Avaliação das infecções parasitárias de bovinos em uma fazenda na região do Vale do Mucuri, MG

Abstract

From november 2007 to september 2009, two groups of heifers were analyzed for the load of endo and ectoparasites, as follows: group A – 32 heifers ¼ Holstein and ¾ Gir and group B – 8 heifers ½ Holstein –Gir. The heifers were kept on the same pasture, on a Brachiaria brizanta, and were monthly put together for weighing and counting of eggs (FEC) and oocysts (OOPC) per gram of feces, fecal culture, partenogenas engorged females of Rhipicephalus (Boophilus) microplus (tick), adults Haematobia irritans (horn fly) and nodules caused by larvae Dermtobia hominis (humam botfly). The experimental region is characterized by a rainy season (october to march) and a dry season (april to september) with the average temperature ranging from 14 to 33°C. The average rainfall in the rainy season was 11,9 and 206,7 mm in the years 2007/2008 and 2008/2009 respectively. The relative humidity varied from 56 to 85%. The gain of weight of the two groups was statistically similar (p>0,05), 136 kg in group A and 147 in group B. The average EPG counts ranged from 13 to 584 and were lower in the dry season. There was no statistical difference (p>0,05) between groups and the larvae found in fecal culture were Cooperia spp., Haemonchus spp., Oesophagostomum spp. and Trichostrongylus spp. with predominance of Haemonchus spp. followed by Cooperia spp.. The average number of oocysts found in OOPG countings ranged from 750 to 21,9 with higher level in the rainy season. In this period of study, groups A and B were statistically similar (p>0,05), while group B had shown higher countings in three months. None of the animals exhibited clinical symptons despite the presence of E. bovis and E. zuernii considered pathogenic. Among the 10 species identified, the most prevalent were E. auburnensis, E. bovis and E. ellipsoidalis. The number of ectoparasites during the experiment was different between groups, while group B showed significantly higher parasite load than group A (p>0,05), H. irritans presented the highest ectoparasite infestation reaching levels above 93 flies per animal. The highest average of nodules D. hominis coincided with increase of temperature and decrease of rainfall and the largest peak R. (B.) microplus occurred with concomitant slight increase of the temperature and rainfall. Twelve dung pats were deposited monthly in the pasture during the period from october 2008 to september 2009. The genera of gastrointestinal helminthes found in feces and pasture were Cooperia spp., Haemonchus spp., Oesophagostomum spp. and Trichostrongylus spp.. The larvae of Cooperia spp.were present in the pasture while the larvae of Haemonchus spp. were more common in feces. In tracer calves analysis the main identified species were Haemonchus contortus and Cooperia punctata.The highest recoveries of helminthes of small and large intestine occurred at the end of the rainy and the dry seasons and abomasum at the beginninig and the end of the rainy season. Parasitological survey was carried out on 19 primiprous heifers ¼ Holstein and ¾ Gir from 24th week pregnancy up to the 13th week after parturition. Eggs (FEC) and oocysts (OOPC) per gram of feces, as well as fecal culture were counted weekly.The highest mean EPG counting was observed in the following weeks before and after parturition: 28th, 34th, 36th, 9th and 12th weeks. Cooperia spp.and Haemonchus spp. Oesophagostomum spp. and Trichostrongylus spp larvae could be identified during the fecal cultures period and Cooperia spp.and Haemonchus spp. predominated over other genera. The oocysts of Eimeria were present throughout the study period. The highest mean scores OOPG were presented in the following weeks of pregnancy and post parturition: 24th, 25th, 28th, 35th, 36th, 3rd, 4th and 7th weeks and identified 10 species where E. auburnensis, E. bovis, E canadensis and E. cylindrica were the most frequent and E. subspherica the less frequent