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A survey of dairy cattle worm control practices in Southeast Brazil
veterinary _
par~tology ELSEVIER
Veterinary Parasitology 65 (1996) 65-73
A survey of dairy cattle worm control practices in Southeast Brazil T.P. Charles *, J. Furlong EMBRAPA, Centro Nacional de Pesquisa de Gado de Leite, Rodovia MG 133, km 42, Coronel Pacheco MG 36155-000, Brazil
Received 8 August 1995; accepted 28 December 1995
Abstract
A survey on the nematode control strategies utilized by dairy farmers in Southeastern Brazil, a region accounting for 46.4% of the national milk production, was conducted through interviews with farmers. To select the producers to be interviewed, the region was split into 16 non-contiguous clusters, according to the level of milk production. A systematic sample was then selected in each of the clusters. The interview questionnaire consisted of one-way, multiple-choice and open-ended questions. Data collected were represented by numbers and digitized on a data base (Epi Info, version 5.01b) and analyzed. Out of the 89 farmers interviewed, 37.5% deworm their herd after clinical signs and 62.5% preventively. Generally, anthelmintics are applied from one to 12 times a year (average of 3.79 times a year) in all age categories of animals. Of the anthelmintics used in the last deworming, imidazothiazole was used exclusively by 17.1% of the farmers, benzimidazole by 9.8% and avermectin by 18.3%, while 55.8% used more than one anthelmintic class to deworm their animals. To choose the dosage, most farmers consult the product label (94.8%) and determine the volume to be applied, based on an estimate of the average body weight of each animal (62.9%). Improvements in the general appearance of the herd and weight gains of growing animals were observed by most farmers after deworming (87.3%). However, most of them (66.2%) recalled interrupting the use of some compound in the last few years, due to the detection of no improvement following treatment (32.7%), rising costs of the medication (28.6%), adverse reaction (8.2%), product not being available at the time of purchase (4.1%) and decision to change the compound in use (10.2%). Most farmers (95.3%) intend to continue using the same control measures in the following year. Veterinarians play an important role in the farmer's choice to deworm their animals, as many seek advice from them. Therefore,
* Corresponding author. Tel/Fax: + 55-32-215-8550. 0304-4017/96/$15.00 Copyright © 1996 Elsevier Science B.V. All fights reserved. PH S0304-4017(96)00949-1
66
T.P. Charles, J. Furlong/Veterinary Parasitology 65 (1996) 65-73
programs aimed at technology transfer should include continuous updates on the subject, especially for veterinarians. Keywords: Cattle-Nematoda; Control methods-Nematoda; Brazil
1. Introduction
In the last 10-15 years several studies about epidemiology of gastrointestinal nematode infection and other helminths in cattle were carried out in Brazil (Bianchin, 1996; Charles, 1992; Honer and Bressan, 1992). With the available information it is now possible to establish control measures to decrease losses due to clinical and subclinical infection in most production areas. However, it is unknown to what extent the available information is used by dairy farmers. In Brazil, dairy cattle are raised mainly on pasture. To maintain productivity, animals need to receive anthelmintics to treat and/or prevent losses. Anthelmintic treatment not based on parasite epidemiology can be ineffective, costly and potentially harmful (Pilchard, 1990; Dorchies, 1991; Bjorn, 1992; Waller, 1994; Waller et al., 1995). Information about the compounds used by farmers, the period of the year they are applied and the frequency of application are important factors to consider in evaluating the efficiency of the controlling measures used at the farm. For example, a survey conducted in UK and the USA, showed that anthelmintics were used in excess and applied on inadequate age categories and at the wrong time of the year. The surveys conducted in these countries also showed that the producers had little awareness of the available information on parasite control (Michel et al., 1981; American Association of Veterinary Parasitologists, 1983). Most dairy cattle in Brazil are concentrated in the four States of the Southeastern region: Minas Gerais, S~o Paulo, Rio de Janeiro and Espirito Santo, a region accounting for 46.4% of the national milk production (Zoccal, 1994). In the region, the epidemiology of gastrointestinal nematode infection has been known since the early 1980s (Furlong, 1984; Bianchin, 1996; Furlong et al., 1985a; Furlong et al., 1985b; Charles, 1992; Honer and Bressan, 1992). However, it is still unknown if farmers are using control practices based on the known epidemiology. To approach such a question, the survey reported here was carried out in order to assess the deworming practices of a representative sample of dairy cattle producers in Southeast Brazil.
2. Materials and methods
A survey questionnaire containing one-way, multiple choices and open-ended questions was applied to farmers in Southeast Brazil through an interview. The questionnaire was divided into two sections: the first section contained questions related to the farm and its general management, including the area of the farm, number of animals in different categories, milk production and identification of the decision making person regarding the health management of the herd. The second part contained specific
T.P. Charles, J. Furlong / Veterinary Parasitology 65 (1996) 65-73
67
Fig. 1. Non-contiguous regions in which farmers were selected to be interviewed in the four States of Southeast Brazil: Minas Gerais (MG); S~o Paulo (SP); Rio de Janeiro (ILl); and Espfrito Santo (ES).
