Camila Balconi Marques - Academia.edu (original) (raw)

Papers by Camila Balconi Marques

Research paper thumbnail of 28. Genetic parameters for feed efficiency, gas emissions, oxygen consumption and wool traits in Australian Merino

The purpose of the present study was to estimate genetic parameters of growing globally important... more The purpose of the present study was to estimate genetic parameters of growing globally important traits such as feed intake, residual feed intake, methane, carbon dioxide, oxygen consumption and greasy fleece weight in Uruguay. Data of three Australian Merino generations which integrate the Uruguayan National Genetic Evaluation for sheep were recorded (from 2019 to 2021). Heritabilities and genetic and phenotypic correlations were estimated for 930 animals sired by 19 rams. Results presented suggest that relevant genetic progress can be achieved in all traits (heritabilities between 0.23 and 0.41). Methane emission present moderate to high genetic correlations with the other traits (0.57-0.88). The most efficient animals will tend to consume less feed and emit less methane, without affecting wool production. The genetic correlation between wool production and the other traits were not significantly different from zero. The developing of this work will be the basis for the construction of agroecological breeding objectives.

Research paper thumbnail of Economic losses caused by the use of low-efficacy anthelmintic drugs in growing heifers

Tropical Animal Health and Production, Nov 22, 2019

The aim of this study was to compare the economic revenue related to the use of low-or high-effic... more The aim of this study was to compare the economic revenue related to the use of low-or high-efficacy anthelmintic drugs within suppressive or strategic schemes of treatment in growing heifers. Heifers raised in a semi-intensive grazing system in southern Brazil were used. Levamisole and ivermectin were selected as the high-and the low-efficacy drugs, respectively, based on a previous efficacy test. Subsequently, these drugs were used within strategic (Strat; four times per year) or suppressive (Supp; once a month) treatment regimens in the heifers, and their liveweight and eggs per gram of feces counts were monthly evaluated during a 13-month period. The total costs of the treatments and their cost-benefit ratio in regard to liveweight gain were calculated. Final mean liveweight gains (kg) observed were 126.7 (Strat-Low), 133.6 (Supp-Low), 141.3 (Strat-High), 142.9 (Supp-High), and 125.8 (Control). Treatments with a high-efficacy drug resulted in monetary gains of US$ 19.56 (Strat-High) and US$ 14.98 (Supp-High), but Supp-Low and Strat-Low treatments caused economic losses. Total cost of the efficacy test (US$ 374.79) could be paid by the additional liveweight gain of 20 heifers from the Strat-High group. These results showed that it would be preferable not to treat the heifers against GIN if compared with treating them with a low-efficacy drug. In addition, we showed that the use of four treatments per year with a high-efficacy drug-selected by efficacy test-resulted in a profitable management to control GIN in growing heifers raised in a semi-intensive gazing system in southern Brazil.

Research paper thumbnail of Multiple resistance in equine cyathostomins: a case study from military establishments in Rio Grande do Sul, Brazil

Revista Brasileira De Parasitologia Veterinaria, 2020

Semi-intensive equine breeding system favors gastrointestinal nematode infections. The treatment ... more Semi-intensive equine breeding system favors gastrointestinal nematode infections. The treatment of these infections is based on the use of anthelmintics. However, the inappropriate use of these drugs has led to parasitic resistance to the available active principles. The objective of this study was to evaluate the efficacy of the main classes of antiparasitic (ATP) used in control in adult and young animals, including: benzimidazoles (fenbendazole), pyrimidines (pyrantel pamoate), macrocyclic lactones (ivermectin and moxidectin), as well as the combination of active ingredients (ivermectin + pyrantel pamoate). The study was carried out in two military establishments, located in Rio Grande do Sul (RS), from January to December, 2018. The intervals between the treatments of the animals were performed from 30 to 90 days. Coproparasitological evaluations were determined by the egg count reduction in the faeces. Cyatostomine larvae were identified in pre and post-treatment cultures. The results demonstrated the multiple parasitic resistance of cyathostomins to fenbendazole, moxidectin in young animals, and to fenbendazole, pyrantel pamoate in adult animals. Thus, it is necessary to define or diagnose parasitic resistance to assist in the creation of prophylactic parasitic control, using suppressive treatment with ATP associated with integrated alternatives. The progress of parasitic resistance can be slowed.

