Small ruminant feed production in a farming systems context
Small ruminant production under pressure: the example of goats in southeast Nigeria
J.E. SUMBERG
Abstract
Introduction
Alley farming
Cut-and-carry browse feeding
Grazed fallow in integrated alley farming
Browse and alley farming in West Africa
References
ILCA's research with integrated alley farming and browse feeding is discussed in relation to the role of small ruminants in the farming systems of southwest Nigeria. Cut-and-carry browse feeding for sheep and goats, and a grazed fallow system for sheep, are outlined. Preliminary biological and economic parameters for both systems are presented. The potential application of these approaches in other areas of humid West Africa is discussed.
In southwest Nigeria agriculture is dominated by arable food and tree crops, including maize (Zea mays L.), yam (Dioscorea spp.), cassava (Manihot esculenta), cocoa (Theobroma cacao) and oil palm (Elaeis guineensis). Although sheep and goats are present in many rural households, they appear to be poorly integrated in the agricultural production system (Matthewman, 1980). The majority of small ruminants in this part of Nigeria are kept in free-roaming village flocks with only limited management or capital inputs. The average flock ranges from two to five animals per owner, with goats being more common than sheep. Feeding household scraps to animals is a common practice. Few animals receive veterinary care, and mortalities within the first 3 months after birth are high. Peste des petits ruminants (PPR), a rinderpest-related disease, is perhaps the most important cause of early mortality, particularly among goats. Preliminary results from village trials show that PPR can be effectively and economically controlled with tissue culture rinderpest vaccine (TCRV) (Opasina, 1984; Adeoye, 1984).
The Small Ruminant Programme of the International Livestock Centre for Africa (ILCA) at Ibadan, Nigeria, is aimed at improving the productivity of indigenous breeds of sheep and goats in this area. Apart from disease, nutrition is probably the most important factor limiting productivity. While it is difficult to demonstrate a seasonal feed shortage under present management conditions, there are compelling reasons why the feed situation deserves attention. PPR control is expected to reduce mortalities substantially, and may thus increase animal numbers and heighten demand for feed. Larger animal populations, in combination with future pressure to control animal movement around villages, gardens and farms, will likely result in some form of animal confinement. Total confinement of sheep and goats is already common in some parts of eastern Nigeria, necessitating cut-and-carry feeding and an easily accessible feed supply.
The importance of crop production relative to livestock production in this area dictates that the increased attention given to small ruminant production must also show a positive effect on crop production. For this reason, ILCA is evaluating ways of linking crop and small ruminant production based on the use of fast-growing leguminous trees such as Leucaena leucocephala and Gliricidia sepium. The foliage of these trees can be used as a high-quality fodder and as a nitrogen-rich mulch for crop production.
Kang et al (1981) described an alley cropping system in which crops are grown in alleys between rows of frequently pruned trees. The large input of nitrogen and organic matter from the tree foliage can potentially support continuous cropping at intermediate yield levels. Alley cropping appears to be an attractive alternative to the traditional bush fallow system of maintaining soil fertility. Small ruminant production can be integrated with alley cropping by cut-and-carry feeding of a portion of the tree foliage, or, at a somewhat higher management level, by grazing the natural fallow regrowth and trees during periodic fallow years. While cut-and-carry feeding is applicable to sheep and goats, the grazing system is limited to sheep because goats readily de-bark the trees.
This paper describes ILCA's experiences and current research with both approaches to integrated alley farming. The rationale for emphasizing alley farming and browse feeding will be developed, and the potential for these approaches in other areas of West Africa will be discussed.
The fast-growing leguminous trees Leucaena leucocephala and Gliricidia sepium are the focus of much of ILCA's agronomy, feed and nutrition work because of their potential role in linking crop and animal production. These trees can provide high-quality fodder and nitrogen-rich mulch for crop production-. When properly managed, the trees will provide fodder throughout- the year. Unlike grasses and some herbaceous legumes, browse shows relatively little decline in nutritional quality during the dry season. Trees have traditionally played an important role in the farming systems of humid West Africa, and the browse trees that are the basis of alley farming can be seen as an extension of this tradition.
The integrated alley farming approach is based on the initial work of the Farming Systems Program of the International Institute of Tropical Agriculture (IITA). Crops are grown in 4-m wide alleys between rows of densely planted trees which are pruned three to five times during each growing season. Trees managed in this way can produce 4 to 8 t of mulch DM/ha/year, yielding over 100 kg of N for crop production.