questions about worm control, including reasons for deworming, frequency and timing for deworming, age categories of animals which received the treatment, compounds used, how farmers chose the compounds, dosage determinations, source of information about worm control and farmer's attitude about new methods of worm control. To choose the farmers to be interviewed, the region was first split into 16 non-continuous clusters according to milk production (Fig. 1). Then, with the help of extension officers, a systematic sample was selected in each of the clusters, according to the following three levels of milk production per herd: up to 150 kg day -l (Level 1), 150-300 kg day-i (Level 2) and more than 300 kg day-i (Level 3). A total of 89 producers, from 36 counties in the four States of Southeast Brazil were interviewed from March, 1993 to May, 1995, 48 being in Minas Gerais, 19 in S~o Paulo, 11 in Rio de Janeiro and 11 in Espfrito Santo. Out of the total sample, 31 farmers ranked in Production Level 1, 28 in Level 2 and 30 in Level 3. The data collected in the questionnaire were numerically coded and manually added into a database and analyzed with the help of a software for epidemiology (Epi Info, Public Domain Software for Epidemiology and Disease Surveillance, Center for Disease Control, Epidemiology Program Office, Atlanta, GA). Only questions which where answered by more than 90% of the interviewed farmers were analyzed. Frequency was calculated, considering the total for each answer. 3. Results
The areas occupied by the selected dairy farms ranged from 4-1300 ha, with a mean of 239.1 ha. In these farms, an average of 57 heifers and 75 cows are raised in which crossbred 1 / 2 Zebu x Holstein animals predominated. Artificial insemination is used in
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T.P. Charles, J. Furlong / Veterinary Parasitology 65 (1996) 65-73
Table 1 Characteristics of the surveyed dairy farms in Southeast Brazil Farm characteristics
T *
Total area (ha) Mean Range
239.1 4-1300
Area used for dairy cattle Number of separate pastures
2b
3c
175.1 9-1200
198.6 27-600
343.6 4--1300
146 12
79 8
129 12
228 17
57 75
35 36
61 67
80 125
3
1
2
4
1/2HoZ e
1/2 HZ
3 / 4 HZ
Animals Heifers Cows Bulls Breed predominance
1a
* Average of the total number of farmers interviewed. a Average of farmers ranked in Production Level 1 (up to 150 g day- ' ). b Average of farmers ranked in production Level 2 (from 150-300 kg day- l ). c Average of farmers ranked in Production Level 3 (more than 300 kg day- l ). d H: Holstein. c Z: Zebu.
4 4 . 9 % o f the farms, respectively. M o s t farms are m a n a g e d by the farmers t h e m s e l v e s (98.6%). Characteristics o f the farms, a c c o r d i n g to the different levels o f production, are presented in T a b l e 1. Parasitic gastroenteritis is considered an important disease by dairy farmers. W h e n asked to rank its importance in c o m p a r i s o n to o t h e r c o m m o n parasitic diseases in the region, m o s t f a r m e r s considered v e r m i n o s i s either the m o s t important (25.0%), the s e c o n d ( 5 1 . 1 % ) or the third (23.9%) m o s t important parasitic disease o f dairy cattle. All f a r m e r s d e w o r m their animals. O n m o s t farms, the p r o d u c e r s t h e m s e l v e s c h o o s e the t i m i n g to d e w o r m (84.1%). M o s t h a v e veterinarians as their sole source o f i n f o r m a t i o n about the t i m i n g o f d e w o r m i n g and class o f c o m p o u n d to be used (54.3%), s o m e m a k e their d e c i s i o n based on their o w n e x p e r i e n c e or on the n e e d to m a k e the
Table 2 Annual fTequency of anthelmintic treatments of dairy cattle in Southeast Brazil Treatment frequency
T *
1a
2b
3c
Mean Range
3.79 1-12
3.35 1-12
3.88 2-12
4.17 2-12
predominant range
2-4
1-4
2-4
* Average of the total number of farmers interviewed. a Average of farmers ranked in Production Level 1 (up to 150 kg day= I). b Average of farmers ranked in Production Level 2 (from 150-300 kg day- '). c Average of farmers ranked in Production Level 3 (more than 300 kg day- l ).
2-4
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Table 3 Percentage of dairy farmers which used each antheimintic class or a combination of more than one class of anthelmintic in Southeast Brazil in the last 5 years to deworm their herds Compound Class
T *
Ia
2 b
3c
IMI t BZD 2 AVM 3 ORG 4 IM1 + BZD IMI + AVM IMI + ORG BZD + AVM IM1 + BZD + AVM IMI + BZD + ORG
14.3 17.9 13.1 1.2
13.3 16.7 10.0
19.2 19.2 19.2
16.7 16.7 3.3 10.0 10.0 3.3
11.5 7.7
10.7 17.9 10.7 3.6 3.6 7.1 3.6 21.4 21.4
10.7 13.1 13.1 15.5 1.2
7.7 15.3
IMI: lmidazothiazoles; 2 BZD: Benzimidazoles; 3 AVM: Avermectins; 40RG: Organophosphates. * Average of the total number of farmers interviewed. a Average of farmers ranked in Production Level 1 (up to 150 kg d a y - t ) . b Average of farmers ranked in Production Level 2 (from 150-300 kg day- i). c Average of farmers ranked in Production Level 3 (more than 300 kg day- t ). t
practice coincide with others on the farm (39.4%). Most treat preventively (62.5%) while others treat according to the general condition of the herd which may suggest infection (37.5%). Generally, all animals are dewormed (96.6%). The annual frequency of treatments is presented in Table 2. Farmers who apply anthelmintic compounds following symptoms utilize from 1-9 treatments per animal a year (average, 3.79) in all age categories of animals. The farmers who treat the herd preventively use from 1-12 drenches a year (mean, 3.96),
