THE EFFECT OF STRATEGIC ANTHELMINTIC TREATMENT ON THE BREEDING PERFORMANCE AND SURVIVAL OF EWES

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1 THE EFFECT OF STRATEGIC ANTHELMINTIC TREATMENT ON THE BREEDING PERFORMANCE AND SURVIVAL OF EWES NATURALLY INFECTED WITH GASTRO-INTESTINAL STRONGYLES AND PROTOSTRONGYLIDS V.S. Pandey, J. Cabaret, A. Fikri To cite this version: V.S. Pandey, J. Cabaret, A. Fikri. THE EFFECT OF STRATEGIC ANTHELMINTIC TREATMENT ON THE BREEDING PERFORMANCE AND SURVIVAL OF EWES NATURALLY INFECTED WITH GASTRO-INTESTINAL STRONGYLES AND PROTO- STRONGYLIDS. Annales de Recherches Vétérinaires, INRA Editions, 1984, 15 (4), pp <hal > HAL Id: hal Submitted on 1 Jan 1984 HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

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3 THE EFFECT OF STRATEGIC ANTHELMINTIC TREATMENT ON THE BREEDING PERFORMANCE AND SURVIVAL OF EWES NATURALLY INFECTED WITH GASTRO-INTESTINAL STRONGYLES AND PROTOSTRONGYLIDS V.S. PANDEY J. 2CABARET A. 3FIKRI 1 : Institut Agronomique et Vétérinaire Hassan Il, BP 704 Rabat-Agdal, Morocco 2: //VRA, Station de Pathologie Aviaire et de Parasitologie, Unité d Écologie Parasitaire, Monnaie, France 3: Service de l Élevage, Ministry of Agriculture, Rabat, Morocco Résumé EFFET DES TRAITEMENTS ANTHELMINTHIQUES STRATÉGIQUES SUR LES PERFORMANCES DE REPRODUCTION ET LA SURVIE DES BREBIS INFESTÉES NATURELLEMENT PAR DES STRONGLES GASTRO-INTESTINAUX ET DES PROTOSTRONGLES. &horbar; Au cours de deux essais, des lots de brebis infestées naturellement par des strongles gastro-intestinaux et des protostrongles (petits strongles pulmonaires) ont été traités avec du fenbendazole (10 mg/kg de poids vif) et du tartrate de Morantel (8 mg/kg poids vif) à des périodes stratégiques. Lors du premier essai, des traitements au fenbendazole au cours du milieu de la gestation ou en début de lactation réduisent le taux d avortement, le nombre de mort-nés, la mortalité des brebis et de leurs agneaux. Dans un second essai des lots de brebis ont été traités soit avec du fenbendazole soit avec du tartrate de Morantel ou une combinaison des deux produits aux périodes stratégiques. Dans tous les lots traités des réductions de mortalité des brebis et de leurs agneaux sont enregistrées; ces réductions varient selon le calendrier de traitement et la nature de l anthelminthique. La surmortalité en liaison avec le parasitisme est de 3,62 % chez les brebis et de 13,8 % chez les agneaux. Les protostrongles et les strongles gastro-intestinaux jouent un rôle équivalent chez les premières; l infestation des brebis par les protostongles paraît être le facteur principal de la surmortalité induite indirectement par les parasites chez les agneaux. La réduction de l élimination des oeufs de strongles ou de larves de protostrongles a suivi une évolution semblable à celles des performances de reproduction ou des taux de mortalité des animaux. Gastro-intestinal and respiratory (Protostrongylids) nematode infections of sheep are widespread and are one of the most important causes of mortality and morbidity with consequent loss in production (Pandey et al., 1980). Although much emphasis is laid on the treatment of these infections, few field trials are reported concerning the effect of anthelmintic treatment of ewes upon their breeding performance (Lewis, 1975; Baines a: Present address: University of Brussels, Brussels, Belgium Reprints should be requested from J. Cabaret and Colegrave, 1977; Morris et al&dquo; 1977; Mackay, 1980). In the Rabat region of Morocco, where work was undertaken, Ostertagia spp. and Trichostron,gylus spp. are the dominant digestive parasites (Pandey et al., 1980). The small lungworms (protostrongylids) are represented by Muellerius capillaris and Neostrongylus linearis (Cabaret et al., 1980a). The aim of work being undertaken at present is to assess the effect of positive treatment of ewes on their breeding performance and mortality, under field conditions. A tentative estimation of

