Research highlights from the small ruminant collaborative research support program: the Dual-Purpose Goat (DPG) - La recherche au small ruminant collaborative research support program du Kenya: la chèvre 3 aptitudes mixtes lait/viande

Summary
Résumé
Introduction
Results and discussion
Acknowledgements
References

P.P. Semenye, A.N. Mbabu, B. Mwandotto, F.B. Nyaribo,
J.M. Onim and F. Rurangirwa

Small Ruminant Collaborative Research Support Program
P O Box 252, Maseno, Kenya

Summary

The Small Ruminant Collaborative Research Support Program (SR-CRSP) in Kenya is engaged in a multidisciplinary research programme with a farming-system perspective. Its overall objective is to carry out research on dual-purpose goat production systems, to enhance production of food protein through meat and milk, and to improve cash flow through sale of goats and products in small-scale intensive farming systems. Research highlights are presented on feed production, preservation and utilisation, goat production and management, development and performance testing of a composite dual-purpose goat breed, immunoprophylaxis and diagnosis of contagious caprine pleuropneumonia (CCPP), heartwater and helminthiasis. The economy of raising dualpurpose goats, their acceptability end the utilisation of their products by farmers in western Kenya are also highlighted.

Résumé

Le Small Ruminant Collaborative Research Support Program du Kenya (SR-CRSP) est un programme de recherches pluridisciplinaires dont les travaux sont essentiellement axés sur l'étude des systèmes de production. Son mandat consiste à effectuer des recherches sur les systèmes d'élevage caprin en vue de promouvoir la production de lait et de viande et partant d'augmenter le niveau d'alimentation protéique des petits éleveurs tout en accroissant le revenu monétaire de ces systèmes de production intensifs sur de petites exploitations grâce à la vente d'animaux sur pied, de viande et de lait. Les principaux résultats obtenus sont présentés, qui concernent notamment la production, la conservation et l'utilisation des aliments du bétail, la conduite des troupeaux caprins, la mise au point d'une race composite de caprins destinée à la production de lait et de viande et l'évaluation de ses performances ainsi que l'immunoprophylaxie et le diagnostic de la péripneumonie contagieuse des caprins, de l'hydropéricardite et des helminthiases. Il aborde également les aspects économiques de ce type d'élevage, l'accueil qui lui est fait par les paysans de l'ouest du Kenya ainsi que l'utilisation qu'ils font des produits ainsi obtenus.

Introduction

The twofold objectives of the Small Ruminant Collaborative Research Support Program (SR-CRSP) in Kenya are: (1) to carry out research on dual-purpose goat (DPGs) to develop production systems which would contribute to increased production of food protein through milk and meat and improved cash flow through marketable goats and goat products in small-scale intensive farming systems of Kenya, and (2) to provide training which would enhance the long-term capability for research and development with goats in Kenya and in other tropical countries. With this approach, it has been necessary to characterise existing farming systems to determine how DPG component can be introduced and sustained in western Kenya production systems. The research problem, therefore, has been to develop an animal of appropriate genotype, a health-nutrition-management package appropriate to the small farm resource base, and to ensure the component is economically and sociologically acceptable. Towards these goals a holistic and multidisciplinary approach has been taken by SR-CRSP, Kenya. Research, therefore, has been conducted on-station and on-farm in testing and evaluating the technical feasibility of DPGs including their management and nutrition, as well as their economic viability and social acceptability. On-farm research is conducted on 150 small-scale farms in Siaya, Kisumu and Kakamega districts. What follows are research highlights from on-farm and on-station trials conducted by SR-CRSP, Kenya.

Results and discussion

Constraints

Following farming system characterisation, constraints were identified that would affect successful introduction and management of DPGs. They are appropriate genotype, shortage of pastures due to land pressure for production of staple and cash crops, diseases and lack of husbandry and production performance measures of DPGs. These constraints are not unique to western Kenya, but are found in many other areas with mixed farming practices. The approach undertaken to resolve them can be extrapolated in other areas. The following research efforts have been undertaken to resolve the above constraints.

Appropriate genotype

As no indigenous nor exotic breed fits the dual-purpose goat production characteristics ideal for Kenya, a new breed is necessary. Towards this goal indigenous goat breeds were evaluated for dairy potential and then strains and individuals from within a breed were selected for breeding with proven exotic dairy breeds. A composite dual-purpose goat was planned from a synthesis of two local goat breeds, the Galla (G) and the East African Goat (EA) and two exotic breeds, the Toggenburg (T) and Anglo Nubian (N). The breeding plan for evolving a composite dual-purpose goat breed is justified in performance as shown in Table 1, whereby F1's and four-way crosses outperform the Galla and East African Goat in milk production.

