[Show abstract][Hide abstract] ABSTRACT: Molecular and morphological methods were evaluated to distinguish between Haemonchus contortus and Haemonchus placei species. A total of 141 H. contortus and 89 H. placei male adult specimens collected from artificially infected lambs were identified individually by PCR analysis, using a species-specific primer pair. These PCR results were used as gold standard for Haemonchus spp. identification. Haemonchus placei presented higher mean spicule and barb lengths than H. contortus (P<0.05). However, some measurements overlapped. For this reason, a discriminate function did not allow the correct identification of 13 H. contortus and one H. placei specimen. The sheath tail length of the third stage larvae (L3), which comprises the distance between the tip of the larval tail and the end of the sheath tail, were measured. Only three of the 485 H. placei larvae (0.619%) had a sheath tail shorter than 85 µm, while only four of the 500 H. contortus larvae (0.8%) presented a sheath tail longer than 85 µm. The results indicated that 6.09% of the male adult specimens would be misclassified based on the discriminate function, while only 0.71% of infective larvae would be misclassified. Therefore, identification of L3 can be used as the first method to indicate the presence of H. placei and/or H. contortus in a population of domestic ruminants.
Revista brasileira de parasitologia veterinaria = Brazilian journal of veterinary parasitology: Orgao Oficial do Colegio Brasileiro de Parasitologia Veterinaria 12/2014; 23(4):495-500. · 0.96 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The survival of infective larvae (L3) of Trichostrongylus colubriformis was evaluated on Brachiaria, Coast-cross and Aruana forage grasses. Feces of sheep parasitized exclusively by T. colubriformis were deposited in winter and spring on experimental plots whose grasses were cut at two heights: 5 cm and 30 cm. One, two, four, eight, 12 and 16 weeks after depositing the feces, fecal and forage samples were collected for the retrieval and quantification of L3. Retrieval of L3 from feces and forage was negligible in winter due to the dry weather, although a few larvae were retrieved in the last larval collections. However, L3 retrieval from fecal samples was greater in spring, especially two weeks after feces were deposited on 30 cm high grasses. At this time, the L3 retrieval rate from the three forage grasses differed significantly (P <0.05), with Aruana grass showing the highest average L3 retrieval rate, followed by Coast-cross and Brachiaria. In conclusion, the winter drought proved very unfavorable for the presence of L3 in the environment, and the microclimate of Aruana pastureland was generally the most favorable for the retrieval of infective larvae.
Revista brasileira de parasitologia veterinaria = Brazilian journal of veterinary parasitology: Orgao Oficial do Colegio Brasileiro de Parasitologia Veterinaria 12/2014; 23(4):463-72. · 0.96 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The occurrence of anthelmintic resistance to levamisole, albendazole, ivermectin and moxidectin was investigated in cattle from 10 farms located in São Paulo State, Brazil, using two techniques for counting eggs in faeces: McMaster with a sensitivity of 50 eggs per gram (EPG) and FLOTAC with a sensitivity of two EPG. We also evaluated the use of different mathematical and test design approaches to determine the efficacy of the anthelmintic treatments: one formula/design that compares post-treatment arithmetic mean EPG counts for the treated and control groups (FECRT1) and two methods to analyse data from pre- and post-treatment EPG counts in the same group (FECRT2 and FECRT3, respectively). Treatment groups received either ivermectin (0.2 mg/kg of body weight (BW); moxidectin (0.2 mg/kg BW); albendazole (2.5 mg/kg BW); levamisole (4.7 mg/kg BW); or no treatment (control group). The number of animals in each group ranged from 8 to 11. Faecal samples from each animal were collected 2 days before the treatment and again 10 and 28 days post-treatment. The FEC reduction (FECR) confidence intervals were usually wider when based on data obtained using the McMaster method than when data were obtained using the FLOTAC method. Efficacy estimated from pre- and post-treatment EPG counts in the same group presented smaller confidence intervals. Ivermectin proved to be totally ineffective in all herds evaluated. Cooperia spp. was the major parasite displaying resistance, followed by Haemonchus spp. The results also indicated the presence of Oesophagostomum spp. and Trichostrongylus spp., meaning they, too, were resistant to ivermectin. Resistance to moxidectin was found on nine of the 10 farms investigated; however, only three farms had previously used moxidectin. In contrast, albendazole and levamisole demonstrated high efficacy on the majority of farms. In surveys for anthelmintic resistance in cattle, the use of a diagnostic method with higher sensitivity to detect eggs is recommended, as is the case with the FLOTAC method. This study indicates that by using techniques with high sensitivity and by testing the same animals pre- and post-treatment, good precision can be achieved with group sizes from 8 to 11 animals.