4 - the - the - First - Second the respective influence of digestive strongyle and protostrongylids on these parameters will be attempted. Materials and Methods The farm where the trials are being undertaken is situated 30 km from Rabat (Morocco), where there is a Mediterranean climate characterized by a period of hot dry weather (May to September) and a cold rainy period (October to April). The average annual rainfall is 500 mm, the mean maximum temperature of the hottest month (generally August) is 28 C and the coldest month (generally January) 7 C. Farm management Six flocks of approximately 1 50 ewes of local race were put out to graze, for one year, on permanent pastures of about 1000 hectares. Each flock was tended by a separate shepherd. The individuality of each flock as an entity was reduced for the following reasons: various areas of pastures and the order of their utilization by each flock were not defined for each shepherd; animals were all taken out into the field together and all brought back together; food supplement, when given, was standard. Prior to the trials, parasitism, as assessed by the output of eggs of gastro-intestinal strongyles and larvae of Protostrongylids was similar in all the flocks. There were no apparent differences between them when the number of lambs produced was counted. The rams run with the ewes from mid-july to mid- September. Lambing started in mid-december and the majority of ewes lambed in January. The lambs were kept indoors for the first two weeks after birth and thereafter ran with the ewes until weaned at the beginning of May. All the animals were vaccinated against sheep pox and enterotoxaemia. Parameters The output of eggs and larvae was estimated each month from the examination of the faeces of 25 eartagged ewes in each flock. Strongyle egg counts were performed by the Mc Master method and the output of lungworm larvae by the technique described by Cabaret et al. (1980b). The following parameters were taken into account for the analysis of breeding performance: 1. Apparent fertility rate (number of ewes of reproductive age which conceive in a flock of 100ewesl; 2. Fecundity rate (number of lambs born per 100 ewes of reproductive agel; 3. Prolificity rate (number of lambs born per t001ambings); 4. Miscarriage; 5. Still-born lambs; 6. Mortality of lambs. Experimental designs trial ( ) It concerned two flocks of 156 and 157 breeding ewes and extended from October 1978 to June One flock was treated with fenbendazole at the dose rate of 10 mg/kg body weight and the second flock was kept as untreated control. The first treatment was given when the ewes were approximately 3 months pregnant (end of October) and the second one just after the end of lambing (end of January). The control flock received a placebo at the same time as the first one. As the treatment is effective on both small lungworms and digestive strongyles (Dakkak et al., 1979a; Cabaret et al., 1979) the aim was to determine the influence of polyparasitism on the breeding performance of ewes and survival of lambs. trial ) Six flocks were used in this trial. They were treated with fenbendazole (10 mg/kg body weight) and morantel tartrate (8 mg/kg body weight) according to the schedule presented in table 1. The two different anthelmintics were used with the intention of making a tentative estimation of the influence of protostrongylid lungworms, as morantel tartrate is effective only against digestive strongyles (Dakkak et al., 1979b) and fenbendazole againts both digestive and respiratory worms.

5 Results First trial The parasitological results are presented elsewhere (Pandey et al., No significant difference was observed in the strongyle egg output of ewes; on the contrary the protostrongylid larvae were significantly reduced (80 % reduction) during the period of trial. The elimination of strongyle eggs was significantly lower among the offspring of treated ewes. The results of the breeding performance of ewes are presented in table 2. The apparent fertility rate and fecundity rate were higher for the treated animals; no significant difference was observed in the prolificity rate. Miscarriages and still-birth rates were lower among treated animals. The mortality rate of lambs was significantly reduced, particularly during their first month of life. A lower mortality was observed among the treated ewes. Second trial The parasitological results are presented in table 3. The analysis of variance on monthly values of egg and larval output showed that the following groupings could be established: Digestive strongyle eggs: Protostrongylids: i The death rates of ewes and lambs were significantly reduced among the treated flocks. The details of the findings are presented in table 4. The following regressions (2 arc sin!ransformation) account for the results:

