| dc.description.abstract | A survey of gastrointestinal nematode infections of goats reared under extensive grazing
conditions was conducted for 18 months on 4 farms in Kathiani Division of Machakos
District, Kenya. The survey was based on monthly coproparasitological examination of kids
« 6 month), immature (6-12 months) and adult (> 12 month) goats. The effects of season
and age on the prevalence and intensity of infection were determined. Faecal egg counts
(FEC) revealed that the overall prevalence of strongyles was 52.0% and the wet season
prevalence was significantly (p <0.05) higher than for the dry season in the 3 age groups on
the 4 farms. Majority of the animals had FEC of below 400 eggs per gram and did not vary
significantly (p > 0.05) between the 3 age groups. The FEC followed a typical overdispersed
distribution. Haemonchus contortus was the main nematode encountered in coprocultures
(75 %) and post mortem total worm counts. Other nematodes encountered included
Trichostrongylus axei, T. colubriformis, Bunostomum trigonocephalum, Oesophagostomum
columbianum, O. venulosum and Trichuris ovis. Based on these findings, it is now possible
to explore the possibility of using strategic treatments for the control of strongylosis in the
study area.
ii) Control experiments
The persistent anthelmintic effect of closantel (CLO) plus albendazole (ABZ) mixture against
common gastrointestinal nematodes (GIN) of goats was evaluated in 2 experiments. In the
1st experiment, the suppresion of strongyle egg output in faeces was examined in goats
treated orally with either ABZ or CLO plus ABZ liquid suspension. Sixty goats with
naturally acquired infections were randomly assigned to 3 groups of 20 goats each. The 1st
group served as the untreated controls and the other groups received respectively single doses
of 5 mg kg' body weight ABZ or CLO (10 mg kg') plus ABZ (5 mg kg:') orally. Faecal egg
counts (FEC) and generic determination of third-stage larvae (Lj) were performed at weekly
intervals, from the time of treatment (day 0) until week 7 post treatment. In the 2nd
X
experiment, a controlled trial was conducted in goats infected experimentally with GIN L,
including a benzimidazole (BZ)-resistant isolate of H. contortus. Twenty-one goats were
randomly assigned to 3 groups of 7 each and drenched with either ABZ (5 mg kg'), CLO
(10 mg kg") plus ABZ (5 mg kg:'), or untreated controls. Ten days post treatment, goats
were killed and necropsied for parasite recovery. Results revealed that a single dose of either
CLOIABZ mixture or ABZ were highly effective (100 %) in suppressing faecal egg output
up to 2 weeks post treatment, and FEC of CLOIABZ treated groups remained significantly
lower than those of ABZ treated group up to 4 weeks post treatment (p < 0.05). CLOIABZ
mixture was 99-100% effective against H. contortus, T. axei, T. colubriformis and O.
columbianum. Efficacy of ABZ was poor for H. contortus (29%) but approached 100% for
most of the other parasites. The results demonstrated an advantage of the CLOIABZ mixture
over ABZ in that excellent anthelmintic efficacy persisted for 3 weeks after treatment in
preventing establishment of GIN of goats and, was highly effective against a BZ-resistant
isolate of H. contortus.
In conclusion, the results of this study suggest that strongyle infections, especially
haemonchosis, are major constraints to the health of goats of the study area. Most of the
infections were subclinical and could indirectly cause production losses without attracting the
farmer's attention to institute control measures. To increase the productivity of goats,
helminthosis control should be based on epidemiological observations of an area before
initiating strategic control programmes. Use of anthelmintic mixtures of different classes
(i.e., CLOIABZ) is one such programme. | en |