Table 4 Percentage of dairy farmers which used each antheimintic class or a combination of more than one class of anthelmintic in Southeast Brazil in the last deworming of their herds Compound Class
T *
1a
2b
3c
IMI I BZD 2 AVM 3 ORG 4 IMl + BZD IMI + AVM BZD + AVM BZD + ORG IMI + BZD + AVM
17.1 9.8 18.3 1.2 4.9 14.6 14.6 1.2 18.3
13.8 3.4 20.6
26.9 15.4 23.1
6.9 20.7 10.3
19.2 7.7
24.1
7.6
11.1 11.1 11.1 3.7 7.4 3.7 25.9 3.7 22.2
IMI: Imidazothiazoles; 2 BZD: Benzimidazoles; 3 AVM: Avermectins; 40RG: Organophosphates. * Average of the total number of farmers interviewed. a Average of farmers ranked in Production Level 1 (up to 150 kg day- t ). b Average of farmers ranked in Production Level 2 (from 150-300 kg d a y - t ) . c Average of farmers ranked in Production Level 3 (more than 300 kg day- ~). i
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T.P. Charles, J. Furlong/ Veterinary Parasitology65 (1996) 65-73
Table 5 Percentage of dairy farmers which would be using each anthelmintic class or a combination of more than one class of antheimintic in Southeast Brazil in the next deworming of their herds Compound class
T *
1a
2b
3c
IMI i BZD 2 AVM 3 ORG 4 IMI + BZD IMI + AVM BZD + AVM IMI + BZD + AVM Did not know
16.3 30.1 22.6 1.3 3.8 5.1 I 0.0 3.8 7.5
17.2 27.5 24.1
24.0 20.0 28.0
6.9 3.4 10.3 3.4 6.9
8.0 4.0 8.0 8.0
7.7 42.3 15,4 3.8 3.8 3.8 15.4 7.7
i IMI: lmidazothiazoles; 2 BZD: Benzimidazoles; 3 AVM: Avermectins; 40RG: Organophosphates. * Average of the total number of farmers interviewed. a Average of farmers ranked in Production Level 1 (up to 150 kg day- H). b Average of farmers ranked in Production Level 2 (from 150-300 kg day- J ). c Average of farmers ranked in Production Level 3 (more than 300 kg day- l ).
generally in all age categories (94.5%), mostly at random (58.2%) or with inadequate timing (40.0%). Farmers use all classes of anthelmintic available on the Brazilian market. Most use only one compound at a given treatment,-but a considerable percentage of them use more than one class at a given treatment. Table 3, Tables 4 and 5 present the percentages in which each class of anthelmintic compound was chosen to be used exclusively or in combination with other classes to deworm the herds in the last 5 years, in the last deworming or would be used in the next deworming of the herd, respectively. Farmers made the choice of compound to be used based either on veterinary recommendation (36.0%), example of neighbors' experience (18.6%) or the price they could afford at the time of purchase (4.7%). To choose the dosage to be given, most farmers consult the product label (94.8%). To determine the volume to be given to each animal, most visually estimate the weight of each animal and then adjust the syringe (62.9%), whereas a few estimate it by measuring the perimeter of the thorax using a calibrated measuring tape (10.1%). Most (50.6%) preferred injectable while some preferred oral formulations (27.0%). After an anthelmintic application, most farmers could visually detect increase in weight gain or improvement in the appearance of the herd (87.3%). Most of them (66.2%) recalled interrupting the use of some compound in the last few years. The reason for the discontinuance was the detection of no improvement following treatment (32.7%), the rising costs of the medication (28.6%), adverse reaction (8.2%), product not being available at the time of purchase (4. 1%) and decision to change the compound in use (10.2%). Most farmers planned to use the same worm control measures in the following year (95.3%). However, if they knew of ways to improve the worm control used in their farms, they would be willing to try (97.4%).
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4. Discussion This survey provides a representation of the dairy farmers in Southeast Brazil. The demographic profile reported here (Table 1) agrees with previous survey of management in the region (Teixeira and Valente, 1995; Zoccal, 1994). Based on the epidemiological studies conducted in Brazil, three to four preventive anthelmintic treatments are recommended for growing beef or dairy cattle (Bianchin, 1996; Charles, 1992; Furlong et al., 1993). These treatments are applied mainly in the driest months to decrease pasture infectivity. This survey showed that the average number of treatments given to the herd per year by most farmers is adequate (Table 2). However, most treatments are not applied at the proper time. Some use an excessive number of dewormings (up to 12 times a year). In addition, farmers apply anthelmintics to all age categories of animals. Studies conducted in the region do not recommend preventive treatment to be applied to adult animals (reviewed by Charles, 1992). Consequently, the habit of deworming all age categories increases the costs of the worm control program used in the region. It is important to note that when we compare the anthelmintic classes to deworm the herds in the last 5 years (Table 3) with the compounds used in the last deworming (Table 4), it is clear that an increment of the use of avermectin compounds was used, exclusively, or in combination with other classes. However, when asked about the anthelmintic class to be used in the next deworming of the herd (Table 5), the proportion of farmers which would be using it exclusively, is higher. This fact possibly reflects the decrease in the price of the compounds of this class in the last few years. As the avermectins act on endoparasites and ectoparasites, they have advantages when used in tropical regions compared with the other classes. Different classes of anthelmintic compounds can