The trees in an alley farming system are effective nutrient pumps, bringing minerals from the lower soil profile to the surface where they can be used by the crop. If leguminous trees are used, significant quantities of N are also added to the soil; indirectly from the foliage as mulch, and directly from decaying roots and nodules. This large input of minerals and organic matter can support continuous cropping at intermediate yield levels. In addition, alley cropping addresses two key issues related to the loss of bush fallow as a useful strategy for maintaining soil fertility in the humid zone - a rural labour shortage for bush clearing, and a consequent inability to maintain fertility with ever shorter fallow periods.
With cut-and-carry feeding of some portion of the tree foliage, small ruminant production can be linked with alley farming. The cut-and-carry system is highly flexible and can be used with free-roaming or confined animals. Depending on the availability and quality of other fodder resources, a range of browse feeding strategies can be developed. For example, browse may be fed as a protein supplement or as a sole feed. It may be fed on a year-round basis or only during the dry season. Feeding browse to only particular classes of animals, such as growing weaners or lactating dams, may be desirable in some circumstances. In order to give sufficient benefit to the crop, and avoid the possibility of soil mining, we currently recommend that approximately 75% of the available tree foliage be applied to the soil as mulch. An annual tree foliage yield of 4 t DM/ha would then give 1 t of DM for feed. This amount would be sufficient to support approximately 14 adult animals per hectare as a year-round supplement (25% of daily feed intake), or 4 animals per hectare as a sole feed.
The management of browse trees within the alley farming context must take into account the requirements of the crop for nutrients and light, as well as the seasonality of the demand for fodder. Year-round browse feeding, for example, will require a different tree management strategy than simple dry-season supplementation. One aspect of our current research involves this relationship between tree management and feed requirements.
In two long-term browse supplementation trials, West African Dwarf sheep and goats are being fed varying amounts of a mixed browse supplement in conjunction with an ad libitum basal diet. The objective of the trial is to determine the effect of browse supplementation on long-term dam productivity and short-term weaner growth. The basal diet consists of Panicum maximum of reasonable quality (freshly chopped, green, primarily vegetative growth). The diet is meant to mimic a diet of reasonable but seasonally variable quality which might be consumed by free-roaming animals in this zone. While the limitations of this approach are fully acknowledged, the experimental difficulties inherent in working with free-roaming animals are considerable.
Over 14 weeks, a mixed Leucaena/Gliricidia browse supplement fed at approximately 200 g DM/doe/day increased the total intake of goats by 30% (Figure 1). Fed at this level, browse constituted nearly 35% of the total DM intake. With sheep, browse supplementation of 200 and 400 g DM/ewe/day increased the total DM intake by 6 and 18 % respectively. At 200 g DM/day, browse constituted 22 % of dry matter intake, whereas with 400 g DM/day, it accounted for 43% of total intake.
Figure 1. Effect of controlled browse supplementation on daily dry matter intake.
Browse supplementation appeared to have little effect on the body weights of breeding ewes and does. Preliminary analysis of a limited number of lamb records indicates that lambs from supplemented dams were 30% heavier at 30 days of age than those from unsupplemented dams.
Over a period of approximately 2 years, the reproductive performance of dams and the survival and growth of offspring will be monitored. It is hoped that these trials will eventually provide sufficient information to evaluate browse supplementation of small ruminants under an alley farming system.
Cut-and-carry browse feeding represents a highly flexible, relatively simple, improved feeding strategy which can be implemented with minimal capital or management inputs. The grazed fallow approach with sheep will demand greater management skills, but at the same time it represents a higher degree of integration of crop and livestock production, since all manure is potentially returned to the soil.
ILCA has stressed the use of natural fallow vegetation grazed in combination with browse trees to avoid the problems inherent in establishing, managing and controlling introduced pasture species. In any case, it would probably be unrealistic to establish pasture species for the small flocks, and relatively short-term fallows are envisioned in this system. The grazed fallow system, as it is now conceived, consists of a rotation of blocks of alleys with 3 to 5 years of alley cropping followed by 2 to 3 years of grazing.
In a preliminary evaluation of the grazed fallow system, two 0.25 ha paddocks containing natural fallow regrowth and Leucaena and Gliricidia planted in rows 4 m apart, were grazed by sheep between June 1982 and May 1983. Ground vegetation, browse and animal performance were monitored to estimate appropriate stocking rates for similar alley grazing systems, and to identify potential problems and limitations of the system.