Research paper thumbnail of O41 Breeding for improved feed efficiency and decreased methane emissions in sheep

Animal - science proceedings

Research paper thumbnail of O59 Breeding for improved feed efficiency and decreased methane emissions in sheep

Animal - science proceedings

Research paper thumbnail of 29. Genetic selection of feed efficiency and methane emissions in sheep and cattle in Uruguay: progress and limitations

Proceeding of 12th World Congress on Genetics Applied to Livestock Production (WCGALP)

Research paper thumbnail of Multiple resistance in equine cyathostomins: a case study from military establishments in Rio Grande do Sul, Brazil

Revista Brasileira de Parasitologia Veterinária, Sep 28, 2020

Semi-intensive equine breeding system favors gastrointestinal nematode infections. The treatment ... more Semi-intensive equine breeding system favors gastrointestinal nematode infections. The treatment of these infections is based on the use of anthelmintics. However, the inappropriate use of these drugs has led to parasitic resistance to the available active principles. The objective of this study was to evaluate the efficacy of the main classes of antiparasitic (ATP) used in control in adult and young animals, including: benzimidazoles (fenbendazole), pyrimidines (pyrantel pamoate), macrocyclic lactones (ivermectin and moxidectin), as well as the combination of active ingredients (ivermectin + pyrantel pamoate). The study was carried out in two military establishments, located in Rio Grande do Sul (RS), from January to December, 2018. The intervals between the treatments of the animals were performed from 30 to 90 days. Coproparasitological evaluations were determined by the egg count reduction in the faeces. Cyatostomine larvae were identified in pre and post-treatment cultures. The results demonstrated the multiple parasitic resistance of cyathostomins to fenbendazole, moxidectin in young animals, and to fenbendazole, pyrantel pamoate in adult animals. Thus, it is necessary to define or diagnose parasitic resistance to assist in the creation of prophylactic parasitic control, using suppressive treatment with ATP associated with integrated alternatives. The progress of parasitic resistance can be slowed.

Research paper thumbnail of Economic losses caused by the use of low-efficacy anthelmintic drugs in growing heifers

Tropical Animal Health and Production, 2019

The aim of this study was to compare the economic revenue related to the use of low-or high-effic... more The aim of this study was to compare the economic revenue related to the use of low-or high-efficacy anthelmintic drugs within suppressive or strategic schemes of treatment in growing heifers. Heifers raised in a semi-intensive grazing system in southern Brazil were used. Levamisole and ivermectin were selected as the high-and the low-efficacy drugs, respectively, based on a previous efficacy test. Subsequently, these drugs were used within strategic (Strat; four times per year) or suppressive (Supp; once a month) treatment regimens in the heifers, and their liveweight and eggs per gram of feces counts were monthly evaluated during a 13-month period. The total costs of the treatments and their cost-benefit ratio in regard to liveweight gain were calculated. Final mean liveweight gains (kg) observed were 126.7 (Strat-Low), 133.6 (Supp-Low), 141.3 (Strat-High), 142.9 (Supp-High), and 125.8 (Control). Treatments with a high-efficacy drug resulted in monetary gains of US$ 19.56 (Strat-High) and US$ 14.98 (Supp-High), but Supp-Low and Strat-Low treatments caused economic losses. Total cost of the efficacy test (US$ 374.79) could be paid by the additional liveweight gain of 20 heifers from the Strat-High group. These results showed that it would be preferable not to treat the heifers against GIN if compared with treating them with a low-efficacy drug. In addition, we showed that the use of four treatments per year with a high-efficacy drug-selected by efficacy test-resulted in a profitable management to control GIN in growing heifers raised in a semi-intensive gazing system in southern Brazil.