6 where M : mortality rate DS : percentage of reduction of the output of strongyle eggs in faeces among ewes during the period of study. P: percentage of reduction of the output of Protostrongylid larvae in faeces among ewes. The calculated results for mortality (batches 1 to 6) are 4.8, 3.3, 3.1, 2.6, 3.3, 1.6 for ewes and 4.4, 11.9, 7.1, 9.2, 12.0, 15.3 for lambs. Discussion The anthelmintic treatment of ewes during gestation and early lactation reduced the rate of miscarriages, still-births and the mortality of lambs, thus giving a better rearing percentage. These results are in agreement with those of Marinov and Fassi-Fehri (1974), Lewis (1975), Baines and Colegrave (1977) and Mackay (1980). The increase in fecundity rate is mostly due to the reduced death of foetus during intra-uterine life and is not related to an increase in prolificity (table 2). The mortality rate of ewes was reduced as also observed previously by Marinov and Fassi- Fehri (1974). The better survival of lambs born of treated ewes was also demonstrated with some other anthelmintic treatments (Baines and Colegrave, 1977 ; Schmidt et al., 1979). This was not associated with better weight gain which agrees with the opinion of Anderson et al. (1976) that severe parasitism induces differences in mortality but not in the productivity of the survivors of treated groups. The better survival of lambs born of treated ewes could be related to better food utilisation of ewes during the last months of pregnancy and to higher milk production : the different treatments in the second trial also demonstrated a reduction of the death rate of ewes and their offspring. It should be noticed that the mortality of lambs born of ewes of the untreated control group varies very much from one year to another: I 5.80 to % (tables 2 and 4). The first trial does therefore represent a year with low natural mortality and the second with a high natural mortality. The variations between years are much more important than those between flocks; this suggests that they could be related either to climatic conditions and subsequently to poor feeding and increased parasitism, or to the large spreading of infectious diseases owing to poor hygiene and lack of treatment. The polyparasitism thus implies a reduction of breeding performances of ewes. The obtained results suggest that there is a direct influence on ewes and an indirect influence on lambs, even when untreated, as their mortality rate is related to the infection of the ewes. This aspect is new as other trials were estimating the effect of treatments of ewes on their barrenness or on the survival of lambs which were treated afterwards. The indirect influence on lambs might be related to a probable increase in milk production by the ewes and thus to improved growth and resistance in lambs. This is supported by the fact that there is a marked reduction in the mortality: in lambing mortality during the first two months after birth which continues until the lambs are five months old (table 2). The influence of treatment of the ewes on lambs could hardly be related to a smaller input of infective larvae as they all grazed similarly infected pastures. In Mediterranean countries, such as Morocco, where small lungworms represent an important part in sheep pathology, it is of interest to assess, under field conditions, their influence on the mortality of sheep. No data are available; this could be explained by the fact that effective anthelmintics on these nematodes were available only in recent years. It should also be remembered that two possibilities occur: anthelmintics effective against digestive strongyles or anthelmintics effective against both parasites. Thus the effect of Protostrongylids can be assessed only by differences between the results of different batches of ewes. The examination of the regression formulas shows that over mortality related to the worm burdens of ewes (estimated by egg or larval output) is equally due to Protostrongylids and gastro-intestinal strongyles among ewes; on the contrary, lamb over-mortality is related to the sole Protostrongylids infection of the ewes. This implies that the latter, at least in Moroccan conditions, are of importance, in agreement with the results of Schmidt et al. (1979) in bighorn-sheep. The influence on the offspring could be partly rela-