The components of animal liveweight (LW) supported per hectare during the grazing period are presented in Figure 2. From 1 June to 15 November, with a stocking rate of 16 ewes/ha, the paddocks supported an average of 472 kg LW/ha. Between 15 November and the end of March, with a stocking rate of 8 ewes/ha, they supported an average of 218 kg LW/ha.
The stocking rate was reduced from 16 to 8 ewes/ha because of what appeared to be nutrition-related health problems. In addition to reducing the stocking rate, a daily Leucaena supplement was given to the remaining animals, by bending down and tying two to three trees daily so that the upper foliage became available for consumption. This method of supplementation provided between 100 and 200 g DM/ewe/day and approximately 20 to 40 g CP/ewe/day. No further health problems were encountered after the initiation of supplementation, and it would appear that the original stocking rate might have been maintained if supplementation had been started somewhat earlier.
Figure 2. Components of animal liveweight supported over a 10-month grazing period, Ibadan, Nigeria.
During the rainy season the natural fallow vegetation provided an ample supply of good-quality herbage to support the stocking rate of 16 ewes/ha (Table 1). Standing dead plant material probably provided an important source of roughage during the dry season. Although no information on feed intake was collected, it would appear that Leucaena became an increasingly important component of the diet as the dry season progressed. Indeed, the success of this type of alley grazing system depends on the accumulation of browse during the wet season to supplement the diminishing ground vegetation in the dry season.
Table 1. Monthly rainfall (mm) and feed components (kg DM/ha) on offer during a 10-month grazing period, Ibadan, Nigeria.
|
Month |
Rainfall (mm)a |
Green grass |
Other green plants |
Dead plants |
Leucaena |
Gliricidia |
Total DM on offer |
|
J (1982) |
1.6 |
- |
- |
- |
- |
- |
- |
|
F |
44.6 |
- |
- |
- |
- |
- |
- |
|
M |
92.7 |
- |
- |
- |
- |
- |
- |
|
A |
87.9 |
- |
- |
- |
- |
- |
- |
|
M |
124.4 |
- |
- |
- |
- |
- |
- |
|
J |
166.7 |
566.7 |
1 147.3 |
550.1 |
694.4 |
104.0 |
3 062.5 |
|
J |
136.9 |
1 264.5 |
1 869.0 |
460.1 |
968.7 |
111.7 |
4 673.9 |
|
A |
75.6 |
1 441.8 |
2 178.8 |
714.6 |
1 086.1 |
129.2 |
5 550.5 |
|
S |
66.1 |
758.7 |
1 574.7 |
929.8 |
727.5 |
92.5 |
4 083.2 |
|
O |
102.2 |
754.4 |
1 642.3 |
851.0 |
1 089.7 |
0.0 |
4 337.4 |
|
N |
8.9 |
507.8 |
1 974.0 |
984.8 |
845.3 |
0.0 |
4 311.9 |
|
D |
0.0 |
115.9 |
681.8 |
1 553.0 |
585.1 |
0.0 |
2 935.8 |
|
J (1983) |
0.0 |
0.0 |
0.0 |
1 379.3 |
488.7 |
0.0 |
1 868.0 |
|
F |
3.9 |
0.0 |
0.0 |
1 417.4 |
259.3 |
0.0 |
1 676.7 |
|
M |
3.2 |
0.0 |
0.0 |
1 003.0 |
210.8 |
0.0 |
1 213.8 |
a Rainfall data courtesy of T.L. Lawson, Farming Systems Program, IITA.
The height and flexibility of the Leucaena trees played an important role in restricting animal access during the wet season. At the end of the grazing period the Leucaena trees were as tall as 7 m. While the trees with thinner trunks (1 to 3 cm in diameter) were still being successfully browsed by the sheep, larger trees were no longer accessible. The method of controlled supplementation by bending trees daily worked satisfactorily and required a minimum of labour. After all foliage was consumed, the trees were released and allowed to recover out of the reach of the animals.
Similar alley farming systems could be based on one or a combination of tree species. There may be an advantage to including several browse species to provide diversity of diet, particularly where mimosine toxicity from Leucaena can be important. No adverse effects from Leucaena were observed during the course of this trial.
