ABSTRACT
Conservation agriculture (CONS A) is a sustainable agriculture system based on crop rotation with no tillage. It has various environmental advantages compared to conventional agriculture (CONV A): decreased water evaporation, erosion, and CO2 emissions. In this first study of its kind, we aim to evaluate the impact of this type of agriculture on sheep gastrointestinal parasites. Two lamb groups aged between 5 and 10 months were randomly included to graze separately on CONS A and CONV A pastures. Each group was composed of two batches of three lambs, and these were followed up for two rearing months. Liveweight, hematological parameter variation, and digestive parasites were studied. At the end of the study period, lambs were slaughtered the carcass yield was determined, and a helminthological autopsy was performed on the digestive tracts of the animals to estimate different parasitological indicators. There was no difference between lambs reared on CONS A and those reared on CONV A for all parasite indicators (infestation intensity, abundance, and prevalence). The same trend was also obtained for hematological parameters, liveweight evolution, and carcass yield. These results prove that there is no impact of CONS A on the sheep's digestive parasitism. Further studies are needed to support these findings on larger animal samples and to investigate the impact of conservation agriculture on other parasite species. Similar studies could also be conducted on ruminant species.
ABSTRACT
We conducted a 5-month-long screening of Anaplasma spp. and Anaplasma ovis infection in sheep from central Tunisia. During this longitudinal study, we investigated the infection dynamics using both direct and indirect assessments validated with a polymerase chain reaction (PCR) as the gold standard method. The experimental design included 84 male lambs aged from 6 to 8 months, and 32 ewes, both chosen randomly from June to November with a periodicity of 2 weeks approximately between June and September, and 1 month between September and November. A total of 9 field visits were carried out in this period during which animals were clinically examined and biological samples were extracted. Thus, a total of 716 blood smears, 698 sera from the nine sampling dates, as well as 220 blood samples from the first and the ninth sampling dates were collected from apparently healthy lambs and ewes, respectively, and analyzed by competitive enzyme-linked immunosorbent assay (cELISA) and polymerase chain reaction (PCR) assay, for the detection of Anaplasma antibodies and A. ovis DNA, respectively. Sera were analyzed by competitive enzyme-linked immunosorbent assay (cELISA) and PCR, for the detection of Anaplasma antibodies and A. ovis DNA, respectively. The Anaplasma spp. initial seroprevalence rate was 33.3% in lambs and 100% in ewes, and it then flowed in an upward trend to reach a maximum of 52.6% in lambs, whereas in ewes, the Anaplasma spp. seroprevalence rate remained unchanged and equal to 100%. Meanwhile, the A. ovis initial molecular prevalence was 22.6% at the first visit and 26.3% at the last visit in lambs, whereas in ewes, the molecular prevalence rates of A. ovis were higher in both the first and the last visit estimated at 100% and 85.7%, respectively. The Kappa coefficient between cELISA and PCR indicated a moderate level of agreement on the first sampling date (0.67) and a low agreement level on the last (0.43). Furthermore, an exploratory data analysis using a multimodal machine learning approach highlighted the underlying pattern of each analytical technique used in this study. In this prospect, we were able to establish the performance of each technique at detecting Anaplasma spp. in sheep. The combination of these approaches should improve the field assessment while promoting a data-based decision in precision epidemiology. The genetic follow-up test relevant to A. ovis msp4 sequences revealed three different genotypes, two of which were previously described in Italy.