be used for each age category of animals or some age categories can be dewormed with one anthelmintic class while others are dewormed with another class of compound at the same deworming time. There is no planned rotation being used. The practice of using more than one class of anthelmintic compound at each herd deworming may contribute to the development of resistance as the parasite population of the farm is exposed to chemicals with different mechanisms of action (Waller et al., 1988; Scott et al., 1991; Maes and Vanparijs, 1991; Kinoti et al., 1994). The contrary can also be argued, that is, the exposition of the worm population to different classes of anthelmintic at the same deworming time can minimize or prevent the development of resistance (McKenna, 1990; Waller et al., 1990; Maes and Vanparijs, 1991). It is noteworthy that there are a few reports in which anthelmintic resistance in cattle worms is suspected to occur in Brazil (Reinecke, 1993; Pinheiro and Echevarria, 1990). Also, in this survey, some producers have already suspected resistance in their herds, as 32.7% stated they discontinued the use of some compounds because of poor clinical response after treatment. It should be noted, however, that producers' experiences with anthelmintic failure are subjective and resistance in cattle helminths has not been confirmed in the region. These data suggest additional studies aimed at surveying the efficacy of different anthelmintic classes should be undertaken in the region using in vitro and in vivo studies. Several deficiencies in the practices for controlling worms in dairy cattle were
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TJ ~. Charles, J. Furlong / Veterinary Parasitology 65 (1996) 65 - 73
detected in this survey. It is not possible to recommend a general control program which would apply to all dairy production systems in the region. However, a few recommendations could be applied to all herds. For example, preventive treatment should be applied to growing animals during the driest months, to reduce pasture infectivity (Furlong et al., 1993; Bianchin, 1996). Adult animals should be dewormed if symptoms which suggest infection are observed. According to the strategic control program developed for the region, anthelmintic class compounds should be used one at a time, on a yearly basis (reviewed by Charles, 1992). Finally, there is an urgent need to train extension officers in the region to improve their ability in providing farmers with technical advice on long-term strategies for controlling worms in dairy cattle. As veterinarians from public and private institutions play an important role as information sources about worm control, technology transfer programs should offer continuous training to these professionals.
References American Association of Veterinary Parasitologists, 1983. Report of committee on ruminant diseases. Research needs and priorities for ruminant internal parasites in the United States. Am. J. Vet. Res., 44: 1836--1847. Bianchin, 1., 1996. Epidemioiogia dos nemat6deos gastrintestinais em bovinos de cone nos cerrados e o controle eswat~gico no Brasil. In: Charles, T.P. (Editor), Controle da verminose em ruminantes. EMBRAPA-CNPGL, Coronel Pacheco, (in press). Bjoru, H., 1992. Anthelmintic resistance in parasitic nematodes of domestic animals. A review with reference to the situation in the Nordic countries 1992. Bull. Scand. Soc. Parasitol., 2: 9-29. Charles, T.P., 1992. Verminoses dos bovinos de ieite. In: Charles, T.P., Furlong, J. (Editors), Doenqas parasit,'kias dos bovinos de leite. EMBRAPA-CNPGL, Colonel Pacheco, pp. 55-110. Dorchies, P., 1991. Les resistances aux anthelmintiques: position du probleme. Rev. Meal. Vet., 142: 615-621. Furlong, J., 1984. Identificaq~o e conU'ole de helmintos gastrintestinals de bezerros na microregi~o de Juiz de Fora. Coronel Pacheco: EMBRAPA-CNPGL, 1984. (EMBRAPA. PNP de Gado de Leite. Projeto 007.80.016-2). Projeto conclnfdo. Furlong, J., Abreu, H.G.L. de, Verneque, R. da S., 1985a. Parasitoses dos bovinos na regi~o da Zona da Mata de Minas Gerais. I. Comportamento estacional de nemat&leos gastrointestinais. Pesq. Agropec. Bras., 20: 143-153. Furlong, J., Vilas-Novas, J.C., Cardoso-Fiiho, J.B., 1985b. Parasimses dos bovinos na regi~o da Zona de Mata de Minas Gerais. II. Incid~ncia estacional de nemat6deos pulmonares. Pesq. Agropec. Bras., 20:1 d09-1413. Furlong, J., Silva, A.M. da, Verneque, R. da S., Gardner, A., Brockington, N.R., 1993. An~ilise bioecon6mica do nso de anfi-helmintico em bezerros na Zona da Mata de Minas Gerais. Rev. Bras. Parasitol. Vet., 2: 119-126. Honer, M.R., Bressan, M.C.R.V., 1992. Nemat6deos de Bovinos no Brasil. O Estado da Pesquisa, 1991. Rev. Bras. Parasitol, Vet., 1: 67-79. Kinoti, G.K., Maingi, N., Coles, G.C., 1994. Anthelmintic usage in Kenya and its implications. Bull. Anim. Health Prod. Aft'., 42: 71-73. Maes, L., Vanparijs, O., 1991. Comments aborder ia resistance aux antheimintiques. Quelques reflexions theoretiques et pratiques. Rev. Mead. Vet., 142: 645-649. McKenna, P.B., 1990. The use of benzimidazole-levamisole mixtures for the control and prevention of anthehnintic resistance in sheep nematodes: an assessment of their likely effects. N.Z. Vet. J., 38: 45-49. Michel, J.F., Latham, J.O., Church, B.M., Leech, P.K., 1981. Use of anthelmintic for cattle in England and Wales during 1978. Vet. Rec., 21: 252-258. Pinheiro, A.C., Echevarria, F.A.M., 1990. Susccptibilidade de Haemonchus spp em bovinos ao tratamento anti-helmfntico corn albendazole e oxfendazole. Pesq. Vet. Bras., 10: 19-21.