Gliricidia trees suffered heavy damage from the grazing animals, and the disappointing performance of these trees largely appeared to be related to the stake establishment method. Gliricidia has traditionally been used for living fence posts and as plantation shade, and for these uses stake establishment has obvious advantages. Observations by ILCA in Ibadan suggest that the root systems of stake-established trees are shallow, less extensive, and significantly less tap rooted than those of seed-established trees. It is unlikely that the sheep would have been able to uproot seed-established Gliricidia trees, and certainly no problem of uprooting was seen with the seed-established Leucaena It would also be expected that the root system morphology would have an important effect on dry-season growth and foliage production, as well as adaptation to increasingly arid environments.
The branch damage that occurred during browsing was also related to the stake establishment method. Stake-grown trees tend to sprout and branch from the top of the stake, and it was these branches which were damaged. Seed-grown Gliricidia can be managed to branch closer to ground level, and may be less susceptible to damage.
A partial budget analysis of this alley grazing system compared to a common crop production sequence, is presented in Table 2. At a stocking rate of 12 ewes/ha, it would appear that a short-term, grazed fallow period would be economically competitive with more traditional cropping activities. The grazed fallow period might also be advantageous with regard to improved soil fertility and crop yields. The effects of short-term grazed fallows on subsequent crop yields are currently being investigated in two major alley farming trials.
These preliminary observations indicate that alley grazing using short-term fallows and fast-growing trees is a promising approach to the integration of crop and livestock production in the humid zone of West Africa. The attractiveness of the system is its relatively low capital and management requirements. ILCA has developed an inexpensive living fence woven from Leucaena, which eliminates the need for purchased fencing (Sumberg, 1983). The use of natural fallow regrowth instead of planted grasses and legumes eliminates several important management problems. Natural fallow is ready to be grazed shortly after the end of the cropping cycle, whereas planted pasture would need 3 to 12 months without grazing to ensure proper establishment. The investment involved in pasture establishment would make short-term rotations unattractive and reduce the overall flexibility of the system. The problems of pasture seed scarcity and overproduction of herbage during the wet season are also avoided, as is the danger of introducing new weed problems.
Table 2. Partial budget analysis (US$/ha) of alley grazing with sheep and maize-cassava intercropping.
|
|
Alley grazinga |
Maize-cassavab |
||
|
Gross returns |
weaners (16) |
768 |
maize |
985 |
|
adults (3) |
288 |
cassava |
728 |
|
|
Total |
|
1 056 |
|
1 713 |
|
Variable costs |
labour |
288 |
labour |
808 |
|
salt lick |
29 |
seed/stakes |
32 |
|
|
drugs |
20 |
fertilizer |
128 |
|
|
Total |
|
337 |
|
968 |
|
Net returns |
|
719 |
|
745 |
a Sale of weaners at 15 kg, adults at 30 kg at US$ 3.20/kg liveweight. Labour includes provision of water, checking of animals and tree management at 0.5 hr/day at US$ 1.00/hr. Cost of initial stock is not included, but provision is made for replacements. Assumes fertility rate of 1.3 lambs/ewe/year, and mortalities of 12, 7 and 5% in the age groups 0-4 months, 4-12 months and adults respectively. Budget covers 18 months.
b Maize yield of 2.5 t; cassava yield of 3.5 t as intercrop. Maize sold at US$ 448/t, cassava at US$ 208/t. Labour at US$ 1.00/hr includes 25 days for pruning tree rows. Budget covers 18 months.
Several areas need further study, particularly the problem of tree management in the transition from cropping to grazing and grazing to cropping. Factors affecting the species composition and productivity of natural fallows also need clarification. In this regard, the effects of different weed control strategies during cropping years on the composition and productivity of subsequent fallow vegetation are being studied.
Small ruminant production is a common minor farm enterprise throughout humid West Africa, and improved feeding will most certainly be an important component of intensified and/or more efficient production systems. Leguminous browse trees provide a flexible, easily managed fodder resource which appears to be particularly well suited to small-scale livestock production where more intensive technology is not applicable. Depending on the characteristics of the other farm enterprises, browse production might be integrated with cropping in a system such as alley farming, or browse trees might be grown in special feed production plots. ILCA is currently investigating the management and use of this kind of 'intensive feed garden' in eastern Nigeria where animal movement is commonly restricted, necessitating daily cut-and-carry feeding.
Alley farming addresses several important issues facing small farmers in the region, for whom fodder production is presently a minor farm concern. Alley farming, therefore, will be considered by these farmers for adaptation primarily as a crop production strategy, and only secondarily for its potential contribution to sheep and goat production. This realization should influence the way alley farming and browse feeding are portrayed by research and extension organizations. In our own on-farm research, for example, the browse trees are presented firstly for their considerable mulch and fertilizer value, and only secondly for their value as livestock feed.