Research paper thumbnail of Genetic parameters for production traits, resistance and resilience to Nematode parasites under different worm burden challenges in Corriedale sheep

Veterinary Parasitology, 2020

Characterized as the most important gastrointestinal parasite (GIP) in the world, Haemonchus cont... more Characterized as the most important gastrointestinal parasite (GIP) in the world, Haemonchus contortus is also the most predominant and pathogenic genus in Uruguay, causing high morbidity and mortality rates in sheep flocks. For approximately 26 years resistance to GIP has been included in the National Genetic Evaluation (NGE) of Corriedale and Merino breeds, using Faecal Egg Count (FEC) as the selection criterion. The aim of the present study was to estimate genetic parameters for FEC, post-weaning Body Weight (BW), Packed Cell Volume (PCV), FAMACHA© and Body Condition Score (BCS), to determine the possibility to include these traits in the NGE of GIP resistance and resilience, as complementary selection criteria and to investigate the sensitivity of breeding values to different environmental worm burden challenges. Data were collected on 19,510 lambs from 2000 to 2009 in 24 Corriedale studs that participated in the NGE of sheep in Uruguay. (Co)variances components were estimated using a multi-trait animal model performing a Bayesian analysis. Posterior means estimated for heritability (h 2) were of low to moderate magnitude (between 0.10 and 0.33) for the traits analysed. Genetic correlations (r g) were not significantly different from zero for BW-Log e (FEC + 100), BW-FAMACHA©, BW-PCV, Log e (FEC + 100)-PCV, BCS-FAMACHA©, moderate favourable r g for Log e (FEC + 100)-FAMACHA and PCV-BCS (0.55, 0.41) and high favourable r g for BW-BCS (0.66). These results indicate the possibility to complement selection programs incorporating BW, Log e (FEC + 100), FAMACHA©, PCV and BCS in order to select resistant and resilient animal to GIP. Furthermore, genetic parameters for BW and Log e (FEC + 100) to different environmental worm burden challenge was investigated. Two contemporary groups of low worm environment (Log e (FEC + 100) below 6.40) and a high worm environment (Log e (FEC + 100) above 6.75) were considered. In this model, h 2 estimated for BW and Log e (FEC + 100) were found to be not statistically different between low and high environmental worm burden, furthermore, high correlations between traits at both environments were also presented.

Research paper thumbnail of Field and Molecular Evaluation of Anthelmintic Resistance of Nematode Populations from Cattle and Sheep Naturally Infected Pastured on Mixed Grazing areas at Rio Grande do Sul, Brazil

Acta Parasitologica, 2019

Background Reports of a lack of efficacy of most of the anthelmintic compounds for ruminants asso... more Background Reports of a lack of efficacy of most of the anthelmintic compounds for ruminants associated with the longtime necessity for creating new molecules have stressed the urgency to adopt alternative methods to control gastrointestinal parasites infection, such as strategies of sharing grazing areas. Therefore, this study aimed to evaluate nematode populations affecting cattle and sheep that share grazing areas before and after treatment with different anthelmintic compounds, and investigate the efficacy of anthelmintic treatment in these naturally infected ruminants at farms in the state of Rio Grande do Sul, Brazil. Methods The presence of co-infections by Haemonchus species was investigated by polymerase chain reaction (PCR) for groups treated with a benzimidazole. Farms were selected by: farmers' consent, presence of 42-60 (or more) calves and sheep per farm with counts of ≥ 200 eggs per gram of feces (EPG), availability of calves and lambs aging from 6 to 9 months, absence of anthelmintic treatment for both species for 60 days before the experimental period, and shared grazing areas between this species on each farm. Animals were distributed into six treatment groups for each ruminant species per farm and treated with: ivermectin, doramectin, moxidectin, levamisole, albendazole, and closantel. Results Levamisol was the most effective anthelmintic compound for both ruminant species. In general, Cooperia spp., Haemonchus spp., and Trichostrongylus spp. were the genus present after tested treatments that were ineffective. PCR showed the presence of Haemonchus species co-infections between cattle and sheep. Conclusion Therefore, this study demonstrated the similarity between nematode population, the presence of multi-resistant nematodes, and the presence of Haemonchus species co-infections affecting different ruminant species that share pastures.

