Out of the 410 goats sampled, 314 were between 1 - 1½ years of age and of both sexes. They comprised of three phonetypically different breeds adjudged apparently healthy. The goats consisted of 108 WAD, 108 RS and 98 BW and were obtained from Ibadan, Oyo State and Maiduguri, Borno State, Nigeria, from various household units and livestock markets. The ages of all the animals were determined using the rostral teeth development as described by Otesile and Obasaju (1981).

Blood samples were collected from the external jugular vein. 8mls of blood was collected from which 2mls was immediately dispensed into a Bijou bottle containing 100µl of 100nm of disodium ethylene diamine tetracetic acid (EDTA) solution as anticoagulant. The remaining 6mls of blood was dispensed into plain test-tube to clot. The samples were labeled appropriately and transported to the laboratory on ice pack.

Preparation of goat anti-rabbit haemolysin

The procedure of Mayer (1971) and Lanchman et al., (1973) were used with slight modifications, to raise haemolysins against goat red cells. Briefly, two adult chinchilla rabbits weighing between 1.8 to 2 kg were inoculated intravenously with 1ml of goat RBC membranes (containing 2 mg suspension) in isotonic saline solution as described by Dodge et al. (1963). Intravenous injection of RBC membranes was repeated at a 24 hourly interval with 11 injections administered. Seventy-two hours after the last injection, blood collected from the rabbits was allowed to clot for one hour at room temperature. Serum containing haemolysin was collected by centrifugation at 5,000-x g for 10 minutes at 4^oC. Haemolysins from the two rabbits were pooled together, dispensed in 0.5ml aliquots into sterilized Bijou bottles, and immediately stored at -20^oC until used.

Anti-C3 serum was prepared as described by Hudson and Hay, (1980). Briefly, goat serum was activated with zymoson by mixing 13.5 mg/ ml serum and incubated at 37^oC for 30 minutes. The zymoson C3 complex was washed six times in barbitone buffered saline ^{(pH 8.6). Freund’s incomplete adjuvant (FIA) was added and contents thoroughly mixed. Appropriately, 0.2ml of zymoson – C3/FIA mixture was injected subcutaneously to each of the four sites of an adult chinchilla rabbit namely; the right and left shoulder regions and right and left rump regions. Seven days after the last immunization with zymoson C3/ FIA emulsion, blood from the rabbits were collected through the marginal ear veins and Anti- C3 serum was collected and dispensed in 0.5ml aliquots and stored at -20oC until use.}

A micro method of the standard haemolytic assay was used for the determination of total serum complement (THC) level as described by Ogundele (1988). Briefly, 50µl of 1:50 initially titrated dilution complement was pipetted into 84 wells of U-shaped bottom microtitre plates and 50µl of 5 x 10⁸ cells/ml of washed sheet red cell was added into each well. The plates were incubated at 37^oC for one hour with constant shaking at 10 minutes interval after which, the sensitized rabbit red cell suspension was washed three times with Tris-Saline buffer and supernatant solution decanted. The volume of sensitized RBC was adjusted to 50µl with Tris-saline buffer and 50µl of 40 percent fresh goat serum (FGS) added into each test well and gently shaken to ensure even suspension of erythrocytes with FGS (giving a final reaction concentration of 20 percent FGS). Positive and negative control wells were set up. The plates were incubated for one hour at 37^oC with constant shaking at 10 minutes intervals and later spurn at 200 x g for 10 minutes. The supernatant was pipetted and transferred into flat bottom microtitre plates. The optical density (OD) reading of the released haemoglobin was read at 541mm. The degree of lysis (which reflects complement activity) was calculated and converted into CH₅₀ as described by Mayer (1971).

The method of assaying the alternative haemolytic complement level (AHC) is the same as described for THC. The only exception was that, rabbit erythrocyte replaced sheep erythrocyte (without sensitization with haemolysin) while, Ethylene- Glycol bis- amino tetra-acetic acid (EGTA) replaced calcium chloride in Tris- saline buffer (Talwar, 1983).

Serum levels of complement C3 was determined by single radial immuno diffusion (RID) technique as described by Tabel (1982). The levels were expressed in relation to the level in a standard reference pool of apparently healthy goat serum.

Packed cell volume (PCV) and haemoglobin concentration (Hb) concentration were estimated using autohaemolyzer.* (* Autohaematology Analyser (Mindray) Bc 2800 Vet.).

Each blood sample was examined for haemoprotozoans by preparing thin blood smears stained with 10% Giemsa stain and positive blood samples were discarded. In addition, the buffy coat examination technique and ELISA was used to screen for trypanosome infection (Murray et al., 1977, and Luckins 1992).

To screen for gastrointestinal parasites, fresh faecal samples were collected directly from the rectum of the goats. They were subjected to sedimentation and floatation techniques using saturated sodium chloride or zinc sulphate solution as floatation medium (Anon, 1977).

The mean packed cell volume (PCV %) and haemoglobin (Hb) concentration of apparently healthy three breeds of indigenous goats is presented in Table 1. There was no significant (P>0.05) difference between the PCV and Hb concentration of the three breeds of goats studied. In addition, there was no significant (P>0.05) difference between the PCV and haemoglobin (Hb) concentration of the males and females of the three breeds.

Figure 1

Table 1: Mean packed cell volume and haemoglobin concentration (± SE %) of apparently healthy 3 breeds of indigenous goats

The mean relative complement C3 concentration of apparently healthy three breeds of indigenous goats is presented in Table 2. C3 levels of WAD goats (133.2 ±3 units) was significantly (P<0.05) higher than the corresponding values in BW goats (92.7 ± 18.7 units) and RS goats (107.7 ± 12.6 units). Similarly, the C3 levels of RS goats was significantly (P<0.05) higher than the corresponding value in BW goats. There was no significant (P>0.05) difference between the C3 concentration of males and females of the three breeds (Table 2).

The mean total and alternative hemolytic complement levels (CH₅₀ and AP- CH₅₀ ) of apparently healthy three breeds of indigenous goats are presented in Table 3. CH₅₀ of WAD goats (59.0 ± 6.2 units) was significantly (P<0.001) higher than the corresponding value in BW goats (43.1 ± 3.8 units) but was not significantly (P>0.05) different from the value in RS goats (57.4 ± 9.8 units). Mean CH₅₀ of RS goats was significantly (P<0.05) higher than the corresponding values in BW goats (Table 3). There was no significant (P<0.05) difference between the CH₅₀ of the males and females of the three breeds (Table 3). In addition, there was no significant (P>0.05) variation in the AP-CH₅₀ of WAD goats (19.9 units), RS goats (21.8 units) and BW goats (20.3 units).

Figure 2

Table 2: Mean relative complement (C3) concentration of apparently healthy breeds of indigenous goats (± SE %)

Figure 3

Table 3: Mean total haemolytic complement and alternative haemolytic complement levels (CH and AP ± SE %) of apparently healthy breeds of indigenous goats