Alley farming is an intensive production technique which has sufficient promise to be tested under a variety of conditions throughout the region. Leucaena and Gliricidia are the most widely used alley farming browse species, and although other potentially useful species are under investigation, ILCA's work will continue to focus on these two widely adapted, versatile species. It is hoped that our collection and evaluation of new Gliricidia germplasm will identify types that are more productive than the present materials, and better adapted to more arid environments (Sumberg, in press). In the coming years we will be interested in having these unique genetic resources evaluated under as wide a range of environmental and management conditions as possible.
Adeoye S A O. 1984. The incidence of diseases and pests in sheep and goats in two village groups in the forest zone of southwest Nigeria. Unpublished M.Vet.Sci. thesis, University of Ibadan.
Kang B T. Wilson G F and Sipkens L. 1981. Alley cropping maize (Zea mays L.) and Leucaena (Leucaena leucocephala Lam.) in southern Nigeria. Plant and Soil 63: 165-179;
Matthewman R W. 1980. Small ruminant production in the humid tropical zone of southern Nigeria. Trop. Anim. Health Prod. 12: 234-242.
Opasina B A. 1984. Disease constraints on village goat production in southwest Nigeria. Unpublished M.Phil. thesis, University of Reading.
Sumberg J E. 1983. Leuca-fence: Living fence for sheep using Leucaena leucocephala. World Anim. Rev. 47: 49.
Sumberg J E. (In press). Collection and initial evaluation of Gliricidia sepium from Costa Rica. Agroforestry Systems.
S.D. MACK, J.E. SUMBERG and C. OKALI
Introduction
Materials and methods
Results and discussion
References
Goat husbandry in the humid zone of Nigeria is a low-input, minor farm enterprise offering potentially good but highly variable returns. The majority of rural owners are farmers involved in food and tree crop production, or women involved in food processing and marketing. Both groups of owners have relatively limited skills in livestock husbandry.
The traditional practice of permitting goats to roam freely around the village still predominates in southwest Nigeria (Matthewman, 1979). Specialized housing, systematic feeding and veterinary care are uncommon in this region. Goats depend on their ability to select an adequate diet from the naturally available vegetation. Household scraps are often available, but are probably of limited nutritional significance. The majority of goats appear to be in good condition. The mean weights of dams at 90 days post partum show no evidence of seasonality, which may indicate that they are able to obtain an adequate diet even during the dry season. However, growth rates of kids are low at 35 g/day, and the probability of kids surviving to 90 days is only 0.67 (Mack, 1983). The low levels of both of these parameters might be seen as indirect indications of nutritional stress.
The West African Dwarf goat is both fertile and prolific. Data from villages in southwest Nigeria indicate a mean litter size of 1.5 kids/litter and a mean parturition interval of 259 days (Mack, 1983). The traditional free-roaming system of management takes advantage of this reproductive potential through continuous and uncontrolled breeding. However, early conception in immature females is a potential disadvantage of this strategy, and may contribute to high kid mortality.
In southeast Nigeria, traditional goat husbandry systems are being modified by high human population density and increasing pressure on agricultural land. Lagemann (1977) noted that both goats and sheep may be restricted, either in small stockades or by tethering, to protect crops during the growing season. He further noted that with increasing population pressure compound gardens become smaller and more intensively managed, while the number of goats kept per household increases. In such areas, it would appear that free-roaming animals pose an increasingly important threat of damage to growing crops. This would seem to explain the relatively recent introduction of local laws banning free-roaming animals in ILCA's two village sites in the southeast.
The consequences of such mandated restrictions on animal movement, are unclear, yet they surely demand major changes in goat management strategies. Housing, feed, water and breeding strategy become critical once animal movement is restricted. Restricted animals require a higher level of input and management than free-roaming animals, and in no area is this more clear than in the need for daily feeding.
This paper presents a preliminary analysis of some biological parameters of free-roaming and recently restricted animals. The objectives of this work are not so much to compare animal productivity under the two management systems as to describe the animals' and farmers' responses to forced changes in traditional livestock husbandry practices.
Data for free-roaming goats have been extracted from a larger data set gathered from villages near Fasola, 60 km north of Ibadan in southwest Nigeria. Mgbakwu village in Anambra State and Okwe village in Imo State, southeast Nigeria, are used to assess the impact of restricted animal movement on management and productivity. Animal monitoring was initiated in August 1982 and February 1983 at Mgbakwu and Okwe respectively.
