Saccharomyces cerevisiae (YT001) supplementation for the control of Haemonchus contortus and modulation of the immune response of sheep.

Studies aiming at the development and evaluation of alternative methods to minimise losses caused by the gastrointestinal nematode Haemonchus contortus are extremely important. Such research is essential, given the high morbidity rates among sheep and the significant mortality rates of lambs, allied to the low efficacy of commercial products for the control of this parasite. The purpose of this study was to evaluate the effect of the Saccharomyces cerevisiae (YT001 - YEASTECH) on the control of H. contortus and its modulation of the immune response in experimentally infected sheep. Eighteen sheep were divided into two groups. Group 1, the control group, comprised animals infected with H. contortus and supplemented with distilled water, while Group 2, the treated group, consisted of animals infected and supplemented with S. cerevisiae (400 million cfu/day of suspension for 49 days). The following parasitological parameters were evaluated: number of eggs per gram of faeces, number of infective larvae (L3) recovered per faecal culture, and parasitic load of the abomasum. The following immunological parameters were quantified: immunoglobulin (Ig)A in the mucous secretions and serum IgG; cytokines interleukin (IL)-4, IL-5 and IL-10; number of eosinophils in the abomasal mucosa and groups of cells positive for the markers: MHCII, CD4+CD25+, CD5+CD8+, WC4, CD5+CD4+, CD8+CD11b+ and CD5+WC1 by whole blood flow cytometry. The results revealed a significant decrease (P<0.05) in the number of larvae and significantly higher serum IgG levels (P<0.05) in the group supplemented with S. cerevisiae. The supplemented animals showed significantly larger numbers of eosinophils (P<0.05), as well as more cells positive for MHCII, CD4+CD25+, CD5+CD8+ than the control animals. This study confirmed the beneficial action of S. cerevisiae on the host immune response to H. contortus, as evidenced mainly by the smaller number of L3 recovered from the faeces of sheep supplemented with S. cerevisiae.

In vitro activity of essential oils of free and nanostructured Melaleuca alternifolia and of terpinen-4-ol on eggs and larvae of Haemonchus contortus.

Haemonchus contortus is one of the major gastrointestinal nematodes responsible for significant economic and production losses of sheep. Diseases caused by this species lack effective anthelmintic products, and the search for new compounds to replace synthetic anthelmintics has been extensive. The present investigation assesses the in vitro activity of the essential oil of melaleuca (Melaleuca alternifolia), both free (TTO) and nanostructured (nanoTTO), and terpinen-4-ol (terp-4-ol) on eggs and larvae of H. contortus. Tests of egg hatching (EHT) and inhibition of larval migration (LMIT) were used to assess the in vitro efficacy of TTO, nanoTTO and terp-4-ol. Using EHT, at a concentration of 3.5 mg/ml, 100% inhibition occurred using TTO and terp-4-ol, with LC50 values of 0.43 and 0.63 mg/ml, and LC90 values of 1.75 mg/ml and 3.12 mg/ml, respectively. NanoTTO had lower activity, with 82.6% inhibition at the same concentration. Using LMIT, TTO and nanoTTO had a similar activity with 88.0% and 84.8% inhibition, respectively, at a concentration of 56 mg/ml. Terp-4-ol had a greater effect on larvae, with 85.7% inhibition at a concentration of 56 mg/ml and 82.4% at 3.5 mg/ml, demonstrating high activity at the lowest concentration tested. Therefore, the results indicate that all substances tested showed ovicidal and larvicidal activity against H. contortus. TTO, terp-4-ol and, mainly, nanoTTO may be targeted in in vivo studies, besides being a promising line of research into the control and treatment of veterinary important helminths.

Effects of condensed tannin from Acacia mearnsii on sheep infected naturally with gastrointestinal helminthes.

The effect of tannins on endoparasite control in hair sheep was investigated using 20 entire lambs of the Santa Inês breed. At the beginning of the experiment these animals were 6-months old and weighed 22.5kg+/-4.7. The treatments used were (10 animals each): GT (animals receiving 18g of Acácia negra containing 18% of condensed tannin/animal/week) and GC (animals not receiving tannin). The experiment lasted 84 days, with animals kept on an Andropogon gayanus pasture. Faeces were collected weekly, with weighing and blood collection carried out fortnightly. At slaughter, the adult worms were harvested for identification and counting. Although the GT animals weighed more than the GC lambs at slaughter, these differences were not significant (P>0.05). In general, the values for haemoglobin, hematocrit, total protein, urea, phosphorus and calcium in the serum were within normal levels and no significant differences between groups were observed. For faecal egg count (FEC), lower values were observed throughout the experiment in the group receiving tannin, but these differences were only significant in the eighth week. There was a lower output of eggs by regression for GT compared with GC (P<0.05). The species identified, in decreasing order of worm count, were: Trichostrongylus colubriformis, Haemonchus contortus, Oesophagostomum columbianum, Cooperia sp., Strongyloides papillosus, Trichuris globulosa and Moniezia expansa. The total worm count and number of each species of worm were lower for GT compared with GC for T. colubriformis and Cooperia sp. (P<0.05). Condensed tannin (CT) from A. negra had an antiparasitic effect, thereby representing an alternative for worm control in sheep.