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Prichard, R., 1990. Anthelmintic resistance in nematode: extent, recent understanding and future directions for control and research. Int. J. Parasitoi., 20: 515-523. Reinecke, R.K., 1993. First stage larval reduction test L]RT for detection of nematode resistance to antheireintics in cattle. In: 14th Conference of the World Association for the Advancement of Veterinary Parasitology, Cambridge. Abstracts, Cambridge, pp. 375. Scott, E.W., Duncan, LL., McKellar, Q.A., Coop, R.L., Jackson, F., Mitchell, G.B.B., 1991. Benzireidazole resistance in sheep nematodes. Vet. Rec., 128: 618-619. Teixeira, N.M., Valente, J., 1995. A estrutura da produqSo de leite entre criadores de gado holandSs no Estado de Minas Gerais, 1993. Coreunica~o pessoal. Waller, PJ., 1994. The development of anthelreintic resistance in ruminant livestock. Acta Trop., 56: 233-243. Waller, P.J., Dobson, R.J., Axelsen, A., 1988. Anthelreintic resistance in the field: changes in resistance status of parasitic populations in response to anthelreintic treatment. Austral. Vet. J., 65: 376-379. Waller, P.J., Dobson, R.J., Haughey, K.G., 1990. The effect of combinations of anthelreintics on parasite populations in sheep. Austral. Vet. J., 67: 138-140. Waller, PJ., Dash, K.M., Barger, I.A., LeJambre, L.F., Plant, J., 1995. Antheireintic resistance in nematode parasites of sheep: learning from the Australian experience. Vet. Rex:., 136:411-413. Zoccal, R., 1994. Leite ere ndreeros. EMBRAPA-CNPGL, Coronel Pacheco; FAEMG, Belo Horizonte, 131 PP.
par~tology ELSEVIER
Veterinary Parasitology 65 (1996) 65-73
A survey of dairy cattle worm control practices in Southeast Brazil T.P. Charles *, J. Furlong EMBRAPA, Centro Nacional de Pesquisa de Gado de Leite, Rodovia MG 133, km 42, Coronel Pacheco MG 36155-000, Brazil
Received 8 August 1995; accepted 28 December 1995
Abstract
A survey on the nematode control strategies utilized by dairy farmers in Southeastern Brazil, a region accounting for 46.4% of the national milk production, was conducted through interviews with farmers. To select the producers to be interviewed, the region was split into 16 non-contiguous clusters, according to the level of milk production. A systematic sample was then selected in each of the clusters. The interview questionnaire consisted of one-way, multiple-choice and open-ended questions. Data collected were represented by numbers and digitized on a data base (Epi Info, version 5.01b) and analyzed. Out of the 89 farmers interviewed, 37.5% deworm their herd after clinical signs and 62.5% preventively. Generally, anthelmintics are applied from one to 12 times a year (average of 3.79 times a year) in all age categories of animals. Of the anthelmintics used in the last deworming, imidazothiazole was used exclusively by 17.1% of the farmers, benzimidazole by 9.8% and avermectin by 18.3%, while 55.8% used more than one anthelmintic class to deworm their animals. To choose the dosage, most farmers consult the product label (94.8%) and determine the volume to be applied, based on an estimate of the average body weight of each animal (62.9%). Improvements in the general appearance of the herd and weight gains of growing animals were observed by most farmers after deworming (87.3%). However, most of them (66.2%) recalled interrupting the use of some compound in the last few years, due to the detection of no improvement following treatment (32.7%), rising costs of the medication (28.6%), adverse reaction (8.2%), product not being available at the time of purchase (4.1%) and decision to change the compound in use (10.2%). Most farmers (95.3%) intend to continue using the same control measures in the following year. Veterinarians play an important role in the farmer's choice to deworm their animals, as many seek advice from them. Therefore,
* Corresponding author. Tel/Fax: + 55-32-215-8550. 0304-4017/96/$15.00 Copyright © 1996 Elsevier Science B.V. All fights reserved. PH S0304-4017(96)00949-1
66
T.P. Charles, J. Furlong/Veterinary Parasitology 65 (1996) 65-73
programs aimed at technology transfer should include continuous updates on the subject, especially for veterinarians. Keywords: Cattle-Nematoda; Control methods-Nematoda; Brazil
1. Introduction
In the last 10-15 years several studies about epidemiology of gastrointestinal nematode infection and other helminths in cattle were carried out in Brazil (Bianchin, 1996; Charles, 1992; Honer and Bressan, 1992). With the available information it is now possible to establish control measures to decrease losses due to clinical and subclinical infection in most production areas. However, it is unknown to what extent the available information is used by dairy farmers. In Brazil, dairy cattle are raised mainly on pasture. To maintain productivity, animals need to receive anthelmintics to treat and/or prevent losses. Anthelmintic treatment not based on parasite epidemiology can be ineffective, costly and potentially harmful (Pilchard, 1990; Dorchies, 1991; Bjorn, 1992; Waller, 1994; Waller et al., 1995). Information about the compounds used by farmers, the period of the year they are applied and the frequency of application are important factors to consider in evaluating the efficiency of the controlling measures used at the farm. For example, a survey conducted in UK and the USA, showed that anthelmintics were used in excess and applied on inadequate age categories and at the wrong time of the year. The surveys conducted in these countries also showed that the producers had little awareness of the available information on parasite control (Michel et al., 1981; American Association of Veterinary Parasitologists, 1983). Most dairy cattle in Brazil are concentrated in the four States of the Southeastern region: Minas Gerais, S~o Paulo, Rio de Janeiro and Espirito Santo, a region accounting for 46.4% of the national milk production (Zoccal, 1994). In the region, the epidemiology of gastrointestinal nematode infection has been known since the early 1980s (Furlong, 1984; Bianchin, 1996; Furlong et al., 1985a; Furlong et al., 1985b; Charles, 1992; Honer and Bressan, 1992). However, it is still unknown if farmers are using control practices based on the known epidemiology. To approach such a question, the survey reported here was carried out in order to assess the deworming practices of a representative sample of dairy cattle producers in Southeast Brazil.