Table 1. Daily milk yield least squares means ± SE (g)*.

Breed type **	Mean	SE
East African Goat	88.9	207.9
Galla	542.4	143.2
F1's	709.0	98.4
4-way crosses	1077.8	153.0

* After Mwandotto et al (1990).
** F1's and 4-ways-pooled.

Feed shortage

Following on-farm determinations of dry-matter intake, it is clear that the most limiting nutritional factor is quantity rather than quality of available forages. This claim is substantiated in Table 2 which shows crude-protein (CP) content and dry-matter digestibility (DMD) of dietary component are above average, while dry-matter intake (DMI) is below average for a pregnant or lactating doe.

Table 2. Mean nutritive values of the diet of dual-purpose goats in western Kenya.

	DM %	CP %	DMD %	DMI kg	% BWT	ME
N	36	36	36	36	36	36
Mean	28	16	65	0.7	2.4	1.8
SD	12	3	6.5	0.3	0.8	0.5

Due to high population densities, up to 900 people per sq km in some areas in western Kenya, sub-division of farms has substantially reduced pasture and fallow lands rendering reduction in cattle population (Russo et al, 1983). Lack of adequate pasture has led to intensive management methods such as tethering and stall-feeding. In response to this challenge SR-CRSP scientists are solving the problem through integration of DPG with crop agriculture. This is achieved through dual-purpose crops, crop residues and by growing fodders and legume trees in alley cropping or soil conservation practices. Table 3 gives an indication of the quality of some of the forages derived from dual-purpose crops and crop residues.

In testing the hypothesis that integration of DPG with crop production would result in adequate production of forage for goats, a model farm was established at Maseno. The farm is 0.5 ha in size and is designed to produce enough major food crops for the farmer's needs as well as feeds for four goats or one adult cow. Food crops (maize, beans and sweet potato) one adult cow. Food crops (maize, beans and sweet potato) are planted on 60% of the land, while forages, Napier grass, two species of Leucaena, Sesbania and Calliandra, that are planted both as borders and alleys took 40% of the land. In one year this farm produced food crops and forage as shown in Table 4. Four DPGs were exclusively fed from the model farm forages for the whole year with large surpluses realised every month.

Diseases

The main goat diseases in western Kenya and in Kenya at large are contagious caprine pleuropneumonia (CCPP), heartwater and haemonchosis. SR-CRSP has had success in these diseases in vaccine and diagnostic kit development.

Contagious caprine pleuropneumonia

In an endeavour to evaluate the inactivated and lyophilized CCPP vaccine developed by SRCRSP and Kenya Agricultural Research Institute (KARI) scientists, 50 goats were immunised with a single dose of vaccine and 50 others were left as unimmunised controls. All the goats were left on the same farm for two months and then moved to Kabete Veterinary Laboratory farm for challenge. The two groups were mixed and allowed to graze during the day and at night they were housed with five goats with experimental challenge of CCPP. During the first two weeks after movement of the goats to Kabete, 12 vaccinates and 14 unimmunised goats died of diarrhoea. None of these goats had evidence of CCPP infection. Of the remaining 38 vaccinated goats, two became infected with CCPP and had a fever for two days. None of the 38 vaccinated died. At the end of the experiment (four months later), all 38 goats were euthanised and examined for lesions and organisms. Only the two with fever had mild adhesion of the cardiac lung lobes to the thoracic wall and no F38 organisms were isolated from any of the 38 vaccinated goats. In contrast, 30 of the 36 unimmunised goats developed fever and 27 died of CCPP. The three unimmunised goats that developed fever and survival had adhesions of the cardiac and apical lobes of the lungs to the thoracic wall. The six control goats without clinical signs did not have lesions or detectable organisms at the end of the experiment.

Table 3. Chemical composition and digestibility values (mean ± SE) of forages derived from dualpurpose crops and crop residues in western Kenya.

