Gabriela Almeida Bastos

In vitro and in vivo action of Piptadenia viridiflora (Kunth) Benth against Haemonchus contortus in sheep.

Anthelminthic resistant populations of Haemonchus contortus are a major problem in sheep rearing, but plant extracts may offer viable alternative treatments. In our preliminary studies, Piptadenia viridiflora was frequently selected by sheep grazing in the Cerrado. The present research evaluated its in vitro and in vivo anthelmintic activity. The HPLC chromatograms of P. viridiflora aqueous extract (AE) and ethanolic extract (EE) showed the presence of flavonoids. The total condensed tannin (proanthocyanidin) was 0.2 and 1.01% in AE and EE, respectively. In an egg hatching inhibition (EHI) test, the LC90 of AE was 2.4mg/mL, and, of EE, was 2.1mg/mL. After tannin extraction, higher EHI and lower LC90 were observed. In a larval development inhibition test, the LC90 of AE was 13.66mg/g of fecal culture. The highest dose of AE administered to mice (203.0mg/kg bw) was well tolerated, suggesting low toxicity. In vivo, AE was orally administered to lambs at 283mg/kg bw, and, at weeks one, two, and three post-treatment, the mean fecal egg count (FEC) was significantly lower than in untreated lambs (P<0.05). Blood parameters were normal and similar in untreated and treated sheep. For all lamb groups, the mean total serum protein was significantly higher at week two post-treatment than at other evaluated periods (P<0.05). Piptadenia viridiflora extracts had low condensed tannin content and exhibited high anthelminthic efficacy in vitro and significantly reduced FEC. Tannins were not shown to be the principal components affecting EHI, hence it is necessary to isolate and characterize the principal active P. viridiflora compounds, and to assess their possible synergism.

Control of Haematobia irritans in the Minas Gerais Semiarid

Background: Beef cattle is considered to be one of the most important economic activities, however, it presents problems in the production chain such as the occurrence of parasites that reduce the growth, performance, productivity and may cause mortalities occasionally. The chemical control is the most used alternative to reduce ectoparasites. Nevertheless, inappropriate management of insecticides has contributed to the selection of population resistant to the products available on the market. This paper aimed to evaluate the practices of management and the application of insecticides used to control horn flies in farms of dairy cattle in the North of the state of Minas Gerais. Materials, Methods & Results: It was visited 62 rural properties, which produce milk. Semi-structured questionnaires were applied in order to obtain information on the characteristics of the properties (location, size and type of the cattle), on the knowledge about the epidemiology of the horn flies, and on the practices adopted to the control of those parasites. The practices adopted include the moment of application of the insecticides, frequency of the cattle treatment, used products, method of application, number of animals treated, and choice and substitution criteria of insecticides. The data collected were tabulated in contingency tables, and they were analyzed using the chi-square test, considering a significance of 5%. The racial composition of the cattle in the farms was mainly mixed-race of unknown origin, representing 77% of the animals evaluated. In this research, it was reported a greater incidence of horn flies infestation on adult beef herd, and 23.6% of the producers reported occurrences of infestation in the whole herd, not differing by categories. The infestation peaks of the fly occurred from November to March. It was also found a greater frequency of pyrethroid use in the region (P < 0.001), where 43.1% of the producers used associations of pyrethroid or organophosphate to control the flies, high efficiency being reported. From the properties assessed, 92% presented inadequacy in the practices of control of horn flies, for instance, the lack of using cattle manure tank, the accumulation of open waste, the lack of rotation of insecticides, which can favor the selection of resistant flies. Discussion: In this paper, it was reported 77.19% of predominance of Haematobia irritans infestation from November to March mainly in animals with a higher percentage of European or mixed-race genetics. Such results corroborate with the literature, because it was verified the influence of race and hair color in the level of infestation in the animals, although, in the same race, each individual presents different susceptibilities. Taurine beef cattle are more susceptible to infestation by horn flies than zebu cattle. Thus, the lower the proportion of zebu cattle genetics in the herd, the greater the infestation. Taurine beef cattle are more infested because shows a greater number of sebaceous glands and greater concentration of testosterone being attractive before the calves castrated, cows, and after, young animals. Cypermethrin was predominant in most part of the commercial insecticides used in the properties to control this ectoparasite, which could be justified by the large number of products available on the market with such compound in the formulations. The high efficiency of the associations of the insecticides reported by the producers could justify itself by the presence of active ingredients with different mechanisms of action. However, the limitation on the use of these associations is that not always the chemical compounds contained in the drug act simultaneously, being able to favor the selection of parasites resistant to different insecticides present in these formulations.

Perfil sanguíneo e peso de órgãos internos de bezerros leiteiros criados em diferentes sistemas de aleitamento

ABSTRACT.- Azevedo R.A., Soares A.C.M., Rufino S.R.A., Bastos G.A., Coelho S.G., Duarte E.R., Geraseev L.C. & Oliveira N.J.F. 2014. [Blood profile and weight of internal organs of dairy calves in different nursing systems.] Perfil sanguineo e peso de orgaos internos de bezerros leiteiros criados em diferentes sistemas de aleitamento. Pesquisa Veterinaria Bra -sileira 34(8):785-790. Departamento de Zootecnia, Instituto de Ciencias Agrarias, Universi-dade Federal de Minas Gerais, Avenida Universitaria 1000, Montes Claros, MG 39404-547, Brazil. E-mail: rafaelzooufmg@gmail.comThe objective was to evaluate the blood profile together with the relative and absolute size of the internal organs of calves in conventional or fractionated feeding system. Ten females were used, with an average initial body weight of 37.53 kg (±2.36), and 12 males with a mean body weight of 81.6 kg (±8.6), both Holstein breed. The conventional feeding consisted of four liter milk supplied daily for 54 days of evaluation, and fractioned six liter milk was given from 6 to 25 days of age, four liter from 26 to 45 days of ager, and two liter from 46 to 59 days of age.