Research paper thumbnail of Anti-Sarcocystis Antibodies in Lambs Deprived of Colostrum

Acta Parasitologica, 2019

Introduction The objective of this study was to evaluate the presence of anti-Sarcocystis spp. sp... more Introduction The objective of this study was to evaluate the presence of anti-Sarcocystis spp. specific IgG antibodies in serum samples from precolostral lambs to determine the occurrence of transplacental transmission of Sarcocystis spp. in sheep. Methods Blood samples were collected from 80 ewes and their respective lambs, immediately after lambing and before colostrum ingestion, respectively. The presence of anti-Sarcocystis spp. IgG was evaluated in serum samples using the indirect fluorescent antibody test (IFAT). Positive samples of the lambs were submitted to titration and IFAT to detect anti-T. gondii and anti-N. caninum specific IgG. Results Anti-Sarcocystis spp. IgG was detected in 62.5% of the ewes (50/80) and in 4% of the lambs of the seropositive ewes (2/50). None of the lambs from seronegative ewes were positive. The final titers of the positive lambs were 80. No cross reaction was detected among the positive samples to anti-Sarcocystis spp., anti-N. caninum, and anti-T. gondii IgG. The detection of anti-Sarcocystis spp. antibodies in serum samples of lambs deprived of colostrum suggests transplacental transmission of infection. Thus, the vertical transmission may be an alternative route of infection of Sarcocystis spp. also in sheep. Further studies are warranted to confirm transplacental transmission in sheep and to explain the importance of this infection pathway.

Research paper thumbnail of In vitro and in vivo acaricidal activity evaluation of organo-modified siloxanes in populations of Rhipicephalus microplus

Veterinary Parasitology, 2019

Infestations of Rhipicephalus microplus cause significant damage to cattle breeding and their con... more Infestations of Rhipicephalus microplus cause significant damage to cattle breeding and their control is primarily based on chemical products. There are extensive reports of efficacy losses of acaricid products over time, as well as resistance of the parasites to them, thereby making it necessary to search for new alternatives. The present work aimed to determine the in vitro and in vivo acaricidal activity of organo-modified siloxanes with and without piperonyl butoxide (PBO) in southern Brazil. For the in vitro test, engorged females of R. microplus were collected and submitted to the immersion test. The formulation containing organo-modified siloxanes was tested at 4 different concentrations: 0.6, 1.0, 2.5, and 5.0%. The lowest dilutions (0.6, 1.0, and 2.5%) were also tested with the inclusion of 10% PBO. The in vivo test was performed by applying 2.5% organo-modified siloxanes, and the addition of 10% PBO was applied by spraying. The results showed high acaricidal activity (100%) in vitro in the concentration of 5% on non-associated forms, and in combinations of concentrations of 0.6, 1.0, 2.5% with PBO. The in vivo results also increased the efficacy with the association of PBO. In view of the current multiresistance scenario of the R. microplus tick to the different commercially available acaricidal products, this study investigated the use of this product in association with PBO as an alternative to R. microplus control and found positive results. To the authors' knowledge, this is the first study to use organo-modified siloxanes against ticks.

Research paper thumbnail of Multiple resistance in equine cyathostomins: a case study from military establishments in Rio Grande do Sul, Brazil

Revista Brasileira de Parasitologia Veterinária, 2020

Semi-intensive equine breeding system favors gastrointestinal nematode infections. The treatment ... more Semi-intensive equine breeding system favors gastrointestinal nematode infections. The treatment of these infections is based on the use of anthelmintics. However, the inappropriate use of these drugs has led to parasitic resistance to the available active principles. The objective of this study was to evaluate the efficacy of the main classes of antiparasitic (ATP) used in control in adult and young animals, including: benzimidazoles (fenbendazole), pyrimidines (pyrantel pamoate), macrocyclic lactones (ivermectin and moxidectin), as well as the combination of active ingredients (ivermectin + pyrantel pamoate). The study was carried out in two military establishments, located in Rio Grande do Sul (RS), from January to December, 2018. The intervals between the treatments of the animals were performed from 30 to 90 days. Coproparasitological evaluations were determined by the egg count reduction in the faeces. Cyatostomine larvae were identified in pre and post-treatment cultures. The...

