Controle de helmintoses em potros Mangalarga Marchador criados extensivamente no Norte de Minas Gerais

Abstract

The scarcity of researches related to the helminth control for horses in Brazil and the need to know the prevalence of helminths that affect Mangalarga Marchador colts raised extensively and the influence of helminths on the foals’ growth during the period of their greater body development motivated the accomplishment of this work. This thesis was divided into four chapters, the first one a literature review on the subject and the three later chapters are presented in the article format with the following objectives: First article (Chapter II) was to check the effects of deworming mares in the last month of gestation, created extensively in Montes Claros - MG, on helminth infection and development of the foal. Eighteen pregnant Mangalarga Marchador mares were used, aged 8.71 ± 3.77 years old, divided into two groups, V and NV. Group V mares received anthelmintic (0.02 mg/kg of ivermectin of body weight -BW- 2.5 mg/kg praziquantel BW) 15-20 days before the birth date. At 1, 10, 20 and 30 days of age, the foals were weighed and fecal samples were collected for counts of eggs per gram of feces (EPG). The withers height (WH), height at croup (HC), body length (BL), thoracic perimeter (TP) and body condition score (BCS), color, consistency (CONSIST) and pH of feces. Although numerical differences were observed, there was no statistical difference (p>0.05) between the groups, only between the evaluation days. The objective of the second article (Chapter III) was to identify the genus and species of helminths that affect foals from birth to 180 days of age and to determine the period of reinfection after vermifugation. EPGs were performed on days 1, 10, 20, 30, 40, 50, 60, 70, 80, 90, 120, 150 and 180. Monthly, weight, BCS, color, CONSIST and fecal pH were recorded. The foals received the same anthelmintic used in Article I (Chapter II) whenever the EPG result was ≥500. The average time between two consecutive dewormngs (REINFECT) was calculated using a cutoff value of ≥500 EPG. Eggs of Strongyloides westeri from 30 to 120 days old were found; small strongyles after 90 days and Parascaris equorum at 180 days. REINFECT was 63 days. The objective of the third article (Chapter IV) was to evaluate the effects of deworming of weanlings on body development, blood parameters and apparent digestibility of dietary nutrients. Fourteen Mangalarga Marchador foals were weaned at six months of age and divided into two groups: V and NV. EPGs were performed at weaning and monthly, up to nine months of age, and group V was dewormed using the same anthelmintic, whenever the OPG was ≥500. The groups were kept separated in two pastures of Cynodon nlemfuensis cv. White African Star grass, supplemented with pre-dried Cynodon dactylon cv. Tifton 85 ad libtum and 1.5% BW in concentrate. Two months later, the foals were confined in individual stalls and subjected to an apparent digestibility assay. They were also weighed, evaluated for BCS and measured for WH, HC, BL and TP, and blood samples were collected for hemogram. The NV group was infected mainly by cyathostomins (6000 EPG). There was a difference between groups (p>0.05) only for calcium digestibility, which was higher (p<0.05) in group V, but there were numerical differences in other coefficients of digestibility, dry matter intake and body weight.