All animals entering the survey were identified by ear tags. Information on age, sex, dam and parity was collected for all animals entering the survey. Reasons for entry and exit were also recorded. All- animals were weighed monthly. Some characteristics of the three survey areas are presented in Table 1.
Table 1. Some characteristics of three village survey sites.
|
Location |
Management |
Number of households |
Number of animals |
Animals/ |
Breeding |
|
Fasola |
free-roaming |
15 |
68 |
4.5 |
1:4 |
|
Mgbakwu |
restricted (tethered/confined) |
105 |
284 |
2.7 |
1:2.6 |
|
Okwe |
restricted (confined) |
65 |
234 |
3.6 |
1:3.8 |
Due to the relatively short monitoring periods at the two southeastern sites, only a preliminary analysis of animal performance is possible. In none of the locations are the data sufficient to construct a comprehensive productivity index; as an alternative, the various components which would normally be used to compile an index are presented.
Flock dynamics
The structure of the goat populations in each location at the beginning and end of the survey periods is given in Table 2. While the total number of goats in the free-roaming flocks at Fasola increased by 59%, goat populations decreased by 2 and 18% at Okwe and Mgbakwu respectively. In Mgbakwu 65% of households had smaller flocks at the end of the survey period than at the beginning, 14% abandoned goat keeping and 4% lost all their animals due to high mortality. In the village with free-roaming animals only 24% of households had smaller flocks at the end of the period, while none abandoned goat keeping or lost all their animals.
The ratios of males to females were similar at all locations and averaged 1:1.7. The ratio of breeding males (³ 6 months) to breeding females (³ 18 months) ranged from 1:2.6 in Mgbakwu to 1:4 in Fasola.
Table 2. Goat populations at three survey sites.
|
Location |
Date |
Total goats |
All females |
Breeding females |
All males |
Breeding males |
|
Fasola |
30-4-82 |
68 |
57 |
29 |
11 |
2 |
|
31-8-83 |
108 |
68 |
37 |
40 |
14 |
|
|
Mgbakwu |
31-8-82 |
284 |
200 |
111 |
84 |
39 |
|
31-8-83 |
234 |
166 |
100 |
68 |
41 |
|
|
Okwe |
31-3-83 |
238 |
177 |
106 |
61 |
30 |
|
31-8-83 |
235 |
172 |
114 |
63 |
28 |
Reproductive performance
Reproductive performance of does at the three locations is summarized in Table 3. The limited number of parturitions involved to date makes comparisons between sites or management systems difficult. In any case, as has been well illustrated by Upton (1985), changes in mortality (survival) of offspring have a far greater effect on productivity and potential profitability than changes in reproductive performance.
Table 3. Reproductive performance of goats at three locations.
|
Location |
Number of parturitions |
Litter size1 |
Parturition interval (days) |
Kids/doe year2 |
% of breeding does kidding per month |
|
Fasola |
41 |
1.7a |
271 (± 89) |
2.3 |
8.1 |
|
Mgbakwu |
109 |
1.5b |
263 (± 42) |
2.0 |
8.5 |
|
Okwe |
57 |
1.3c |
- |
- |
8.8 |
1 Means within columns followed by the same letter are not significantly different at P = 0.05.
2 
Growth
Estimated least square means for kid weights at 30 and 90 days, and growth rate between 30 and 90 days, are given in Table 4. Kids from free-roaming does at the Fasola site were significantly heavier at both 30 and 90 days than kids from restricted does at the southeastern sites. Since there was no difference in growth rates between the sites, these differences in kid weight can be assumed to be related to lighter birth weights at the southeastern sites.
Table 4. Estimated least square means for weights of 30- and 90-day kids and daily liveweight gains between 30 and 90 days.
|
Location |
Management system |
Kid weight (kg) at: |
Growth rate (g/day); |
|
|
|
30 days |
90 days |
30-90 days |
|
|
Fasola |
free-roaming |
3.5a |
5.7a |
36.6a |
|
Mgbakwu |
restricted |
2.5b |
4.7b |
36.6a |
|
Okwe |
restricted |
2.4b |
4.4b |
33.3a |
Means within columns followed by the same letter are not significantly different at P = 0.05.
