O., 1979. The indigenous sheep of Nigeria. World Rev. Anim. Prod., 15 (3): 51-62. Agu, W.E., Ige, K. and Olatunde, D.S., 1986. Evaluation of semen quality of rams infected with Trypanosoma vivax. Anim. Reprod. Sci., 11: 123-127. Akpavie, S.O., Ikede, B.O. and Egbunike, G.N., 1987. Ejaculate characteristics of sheep infected with Trypanosoma brucei and T. vivax: Changes caused by treatment with diminazene aceturate. Res. Vet. Sci., 42: 1-6. Anosa, V.O. and Isoun, T.T., 1980. Further observations on the testicular pathology in Trypanosoma vivax infection of sheep and goats. Res. Vet. Sci., 28:151-160. Coles, H.E., 1967. Veterinary Clinical Pathology. W.B. Saunders, Philadelphia and London, pp. 72-165. Hancock, J.L., 1957. The morphology of boar spermatozoa. J. R. Micro. Soc., 76: 84-97. Ikede, B.O., 1979. Genital lesions in experimental chronic Trypanosoma brucei infection in rams. Res. Vet. Sci., 26: 145-151.
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