[Show abstract][Hide abstract] ABSTRACT: Gastrointestinal nematode infections were evaluated in sheep raised in Botucatu, state of São Paulo, Brazil between April 2008 and March 2011. Every month, two tracer lambs grazing with a flock of sheep were exposed to natural infection with gastrointestinal nematodes for 28 consecutive days. At the end of this period, the lambs were sacrificed for worm counts. Haemonchus contortus presented 100% of prevalence. The seasons exerted no significant influence on the mean intensity of H. contortus, which ranged from 315 worms in November 2010 to 2,5205 worms in January 2011. The prevalence of Trichostrongylus colubriformis was also 100%, with the lowest mean intensity (15 worms) recorded in February 2011 and the highest (9,760 worms) in October 2009. In the case of T. colubriformis, a significant correlation coefficient was found between worm counts vs. rainfall (r = -0.32; P <0.05). Three other nematodes species were found in tracer lambs, albeit in small numbers. Their prevalence and mean intensity (in parenthesis) were as follows: Oesophagostomum columbianum 28% (25.2), Cooperia curticei 7% (4.5) and Trichuris spp. 2% (1). In conclusion, the environmental conditions of the area proved to be highly favorable for the year-round transmission of H. contortus and T. colubriformis.
Revista brasileira de parasitologia veterinaria = Brazilian journal of veterinary parasitology: Orgao Oficial do Colegio Brasileiro de Parasitologia Veterinaria 09/2014; 23(3):348-354. · 0.96 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A vaccine containing integral membrane glycoproteins from the intestine of Haemonchus contortus was evaluated in three groups of eight 5 month old grazing calves, naturally infected by Haemonchus similis, Haemonchus placei and other gastrointestinal nematodes. Vaccinated calves received 5 μg or 50 μg of the antigen and 1 mg of saponin adjuvant, while the controls received adjuvant alone, initially three times, 3 weeks apart and then four more times at 6 weeks intervals. Three weeks after the last immunization all of the calves were euthanised for worm counts. Immunization stimulated high titre antibodies against the vaccine antigens, reduced the egg output of Haemonchus spp. by 85% and the numbers of H. placei and H. similis by 63% and 32%, respectively, compared with control calves. It was concluded that vaccination with intestinal membrane glycoproteins from H. contortus could substantially reduce the transmission of H. placei and H. similis, thus providing protective benefit downstream. This appears to be the first known successful demonstration of a vaccine protective for cattle naturally exposed to infection with any gastrointestinal nematode parasite.
International Journal for Parasitology 06/2014; · 3.40 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Two trials were conducted to determine the prepatent and the patent period of Haemonchus contortus and Haemonchus placei in Santa Ines crossbred sheep and to determine whether serial infections with both species confer protection against homologous or heterologous challenge. To evaluate the prepatent and patent periods of infection, five lambs received a single infection with 4,000 H. contortus-infective larvae (L3), and another five received a single infection with 4,000 H. placei L3. H. contortus presented patency earlier than H. placei. Animals infected with both species shed a large number of eggs in the faeces for several months with the highest counts, with means higher than 3,000 eggs per gram of faeces (EPG) between 24 and 106 days and between 38 and 73 days post infection with H. contortus and H. placei, respectively. H. contortus eggs were detected in the faeces for a minimum of 302 days and a maximum of 538 days post infection, while the H. placei patent period lasted from 288 to 364 days. In the second trial, one group of lambs (n = 12) was serially infected 12 times (three times per week for four weeks) with 500 L3 of H. placei and then challenged with either H. placei (n = 6) or with H. contortus (n = 6). The lambs in the second group (n = 12) were serially infected 12 times with 500 L3 of H. contortus and then challenged with H. contortus (n = 6) or with H. placei (n = 6), and a third group of lambs was single challenged with H. placei (n = 6), H. contortus (n = 6), or remained uninfected throughout the trial period (Control group, n = 6). Animals serially infected with H. placei and then challenged with the same species presented the most intense immune response with the highest levels of anti-parasitic immunoglobulin and number of inflammatory cells in the abomasal mucosa. As a result, this group had the lowest rate of parasite establishment (2.68% of the 4000 L3 given), but this phenomenon did not occur in animals single challenged with H. placei, in which the rate of establishment was relatively high (25.3%), confirming that the protective immune response to H. placei develops only when animals are repeatedly infected with this species. However, when the animals were previously serially infected with H. placei and then challenged with H. contortus, no evidence of significant protection was observed (establishment of 19.18%). The results of the trials showed an important role played by the immune response on parasite-host specificity.
