Validation of targeted selective treatment (TST) methodology for gastrointestinal parasites of adult sheep in different physiological states.

We aimed to validate a targeted selective treatment (TST) methodology for treating parasitic gastrointestinal infections in ewes in different physiological states using parasitological and hematological parameters. Forty ewes were monitored from December 2021 to June 2022 and evaluated during various physiological stages in their life cycle. Before starting the experiment, a fecal egg count (FEC) reduction test was performed to evaluate the efficacy of the anthelmintic (AH) treatment. Weekly assessments were performed based on the Famacha© (F) system and body condition score (BCS), and ewes were subjected to AH treatment when necessary, with their physiological states recorded. Ewes were treated when they presented F ≥ 3, BCS ≤ 2.0 (when F = 2), or submandibular edema. Parasitological, i.e., FEC, and hematological, i.e., hematocrit (Ht), parameters were evaluated monthly to determine the efficiency of the TST methodology. Comparisons between the mean Ht and FEC values in ewes subjected to AH treatment and untreated ewes were performed using analysis of variance, followed by Tukey's test. Spearman's correlation was performed to determine the correlation between the variables, i.e., F scores, BCS, Ht, and FEC. All tests were performed at a significance level of 5 %. During the experimental period, 1138 evaluations were performed. The main reason for AH treatment was F ≥ 3. Ewes in early pregnancy, lactation and late pregnancy received comparatively more AH treatments than the other physiological states. Ewes in late pregnancy and lactation exhibited lower mean Ht values (23.5 % and 22.9 %) and higher mean FEC values (3269 and 1426) compared with those in early pregnancy (30.2 % and 727 EPG). In addition, a statistically significant difference was observed in the Ht and FEC values of ewes that presented submandibular edema (P < 0.001) compared with those that did not exhibit submandibular edema. The genus Haemonchus sp. showed a 96.4 % prevalence in coprocultures. A positive correlation existed between F scores and FEC (r = 0.3819) and a negative correlation between F scores and Ht (r = -0.4728). Ewes that needed AH treatment had lower mean Ht values than ewes that did not need the treatment (19.2 % × 29.3 %; P < 0.001) and higher mean FEC values (8747 × 1163; P < 0.001), confirming that these ewes needed AH treatment. The TST methodology based on F scores, BCS, and submandibular edema could effectively identify individuals in the herd needing AH treatment, identifying 13 % additional cases requiring treatment than using only the F score criterion.

Influence of probiotic supplementation on parasitological parameters in lambs.

The control of parasitosis is based on the use of anthelmintics. However, its long-term and indiscriminate use can select populations of resistant nematodes. New alternatives such as probiotics are being studied to solve this problem. This study aimed to investigate the effects of an oral probiotic containing six different bacterial strains and the yeast Saccharomyces cerevisiae on the blood biochemistry, parasitological, and histological parameters of naturally infected lambs. Forty-two weaned Texel or Ile de France crossbred lambs aged 86.9 ± 8.0 days and weighing 27.4 ± 3.7 kg were randomly allocated into three groups (n = 14 lambs). The control group (CG) was fed a basal diet without probiotic supplementation. The treatment group 1 g (T1G) was fed a basal diet with commercial probiotic supplementation at a dose of 1 g/lamb/day. The treatment group 5 g (T5G) was fed a basal diet with commercial probiotic supplementation at a dose of 5 g/lamb/day. The experimental period was 84 days, where the groups undergo mild natural infection. Every two weeks the hematocrit, total protein, albumin, globulin, fibrinogen, plasma protein, fecal egg count (FEC), and fecal consistency score were evaluated. Twenty lambs were slaughtered for histological evaluation of the rumen and abomasal wall and for counting abomasal nematodes. The area, length, and number of eggs from the recovered Haemonchus contortus female uteri were measured. Data were analyzed using analysis of variance (ANOVA) and Tukey's test (p ≤ 0.05). The area and length of Haemonchus contortus females from T1G were smaller (p < 0.01) than those of CG and T5G. The number of eggs from the H. contortus female uterus was lower (p < 0.01) in T1G and T5G. Evaluating the incidence of diarrhea, the T1G and T5G groups had a higher prevalence with a 35% and 39% score of zero, respectively (p < 0.05), while the CG group had 22%. All other evaluated parameters showed no significant differences (p > 0.05) between the groups. The probiotic had a beneficial effect on the gastrointestinal health of the weaned lambs through a decrease of the area, length, and the number of eggs of female H. contortus and an improvement in fecal consistency.

Can orange essential oil reduce the severity of parasitic infection in sheep?

In this study, a three-step experiment was conducted to evaluate the effectiveness of orange essential oil (OEO) to reduce the severity of parasitic infection in lambs naturally infected with gastrointestinal parasites. In the first and second stages of the experiment, the lambs were distributed in groups (n = 10): without treatment (control), treated with levamisole (7.5 mg/kg), and treated either with 200, 300 or 400 mg/kg OEO in the first stage and with two doses of 300 or 350 mg/kg each of OEO with a six-hour interval in the second stage. In the third stage of the experiment, 20 lambs were distributed into control and treated groups (two doses of 350 mg/kg OEO) and slaughtered for determining the parasite count in the abomasum and small intestine. Evaluations were performed on D0, D3, D7, D10, and D14 by determining the egg count per gram of feces (EPG), and the percentage of EPG reduction was calculated in comparison to D0. Coproculture was performed on days D0 and D14 of the first and second stages of the study. In the first stage, the EPG increased by 20.90 and 100.99% and decreased by 5.54% on D14 in the groups treated with 200, 300, or 400 mg/kg OEO, respectively. At the second stage, the EPG of the OEO groups decreased by more than 96% on D3, but on D14 was decreased by 0.82% and 77.07% in the 2 × 300 and 2 × 350 mg/kg groups, respectively. Haemonchus sp. was the highest percentage of collected larvae in all coproculture tests, ranging from 90 to 100%. In the third stage, there was no difference (P > 0.05) in the mean number of parasites between the OEO groups and the control. Although the decrease in EPG of more than 96% on D3 did not persist in the other evaluations, and immature forms and adult parasites were collected at slaughter, the EPG reduction of 77.07% on D14 with the dose of 700 mg/kg (OEO2 × 350) suggests that OEO can help to reduce the severity of parasitic infection and, consequently, to diminish pastures contamination, when used together with other methods to control gastrointestinal parasites in sheep.