Perdidas Economicas Causadas Por Fasciolosis Ovina En Las Tierras Altas De Etiopia

Trop. Anita. Hlth Prod. (1993) 25, 155-161

F I N A N C I A L L O S S E S C A U S E D B Y O V I N E F A S C I O L O S I S IN T H E ETHIOPIAN HIGHLANDS P. K. NGATEGIZE,1 TEKELYE BEKELE 1'3 and GETACHEW TILAHUN2 t International Livestock Centrefor Africa ([LCA), PO Box 5689, Addis Ababa, Ethiopia; 21nstitute of Pathobiology, PO Box 1176, Addis Ababa, Ethiopia SUMMARY

An estimate of the economic loss due to ovine fasciolosis in the Ethiopian highlands was made based on available data on mortality, weight loss, reduced reproductive efficiency and liver condemnation at slaughter. The economic effects of fasciolosis were identified and models for estimating the financial loss presented. Ovine fasciolosis losses were estimated at 48"4 million Ethiopian Birr per year of which 46.5, 48.8 and 4"7% were due to mortality, productivity (weight loss and reproductive wastage) and liver condemnation, respectively. These losses can be reduced substantially by fasciolosis control programmes that may include the use of anthelmintics, grazing management and nutritional supplementation. INTRODUCTION

Small ruminant production in Ethiopia is constrained by a number of factors including nutrition, disease, government policies and socio-cultural values and attitudes (Gryseels, 1988). Economic losses resulting from mortality and morbidity (reduced meat, milk and wool production and reproductive inefficiency) impose serious limitations on small ruminant production. One of the major causes of sheep mortality and morbidity is fasciolosis (Njau et al., 1988a; ILCA, 1991). The direct impacts of Fasciola are liver lesions, reduction in feed utilisation efficiency, deprivation of the animal of digested nutrients, and reduced feed intake through loss of apperite and discomfort leading to reduced feeding time. The economic implications are, however, best assescd at the output and input levels. The effects include reduced growth rates, reduced production of meat, milk and wool, reduced reproductive efficiency and mortality. Reduced reproductive efficiency manifests itself through reduced pubertal development, extended lambing interval, reduced weight and number of weaned offspring per ewe and subsequent effect on the age and sex structure, and genetic improvement of the flock. Estimation of the economic loss due to fasciolosis at a national or regional level is, however, limited by lack of accurate estimates of the disease prevalence, complexity in disaggregating and quantifying the direct and indirect effects of the disease and lack of a common methodology for assessing the economic loss (Ogunrinade and Ogunrinadc, 1980; Fabiyi and Adeleye, 1982). The annual loss due to endoparasitism including fasciolosis in Ethiopia is estimated at 700 million Birr4 (Mulugeta et al., 1989). Decreased productivity alone (excluding mortality losses) due to bovine fasciolosis is estimated at 300 million Birr (Gemcchu and Marne, 1979). Despite the widespread concern about fasciolosis in sheep, no comprehensive estimates of the economic loss due to ovine fasciolosis have been made. Estimates of the economic loss due to the disease are useful for policy makers and researchers in 3Addresse~ for correspondence. 41-00 US$ = 2"07 Ethiopian Bin'.

155

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N G A T E G I Z E E T AL.

making decisions on resource allocations and in setting research priorities and direction. The objectives of this paper are to present a methodology for estimating economic losses and use it to estimate the financial losses at the output level due to ovine fasciolosis in the Ethiopian highlands. MATERJALS,METHODSA N D RESULTS

The study area

The Ethiopian highlands constitute 40% of the Ethiopian land mass of 1"2 million km 2. The area is at an altitude of 1,500 metres or more above sea level with average temperatures of below 20°C. Eighty-eight per cent of Ethiopia's 42 million people and 75% of the 23.4 million sheep (about 18 million) are found in this area (Gryseels, 1988). Most households own sheep which provide a source of income and security. Sheep are marketed mainly for social and religious festivals which occur regularly throughout the year. They are grazed in private and communal pastures, in stubble fields and are sometimes provided with supplements of straw, hay and/or grain during periods of feed scarcity. Fasciola infection mainly occurs after the rainy season (September to December) when sheep are grazed in the wet bottomlands (Scott and Goll, 1977). Clinical signs normally occur 12 or more weeks after infection coinciding with the period of least feed availability. Most deaths occur during the dry season (Jacinta, 1983). Data and analysis