2. Materials and methods
A survey questionnaire containing one-way, multiple choices and open-ended questions was applied to farmers in Southeast Brazil through an interview. The questionnaire was divided into two sections: the first section contained questions related to the farm and its general management, including the area of the farm, number of animals in different categories, milk production and identification of the decision making person regarding the health management of the herd. The second part contained specific
T.P. Charles, J. Furlong / Veterinary Parasitology 65 (1996) 65-73
67
Fig. 1. Non-contiguous regions in which farmers were selected to be interviewed in the four States of Southeast Brazil: Minas Gerais (MG); S~o Paulo (SP); Rio de Janeiro (ILl); and Espfrito Santo (ES).
questions about worm control, including reasons for deworming, frequency and timing for deworming, age categories of animals which received the treatment, compounds used, how farmers chose the compounds, dosage determinations, source of information about worm control and farmer's attitude about new methods of worm control. To choose the farmers to be interviewed, the region was first split into 16 non-continuous clusters according to milk production (Fig. 1). Then, with the help of extension officers, a systematic sample was selected in each of the clusters, according to the following three levels of milk production per herd: up to 150 kg day -l (Level 1), 150-300 kg day-i (Level 2) and more than 300 kg day-i (Level 3). A total of 89 producers, from 36 counties in the four States of Southeast Brazil were interviewed from March, 1993 to May, 1995, 48 being in Minas Gerais, 19 in S~o Paulo, 11 in Rio de Janeiro and 11 in Espfrito Santo. Out of the total sample, 31 farmers ranked in Production Level 1, 28 in Level 2 and 30 in Level 3. The data collected in the questionnaire were numerically coded and manually added into a database and analyzed with the help of a software for epidemiology (Epi Info, Public Domain Software for Epidemiology and Disease Surveillance, Center for Disease Control, Epidemiology Program Office, Atlanta, GA). Only questions which where answered by more than 90% of the interviewed farmers were analyzed. Frequency was calculated, considering the total for each answer. 3. Results
The areas occupied by the selected dairy farms ranged from 4-1300 ha, with a mean of 239.1 ha. In these farms, an average of 57 heifers and 75 cows are raised in which crossbred 1 / 2 Zebu x Holstein animals predominated. Artificial insemination is used in
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T.P. Charles, J. Furlong / Veterinary Parasitology 65 (1996) 65-73
Table 1 Characteristics of the surveyed dairy farms in Southeast Brazil Farm characteristics
T *
Total area (ha) Mean Range
239.1 4-1300
Area used for dairy cattle Number of separate pastures
2b
3c
175.1 9-1200
198.6 27-600
343.6 4--1300
146 12
79 8
129 12
228 17
57 75
35 36
61 67
80 125
3
1
2
4
1/2HoZ e
1/2 HZ
3 / 4 HZ
Animals Heifers Cows Bulls Breed predominance
1a
* Average of the total number of farmers interviewed. a Average of farmers ranked in Production Level 1 (up to 150 g day- ' ). b Average of farmers ranked in production Level 2 (from 150-300 kg day- l ). c Average of farmers ranked in Production Level 3 (more than 300 kg day- l ). d H: Holstein. c Z: Zebu.
4 4 . 9 % o f the farms, respectively. M o s t farms are m a n a g e d by the farmers t h e m s e l v e s (98.6%). Characteristics o f the farms, a c c o r d i n g to the different levels o f production, are presented in T a b l e 1. Parasitic gastroenteritis is considered an important disease by dairy farmers. W h e n asked to rank its importance in c o m p a r i s o n to o t h e r c o m m o n parasitic diseases in the region, m o s t f a r m e r s considered v e r m i n o s i s either the m o s t important (25.0%), the s e c o n d ( 5 1 . 1 % ) or the third (23.9%) m o s t important parasitic disease o f dairy cattle. All f a r m e r s d e w o r m their animals. O n m o s t farms, the p r o d u c e r s t h e m s e l v e s c h o o s e the t i m i n g to d e w o r m (84.1%). M o s t h a v e veterinarians as their sole source o f i n f o r m a t i o n about the t i m i n g o f d e w o r m i n g and class o f c o m p o u n d to be used (54.3%), s o m e m a k e their d e c i s i o n based on their o w n e x p e r i e n c e or on the n e e d to m a k e the
Table 2 Annual fTequency of anthelmintic treatments of dairy cattle in Southeast Brazil Treatment frequency
T *
1a
2b
3c
Mean Range
3.79 1-12
3.35 1-12
3.88 2-12
4.17 2-12
predominant range
2-4
1-4
2-4
* Average of the total number of farmers interviewed. a Average of farmers ranked in Production Level 1 (up to 150 kg day= I). b Average of farmers ranked in Production Level 2 (from 150-300 kg day- '). c Average of farmers ranked in Production Level 3 (more than 300 kg day- l ).