[Show abstract][Hide abstract] ABSTRACT: To better evaluate the usefulness of female Haemonchus specimens for specific identification, we undertook a detailed analysis of the morphology of a collection of worms obtained from cattle and sheep in shared pastures. Based on the results, we also more precisely evaluated the host-specificity of Haemonchus contortus, H. placei and H. similis occurring sympatrically in a farm located in the western region of São Paulo State, Brazil. A synlophe analysis was employed to identify the three species of Haemonchus. In cattle, the predominant species was H. similis (90.9%), followed by H. placei (9.1%). With the exception of one H. placei specimen, only H. contortus was found in sheep. The longest body length was found for H. placei specimens, followed by H. contortus and then H. similis. It was possible to distinguish H. similis females from H. contortus and H. placei on the basis of vulval structure. The synlophe analysis proved to be very useful for identification of H. contortus, H. placei and H. similis in epidemiological studies involving different species of ruminants in the same pastures. The finding that H. placei and H. similis were adapted to cattle and that H. contortus was adapted to sheep also confirmed the high host-specificity of the three nematodes species.
Journal of Helminthology 03/2014; · 1.30 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In this paper we report the occurrence of zoonotic species of Cryptosporidium (C. ubiquitum and C. parvum subtype IIaA15G2R1) and the host-specific Giardia duodenalis genotype E in a sheep farm from Brazil. Fecal specimens were collected from 100 animals and screened for the presence of G. duodenalis and Cryptosporidium spp. by enzyme immunoassay (EIA) and polymerase chain reaction (PCR). Restriction fragment length polymorphism (RFLP) and sequence analysis of selected samples was used to confirm the species and to characterize the isolates. Of 100 specimens, 34 were positive for Giardia (34%) and 25 were positive for Cryptosporidium (25%). The prevalence of Giardia and Cryptosporidium was higher in lambs than in ewes. Co-infection was observed in 14% of animals. All G. duodenalis isolates belonged to genotype E. The genetic characterization performed in 22 Cryptosporidium-positive samples revealed the presence of zoonotic C. ubiquitum and C. parvum in 76% (19/25) and 12% (3/25) of infected animals, respectively. The presence of zoonotic Cryptosporidium subtypes in lambs was of epidemiological and public health relevance.
[Show abstract][Hide abstract] ABSTRACT: This study was carried out to evaluate the breed resistance against ectoparasites infestations
in Crioula Lageana and crossbred Angus male calves under natural condition. Ten weaned
and neutered male calves (6-8 months) of each group were kept together in winter and
summer pastures in Monte Castelo, Santa Catarina State. Every 28 days, female ticks (Rhipicephalus
(Boophilus) microplus) more than 4 mm long were counted on the right and left side
of the body of each animal, as well as the D. hominis nodules. Coat thickness also was measured
at each sampling and all animals were classified according coat color. Crioula Lageana
group was less infested by D. hominis than crossbred Angus in five times and by ticks in the
infestation peak (P<0.05). There were no differences in the distribution of the ticks and grubs
between animal body sides. Dark-haired animal in both groups were the most susceptible.
[Show abstract][Hide abstract] ABSTRACT: Sheep and goat farming requires an efficient management program, due to losses caused by parasites in susceptible animals. Many factors may collaborate to improve infection tolerance in the herd, such as: genetics, nutrition, physiological status, and age. The problem caused by resistance to antihelmintic agents has led to the spread of alternative techniques for parasite controls. The latest strategies include selective treatment with the FAMACHA method, phytotherapy, biological control with predatory fungi, and strategies that still await scientific confirmation, such as homeopathy, the dilution of resistance with the introduction of susceptible parasites, and the combination of drugs without antihelmintic effect. The main objective of these methods is to reduce the usage of antiparasitic agents, thus slowing the development of resistance and promoting the better use of effective products and newly released products. The objective of this article is to describe techniques for controlling nematodes in small ruminants, and it is aimed at technicians interested in increasing their knowledge about the mechanisms of resistance to antihelmintic agents as well as alternatives to the use of these products.
Arquivos do Instituto Biológico. 06/2013; 80(2):253-263.
