Effect of antihelminths with contrasting efficacy against gastrointestinal nematodes on the live-weight gain of young Nellore cattle.

We estimated the losses caused by gastrointestinal nematode (GIN) infections in young Nellore cattle born in three consecutive calving seasons (Cycles I, II and III). Three groups of animals: Group 1 - free from GIN using 2.5 mg/kg of albendazole sulfoxide; Group II - free from Oesophagosomum radiatum using 0.2 mg/kg of ivermectin but infected with ivermectin-resistant Haemonchus placei and Cooperia spp.; and Group III - non-treated experimental control animals, infected with all GIN, were observed over a period of 12 months. Male and female calves were evaluated starting before weaning when the animals were an average of approximately four months of age. In Cycle I, only females were evaluated. All the animals continued to graze on pastures of Urochloa spp. (= Brachiaria). All the groups showed median faecal egg counts of fewer than 250 eggs per gram (EPG), and no clinical signs of parasitic gastroenteritis were observed. The blood variables were within the normal ranges, and no calf presented anaemia. In most of the samplings, the median EPGs were significantly lower (P < 0.05) in the group treated with albendazole. Throughout the experiment, the most prevalent parasite observed in the control group was Cooperia spp., followed in decreasing order by Haemonchus spp., O. radiatum and Trichostrongylus spp. All the groups of calves exhibited weight gain throughout the trials with control group displaying the lowest body weight gain. Body weight variables between the albendazole- and ivermectin-treated groups were not significantly different (P > 0.05). After weaning, females animals in albendazole and ivermectin treated groups exhibited higher body weights, 20.4% and 22.7%, respectively, than those of the control group. Likewise, males treated with albendazole and ivermectin exhibited 27.6% and 25.8%, respectively, more body weight gain than animals under control group. Because the main difference between the ivermectin and the control groups was the O. radiatum parasitism, most of the losses in the control group were possibly due to this nematode species. Nevertheless, the other nematodes species that occurred in relatively high intensities in control group could also have an additive effect in such losses.

Performance of lambs under four levels of dietary supplementation and artificially mix-infected with Haemonchus contortus and Trichostrongylus colubriformis.

The effect of four diets on the performance of Dorper lambs that were artificially mix-infected with 1000 infective larvae (L3) of Haemonchus contortus and 1000 L3 of Trichostrongylus colubriformis every three days for 12 weeks was evaluated. For each diet, one infected group (n = 7) and one control group (n = 4) were set up. The four diets contained the following proportions of hay (H) and concentrate (C): Diet 1 - 100%H; Diet 2 - 75%H:25%C; Diet 3 - 50%H:50%C; Diet 4 - 25%H:75. All the infected groups showed decreases in mean packed cell volume (PCV) and total plasma protein, especially the Diet 1-infected, which was also the group with the highest fecal egg count. The diets and infection had significant effects (P < 0.05) on daily body weight gain (DBWG), cold carcass weight and daily food consumption. The control and infected groups had mean DBWG (in kg), respectively, of 0.048 and 0.025 with Diet 1; 0.082 and 0.067 with Diet 2; 0.188 and 0.189 with Diet 3; and 0.303 and 0.221 with Diet 4. In conclusion, the infection affected the productive performance regardless of the diet; however, with increased metabolizable protein and energy, the risk of occurrence of anemia and hypoproteinemia diminished.

Performance of lambs under four levels of dietary supplementation and artificially mix-infected with Haemonchus contortus and Trichostrongylus colubriformis / Efeito de quatro dietas na performance de cordeiros artificialmente infectados com Haemonchus contortus e Trichostrongylus colubriformis