Data on mortality, morbidity and liver condemnation were obtained from ongoing research on livestock performance in the highlands, and experimental results from Debre Berhan Research Station (ILCA, 1989). Secondary data sources were from discussions with experts living or working in the area. The morbidity rates of fasciolosis in the highlands are influenced by environmental conditions including, rainfall, temperature and biotopes which influence the parasite, intermediate and final host (Jacinta, 1983). Determination of morbidity rates is usually made using faecal samples, abattoir sampling of livers and/or necropsy. Prevalences of 60 to 70% in sheep and 61% in cattle were reported by Graber (1975) and Gemechu and Mamo (1979) respectively, for 8 provinces of Ethiopia. Tilahun (1987) reported a prevalence of 51% based on detection of Fasciola in livers of sheep slaughtered at the Addis Ababa abbatoir over a period of one year. A study conducted in the Debre Berhan and Ambo areas in the Ethiopian highlands in 1988 and 1989 reported a prevalence of 52-4% based on faecal egg counts of one or more eggs per gram, with a clinical infection rate of 18"2% based on faecal egg counts of 200 eggs or more per gram. The financial losses due to fasciolosis were assessed under 3 categories; mortality, productivity loss (weight loss and reproductive inefficiency) and liver condemnation. Mortality loss Mortality is defined as death of the animal leading to total loss. A sick animal may be slaughtered and the skin and some of the meat salvaged. However, an animal that dies naturally is normally buried or thrown away for scavengers. Sheep mortality due to fasciolosis is most common in adult sheep of about 17 months of age with a range of between 6 and 50 months (Njau et al., 1988a,b). Field studies reported total sheep mortality rates of 13 to 18% (an average of 15-5% giving an annual survival rate of 84-5 %). Fasciolosis is estimated to cause 40 to 70% of the total sheep mortality in the

FINANCIAL LOSSES CAUSED BY OVINE FASCIOLOSIS IN ETHIOPIA

157

Table I

Estimation of mortality loss 3

ML = )~ SP x PSDF x PSSi x AWGTIx P iz3 Where:

ML SP PSDF PSS AGWT i P

= ffi = -= -ffi

M o r t a l i t y loss Sheep p o p u l a t i o n i n m i l l i o n s P r o p o r t i o n o f sheep d y i n g due to faseiolosis P r o p o r t i o n o f d e a d sheep t h a t are o f sex i A v e r a g e w e i g h t o f sheep o f sex i in k g 1 ffi females, 2 -~ r a m s , 3 -- wethers Price o f sheep p e r k g liveweight (Birr)

M L in females = 18 x 0"029 x 0-748 x 20 x 2-26 = 17-7million Birr M L in r a m s = 18 x 0-029 x 0.224 x 14 x 2.26 = 3.7 million Birr M L in wethers ffi 18 x 0"029 x 0-028 x 34 x 2.26 = 1.1 million Birr T o t a l = 22.5 million Birr

highlands (Njau et al., 1988a; Gryseels, 1988). However, these estimates have been disputed; ILCA (1991) reported that fasciolosis accounted for an average of 19% of the 15-5% total mortality. Thus, a mortality rate of 2.9% (19% of the total 15-5% mortality rate) can be attributed to fasciolosis. This rate was used in estimating the mortality due to fasciolosis based on flock sex structure of 74-8% females, most of which were milk-tooth lambs with an average weight of 20 kg liveweight, 22.45% entire males, also mostly milk-tooth rams weighing about 14 kg liveweight, and 2.8% mature castrates weighing about 34 kg (Agyemang et aL, 1985). The average market price for sheep was 2-26 Birr per kg liveweight at Debre Berhan market in 1989 (Andargachew, 1990). The model used to estimate the mortality loss based on flock sex structure is shown in Table I. Productivity loss This includes losses in body weight and reproductive wastage. Research results from many parts of the world have demonstrated weight losses in sheep resulting from endoparasitism. Loss of up to 4.2kg (Mamo et al., 1982), 5.2kg (Mukhebi et aL, 1985) and 2kg (Muenstermann and Tome, 1989) liveweight per sheep have been attributed to endoparasitism including fasciolosis. These differences are not adjusted for breed, type of parasite and nutritional differences. Hamminga (1989) attributed weight loss of 0-6 kg to fasciolosis in Ethiopian highland sheep when comparing performance of treated and untreated lambs from weaning to 10 months of age at Debre Berhan. These lambs attained a mean liveweight of 11 kg. Thus, using a weighted average liveweight of 19 kg based on Agyemang's (1985) data and assuming a proportional weight loss, fasciolosis is estimated to cause a weight loss of l'0kg (0-6/11 x 19) per infected sheep. Fasciolosis was more prevalent in females (53.2%) than in males (42-9%) and in adults (53.0%) than in young sheep (42"6%) in December, 1989 (Bekele et aL, 1992). Reproductive wastage is assessed through reduced weaning rate and reduced weight at weaning. Reduction in weaning rate results from reduced lambing rate and higher mortality rate, while low weaning weight is caused by a combination of low birth weight and poor mothering ability of the ewe. Studies conducted at

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NGATEGIZE ET AL. Table II

Estimation of productivity loss 1.