The average body weight of free-roaming does at Fasola was 21% greater than that of restricted does in the southeast. Whether due to nutritional or genotypic causes, the difference in doe body weight probably accounts for the heavier kids at the Fasola site. The similar growth rates of kids at all sites might argue against significant nutritional effects, since nutritional stress strong enough to affect dam body weight would almost certainly affect milk output, and consequently kid growth.
Mortality
Mortality of free-roaming goats at Fasola (2.7% per month) was significantly lower than mortality at either Mgbakwu (4.5% per month) or Okwe (4.7% per month) (Table 5). Mortalities for each month of the survey period are depicted in Figure 1. Among free-roaming animals at Fasola, mortalities appeared more sporadic than at the southeastern sites. There was one confirmed outbreak of the disease peste des petits ruminants (PPR) at Fasola in September 1982.
Table 5. Mortalities at three locations.
|
Location |
Management |
Average monthly |
Aver. kid mortality |
|
Fasola |
free-roaming |
2.6 ± 4.4 |
11.1 |
|
Mgbakwu |
restricted |
4.4 ± 1.8 |
24.8 |
|
Okwe |
restricted |
4.2 ± 2.5 |
18.6 |
Figure 1. Monthly mortality of goats at three locations in Nigeria.
Initial health and disease surveys in Mgbakwu and Okwe have been inconclusive, and the major causes of the high mortalities remain unknown. In southwest Nigeria vaccination against PPR reduced mortalities by approximately 75% (Adeoye, 1984; Opasina, 1984). Although PPR is said to be widespread in the southeast, and is identified by owners as a cause of mortality, there have been few confirmed cases of PPR at the two village sites. More intensive disease monitoring has been initiated at these sites in order to identify the causes of high mortality.
While 67% of all households at Fasola experienced some goat mortality during the survey period, most of these houses lost less than 15% of their animals, and none lost more than 50%. At Okwe, mortality occurred in only 43% of households, but a number of these lost over 30% of their animals, and 5% lost all their animals. Mortality was more widespread in households at Mgbakwu, with 80% experiencing some mortality. As at Okwe, many households lost over 30% of their animals, and 4% lost all their animals.
Differences in mortality between households may be indicative of important management variations between households, or may be the effect of some epidemiological characteristics of the primary diseases causing death. In the two southeastern villages where animal movement is restricted, differences in management of individual flocks are apparent in housing, feed quantity and quality, water availability and general concern for the animals' well-being. Without a clear understanding of the causes of morbidity and mortality at these sites, the importance of such management factors is difficult to assess.
Breeding strategies
Few decisions directly related to breeding strategy appear to be made when animal movement is unrestricted. Breeding is uncontrolled and depends on the presence of mature males in the free-roaming village flock. As young males are the principle disposable product of this production system, both sales and mortality can have important implications for the village-wide breeding situation. At Fasola, for example, the ratio of breeding males to breeding females varied from 1:15 at the beginning of the survey, with 2 breeding males in the village, to 1:3 at the end, with 14 breeding males available. Periods when no breeding males were present in village flocks have also been documented in southwestern Nigeria. The effects of these changes in the availability of breeding males on reproductive characteristics such as parturition interval are not yet known.
Breeding management takes on greater importance once animal movement is restricted. At Mgbakwu and Okwe the major breeding options involve keeping a resident male or borrowing/ renting a breeding male when required. At Mgbakwu there is a small number of free-roaming males associated with a local religious shrine. These bucks are relied upon by some goat owners who make receptive does accessible to them. In the two villages studied, approximately 50% of households do not keep a breeding male; the vast majority of the flocks these villages are single-animal flocks.
Concern over transfer of disease has been cited at both southeastern villages in relation to hesitation to either borrow or lend males for breeding. Both borrowing and renting of males are common, however, with males apparently being transferred for short periods of 2 to 5 days. Although cash payment for breeding services has been reported, some borrowers report that the service of feeding the buck for the borrowed period is considered sufficient payment. This situation illustrates the perceived burden of cut-and-carry feeding at these sites.
The free-roaming management system in southwest Nigeria can be described as a low-level, equilibrium system offering potentially good returns with a minimum of capital, labour or management inputs. Returns from this system are highly variable, however, since the disease PPR can cause significant loss of stock and has been known to destroy whole flocks. The risk of PPR is thought to limit animal populations by discouraging flock expansion.