2-4
T.P. Charles, J. Furlong/ Veterinary Parasitology 65 (1996) 65-73
69
Table 3 Percentage of dairy farmers which used each antheimintic class or a combination of more than one class of anthelmintic in Southeast Brazil in the last 5 years to deworm their herds Compound Class
T *
Ia
2 b
3c
IMI t BZD 2 AVM 3 ORG 4 IM1 + BZD IMI + AVM IMI + ORG BZD + AVM IM1 + BZD + AVM IMI + BZD + ORG
14.3 17.9 13.1 1.2
13.3 16.7 10.0
19.2 19.2 19.2
16.7 16.7 3.3 10.0 10.0 3.3
11.5 7.7
10.7 17.9 10.7 3.6 3.6 7.1 3.6 21.4 21.4
10.7 13.1 13.1 15.5 1.2
7.7 15.3
IMI: lmidazothiazoles; 2 BZD: Benzimidazoles; 3 AVM: Avermectins; 40RG: Organophosphates. * Average of the total number of farmers interviewed. a Average of farmers ranked in Production Level 1 (up to 150 kg d a y - t ) . b Average of farmers ranked in Production Level 2 (from 150-300 kg day- i). c Average of farmers ranked in Production Level 3 (more than 300 kg day- t ). t
practice coincide with others on the farm (39.4%). Most treat preventively (62.5%) while others treat according to the general condition of the herd which may suggest infection (37.5%). Generally, all animals are dewormed (96.6%). The annual frequency of treatments is presented in Table 2. Farmers who apply anthelmintic compounds following symptoms utilize from 1-9 treatments per animal a year (average, 3.79) in all age categories of animals. The farmers who treat the herd preventively use from 1-12 drenches a year (mean, 3.96),
Table 4 Percentage of dairy farmers which used each antheimintic class or a combination of more than one class of anthelmintic in Southeast Brazil in the last deworming of their herds Compound Class
T *
1a
2b
3c
IMI I BZD 2 AVM 3 ORG 4 IMl + BZD IMI + AVM BZD + AVM BZD + ORG IMI + BZD + AVM
17.1 9.8 18.3 1.2 4.9 14.6 14.6 1.2 18.3
13.8 3.4 20.6
26.9 15.4 23.1
6.9 20.7 10.3
19.2 7.7
24.1
7.6
11.1 11.1 11.1 3.7 7.4 3.7 25.9 3.7 22.2
IMI: Imidazothiazoles; 2 BZD: Benzimidazoles; 3 AVM: Avermectins; 40RG: Organophosphates. * Average of the total number of farmers interviewed. a Average of farmers ranked in Production Level 1 (up to 150 kg day- t ). b Average of farmers ranked in Production Level 2 (from 150-300 kg d a y - t ) . c Average of farmers ranked in Production Level 3 (more than 300 kg day- ~). i
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T.P. Charles, J. Furlong/ Veterinary Parasitology65 (1996) 65-73
Table 5 Percentage of dairy farmers which would be using each anthelmintic class or a combination of more than one class of antheimintic in Southeast Brazil in the next deworming of their herds Compound class
T *
1a
2b
3c
IMI i BZD 2 AVM 3 ORG 4 IMI + BZD IMI + AVM BZD + AVM IMI + BZD + AVM Did not know
16.3 30.1 22.6 1.3 3.8 5.1 I 0.0 3.8 7.5
17.2 27.5 24.1
24.0 20.0 28.0
6.9 3.4 10.3 3.4 6.9
8.0 4.0 8.0 8.0
7.7 42.3 15,4 3.8 3.8 3.8 15.4 7.7
i IMI: lmidazothiazoles; 2 BZD: Benzimidazoles; 3 AVM: Avermectins; 40RG: Organophosphates. * Average of the total number of farmers interviewed. a Average of farmers ranked in Production Level 1 (up to 150 kg day- H). b Average of farmers ranked in Production Level 2 (from 150-300 kg day- J ). c Average of farmers ranked in Production Level 3 (more than 300 kg day- l ).
generally in all age categories (94.5%), mostly at random (58.2%) or with inadequate timing (40.0%). Farmers use all classes of anthelmintic available on the Brazilian market. Most use only one compound at a given treatment,-but a considerable percentage of them use more than one class at a given treatment. Table 3, Tables 4 and 5 present the percentages in which each class of anthelmintic compound was chosen to be used exclusively or in combination with other classes to deworm the herds in the last 5 years, in the last deworming or would be used in the next deworming of the herd, respectively. Farmers made the choice of compound to be used based either on veterinary recommendation (36.0%), example of neighbors' experience (18.6%) or the price they could afford at the time of purchase (4.7%). To choose the dosage to be given, most farmers consult the product label (94.8%). To determine the volume to be given to each animal, most visually estimate the weight of each animal and then adjust the syringe (62.9%), whereas a few estimate it by measuring the perimeter of the thorax using a calibrated measuring tape (10.1%). Most (50.6%) preferred injectable while some preferred oral formulations (27.0%). After an anthelmintic application, most farmers could visually detect increase in weight gain or improvement in the appearance of the herd (87.3%). Most of them (66.2%) recalled interrupting the use of some compound in the last few years. The reason for the discontinuance was the detection of no improvement following treatment (32.7%), the rising costs of the medication (28.6%), adverse reaction (8.2%), product not being available at the time of purchase (4. 1%) and decision to change the compound in use (10.2%). Most farmers planned to use the same worm control measures in the following year (95.3%). However, if they knew of ways to improve the worm control used in their farms, they would be willing to try (97.4%).