Weight loss in adults VWL = S P × A S R x P I S x W L x P ~= 18 x 0.845 x 0-524 x 1 x 2.26 -- 18.0million Birr

2.

Weaning rate loss L R W R ~- SP x ASR x PIS × PFBF × PRWR x A W W x P = 18 x 0.845 x 0-532 x 0.52 × 0.033 x $ x 2.26 -- 2-5 million Birr

3.

Weaning weight loss L R W W = SP x ASR x PIS x PFBF x A W R T x R W W N x P = 18 x 0-845 x 0-426 x 0.52 x 0-67 x 0.6 x 2.26 = 3.1 million Birr

4.

Total productivity loss = 23-6 million Birr

Where: ASR = Annual survival rate A W R T = Average weaning rate AWW=

Average weight at weaning

L R W R = Loss due to reduced weaning rate L R W W = Loss due to reduced weaning weight P = Price of sheep/kg liveweight

(sift)

PFBF = Proportion of sheep that are breeding females

PIS ffi Proportion of infected sheep P R W R = Percentage reduction in weaning rate PSBF = Proportion of sheep that are breeding females RWW'N ffi Reduced weight at weaning SP = Sheep population in millions VWL = Monetary value of loss due to reduced weight WL = Weight loss per infected sheep in kg

ILCA have shown that weaning rates and weights can be increased by using anthelminities to control endoparasites. Weaning rate and average weight at weaning were 67% and 8 kg liveweight for non-treated animals, and 78% and 10kg for animals treated to control most endoparasites including Fasciola (Zere, unpub, data). Since there is no available data, it is assumed that fasciolosis is probably responsible for 30% of the endoparasite effect in the reduction of weaning rates and body weights in this analysis. Thus a 3.3% ((0.78-0.67) x 0.30) and 0-6kg ((10-8) x 0"30) reduction in weaning rate and weaning weight respectively, were attributed to fasciolosis. The weight loss in adult sheep and losses due to reproductive wastage attributed to faseiolosis are computed using models in Table II. Milk and wool losses are not included in the analysis. Milk is not extracted for human use and the dam's production level is reflected in reduced number and weight of weaned offspring. The majority of Ethiopian highland sheep are not important wool producers; Kassahun (1985) estimated a production level of 0-5kg of wool/ annum/animal. Liver condemnation at slaughter Fasciola infected livers are damaged and not palatable and so most livers are condemned at slaughter causing monetary losses to the owners. Tilahun (1987) found a

FINANCIAL LOSSES CAUSED BY OVINE FASCIOLOSIS IN ETHIOPIA

159

Table I I I

Estimation of liver condemnation loss LLC

==

SP x A S R x O F R x LCR x LP 18 x 0-845 x 0-3 x 0-51 x 1"0 = 2.3 million Birr

Where:

LLC

=~

Liver loss due to condemnation

=

Annual survival rate

S h ~ p population in millions

SP= ASR

OFR

=

LCR = LP=

Off~akerate (%) Liver condemnation rate Price per ovinefiver (Birr)

prevalence of 51% in an abattoir study covering one year in Addis Ababa. No report was made on the rate of condemnation. A one week preliminary study, conducted in May 1990 by the authors, revealed that 66.2% of the livers were condemned at the same abbattoir. In all cases ovine liver condemnation is total. In this analysis, an offtake rate of 30% (Kassahun, 1985), a 51% condemnation rate and a market price of one Birr/sheep liver (Tilahun, 1987) are used to estimate the value of condemned livers in the highlands (Table III). Total financial losses Total financial losses due to mort~/lity, low productivity and liver condemnation were 48.4 million Bin" (Tables I to III). DISCUSSION