Research paper thumbnail of 28. Genetic parameters for feed efficiency, gas emissions, oxygen consumption and wool traits in Australian Merino

The purpose of the present study was to estimate genetic parameters of growing globally important... more The purpose of the present study was to estimate genetic parameters of growing globally important traits such as feed intake, residual feed intake, methane, carbon dioxide, oxygen consumption and greasy fleece weight in Uruguay. Data of three Australian Merino generations which integrate the Uruguayan National Genetic Evaluation for sheep were recorded (from 2019 to 2021). Heritabilities and genetic and phenotypic correlations were estimated for 930 animals sired by 19 rams. Results presented suggest that relevant genetic progress can be achieved in all traits (heritabilities between 0.23 and 0.41). Methane emission present moderate to high genetic correlations with the other traits (0.57-0.88). The most efficient animals will tend to consume less feed and emit less methane, without affecting wool production. The genetic correlation between wool production and the other traits were not significantly different from zero. The developing of this work will be the basis for the construction of agroecological breeding objectives.

Research paper thumbnail of Economic losses caused by the use of low-efficacy anthelmintic drugs in growing heifers

Tropical Animal Health and Production, Nov 22, 2019

The aim of this study was to compare the economic revenue related to the use of low-or high-effic... more The aim of this study was to compare the economic revenue related to the use of low-or high-efficacy anthelmintic drugs within suppressive or strategic schemes of treatment in growing heifers. Heifers raised in a semi-intensive grazing system in southern Brazil were used. Levamisole and ivermectin were selected as the high-and the low-efficacy drugs, respectively, based on a previous efficacy test. Subsequently, these drugs were used within strategic (Strat; four times per year) or suppressive (Supp; once a month) treatment regimens in the heifers, and their liveweight and eggs per gram of feces counts were monthly evaluated during a 13-month period. The total costs of the treatments and their cost-benefit ratio in regard to liveweight gain were calculated. Final mean liveweight gains (kg) observed were 126.7 (Strat-Low), 133.6 (Supp-Low), 141.3 (Strat-High), 142.9 (Supp-High), and 125.8 (Control). Treatments with a high-efficacy drug resulted in monetary gains of US$ 19.56 (Strat-High) and US$ 14.98 (Supp-High), but Supp-Low and Strat-Low treatments caused economic losses. Total cost of the efficacy test (US$ 374.79) could be paid by the additional liveweight gain of 20 heifers from the Strat-High group. These results showed that it would be preferable not to treat the heifers against GIN if compared with treating them with a low-efficacy drug. In addition, we showed that the use of four treatments per year with a high-efficacy drug-selected by efficacy test-resulted in a profitable management to control GIN in growing heifers raised in a semi-intensive gazing system in southern Brazil.

Research paper thumbnail of Multiple resistance in equine cyathostomins: a case study from military establishments in Rio Grande do Sul, Brazil

Revista Brasileira De Parasitologia Veterinaria, 2020

Semi-intensive equine breeding system favors gastrointestinal nematode infections. The treatment ... more Semi-intensive equine breeding system favors gastrointestinal nematode infections. The treatment of these infections is based on the use of anthelmintics. However, the inappropriate use of these drugs has led to parasitic resistance to the available active principles. The objective of this study was to evaluate the efficacy of the main classes of antiparasitic (ATP) used in control in adult and young animals, including: benzimidazoles (fenbendazole), pyrimidines (pyrantel pamoate), macrocyclic lactones (ivermectin and moxidectin), as well as the combination of active ingredients (ivermectin + pyrantel pamoate). The study was carried out in two military establishments, located in Rio Grande do Sul (RS), from January to December, 2018. The intervals between the treatments of the animals were performed from 30 to 90 days. Coproparasitological evaluations were determined by the egg count reduction in the faeces. Cyatostomine larvae were identified in pre and post-treatment cultures. The results demonstrated the multiple parasitic resistance of cyathostomins to fenbendazole, moxidectin in young animals, and to fenbendazole, pyrantel pamoate in adult animals. Thus, it is necessary to define or diagnose parasitic resistance to assist in the creation of prophylactic parasitic control, using suppressive treatment with ATP associated with integrated alternatives. The progress of parasitic resistance can be slowed.