Forage	CP %	NDF%	ADF%	ADL%	IDMD %
Sugar-cane tops	7.4±3.1	73.1±8.7	37.5±9.6	3.7±1.9	42.6±5.2
	(12)	(10)	(10)	(10)	(10)
Maize stover	5.4±2.7	69.9 ±10.1	37.6±9.1	12.1±2.0	55.3+7.4
	(401)	(52)	(49)	(43)	(31)
Maize thinnings	20.7±4.5	-	-	-	63.5±6.9
	(151)	-	-	-	(15)
Maize fresh leaves	13.5± 5.1	72.8±13.1	35.4±16.6	14.4±12.6	59.0±8.0
	(92)	(21)	(18)	(16)	(10)
Finger millet (stover)	7.4±2.4	71.7±4.7	47.3±4.5	10.0±3.0	50.8±6.4
	(21)	(9)	(9)	(9)	(13)
Sorghum stover (serena)	12.6±1.8	69.2±4.2	43.7±5.4	22.8±2.3	50.3
	(9)	(6)	(6)	(6)	(1)
Cassava fresh leaves	17.6± 2.7	39.2±3.9	29.6±6.6	-	-
	(10)	(29)	(29)
Rice stover	4.1±1.1	-	-	-	40.7±8.2
	(5)	-	-	-	(3)
Sweet potato vines	17.9±3.2	51.5±9.6	34.3±4.0	18.5±6.5	62.6±9.8
	(100)	(22)	(21)	(19)	(15)
Bean haulms	7.2±2.5	42.3±6.5	25.8±8.0	12.9±5.2	54.7+7.7
	(100)		(19)	(13)	(20)
Pigeon pea fresh leaves	25.1±1.9	56.5±7.3	-	-	63.8±2.7
	(30)	(23)	(3)

Note: () Number of samples analysed, - analysis not done.

Table 4. Food and forage output from a model farm on- station*.

Size	1/2 ha.
Food crops	Maize beans and sweet potato. Area taken 60%
Forage	Napier grass
Food production	1908 kg or 21 (90 kg) bags of maize 50 kg dry beans
	273 kg sweet potato tubers
Forage production	26 kg DM - fresh maize thinnings
	505 kg DM - fresh maize leaves
	5286 kg DM - sun-dried maize stover
	53 kg DM - bean haulms
	2526 kg DM - fresh Napier grass
	1303 kg DM - fresh forage - Leucaena
	80 kg DM - fresh sweet potato vines

* Two cropping seasons per year.

In summary, 75% of the unimmunised goats died when challenged by contact with CCPPinfected goats and none of the vaccinated goats died.

Heartwater

Heartwater is a severe infection of goats, sheep and cattle caused by rickettsia (Cowdria ruminantium). In goats, the disease causes a very high mortality and can be devastating in susceptible populations. Transmission is by ticks, primarily Ambloyomma variegatum, which are widely distributed in Kenya. Currently, diagnosis is made by post-mortem examination of brain tissue. A more convenient method of diagnosis is needed as well as a method of prevention.

A published method was used to grow C. ruminantium in vitro in bovine endothelial cells. Establishment of the tissue culture system at Kabete made available a renewable source of organisms. Larger quantities of organisms provided Deoxyribonucleic Acid (DNA), protein and infectious organisms for a variety of studies and represents an important advance in our research program on heartwater.

Endothelial cells were infected with Kiswani isolate of heartwater, made in Kenya. DNA purified from C. ruminantium organisms isolated from infected endothelial cells was used to make genomic library. Size-fractionated fragments were ligated into p^UC19 and used to transform Escherichia coli. Two cloned genes were identified that were from the heartwater organism and one of the genes p^cr9, a 744 base pair (bp) fragment has been characterised as DNA probe. Cloned C. ruminantium gene was isolated from plasmids, labelled with biotin and the specificity evaluated. The 744 bp insert from the recombinant plasmid p^cr9 hybridised to C. ruminantium-infected endothelial cell DNA. The 744 bp insert DNA probe did not hybridise to DNAs from uninfected endothelial cells, leukocytes, Babesia bigemina, Mycoplasma sp F38 Anaplasma marginale, A. ovis, A. centrale, Chlamydia psittacci, Chlamydia trachomatis, Ehrlichia risticii and 11 other bacteria. The 744 bp p^cr9 DNA probe detected C. ruminantium in Amblyomma variegatum ticks fed on C. ruminantium -infected goats but not in ticks fed on uninfected goats. Tick infection with C. ruminantium was confirmed by transmission of heartwater to uninfected goats either by feeding of nymphs fed as larva on infected goats or by subinoculation of tick gut homogenates. The p cr9 insert DNA probe detected C. ruminantium in midguts of A. variegatum nymphs infected as larvae and in midguts of A. variegatum adult ticks infected as nymphs but not in midguts from control nymphs and adults. Nucleic acid sequence of this p^cr9 insert DNA was determined for eventual development of oligonucleotide primers for use in polymerase chain reactions in order to increase sensitivity of assays using the DNA probe.