The models used by Ogunrinade and Ogunrinade (1980) and Fabiyi and Adeleye (I 982) for bovine fasciolosis were modified for estimating the loss due to ovine fascioIosis. The total estimated loss due to fasciolosis amounted to 48.4 million Bin" per year. Losses due to mortality and productivity constitute 46-5 and 48.8%, respectively of the total loss. These losses can be reduced substantially by fasciolosis control programmes that may include the use of anthelmintics, grazing management and nutritional supplementation (Berry and Dargie, 1976). Rafoxanide (MSD, AgVet, Merck and Co.) one of the commonly used anthelminitics to control Fasciola is administered at the rate of 5.5 ml per adult sheep 3 times a year. At current prices, this costs 0"136 cents/sh~p/treatment (0.41 cents/sheep/year). For the 18 million sheep, a total cost of 7.38 million Bin. would be required for drug costs alone. Since the infrastructure already exists in the highlands and labour costs are generally low, this implies that the returns from antbelmintic use to control fasciolosis are potentially high. Returns from endoparasitic control including fasciolosis using anthelmintics in the Ethiopian highlands have been estimated to be as high as 215%, and nutritional supplementation has the additional effect of reducing endoparasitism (Ngategize et al., 1990). Control of fasciolosis is justified based on the results from this study. However, for more accurate estimates of the loss further research needs to be conducted, especially on the effects of fasciolosis on reproductive efficiency. Other research areas that require further attention include the evaluation of anthelmintic usage in relation to treatment regimes, resistance and toxicity, and the evaluation of highland breeds

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for their vulnerability to Fasciola and its effects. Estimation of the economic loss due to other endoparasitic diseases is also necessary in order to establish their relative importance and for policy makers and researchers to allocate resources accordingly. ACKNOWLEDGEMENTS

The authors thank the staffat the Addis Ababa abattoir for providing some of the data and the management of I L C A for permission to publish the paper. Accepted for publication June 1992 REFERENCES AGYEMANG,K., NI~U~IF., A., VOORTHUIZEN.A. • ANDERSON.F. M. (1985). A report on a production survey of farmers' sheep flocks in Debre Berhan area of the Ethiopian highlands. Highland Programme Working Paper, ILCA, Addis Ababa, Ethiopia. ArOARGACH~W.K. (1990). Sheep Marketing in the Central Highlands of Ethiopia. Unpublished MSc. Thesis. Alemaya University of Agriculture, Alemaya, Ethiopia. BEKEt~ T., KAnt.t, O. B. & WOt~EMARtAM.W. (1992). Endoparasite prevalence of the highland sheep in Ethiopia. Preventive Veterinary Medicine, 13, 93-102. BARRY,C. I. & DAROm.J. D. (1976). The role of host nutrition in the pathogenesis of ovine fasioliasis. Veterinary Parasitology, 2, 317-332. FAeIYt, J. P. & ADELEY~,G. A. (1982). Bovine fascioliasis on the Jos Plateau, Northern Nigeria with particular reference to economic importance. Bulletin of Animal Health and Production in Africa, 30, 41-43. G~ECHU, B. & MAMO.E. (1979). A preliminary survey of bovine fascioliasis in Ethiopia. Ethiopian Journal of Agricultural Sciences, 1, 5-12. Gm~sE~. M. (1975). Helminths and helminthlasis of different domestic and wild animals of Ethiopia. Bulletin of Animal Health and Production in Africa, 23, 57-86. GR'CSEELS,G. (1988). Role of Livestock on Mixed Smallholder Farms in the Ethiopian Highlands: A Case Study from the Base and Worena Wereda near Debre Berhan. PhD dissertation, Agricultural University, Wageningen, The Netherlands. HAMMKNQA.B. J. (1989). The effect of nematode and trematode infections in the growth performance of Ethiopian highland sheep. ILCA, Addis Ababa. Ethiopia. ILCA (International Livestock Centre for Africa) (1989). ILCA Annual Report 1988. Addis Ababa, Ethiopia. ILCA (International Livestock Centre for Africa) (1991). ILCA Annual Report 1990. Addis Ababa, Ethiopia. Jsc~-rrA, E. (1983). Investigations on Fascioliasis in the Ethiopian Highlands around Debre Berhan. MSc Thesis. Institute of Tropical Medicine and Parasitology, Leiden University, The Netherlands. pp 129. KASSAHUS,A. (1985). The status of sheep and goat research in Ethiopia. Institute of Agricultural Research, Addis Ababa, Ethiopia. MAMO,B., SmnRu, T. & FmSE~'.A,G. (1982). Survey of gastro-intestinal helminths in sheep slaughtered at Addis Ababa abattoir. Ethiopian Journal of Agricultural Sciences, 4, 87-93. MUKHEB[,A. W., SHAVULIMO,R. S., RVVVNA,F. & RURANOmWA,F. (1985). Economics of internal parasitic control among goats in Western Kenya. Paper Presented at the Fourth Small Ruminant Collaboration Research Programme Kenya Workshop. March 11 and 12 1985, Kenya. MULUGFrA,H. S., Gzr^cHEw, T., TAF~SS~M., G~rACHEW,W. M., KrsFE, G. & T~SOME, Y. (1989). The significance of helminth parasites in fivestock production. Paper presented at the Third Livestock Improvement Conference held in Addis Ababa, Ethiopia. 24 to 26 May. MUENS'mRMAtrN,S. & TOME,N. R. (1989). Influence of regular tick and heiminth control on productivity of small ruminants in the Lolgorien area, Narok district, Kenya. Tropical Animal Health and Production, 21, 247-255. NGATEOIZ~P. K., ZERE,A z ~ & BROKgY.N.R.F. (1990). Economics of endoparasitic control and nutritioual supplementation in the Ethiopian highlands. Paper presented at the Eighth Small Ruminant Collaboration Research Support Programme Scientific Workshop, ILRAD, Nairobi, 7 to 8 March 1990. NJAU, B. C., KASALI,O. B., SCHOLTENS,R. G. & MF~FIN,D. (1988a). Review of sheep mortality in the Ethiopian highlands, 1982-1986. ILCA Bulletin, Addis Ababa, Ethiopia. 31, 19-22.