[Show abstract][Hide abstract] ABSTRACT: Agricultural ruminants usually harbour mixed infections of gastrointestinal nematodes. A specific diagnosis is important because distinct species can differ significantly in their fecundity and pathogenicity. Haemonchus spp. and Cooperia spp. are the most important gastrointestinal nematodes infecting ruminants in subtropical/tropical environments. In Brazil, C. punctata is more adapted to cattle than sheep. Additionally, C. spatulata appears to be more adapted to cattle, whereas C. curticei is more adapted to sheep. However, infection of sheep with C. punctata is common when cattle and sheep share the same pasture. Although morphological analyses have been widely used to identify nematodes, molecular methods can overcome technical limitations and help improve species-specific diagnoses. Genetic markers in the first and second internal transcribed spacers (ITS-1 and ITS-2, respectively) of nuclear ribosomal DNA (rDNA) have been used successfully to detect helminths. In the present study, the ITS-1 region was analysed and used to design a species-specific oligonucleotide primer pair to identify C. curticei. The polymerase chain reaction (PCR) product was sequenced and showed 97% similarity to C. oncophora partial ITS-1 clones and 99% similarity to the C. curticei sequence JF680982. The specificity of this primer pair was corroborated by the analysis of 17 species of helminths, including C. curticei, C. punctata and C. spatulata. Species-specific diagnosis, which has implications for rapid and reliable identification, can support studies on the biology, ecology and epidemiology of trichostrongylid nematodes in a particular geographical location.
Journal of Helminthology 05/2013; · 1.30 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Epidemiological and experimental studies support the idea that helminth infections can induce a protective effect against the development of autoimmune and allergic diseases. In this study we characterized the immune response induced by Strongyloides venezuelensis infection in C57BL/6 mice and then evaluated the effect of a previous contact with this helminth in the outcome of type 1 diabetes. Animals were initially infected with 2000 L3 larvae from S. venezuelensis and euthanized 22 days later. An acute phase, identified by a high amount of eggs per gram of feces, was established between days 7 and 9 post-infection. Recovery from infection was associated with a Th2 polarized response characterized by a significant level of serum IgG1 specific antibodies and also a significant production of IL-5 and IL-10 by spleen cells stimulated with S. venezuelensis soluble antigen. Immunization with soluble S. venezuelensis antigen associated with complete Freund's adjuvant followed by infection with S. venezuelensis protected mice from diabetes development induced by streptozotocin. Protection was characterized by a higher body weight gain, lower glycemic levels, much less severe insulitis and preserved insulin production. Together, these results indicate that S. venezuelensis contributed to protect C57BL/6 mice against experimental diabetes induced by streptozotocin.
[Show abstract][Hide abstract] ABSTRACT: The heads of 139 slaughtered sheep were examined with the aim of determining Oestrus ovis prevalence and infestation intensity in the central region of the State of São Paulo, Brazil. Heads from slaughtered sheep were examined and the first (L1), second (L2) and third (L3) O. ovis larval instars were recovered from the nasal and sinus cavities. O. ovis larvae were detected in 13.7% of the sheep analyzed. The monthly mean intensity of infestation ranged from 1 to 10.2 larvae per infested head, with general mean intensity of 4.5 larvae/infested head. Of the total of 85 larvae, 21.2% were L1, 37.6% L2 and 41.2% L3. In conclusion, all different O. ovis larvae instars were recovered from slaughtered animals, which demonstrates the existence of favorable climatic conditions for the fly activity and larval development of O. ovis in sheep raised in the Central region of the State of São Paulo.
Revista brasileira de parasitologia veterinaria = Brazilian journal of veterinary parasitology: Orgao Oficial do Colegio Brasileiro de Parasitologia Veterinaria 03/2013; · 0.96 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In this study, we aimed to introduce a new technique called TF-Test Modified∕Dog for the diagnosis of gastrointestinal parasites in dogs. Fecal samples from 106 dogs were processed by the technique TF-Test Modified∕Dog and the techniques of centrifugation-flotation in zinc sulfate, simple-flotation by saturated solution of sodium chloride, direct microscopy exam and TF-Test Conventional. Sensitivity was higher in the TF-Test Modified∕Dog (98.41%), followed by flotation in saturated zinc sulfate (77.78%), TF-Test Conventional (73.02%), flotation by saturated sodium chloride (55.55%), and direct microscopy exam (30.16%). The diagnostic efficiency varied from 58.49% to 99.06%, with the highest value also obtained by the new proposed technique. Efficiency level of 99.06% with kappa index 0.979 (almost perfect) was obtained with the TF-Test Modified∕Dog. These results represent significant statistical gains (P < 0.05) of 20.63% in sensitivity and 12.27% in efficiency over the best among the other techniques - flotation by saturated zinc sulfate, whose kappa index was 0.738, much lower than that of the TF-Test Modified∕Dog. All techniques presented 100% specificity. In this sense, the high sensitivity of the TF-Test Modified∕Dog makes it suitable for epidemiological surveys of gastrointestinal parasitosis in dogs, zoonoses control and preventive surveillance programs.