Abstract The effect of four diets on the performance of Dorper lambs that were artificially mix-infected with 1000 infective larvae (L3) of Haemonchus contortus and 1000 L3 of Trichostrongylus colubriformis every three days for 12 weeks was evaluated. For each diet, one infected group (n = 7) and one control group (n = 4) were set up. The four diets contained the following proportions of hay (H) and concentrate (C): Diet 1 - 100%H; Diet 2 - 75%H:25%C; Diet 3 - 50%H:50%C; Diet 4 - 25%H:75. All the infected groups showed decreases in mean packed cell volume (PCV) and total plasma protein, especially the Diet 1-infected, which was also the group with the highest fecal egg count. The diets and infection had significant effects (P < 0.05) on daily body weight gain (DBWG), cold carcass weight and daily food consumption. The control and infected groups had mean DBWG (in kg), respectively, of 0.048 and 0.025 with Diet 1; 0.082 and 0.067 with Diet 2; 0.188 and 0.189 with Diet 3; and 0.303 and 0.221 with Diet 4. In conclusion, the infection affected the productive performance regardless of the diet; however, with increased metabolizable protein and energy, the risk of occurrence of anemia and hypoproteinemia diminished.

Resumo Avaliou-se o efeito de quatro dietas sobre o desempenho de cordeiros Dorper infectados artificialmente, a cada três dias, durante 12 semanas, com 1.000 larvas infectantes (L3) de Haemonchus contortus e 1.000 L3 de Trichostrongylus colubriformis. Um grupo infectado (n=7) e um controle (n=4) foram constituídos para cada uma das dietas, que continham a seguinte proporção de feno (F) e concentrado (C): Dieta 1 - 100%F; Dieta 2 - 75%F:25%C; Dieta 3 - 50%F:50%C; Dieta 4 - 25%F:75%C. Todos os grupos infectados apresentaram redução nas médias de hematócrito (VG) e proteína plasmática total (PPT), principalmente o grupo Dieta 1 infectado, que também apresentou maior contagem de ovos nas fezes. Houve efeito significativo da dieta e da infecção (P <0,05) no ganho em peso médio diário, peso da carcaça e consumo diário de alimento. Os grupos controle e infectado tiveram ganho em peso médio diário (em kg), respectivamente, de 0,048 e 0,025 na Dieta 1; 0,082 e 0,067 na Dieta 2; 0,188 e 0,189 na Dieta 3; e 0,303 e 0,221 na Dieta 4. Concluiu-se que a infecção afetou o desempenho produtivo independentemente da dieta, porém, com o aumento da proteína e da energia metabolizável, o risco de ocorrência de anemia e hipoproteinemia diminuiu.

Gastrointestinal nematode infections do not hinder the development of Simmental X Nellore crossbred calves raised with a nutritionally enhanced diet.

An evaluation was made of the effect of anthelmintic treatments on the performance of Simmental X Nellore crossbred calves before and after weaning. To this end, the calves were divided into three groups: (1) treated monthly with a low efficacy anthelmintic drug, ivermectin; (2) treated monthly with a highly effective anthelmintic drug, albendazole; and (3) untreated control group. All the groups in this experiment showed an average fecal egg count of less than 400 eggs per gram (EPG), and no clinical signs of parasitic gastroenteritis. The blood variables were within the normal range and no calf presented anemia. In most of the samplings, mean EPGs were significantly lower (P<0.05) in the group treated with albendazole. The calves received dietary supplementation before and after weaning, which enabled them to gain weight in every month of the experiment and reach a body weight of about 250 kg on the last sampling date, before turning one year old. The anthelmintic treatments did not affect body weight gain, leading to the conclusion that, when fed with suitable dietary supplements, Simmental X Nellore crossbred calves are not affected by gastrointestinal nematode parasites acquired by grazing.

Gastrointestinal nematode infections do not hinder the development of Simmental X Nellore crossbred calves raised with a nutritionally enhanced diet / Infecções por nematódeos gastrintestinais não prejudicam o desenvolvimento de bezerros Simental x Nelore criados em plano nutricional elevado