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NSAU,B. C., KASALI,O. B., SCHOLTENS,R. G. & MF_2$FIN,D. (1988b). Field and laboratory studies ofcauses of sheep mortality in the Ethiopian highlands 1986/1987. ILCA Bulletin, Addis Ababa, Ethiopia. 31, 23-26. O G ~ ^ V E . A. & O¢3t~Rru^v~B. I. (1980). Economic importance of bovine fascioliasisin Nigeria. Tropical Animal Health and Production, 12, 155-160. SCOTT,I. M. & GOLL,P. H. (1977). The epidemiologyand anthelmintic control of ovine fascioliasisin the Ethiopian central highlands. British Veterinary Journal, 133, 273-280. TXLAHUN,(3. (1987). A surveyof fascioliasisin cattle, sheep and goats slaughtered at Addis Ababa Abattoir, Ethiopia. Institute of Pathobiology (IPB) Research Report No. 3, Addis Ababa, Ethiopia. pp 10-11. PERTES FINANCIERES CAUSEES PAR LA FASCIOLOSE CHEZ LES OVINS DANS LES HIGHLANDS D'ETHIOPIE R~Une estimation de la perte ~conomiquedue ~ la fascioloseovine dans los Highlands ,d'Ethiopiea 6t6 faite sur la base de donn~esdisponibles sur la mortalitY,la pert(: de poids, la r~duction de l'oflicacit~de reproduction et la saisiede roles Al'abattage. Les ¢ffets ~onomiques de la fascioloseont ~tc identifl~set dos modSles pour l'estimation des penes finauci~'es ont ~t~ pr~sent~s. Los penes dues ~ la fascioloseovinoont ~t~estim~es~ 48,4 millionsde Birrs ~thiopionspar an, dont 46,5, 48,8 et 4,7 p. 100 ~taient dns r,spcctiveracnt Ala mortalitY, la productivit6 (la porto de poids et la porto de reproduction) et ~ la saisic de foies. Los pertes peuvent ~tre reduites do faqon substanfieUc~ l'aide do programmes de luttc contr¢ la faseiolose pouvant iuclurc Futilisation d'anthclminthiques, la gestion dos pfiturage et une compl6mvntation alimcntairc. PERDIDAS ECONOMICAS CAUSADAS POR FASCIOLOSIS OVINA EN LAS TIERRAS ALTAS DE ETIOPIA Rammm-Se llcvo a cabo un c~culo de las p~rdidas economicas causadas por fasciolosis en la tierras altas de Etiopia, basado en informa¢i6n sobre mortalidad, pcrdidas de peso, reducci6n de la eficacia reproduetoray decomisosde lfigadoson el matadero. So identificaron los efectos econ6micos de la enfermedad, present~ndosc modelos para estimar dichas perdidas econ6micas. Las l~rdidas por fasciolosis ovina fueron estimadas en 48.4 millonesdo Birr/ano, des los euales 46.5, 48-8 y 4-7% se debieron a mortalidad, productividad (p~rdidasdo peso e inoficaciareproductora) y decomisode higados, respectivamente.Estas pfirdidas pueden redu¢irse sustancialmenteinsraurando programas de control con antiholminticos, manejo de praderas y suplementaci6n nutricional.

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