Revista brasileira de parasitologia veterinaria = Brazilian journal of veterinary parasitology: Orgao Oficial do Colegio Brasileiro de Parasitologia Veterinaria 03/2013; 22(1):1-5. · 0.96 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A high prevalence of nematodes, especially Haemonchus contortus and Trichostrongylus colubriformis, that exhibit multiple anthelmintics resistance has been reported in sheep in several South American countries. For this reason, the development of strategies that are less dependent on anthelmintic treatments is imperative for the prophylaxis of gastrointestinal nematode infections in small ruminants. Integrated grazing using cattle and sheep can be used for pasture decontamination with considerable reduction of H. contortus and T. colubriformis infective larvae after cattle grazing. Several breeds of sheep exhibit genetically related resistance against nematode infections, as is the case of “crioulo”, “native” or naturalised breeds of sheep. These breeds descend from livestock introduced by Portuguese and Spanish settlers and have been submitted to a long process of natural selection in various environmental conditions. In the South, the Crioula Lanada breed is more resistant to H. contortus than are Corriedale sheep. In tropical areas, where the minimum temperatures are usually higher than 20 °C, hair sheep flourish, especially the Santa Ines breed, which also display a higher level of resistance to nematode infections compared with certain breeds of European origin. However, Santa Ines sheep have inferior carcass quality compared with other commercial breeds. Recent studies showed that the crossbreeding of Santa Ines ewes with sires of breeds with high potential for growth and meat production, results in crossbred animals with high productivity and a satisfactory degree of resistance against nematode infections. Several studies have indicated that improvement in nutrition has a beneficial effect on the development of resistance in lambs that were naturally or artificially infected with nematodes. Therefore, supplementary feeding and breeding strategies to improve resistance to nematodes are feasible options in the effort to reduce dependence on anthelmintic drugs to control worm infections in sheep.
Small Ruminant Research 01/2013; · 1.10 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A criação de ovinos e caprinos depende de um manejo eficiente, devido, principalmente, ao prejuízo causado por parasitos em animais susceptíveis. Vários fatores colaboram para que os animais tolerem as infecções parasitárias, como: genética, nutrição, estado fisiológico e idade. O grave problema causado pela resistência anti-helmíntica promoveu a difusão de técnicas alterna-tivas de controle parasitário. Dentre essas novas estratégias incluem-se a adoção do tratamento parcial seletivo com o método FAMACHA, fitoterapia, controle biológico com o uso de fungos nematófagos e estratégias que ainda necessitam de mais dados como a homeopatia, a diluição da resistência com a introdução de parasitos sensíveis e a combinação de produtos químicos sem efeito antiparasitário. O objetivo central destes métodos é reduzir o uso de antiparasitários, retardando o desenvolvimento da resistência, e promover melhor utilização de produtos ainda eficazes na propriedade e de novos produtos que venham a ser lançados. Este artigo abordará as técnicas descritas acima para o controle de nematoides de pequenos ruminantes e é direcionado aos técnicos interessados em ampliar seu conhecimento sobre os mecanismos de resistência dos parasitos aos anti-helmínticos e de alternativas ao uso desses produtos. PALAVRAS-CHAVE: Anti-helmíntico, homeopatia, fitoterapia, Famacha, controle biológico, resistência parasitária. ABSTRACT ALTERNATIVE TECHNIQUES FOR THE CONTROL OF GASTROINTESTINAL NEMATODES IN SMALL RUMINANTS. Sheep and goat farming requires an efficient management program, due to losses caused by parasites in susceptible animals. Many factors may collaborate to improve infection tolerance in the herd, such as: genetics, nutrition, physiological status, and age. The problem caused by resistance to antihelmintic agents has led to the spread of alternative techniques for parasite controls. The latest strategies include selective treatment with the FAMACHA method, phytotherapy, biological control with predatory fungi, and strategies that still await scientific confirmation, such as homeopathy, the dilution of resistance with the introduction of susceptible parasites, and the combination of drugs without antihelmintic effect. The main objective of these methods is to reduce the usage of antiparasitic agents, thus slowing the development of resistance and promoting the better use of effective products and newly released products. The objective of this article is to describe techniques for controlling nematodes in small ruminants, and it is aimed at technicians interested in increasing their knowledge about the mechanisms of resistance to antihelmintic agents as well as alternatives to the use of these products.