Haemonchosis

Research on haemonchosis focused on the identification of genetically resistant or tolerant goats as one long-term solution to control this important internal parasite. This research emphasis is based on the findings that several expensive treatments per year are required to prevent clinical disease and associated production losses. The assumption that genetically resistant or tolerant goats can be identified is based on the identification of a resistance trait in sheep and on our work that indicated susceptibility differences occurred among breeds of goats.

Natural Haemonchus contortus infection of 300 kids was evaluated from two months to one year of age. Faecal samples were collected from the rectum and parasite eggs per gram of faeces determined. During the observation period, some kids had very low or no eggs while others had high egg counts. To extend the observation of differences among individuals to natural infection, two groups of goats were selected for further study. Group A contained 11 goats which had a mean egg count of 201±200. The two groups were confined in pens, cleared of worm infection using Ivermectin and challenged with 500 H. contortus larvae per kg bodyweight. Faecal samples were collected once a week for eight weeks and eggs per gram determined. Group A goats had significantly (P <0.05) lower eggs per gram (mean 726±213) than group B (mean 1643±463). Also, individual goats in both groups had low numbers of eggs indicating resistance to the challenge infection. Some animals in group B had very high infection rates indicating that individual differences may be greater than group differences. This study emphasises the importance of experimental challenge to assess genetic resistance of goats to H. contortus and that individual differences in susceptibility occur among goats. Further studies are in progress to define more clearly the occurrence and basis for differences in susceptibility.

On-farm evaluation

As the name implies, on-farm evaluation calls for the researcher to take measurements onfarm and for interaction with the farmer, on the subject of the technology or intervention with regard to its biological and socio-economic aspects. In looking at the biological aspect, the on-farm performance of DPGs was compared with on-station over a period of two years. Results of the comparison are given in Table 5. Judging by these results, it is evident that the on-station DPGs are out-performing their counterparts on-farm. Causes leading to these differences give guidance for further investigations and trials. For example, the kidding rate on-station is 98% as opposed to 65% due to managerial rather than biological problems. Farmers are not fully conversant with heat detection and buck availability is limited to a few farms. This is not a researchable problem but one that requires education and more bucks.

Table 5. Comparison of on-station with on-farm performance of duel-purpose goats in western Kenya.

Variable	On-station	On-farm
Number of does	200	150
Doe survival	95	80
Kidding (%)	98	65
Kid survival (%)	90	85
Kid weight at the age of one year	20	18
Milk offtake (kg)	120	60
Average doe weighs (kg)	38	35
Productivity/doe/year (kg)	27	11
Productivity/metabolic body weight/year (kg)	1.8	0.8

What is the verdict of farmers collaborating in SR-CRSP on-farm research? So far, research findings indicate that SR-CRSP DPG technology packages (techpacks) have been most enthusiastically taken up in the relatively high altitude (1630 m), high rainfall (1800 mm) (Onim et al, 1986), and high population density (700-1000 per km²; Kenya, Republic, 1979) clusters of Muhanda and Hamisi. Conversely, the techpacks have been least enthusiastically taken up in the relatively low altitude (1300 m), low rainfall (1100 mm), and low population density (200-400 per km²) clusters of Masumbi and Lela. For example, both Muhanda and Hamisi have consistently maintained a high proportion of their participating farmers growing all the recommended forages as well as, on average, the highest number of forage trees and a substantial area devoted to production of Napier grass and sweet potato vines (Table 6). Masumbi cluster, and to a certain extent Lela cluster lag behind on both counts.

Table 6. Average number of Leucaena and Sesbania trees; and area under Napier grass and sweet potato vines (SPY) per household and the proportion of households growing them.