Research paper thumbnail of O41 Breeding for improved feed efficiency and decreased methane emissions in sheep

Animal - science proceedings

Research paper thumbnail of O59 Breeding for improved feed efficiency and decreased methane emissions in sheep

Animal - science proceedings

Research paper thumbnail of 29. Genetic selection of feed efficiency and methane emissions in sheep and cattle in Uruguay: progress and limitations

Proceeding of 12th World Congress on Genetics Applied to Livestock Production (WCGALP)

Research paper thumbnail of Multiple resistance in equine cyathostomins: a case study from military establishments in Rio Grande do Sul, Brazil

Revista Brasileira de Parasitologia Veterinária, Sep 28, 2020

Semi-intensive equine breeding system favors gastrointestinal nematode infections. The treatment ... more Semi-intensive equine breeding system favors gastrointestinal nematode infections. The treatment of these infections is based on the use of anthelmintics. However, the inappropriate use of these drugs has led to parasitic resistance to the available active principles. The objective of this study was to evaluate the efficacy of the main classes of antiparasitic (ATP) used in control in adult and young animals, including: benzimidazoles (fenbendazole), pyrimidines (pyrantel pamoate), macrocyclic lactones (ivermectin and moxidectin), as well as the combination of active ingredients (ivermectin + pyrantel pamoate). The study was carried out in two military establishments, located in Rio Grande do Sul (RS), from January to December, 2018. The intervals between the treatments of the animals were performed from 30 to 90 days. Coproparasitological evaluations were determined by the egg count reduction in the faeces. Cyatostomine larvae were identified in pre and post-treatment cultures. The results demonstrated the multiple parasitic resistance of cyathostomins to fenbendazole, moxidectin in young animals, and to fenbendazole, pyrantel pamoate in adult animals. Thus, it is necessary to define or diagnose parasitic resistance to assist in the creation of prophylactic parasitic control, using suppressive treatment with ATP associated with integrated alternatives. The progress of parasitic resistance can be slowed.

Research paper thumbnail of Economic losses caused by the use of low-efficacy anthelmintic drugs in growing heifers

Tropical Animal Health and Production, 2019

The aim of this study was to compare the economic revenue related to the use of low-or high-effic... more The aim of this study was to compare the economic revenue related to the use of low-or high-efficacy anthelmintic drugs within suppressive or strategic schemes of treatment in growing heifers. Heifers raised in a semi-intensive grazing system in southern Brazil were used. Levamisole and ivermectin were selected as the high-and the low-efficacy drugs, respectively, based on a previous efficacy test. Subsequently, these drugs were used within strategic (Strat; four times per year) or suppressive (Supp; once a month) treatment regimens in the heifers, and their liveweight and eggs per gram of feces counts were monthly evaluated during a 13-month period. The total costs of the treatments and their cost-benefit ratio in regard to liveweight gain were calculated. Final mean liveweight gains (kg) observed were 126.7 (Strat-Low), 133.6 (Supp-Low), 141.3 (Strat-High), 142.9 (Supp-High), and 125.8 (Control). Treatments with a high-efficacy drug resulted in monetary gains of US$ 19.56 (Strat-High) and US$ 14.98 (Supp-High), but Supp-Low and Strat-Low treatments caused economic losses. Total cost of the efficacy test (US$ 374.79) could be paid by the additional liveweight gain of 20 heifers from the Strat-High group. These results showed that it would be preferable not to treat the heifers against GIN if compared with treating them with a low-efficacy drug. In addition, we showed that the use of four treatments per year with a high-efficacy drug-selected by efficacy test-resulted in a profitable management to control GIN in growing heifers raised in a semi-intensive gazing system in southern Brazil.