Abstract An evaluation was made of the effect of anthelmintic treatments on the performance of Simmental X Nellore crossbred calves before and after weaning. To this end, the calves were divided into three groups: (1) treated monthly with a low efficacy anthelmintic drug, ivermectin; (2) treated monthly with a highly effective anthelmintic drug, albendazole; and (3) untreated control group. All the groups in this experiment showed an average fecal egg count of less than 400 eggs per gram (EPG), and no clinical signs of parasitic gastroenteritis. The blood variables were within the normal range and no calf presented anemia. In most of the samplings, mean EPGs were significantly lower (P<0.05) in the group treated with albendazole. The calves received dietary supplementation before and after weaning, which enabled them to gain weight in every month of the experiment and reach a body weight of about 250 kg on the last sampling date, before turning one year old. The anthelmintic treatments did not affect body weight gain, leading to the conclusion that, when fed with suitable dietary supplements, Simmental X Nellore crossbred calves are not affected by gastrointestinal nematode parasites acquired by grazing.

Resumo O objetivo do experimento foi avaliar o efeito de tratamentos anti-helmínticos no desempenho de bezerros Simental x Nelore antes e após o desmame. Os bezerros foram alocados em três grupos: (1) tratado mensalmente com anti-helmínticos de baixa eficácia, ivermectina; (2) tratado mensalmente com anti-helmíntico de alta eficácia, albendazol e (3) controle não tratado. A média das contagens de ovos de nematoides durante o experimento foi inferior a 400 ovos por grama (OPG) em todos os grupos sem manifestação clínica de gastroenterite parasitária. As variáveis ​​sanguíneas mantiveram-se dentro dos limites de normalidade e nenhum bezerro apresentou anemia. Na maioria das coletas, as médias de OPG foram significativamente inferiores (P<0,05) no grupo tratado com albendazol. Os bezerros receberam suplementação antes e depois do desmame, o que lhes permitiu ganhar peso em todos os meses do experimento, atingindo peso corporal em torno de 250 kg, ao final do experimento, antes de completarem um ano de idade. Não houve efeito dos tratamentos anti-helmínticos no ganho em peso, o que permitiu concluir que bezerros Nelore x Simental não são afetados pelo parasitismo por nematoides gastrintestinais sob condições de pastejo, quando devidamente suplementados com concentrado.

The effects of diet and corticosteroid-induced immune suppression during infection by Haemonchus contortus in lambs.

To evaluate the effects of Diet and corticosteroid-induced immune suppression during infection by Haemonchus contortus, 28 lambs were allocated to one of four groups treated as follows: Group Basal Diet - Normal; Group Basal Diet - Immune-Suppressed; Group Supplemented Diet - Normal; and Group Supplemented Diet - Immune-Suppressed. The Basal Diet contained Cynodon dactylon (cv. coast cross) hay with 82 g crude protein (CP)/kg dry matter (DM), which was provided to the lambs in all groups ad libitum. In addition, animals on the Supplemented Diet received daily a commercial concentrate containing 171 g CP/kg DM, which was offered in an amount corresponding to 3% of the animal's live weight. The Immune-Suppressed groups received treatments with the glucocorticoid methylprednisolone sodium succinate (1.33 mg/kg of body weight), administered weekly. All lambs received a single infection with 4000 H. contortus infective larvae (L3) and were euthanised 28 days post-infection. Differences in pH and in the short-chain fatty acid (SCFA) concentrations occurred in rumen as a result of the distinct Diets offered to lambs. Such changes, however, did not have any apparent effect on larvae exsheathment and/or larvae survival inside the rumen, with all groups presenting similar worm burdens. However, animals on the Supplemented Diet presented reductions in worm growth and faecal egg counts. There was a significant effect of the Diet on the IgG levels against total antigens of H. contortus L3 from 7 to 27 days post-infection, with supplemented animals showing higher overall mean values (P<0.05). The immunosuppressive treatments had no effect on worm burden despite the reduction in the numbers of inflammatory cells in the abomasal mucosa of the Immune-Suppressed groups. These groups showed longer worms and females with more eggs in comparison with their counterparts fed each Diet; however, only the length of males was significantly affected (P<0.05). In conclusion, the changes caused in the rumen contents by supplementation with concentrate did not impair H. contortus establishment.

Dermatobia hominis: Potencial risk of resistance to macrocyclic lactones.