Cluster	Leucaena		Sesbania		SPV		Napier
	# trees	% households	# trees	% households	m2		m2	% households
Hamisi	22.2	81	56.4	74	195.3	98	231.6	94
Masumbi	18.4	37	27.8	25	54.6	39	74.9	60
Muhanda	51.4	98	55.9	99	238.4	98	153.2	96
Rabour	22.8	90	49.4	28	198.3	97	81.3	89
Lela	27.7	84	46.9	43	380.9	76	685.8	77

Similarly, both Muhanda and Hamisi clusters are noted to be most consistent in feeding the cultivated forages to the DPGs. By contrast, Masumbi farmers merely feed their DPGs with cuttings from growing on shrubs fallow land while Lela farmers prefer to "open graze" their DPGs rather than feed them with large amounts of cultivated forages in the cluster (Table 7).

Table 7. Proportion of participating farmers doing 'cut-and-carry" or "open-grazing" (%).

Cluster	N	Cut-and-carry	Open-grazing
Hamisi	21	70	10
Masumbi	14	54	16
Muhanda	34	100	0
Rabuor	27	69	24
Lela	10	46	73

Linear programming (LP), a procedure for determining efficient resource allocation which uses mathematical procedures consistent with economic concepts to determine optimal farm plans, showed the following based on the results from Table 7, with regards to DPG enterprise (Nyaribo, 1989):

· Dairy production generated higher net returns than food crop production. This makes sense since milk and meat are both high (cash) value commodities.

· The DPG's market potential is very good and can easily out-compete the local zebu cattle.

· As we move from the medium to the large farm, there is a modest 7 per cent increase in livestock sales, but a significant 31 per cent increase in net farm income. This means that with additional factors of production (capital, land and management) farmers can increase their incomes significantly through livestock sales.

It is interesting to note that there were no livestock sales in the small Hamisi farms (0.69 ha) of which only 0.59 ha was cultivable land while the LP model production is at variance with actual observed practices since it does imply that the smallest farms in the area keep livestock under non-optimal conditions for risk aversion reasons and other reasons not related to profitability. In fact, the small farms have been observed to be more attracted to the DPGs and its techpacks than larger farms that are more in commodity agriculture. It is anticipated, with increased production level of the DPGs and particularly, with milk production of over one kg per doe/day, the larger farms are likely to capitalise on it as they are currently doing with cash crops.

Despite these trends, on-farm research results indicate that DPGs contribute positively towards nutritional and economic welfare of participating farmers in western Kenya. From an average of two does a small supply of milk has been produced and used as a nutritious or medicinal drink, in making tea, and vegetable and fish sauces. Culled does and some of their followers have been slaughtered for home consumption, while others have been sold for cash to meet essential needs, for example, paying school or medical fees, buying clothes and farm inputs. In addition, DPG manure has increased productivity of crop land resulting in higher yields of maize and other crops.

Acknowledgements

We gratefully acknowledge material and financial support from Kenya Agricultural Research Institute (KARI) and the United States Agency for International Development (USAID) Grant No. DAN 1328-G-SS-4093-00 and technical assistance from collaborating scientists and farmers from western Kenya. We also express our sincere thanks to Ms. Philomena Pacha for word-processing the final draft.

References

Kenya, Republic. 1979. Population census. Volume II: Analytical report. Central Bureau of Statistics, Ministry of Finance and Planning, Nairobi, Kenya.

Mwandotto BAJ, Ahuya C O. Ruvuna Fand Taylor. 1990. Milk yield potential of the Kenya dualpurpose goat. In: Proceedings of the Eighth Small Ruminant CRSP Workshop, Nairobi, Kenya. Small Ruminant Collaborative Research Support Program, Nairobi, Kenya.

Nyaribo F B. 1989. Integrating dual-purpose goats on small scale farms in PTO western Kenya: A linear programming analysis PhD dissertation, Washington State University, Washington, USA.

Onim J F M, Mathuva M N. Hart R. Fitzhugh H A and Otieno K. 1986. Recommendation domains for dual purpose goat research in Nyanza and western provinces of Kenya. In: Proceedings of the Fifth Small Ruminant-CRSP Workshop, Nairobi, 4-6 November 1986. Small Ruminant Collaborative Research Support Program, Nairobi, Kenya.

Russo S. Hart R. Otieno K, Owino J and Onim J. 1983. Feed production research for smallholder agriculturalists in western Kenya. Paper presented at CIMMYT Networkshop on Draft Power and Livestock Feeding in Eastern and Southern Africa, 4 6 October 1983, Mbabane, Swaziland. 10 pp.