Research paper thumbnail of Genetic parameters for production traits, resistance and resilience to Nematode parasites under different worm burden challenges in Corriedale sheep

Veterinary Parasitology, 2020

Characterized as the most important gastrointestinal parasite (GIP) in the world, Haemonchus cont... more Characterized as the most important gastrointestinal parasite (GIP) in the world, Haemonchus contortus is also the most predominant and pathogenic genus in Uruguay, causing high morbidity and mortality rates in sheep flocks. For approximately 26 years resistance to GIP has been included in the National Genetic Evaluation (NGE) of Corriedale and Merino breeds, using Faecal Egg Count (FEC) as the selection criterion. The aim of the present study was to estimate genetic parameters for FEC, post-weaning Body Weight (BW), Packed Cell Volume (PCV), FAMACHA© and Body Condition Score (BCS), to determine the possibility to include these traits in the NGE of GIP resistance and resilience, as complementary selection criteria and to investigate the sensitivity of breeding values to different environmental worm burden challenges. Data were collected on 19,510 lambs from 2000 to 2009 in 24 Corriedale studs that participated in the NGE of sheep in Uruguay. (Co)variances components were estimated using a multi-trait animal model performing a Bayesian analysis. Posterior means estimated for heritability (h 2) were of low to moderate magnitude (between 0.10 and 0.33) for the traits analysed. Genetic correlations (r g) were not significantly different from zero for BW-Log e (FEC + 100), BW-FAMACHA©, BW-PCV, Log e (FEC + 100)-PCV, BCS-FAMACHA©, moderate favourable r g for Log e (FEC + 100)-FAMACHA and PCV-BCS (0.55, 0.41) and high favourable r g for BW-BCS (0.66). These results indicate the possibility to complement selection programs incorporating BW, Log e (FEC + 100), FAMACHA©, PCV and BCS in order to select resistant and resilient animal to GIP. Furthermore, genetic parameters for BW and Log e (FEC + 100) to different environmental worm burden challenge was investigated. Two contemporary groups of low worm environment (Log e (FEC + 100) below 6.40) and a high worm environment (Log e (FEC + 100) above 6.75) were considered. In this model, h 2 estimated for BW and Log e (FEC + 100) were found to be not statistically different between low and high environmental worm burden, furthermore, high correlations between traits at both environments were also presented.

Research paper thumbnail of Field and Molecular Evaluation of Anthelmintic Resistance of Nematode Populations from Cattle and Sheep Naturally Infected Pastured on Mixed Grazing areas at Rio Grande do Sul, Brazil

Acta Parasitologica, 2019

Background Reports of a lack of efficacy of most of the anthelmintic compounds for ruminants asso... more Background Reports of a lack of efficacy of most of the anthelmintic compounds for ruminants associated with the longtime necessity for creating new molecules have stressed the urgency to adopt alternative methods to control gastrointestinal parasites infection, such as strategies of sharing grazing areas. Therefore, this study aimed to evaluate nematode populations affecting cattle and sheep that share grazing areas before and after treatment with different anthelmintic compounds, and investigate the efficacy of anthelmintic treatment in these naturally infected ruminants at farms in the state of Rio Grande do Sul, Brazil. Methods The presence of co-infections by Haemonchus species was investigated by polymerase chain reaction (PCR) for groups treated with a benzimidazole. Farms were selected by: farmers' consent, presence of 42-60 (or more) calves and sheep per farm with counts of ≥ 200 eggs per gram of feces (EPG), availability of calves and lambs aging from 6 to 9 months, absence of anthelmintic treatment for both species for 60 days before the experimental period, and shared grazing areas between this species on each farm. Animals were distributed into six treatment groups for each ruminant species per farm and treated with: ivermectin, doramectin, moxidectin, levamisole, albendazole, and closantel. Results Levamisol was the most effective anthelmintic compound for both ruminant species. In general, Cooperia spp., Haemonchus spp., and Trichostrongylus spp. were the genus present after tested treatments that were ineffective. PCR showed the presence of Haemonchus species co-infections between cattle and sheep. Conclusion Therefore, this study demonstrated the similarity between nematode population, the presence of multi-resistant nematodes, and the presence of Haemonchus species co-infections affecting different ruminant species that share pastures.