Dermatobia hominis is an ectoparasite that infests various species of mammals, including cattle, impairing the quality of cowhides and leather. After observing natural infestation with D. hominis larvae in cattle on two farms in the state of São Paulo, Brazil, we evaluated the efficacy of two macrocyclic lactones, ivermectin and moxidectin, against this parasite. The drugs were administered to 10 animals in each group, following the manufacturer's instructions. The groups were: Group 1-treated with ivermectin (0.2mg/kg of body weight (BW)); Group 2-treated with moxidectin (0.2mg/kg BW); and Group 3-control (untreated). On the farm in Pardinho, a total of 12 and 16 live larvae were found in 6 and in 8 animals 10 days after the treatment with ivermectin and moxidectin, respectively, while in the control group 4 bovines had a total of 7 live larvae. On the farm in Anhembi, 2, 4 and 6 live larvae were extracted from ivermectin, moxidectin and control groups, respectively, after the treatment. This is the first report of the presence of live D. hominis larvae after the treatment of cattle with ivermectin and moxidectin in Brazil.

Diagnosis of anthelmintic resistance in cattle in Brazil: a comparison of different methodologies.

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.

First record of notoedric mange in ocelot (Leopardus pardalis Linnaeus, 1758) in the Amazon region, Brazil.

This paper describes a case of notoedric mange in an ocelot (Leopardus pardalis) in the Brazilian Amazon region. A young male of approximately four months of age that was illegally kept as a pet was apprehended in Altamira, State of Pará, northern Brazil. The animal was transported to the Mangal das Garças Park in the state's capital city of Belém. The ocelot had pruritus and lesions suggestive of scabies in the head. Skin scraping material was examined under optic microscopy. There was seen a large number of eggs, larvae, nymphs and adult mites. The mean female and male sizes were 230.2 × 200.4 µm and 137.6 × 104.9 µm. Based on the morphologic characteristics and morphometric analysis, this mite was classified as Notoedres cati. This is the first report of notoedric mange in L. pardalis from Brazilian Amazon.

First record of notoedric mange in ocelot (Leopardus pardalis Linnaeus, 1758) in the amazon region, Brazil / Primeiro relato de sarna notoédrica em jaguatirica (Leopardus pardalis Linnaeus, 1758) na região amazônica, Brasil

This paper describes a case of notoedric mange in an ocelot (Leopardus pardalis) in the Brazilian Amazon region. A young male of approximately four months of age that was illegally kept as a pet was apprehended in Altamira, State of Pará, northern Brazil. The animal was transported to the Mangal das Garças Park in the state's capital city of Belém. The ocelot had pruritus and lesions suggestive of scabies in the head. Skin scraping material was examined under optic microscopy. There was seen a large number of eggs, larvae, nymphs and adult mites. The mean female and male sizes were 230.2 × 200.4 µm and 137.6 × 104.9 µm. Based on the morphologic characteristics and morphometric analysis, this mite was classified as Notoedres cati. This is the first report of notoedric mange in L. pardalis from Brazilian Amazon.

O presente estudo descreve um caso de sarna notoédrica em uma jaguatirica (Leopardus pardalis) na região da Amazônia Brasileira. Um macho jovem com aproximadamente quatro meses de idade, ilegalmente mantido como animal de estimação, foi apreendido em uma residência em Altamira, Estado do Pará, Brasil. O animal foi transportado para o Parque Mangal das Garças, município de Belém, estado do Pará. A jaguatirica apresentava prurido e lesões sugestivas de escabiose na cabeça, por isso um raspado cutâneo foi realizado e examinado ao microscópio óptico. Foi observado um grande número de ovos, larvas, ninfas e ácaros adultos. Os exemplares fêmeas mediram em média 230,2 × 200,4 µm, e os exemplares machos mensuraram 137,6 × 104,9 µm. Com base nas características morfológicas e análises morfométricas, o ácaro foi classificado como Notoedres cati. Esse é o primeiro relato da sarna notoédrica em L. pardalis na Amazônia Brasileira.