S. Mack
An ILCA base line survey is being conducted in villages in South West Nigeria. Two ecological zones are represented, the forest and the derived savanna (a man-made fire climax savanna bordering the forest). Annual rainfall in the area is about 1200 - 1800 mm, minimum temperature 18 - 24°C, maximum temperature 29 - 35°C and there is a dry season extending from mid-November through to March. Flock sizes are small with 3-4 animals per household and the ratio of goats to sheep is about 3:1. Very few sheep are found in the savanna zone because many villages ban sheep, as it is sheep not goats that damage crops.
West African Dwarf sheep and goats are both classed as trypanotolerant. Their reputed low productivity may be a result of the environment in which they live rather than a low performance potential. The reproductive performance of these breeds is good. In South West Nigeria the mean age at first parturition is 560 (± 22) days for goats and 540 (± 28) days for sheep. Mean litter size is high (1.6 for goats and 1.3 for sheep) giving annual reproduction rates of 2.1 kids/doe/ year and 1.7 lambs/ewe/year.
During the first 18 months of the survey, disease was identified as a major constraint. Table 39 shows the main causes of morbidity. PPR (Peste des Petits Ruminants) or Kata is a viral disease closely related to rinderpest, human measles and canine distemper. Farmers in the region report PPR to be cyclic with major outbreaks every 1-3 years. Goats were found to have an unexpectedly high incidence of mange, caused mainly by Sarcoptes scabiei. Both PPR and mange were primarily problems with goats rather than sheep. Lice and fleas were the common ecotoparisites in goats, and Rhipicephalus and Amblyomma spp. of tick were found in sheep. Haemonchosis was the major helminth problem. Pneumonia was a commonly reported symptom. In reality it more accurately represents an umbrella syndrome, covering both primary and secondary pneumonias.
Having identified PPR as a major cause of mortality and mange as a major predisposing cause, a veterinary intervention package was instigated. This package consists of control of PPR using an annual vaccination of tissue culture rinderpest vaccine (TCRV) and control of mange and other ectoparasites by monthly dipping with Gammatox.
After 12 months use of this package, preliminary results show a major reduction in reported cases of PPR in goats: from 14% to 4% in the forest and from 18% to zero in the savanna. Dipping had a major impact on the reported incidence of mange from 38% to 11% for forest goats, from 61% to 3% in savanna goats and from 13% to zero in forest sheep. Pneumonia and helminthiasis rose in relative importance. The actual number of observed cases of illness fell from 237 to 56 for forest goats, from 357 to 61 for savanna goats and from 128 to 43 for forest sheep.
Table 39. Main causes of morbidity in small ruminants in Nigeria as % of observed cases, before and after veterinary intervention.
|
Disease |
Goats |
Sheep |
||||
|
Forest |
Savanna |
Forest |
||||
|
Before |
After |
Before |
After |
Before |
After |
|
|
PPR |
13.5 |
3.6 |
17.6 |
0.0 |
0.0 |
0.0 |
|
Pneumonia |
7.6 |
17.9 |
5.0 |
21.3 |
3.1 |
7.0 |
|
Footrot |
0.4 |
8.9 |
0.6 |
3.3 |
7.0 |
23.2 |
|
Helminths |
6.7 |
16.1 |
2.8 |
24.6 |
16.4 |
11.6 |
|
Ecto-parasites |
8.6 |
1.8 |
2.3 |
0.0 |
26.4 |
0.0 |
|
Mange |
37.5 |
10.7 |
60.7 |
3.3 |
13.3 |
0.0 |
|
Accidents |
13.9 |
16.1 |
4.7 |
19.6 |
28.9 |
30.2 |
|
Others |
11.8 |
25.0 |
6.3 |
27.9 |
4.7 |
27.9 |
|
Total numbers |
237 |
56 |
357 |
61 |
128 |
43 |
Table 40 shows the effect of the health package on mortalities. For goats this fell from 30% to 12% in the forest and from 40% to 13% in the savanna. The drop in mortalities for sheep was less from 20% to 14%. This was probably because the health package was aimed more at the goat diseases to which the sheep were less susceptible.
Table 40. The effect of veterinary intervention on the mortality and offtake of small ruminants in Nigeria
|
|
Mortality (%) |
Offtake (%) |
||
|
Before |
After |
Before |
After |
|
|
Goats in forest |
29.9 |
12.1 |
25.4 |
21.0 |
|
Goats in savanna |
40.1 |
13.3 |
20.4 |
17.7 |
|
Sheep in forest |
20.1 |
13.6 |
32.8 |
28.6 |
Overall offtakes were slightly lower after the veterinary intervention than before, but this difference was not significant. However, for bucks in the 0-90 day age class, offtakes fell from 6.5% to 0.9% (significant at p < 0.05). Increased viability would be expected to reduce offtake in this age group, due to the reduction in emergency slaughters.
The consequence of a fall in mortality and a static offtake was that inventories rose (Table 41). In both sheep and goats the major increases in numbers occurred in the post-weaning age group. For forest goats there was an overall increase of 34%, and 18% for sheep, and in the savanna 39% for goats. Excluded from the data in Table 41 were animals transferred into the survey for share cropping. Farmers were quick to see the benefits of the health package and many animals were brought into survey area from friends and relations.
Table 41. Flock inventories before and after veterinary intervention
|
|
Goats |
Sheep |
|||||||
|
Forest |
Savanna |
Forest |
|||||||
|
Age group |
Start |
End |
Difference (%)- |
Start |
End |
Difference (%)- |
Start |
End |
Difference (%) |
|
91-360 days |
45 |
96 |
91.1 |
30 |
56 |
53.6 |
19 |
30 |
57.9 |
|
360 |
114 |
126 |
10.5 |
74 |
98 |
32.4 |
49 |
55 |
12.2 |
|
Total |
204 |
273 |
33.8 |
147 |
204 |
38.7 |
87 |
103 |
18.4 |
The overall benefits of the health package in terms of productivity indices are shown in Table 42. Unfortunately, there were insufficient data for sheep to make a comparison before and after intervention. No statistical significance has yet been attached to the differences in productivity indices. These are preliminary results and a detailed analysis will be carried out once data for a further 12 months have been collated.
Table 42. The effect of veterinary intervention on the productivity indices of small ruminants in Nigeria. Index I is total weight of offspring at 5 months/ dam/year. Index II is total weight of offspring at 5 months/unit weight of dam (kg)/year. Index III is total weight of offspring at 5 months/unit metabolic weight of dam (kg 0.75)/year.
|
|
|
Weight of dam (kg) |
Index I (kg) |
Index II (g) |
Index III(g) |
|
Goats in forest |
Before |
15.1 |
7.5 |
500 |
1010 |
|
|
After |
16.7 |
10.3 |
620 |
1280 |
|
Goats in savanna |
Before |
13.9 |
7.2 |
520 |
1050 |
|
|
After |
14.7 |
10.5 |
710 |
1430 |
|
Sheep |
|
21.1 |
21.1 |
690 |
1480 |