7 ted to the existence of intra-uterine transmission of the disease (Azimov and Kulmamatov, 1977; Hibler et al., 1974). Very few larvae were excreted by the lambs; this is due to the long duration of internal life-cycle within lambs, during the period of study (Cabaret, 1981). Thus larval output was of no use for monitoring their infection. It should also be kept in mind that the over-mortalities thus determined do not mean that only wormburdens are causal ; these mortalities could be due either to the presence of parasite or to its association with another pathologic etiology. It could be concluded that two treatments, effective against both parasitism, one at mating and the other during the last month of pregnancy, are valuable. The interest of such treatment during lactation is still open. Accepted for publication, 1 si February Summary In two trials, batches of ewes naturally infected with gastro-intestinal strongyles and protostrongylids (small lungworms) were treated with fenbendazole (10 mg/kg body weight) and morantel tartrate (8 mg/kg body weight) at strategic periods. In the first trial, treatment with fenbendazole during midgestation and early lactation, reduced miscarriages, stillbirths, mortality of ewes and their offspring, In the second trial, batches of ewes were treated either with fenbendazole or with morantel tartrate or a combination of both at different strategic periods, In all the treated groups there were reductions in the mortality of ewes and their offspring which varied according to the regime of treatment and the nature of the anthelmintic used. The excessive mortality related to the presence of these parasites was 3.62 % in ewes and 13.8 in lambs. For the former, Protostrongylids and gastro-intestinal strongyles played an equal role; Protostrongylids of ewes were the main cause of worm-induced mortality for the latter. The reduction in the output of strongyle eggs and lungworm larvae paralleled the breeding performance and mortality rate of animals. References ANDERSON N., MORRIS R.S., McTAGGART I.K., An economic analysis of two schemes for the anthelmintic control of Helminthiasis in weaned lambs. Aust. Vet. J., 52, AZIMOV D.A., KULMAMATOV E.N., Biology of Protostrongylids. Bull. Vses. Inst. Gelm. l.l. Skrjabin, 21, 5-6. BAINES D.M., COLEGRAVE A.J., Field trials in sheep with the anthelmintic thiophanate. Vet. Rec., 100, CABARET J., Receptivitrs des Mollusques terrestres de la région de Rabat I / infestation par les Protostrongles dans les conditions expérimentales et naturelles. These Docteur 6s Sciences, Paris, 214 p. CABARET J., OUHELLI H., DAKKAK A., Efficacit6 compar6e du fenbendazole et du t6tramisole sur les Helminthes parasites du mouton au Maroc. II. Helminthes du tube digestif. Recl Med. Vet., 155, CABARET J., DAKKAK A., BAHAIDA B., 1980a. On some factors influencing the output of the larvae of Protostrongylids of sheep in natural conditions. Vet. Q, 2, CABARET J., DAKKAK A., BAHAIDA B., 1980b. A technic of the evaluation of the number of Protostrongylid firststage larvae in sheep faeces. Br. Vet. J., 136, DAKKAK A., CABARET J., OUHELLI H., 1979a. Efficacit 6 comparce du fenbendazole et du t6tramisole sur les helminthes du mouton au Maroc. I. Protostrongylid6s et Dictyocaulus filaria. Recl Med. Vet., 155, DAKKAK A., CABARET J., OUHELLI H., 1979b. lnt6r&t zootechnique et épidémiologique des traitements anthelminthiques des agneaux de boucherie par le tartrate de morantel dans les conditions de I elevage marocain. Maroc V6 t., 2, HIBLER C.P., METZGER C.O., SPRAKER T.R., LANGE R.E., Further observations on Protostrongylus sp. infection by transplacental transmission in bighorn sheep. J. Wildl. Dis., 10, LEWIS K.H.C., Ewe fertility response to pre-mating anthelmintic drenching. N.Z. J. Exp. Agric., 3, MACKAY R.R., The effect of strategic anthelmintic treatment on the breeding performances of hill ewes. Vet. Parasito/., 7, MARINOV A., FASSI-FEHRI M., Lutte contre les strongyloses des ovins avec le thiabendazole. Étude de rentabilité dans les conditions maghr6bines. Recl MEd. V!t., 150, MORRIS R.S., ANDERSON N., McTAGGART I.K., An economic analysis of two schemes for the control of Helminthiasis in breeding ewes. Vet. Parasitol, 3,

8 PANDEY V.S., CABARET J., DAKKAK A., Effect of treating ewes with fenbendazole during pregnancy and lactation in a Mediterranean climate. Vet. Rec., 109, 15. PANDEY V.S., CABARET J., FIKRI A., Effect of anthelmintic treatment of ewes on the mortality rate of ewes and their offsprings, Proceedings 10 Int. Cong. Trop. Med. Malaria. Manila, 159. PANDEY V.S., CABARET J., OUHELLI H. DAKKAK A., Étude des Nématodes parasites du tube digestif des Ovins adultes dans deux regions du Maroc. Bull. Off. Int. Epizoot., 92, SCHMIDT R.L., HIBLER C.P., SPRAKER T.R., RUTHERFORD W.H., An evaluation of drug treatment for lungworm in bighorn sheep. J. Wildl. Manage., 43,