[Show abstract][Hide abstract] ABSTRACT: This experiment aimed to assess the recovery of infective larvae (L3) of Trichostrongylus colubriformis from Brachiaria decumbens cv. Australiana, Cynodon dactylon cv. Coast-cross and Panicum maximum cv. Aruana. The experimental module comprised six plots, with two plots per herbage species. Larval survival was assessed from autumn to winter, under the effect of two herbage-paring heights (5 and 30 cm). TThe paring was carried out immediately before contamination with faces containing T. colubriformis eggs. The feces and herbage were collected at one, two, four, eight, 12 and 16 weeks after feces had been deposited in the experimental plots. In general, larvae were recovered from both herbage and feces until the 16th week. The longer persistence of these larvae in the environment was probably due to warmer temperatures. The number of L3 recovered from the pasture was not influenced by the height of plants, except for Brachiaria and Aruana herbage in the fourth week. Regarding the concentrations of larvae per kg of dry matter (L3/kg DM), recovery was higher from low pasture in all three herbage species. During the autumn, the development and survival of the T. colubriformis free-living stages were not affected by the different herbage species.
Revista brasileira de parasitologia veterinaria = Brazilian journal of veterinary parasitology: Orgao Oficial do Colegio Brasileiro de Parasitologia Veterinaria 12/2012; 21(4):372-8. · 0.96 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The seasonal factors that influence Oestrus ovis infestation in sheep were determined in Botucatu, State of São Paulo, Southwestern Brazil, from April 2008 to March 2011. Two tracer lambs were monthly exposed to natural infestation by O. ovis larvae for 28 consecutive days, by grazing with a sheep flock. Tracer animals were then euthanized and the larvae of O. ovis recovered from nasal and sinus cavities. Of the 72 tracer lambs, 50% were infested with O. ovis larvae and the mean intensity of infestation per head infested was 16.8 larvae, with an average of 7.8 L1, 5.3 L2 and 3.7 L3. O. ovis larvae were present during the four seasons of the year, but the mean larval burden was significantly higher during the spring and summer months, compared to winter (P < 0.05). The highest rate of larvae recovery coincided with mean temperatures between 20 °C and 25 °C and air relative humidity around 70%. Results suggest that evolution and development of O. ovis practically occurs throughout the entire year, with larval infestation especially frequent during the spring and summer months.
Revista brasileira de parasitologia veterinaria = Brazilian journal of veterinary parasitology: Orgao Oficial do Colegio Brasileiro de Parasitologia Veterinaria 12/2012; 21(4):386-90. · 0.96 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Gastrointestinal nematode (GIN) infection is a major cause of production losses in cattle. This study was carried out to evaluate the natural resistance against nematode infection in Crioulo Lageano and crossbred Angus male calves. Crioulo Lageano is a local cattle breed in the state of Santa Catarina, in southern Brazil. Ten weaned calves of each breed were grazed together on pasture and naturally infected with nematodes between July 2009 and December 2010. Once every 28 days, we collected fecal and blood samples for parasitological and immunological tests, as well as recording body weights. After 19 samplings, all animals were slaughtered for quantification and identification of GINs. We found that the animals had been infected with the following nematode species, in decreasing order by the mean number of specimens: Trichostrongylus axei, Cooperia punctata, Ostertagia ostertagi, Haemonchus placei, Oesophagostomum radiatum, and Trichuris spp. There were no significant differences between the Crioulo Lageano and crossbred Angus groups in terms of worm burden or nematode fecal egg count, nor in terms of the mean levels of immunoglobulin (G and A) against C. punctata and H. placei antigens, except in IgA mean level in abomasal mucus against H. placei adult worms that was significantly higher in crossbred Angus cattle (p<0.05). At the end of the study, the crossbred Angus cattle were heavier than were the Crioulo Lageano cattle (mean live weight, 507.35 and 390.3kg, respectively). Comparative parasitological and immunological evaluation revealed no difference between two breeds in terms of their natural resistance against GINs.