Research paper thumbnail of Anti-Sarcocystis Antibodies in Lambs Deprived of Colostrum

Acta Parasitologica, 2019

Introduction The objective of this study was to evaluate the presence of anti-Sarcocystis spp. sp... more Introduction The objective of this study was to evaluate the presence of anti-Sarcocystis spp. specific IgG antibodies in serum samples from precolostral lambs to determine the occurrence of transplacental transmission of Sarcocystis spp. in sheep. Methods Blood samples were collected from 80 ewes and their respective lambs, immediately after lambing and before colostrum ingestion, respectively. The presence of anti-Sarcocystis spp. IgG was evaluated in serum samples using the indirect fluorescent antibody test (IFAT). Positive samples of the lambs were submitted to titration and IFAT to detect anti-T. gondii and anti-N. caninum specific IgG. Results Anti-Sarcocystis spp. IgG was detected in 62.5% of the ewes (50/80) and in 4% of the lambs of the seropositive ewes (2/50). None of the lambs from seronegative ewes were positive. The final titers of the positive lambs were 80. No cross reaction was detected among the positive samples to anti-Sarcocystis spp., anti-N. caninum, and anti-T. gondii IgG. The detection of anti-Sarcocystis spp. antibodies in serum samples of lambs deprived of colostrum suggests transplacental transmission of infection. Thus, the vertical transmission may be an alternative route of infection of Sarcocystis spp. also in sheep. Further studies are warranted to confirm transplacental transmission in sheep and to explain the importance of this infection pathway.

Research paper thumbnail of In vitro and in vivo acaricidal activity evaluation of organo-modified siloxanes in populations of Rhipicephalus microplus

Veterinary Parasitology, 2019

Infestations of Rhipicephalus microplus cause significant damage to cattle breeding and their con... more Infestations of Rhipicephalus microplus cause significant damage to cattle breeding and their control is primarily based on chemical products. There are extensive reports of efficacy losses of acaricid products over time, as well as resistance of the parasites to them, thereby making it necessary to search for new alternatives. The present work aimed to determine the in vitro and in vivo acaricidal activity of organo-modified siloxanes with and without piperonyl butoxide (PBO) in southern Brazil. For the in vitro test, engorged females of R. microplus were collected and submitted to the immersion test. The formulation containing organo-modified siloxanes was tested at 4 different concentrations: 0.6, 1.0, 2.5, and 5.0%. The lowest dilutions (0.6, 1.0, and 2.5%) were also tested with the inclusion of 10% PBO. The in vivo test was performed by applying 2.5% organo-modified siloxanes, and the addition of 10% PBO was applied by spraying. The results showed high acaricidal activity (100%) in vitro in the concentration of 5% on non-associated forms, and in combinations of concentrations of 0.6, 1.0, 2.5% with PBO. The in vivo results also increased the efficacy with the association of PBO. In view of the current multiresistance scenario of the R. microplus tick to the different commercially available acaricidal products, this study investigated the use of this product in association with PBO as an alternative to R. microplus control and found positive results. To the authors' knowledge, this is the first study to use organo-modified siloxanes against ticks.

Research paper thumbnail of Multiple resistance in equine cyathostomins: a case study from military establishments in Rio Grande do Sul, Brazil

Revista Brasileira de Parasitologia Veterinária, 2020

Semi-intensive equine breeding system favors gastrointestinal nematode infections. The treatment ... more Semi-intensive equine breeding system favors gastrointestinal nematode infections. The treatment of these infections is based on the use of anthelmintics. However, the inappropriate use of these drugs has led to parasitic resistance to the available active principles. The objective of this study was to evaluate the efficacy of the main classes of antiparasitic (ATP) used in control in adult and young animals, including: benzimidazoles (fenbendazole), pyrimidines (pyrantel pamoate), macrocyclic lactones (ivermectin and moxidectin), as well as the combination of active ingredients (ivermectin + pyrantel pamoate). The study was carried out in two military establishments, located in Rio Grande do Sul (RS), from January to December, 2018. The intervals between the treatments of the animals were performed from 30 to 90 days. Coproparasitological evaluations were determined by the egg count reduction in the faeces. Cyatostomine larvae were identified in pre and post-treatment cultures. The...