PPR can be effectively and economically controlled by annual vaccination with tissue culture rinderpest vaccine (TCRV). While the effects of PPR control on the various components of the free-roaming management system are not known, it seems likely that increased numbers, resulting directly from reduced mortality and indirectly from a reduction in perceived risk, will put significant pressure on available feed resources. Once a form of feed production is introduced, it is not unlikely that some level of restriction of animal movement will follow. PPR will probably cause major shifts in goat management in the region. Some of these changes will be similar to those observed in southeastern Nigeria, where animal movement is being restricted by law.
At the two village sites in southeast Nigeria, both the production environment and the management systems are in dynamic states. Relatively recent legislation mandating restriction of animal movement has forced owners either to confine or tether their animals. These restrictions on animal movement have created the need for immediate changes in housing, feeding and breeding strategies.
The extremely high mortality observed at these sites, averaging over 50% per year, clearly indicates that there are major outstanding issues in the production system which have not yet been addressed successfully. Mortality does not appear uniformly in all flocks, indicating that there may be some important management considerations which are not fully appreciated. Great differences in housing and feeding strategies certainly exist, but the importance of these cannot be assessed until the major causes of mortality are identified.
There can be little doubt that if the current level of mortality continues, more households will be forced to abandon goat keeping altogether. Other owners, unwilling to invest the additional labour required by cut-and-carry feeding, will choose to participate in different economic activities. While both of these situations have been observed in the southeastern villages, it is also evident that some owners willingly invest the additional time and labour in goat keeping, and are, in fact, expanding their flocks.
It is evident that restriction of animal movement is a common and important aspect of the small ruminant production environment in southeast Nigeria. A recent survey of 26 Local Government Areas (LGAs) in four southeastern states indicates that restriction of animal movement is encountered where open, derived savanna vegetation predominates, but is less common in heavily forested areas (Table 6). In 15 LGAs in Anambra and Imo States, for example, 86% of households restricted movement of their animals either during the whole year or at least during the cropping season. In contrast, only 16% of households in Rivers and Bendel States restricted animal movement at any time in the year.
It would appear from these data that restriction of animal movement is directly related to the intensity of agricultural land use. Small ruminants can cause serious damage to growing crops, particularly in areas characterized by open vegetation. Restriction of animal movement can then be seen as a forced response to changes in larger farming and land-use patterns. As is typical of minor farm enterprises in general, and of particular livestock enterprises, the character of the goat production system is determined largely by outside forces. In other words, goat production cannot be usefully discussed in terms of 'optimization' and 'maximization', but rather in terms of its complementarity - lending some measure of additional stability to the overall farming system.
Table 6. Prevalence of restriction of goat movement in four southeastern states, Nigeria.
|
|
% of households in: |
|||
|
Anambra |
Imo |
Rivers |
Bendel |
|
|
Restricted year-round |
65 |
48 |
11 |
9 |
|
Restricted, farming season only |
27 |
42 |
0 |
12 |
|
Free-roaming |
8 |
20 |
89 |
79 |
|
Number of LGAs |
6 |
9 |
5 |
5 |
|
Number of households |
239 |
321 |
244 |
236 |
|
% households without goats |
7 |
7 |
15 |
5 |
It seems likely, nonetheless, that goat production will evolve from a low-input, minor farm enterprise to a more intensive and specialized enterprise. Thus, successful management will be within the reach of a more limited number of persons. This may be particularly true as specialized food production systems are introduced. There is also a strong interest in the introduction and use of exotic breeding stock in the southeast, and this kind of activity might further stimulate specialization.
Adeoye S A O. 1984. The incidence of diseases and pests in sheep and goats in two village groups in the forest zone of southwest Nigeria. Unpublished M.Vet.Sci. thesis, University of Ibadan.
Lagemann J. 1977. Traditional African farming systems in eastern Nigeria. Weltforum Verlag, München.
Mack S D. 1983. Evaluation of the productivities of West African Dwarf sheep and goats. Humid Zone Programme Document No. 7. ILCA, Ibadan.
Matthewman R W. 1979. Small ruminant production in the humid tropical zone of southern Nigeria. Trop. Anim. Health Prod. 12: 234-242.
Opasina B A. 1984. Disease constraints on village goat production in southwest Nigeria. Unpubl. M.Phil. thesis, University of Reading.
Upton M. 1985. Models of improved production systems for small ruminants. In: Sumberg J E and Cassaday K (eds) Sheep and goats in humid West Africa. Proceedings of the workshop on Small Ruminant Production Systems in the Humid Zone of West Africa, held in Ibadan, Nigeria, 23-26 January 1984. ILCA, Addis Ababa. pp. 55-67.