T.P. Charles, J. Furlong/Veterinary Parasitology 65 (1996) 65-73
71
4. Discussion This survey provides a representation of the dairy farmers in Southeast Brazil. The demographic profile reported here (Table 1) agrees with previous survey of management in the region (Teixeira and Valente, 1995; Zoccal, 1994). Based on the epidemiological studies conducted in Brazil, three to four preventive anthelmintic treatments are recommended for growing beef or dairy cattle (Bianchin, 1996; Charles, 1992; Furlong et al., 1993). These treatments are applied mainly in the driest months to decrease pasture infectivity. This survey showed that the average number of treatments given to the herd per year by most farmers is adequate (Table 2). However, most treatments are not applied at the proper time. Some use an excessive number of dewormings (up to 12 times a year). In addition, farmers apply anthelmintics to all age categories of animals. Studies conducted in the region do not recommend preventive treatment to be applied to adult animals (reviewed by Charles, 1992). Consequently, the habit of deworming all age categories increases the costs of the worm control program used in the region. It is important to note that when we compare the anthelmintic classes to deworm the herds in the last 5 years (Table 3) with the compounds used in the last deworming (Table 4), it is clear that an increment of the use of avermectin compounds was used, exclusively, or in combination with other classes. However, when asked about the anthelmintic class to be used in the next deworming of the herd (Table 5), the proportion of farmers which would be using it exclusively, is higher. This fact possibly reflects the decrease in the price of the compounds of this class in the last few years. As the avermectins act on endoparasites and ectoparasites, they have advantages when used in tropical regions compared with the other classes. Different classes of anthelmintic compounds can be used for each age category of animals or some age categories can be dewormed with one anthelmintic class while others are dewormed with another class of compound at the same deworming time. There is no planned rotation being used. The practice of using more than one class of anthelmintic compound at each herd deworming may contribute to the development of resistance as the parasite population of the farm is exposed to chemicals with different mechanisms of action (Waller et al., 1988; Scott et al., 1991; Maes and Vanparijs, 1991; Kinoti et al., 1994). The contrary can also be argued, that is, the exposition of the worm population to different classes of anthelmintic at the same deworming time can minimize or prevent the development of resistance (McKenna, 1990; Waller et al., 1990; Maes and Vanparijs, 1991). It is noteworthy that there are a few reports in which anthelmintic resistance in cattle worms is suspected to occur in Brazil (Reinecke, 1993; Pinheiro and Echevarria, 1990). Also, in this survey, some producers have already suspected resistance in their herds, as 32.7% stated they discontinued the use of some compounds because of poor clinical response after treatment. It should be noted, however, that producers' experiences with anthelmintic failure are subjective and resistance in cattle helminths has not been confirmed in the region. These data suggest additional studies aimed at surveying the efficacy of different anthelmintic classes should be undertaken in the region using in vitro and in vivo studies. Several deficiencies in the practices for controlling worms in dairy cattle were
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TJ ~. Charles, J. Furlong / Veterinary Parasitology 65 (1996) 65 - 73
detected in this survey. It is not possible to recommend a general control program which would apply to all dairy production systems in the region. However, a few recommendations could be applied to all herds. For example, preventive treatment should be applied to growing animals during the driest months, to reduce pasture infectivity (Furlong et al., 1993; Bianchin, 1996). Adult animals should be dewormed if symptoms which suggest infection are observed. According to the strategic control program developed for the region, anthelmintic class compounds should be used one at a time, on a yearly basis (reviewed by Charles, 1992). Finally, there is an urgent need to train extension officers in the region to improve their ability in providing farmers with technical advice on long-term strategies for controlling worms in dairy cattle. As veterinarians from public and private institutions play an important role as information sources about worm control, technology transfer programs should offer continuous training to these professionals.
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Prichard, R., 1990. Anthelmintic resistance in nematode: extent, recent understanding and future directions for control and research. Int. J. Parasitoi., 20: 515-523. Reinecke, R.K., 1993. First stage larval reduction test L]RT for detection of nematode resistance to antheireintics in cattle. In: 14th Conference of the World Association for the Advancement of Veterinary Parasitology, Cambridge. Abstracts, Cambridge, pp. 375. Scott, E.W., Duncan, LL., McKellar, Q.A., Coop, R.L., Jackson, F., Mitchell, G.B.B., 1991. Benzireidazole resistance in sheep nematodes. Vet. Rec., 128: 618-619. Teixeira, N.M., Valente, J., 1995. A estrutura da produqSo de leite entre criadores de gado holandSs no Estado de Minas Gerais, 1993. Coreunica~o pessoal. Waller, PJ., 1994. The development of anthelreintic resistance in ruminant livestock. Acta Trop., 56: 233-243. Waller, P.J., Dobson, R.J., Axelsen, A., 1988. Anthelreintic resistance in the field: changes in resistance status of parasitic populations in response to anthelreintic treatment. Austral. Vet. J., 65: 376-379. Waller, P.J., Dobson, R.J., Haughey, K.G., 1990. The effect of combinations of anthelreintics on parasite populations in sheep. Austral. Vet. J., 67: 138-140. Waller, PJ., Dash, K.M., Barger, I.A., LeJambre, L.F., Plant, J., 1995. Antheireintic resistance in nematode parasites of sheep: learning from the Australian experience. Vet. Rex:., 136:411-413. Zoccal, R., 1994. Leite ere ndreeros. EMBRAPA-CNPGL, Coronel Pacheco; FAEMG, Belo Horizonte, 131 PP.