Response of resistant and susceptible Brazilian Somalis crossbreed sheep naturally infected by Haemonchus contortus.

This study was carried out to evaluate the performance of Brazilian Somalis sheep to natural infections by gastrointestinal nematodes. During 98 days, 75 weaned sheep, initially 3-4 months old, were kept on the same pasture and evaluated. Fecal and blood samples were collected for parasitological and hematological exams. After this period, the eight most resistant and the eight most susceptible animals were selected based on their individual averages of nematode fecal egg counts and were slaughtered for worm burden determination and nematodes identification. Abomasum and abomasum lymph nodes were also recovered for gene expression analysis. The animals selected as resistant had lower fecal egg counts during experimental period and smaller worm burdens than the susceptible ones (P < 0.05). The genus Haemonchus, followed by Trischostrongylus and Oesophagostomum, were identified in composite cultures. Haemonchus contortus was the specie identified in the abomasum. Packed cell volume and total plasma protein means were higher in the resistant group (27.2% and 6.1 g/dL) than in the susceptible one (22.5% and 5.3 g/dL), respectively. Regarding cytokine gene expression, IL-4 (P < 0.05) was up-regulated in the abomasum of resistant animals and TNF-α (P < 0.03) and IFN-γ (P < 0.03) in susceptible ones. In abomasum lymph nodes, IL-4 (P < 0.04) and IL-13 (P < 0.05) were up-regulated in the resistant animals and IFN-γ in the susceptible one (P < 0.01). This work provides further evidence that, within a given animal breed, individuals have different responses when infected by gastrointestinal nematodes. Resistant animals who responded more quickly and efficiently to these infections activated a TH2-type response.

Anthelmintic activity of Cocos nucifera L. against sheep gastrointestinal nematodes.

The development of anthelmintic resistance has made the search for alternatives to control gastrointestinal nematodes of small ruminants imperative. Among these alternatives are several medicinal plants traditionally used as anthelmintics. This work evaluated the efficacy of Cocos nucifera fruit on sheep gastrointestinal parasites. The ethyl acetate extract obtained from the liquid of green coconut husk fiber (LGCHF) was submitted to in vitro and in vivo tests. The in vitro assay was based on egg hatching (EHT) and larval development tests (LDT) with Haemonchus contortus. The concentrations tested in the EHT were 0.31, 0.62, 1.25, 2.5 and 5 mg ml(-1), while in the LDT they were 5, 10, 20, 40 and 80 mg ml(-1). The in vivo assay was a controlled test. In this experiment, 18 sheep infected with gastrointestinal nematodes were divided into three groups (n=6), with the following doses administered: G1-400 mg kg(-1) LGCHF ethyl acetate extract, G2-0.2 mg kg(-1) moxidectin (Cydectin) and G3-3% DMSO. The worm burden was analyzed. The results of the in vitro and in vivo tests were submitted to ANOVA and analyzed by the Tukey and Kruskal-Wallis tests, respectively. The extract efficacy in the EHT and LDT, at the highest concentrations tested, was 100% on egg hatching and 99.77% on larval development. The parameters evaluated in the controlled test were not statistically different, showing that despite the significant results of the in vitro tests, the LGCHF ethyl acetate extract showed no activity against sheep gastrointestinal nematodes.

Anthelmintic activity of Lippia sidoides essential oil on sheep gastrointestinal nematodes.

Medicinal plants have been investigated for their anthelmintic properties and shown to be effective against eggs and larvae of gastrointestinal nematodes. The aim of this study was to evaluate the efficacy of the Lippia sidoides essential oil (LsEO) on sheep gastrointestinal nematodes. Initially, 44 naturally infected sheep were divided and treated with 200 microg kg(-1) ivermectin and 230 and 283 mg kg(-1) LsEO, respectively, plus the control. Fecal samples were collected from each animal to determine epg at 7, 14 and 21 days after treatment. In another test, 21 sheep were distributed and treated with 200 microg kg(-1) ivermectin, 283 mg kg(-1) LsEO and the control, respectively. Seven days after treatment, they were euthanized and necropsied to count and identify the nematodes from the abomasum, small and large intestines. In the first test, the efficacy of 230 and 283 mg kg(-1) LsEO and ivermectin was 38%, 45.9% and 40.2%, respectively, 7 days after treatment, and 30%, 54% and 39.6%, respectively, 14 days after treatment. In the second experiment, the respective efficacy of 283 mg kg(-1) LsEO and ivermectin was 56.9% and 34.4% against Haemonchus spp., and 39.3% and 63.6% against Trichostrongylus spp.

Anthelmintic efficacy of neem (Azadirachta indica A. Juss) and the homeopathic product Fator Vermes in Morada Nova sheep.

Gastrointestinal nematodes are becoming increasingly resistant to the commercial products used to control them. The cost of routine vermifuge applications on herds and the problem of residues in animal products and the environment have prompted research on the anthelmintic activity of plant extracts. This work examines the anthelmintic action of neem and the homeopathic product Fator Vermes in sheep kept in a pasture for 18 months. Forty sheep of the Morada Nova breed were divided into four treatments and the control, according to the EPG. During the experiment, each animal received 100 g/day of shredded corn and did not receive protein supplementation. In treatment 1 (control), the animals received only shredded corn. Treatment 2 received 1.6 g/(animal day) of the homeopathic product mixed with the shredded corn, and treatments 3, 4 and 5 received, respectively, 12.5, 25.0 and 37.5 g/(animal day) of dried Azadirachta indica leaves mixed with the shredded corn. The neem was administered for alternating 15-day periods and the homeopathic product daily for 18 months. There were 39 fortnightly fecal collections made to count the EPG, and fecal cultures were performed monthly. The following genera, in percentage, were identified: Haemonchus: 65.58+/-3.27, Trichostrongylus: 15.92+/-7.38 and Oesophagostomum: 18.50+/-6.22. The treatments evaluated were not effective in controlling gastrointestinal nematodes (P>0.05), whose mean log(10) counts (EPG +1) and standard errors for treatments 1-5 were respectively 3.55+/-0.28; 3.48+/-0.31; 3.90+/-0.29; 2.78+/-0.29 and 3.48+/-0.30. A significant effect (P<0.0001) was observed of the periods of the year when the 39 collections occurred. Because of the diet deficient in raw protein, the sheep had higher average EPG counts, for all the treatments, at the end of the dry season, and the opposite occurred in the middle of the rainy season.