Parasitological analyses

Saturated sodium nitrate solution floatation method was used to identify parasite groups. Parasite groups (strongyles, Eimeria spp., Moniezia spp., and Trichuris spp.) were identified based on the criteria given by Bowman (2008). It was impossible to determine the exact genus of the strongyle-type parasites based on the eggs (Bowman, 2008). The group of strongyles include superfamilies Strongyloidea, Trichostrongyloidea, and Ancylostomatoidea (Bowman, 2008). Therefore, the “strongyles” was used to refer them in this article. When a more specific diagnosis is required, it is necessary to culture the stages present in the faeces to the infective stage(third-stage) (Bowman, 2008). But in order to reduce the difference caused by the hatching of the eggs during the experiment (the inspection time is sequential), the faeces were soaked by formalin, so the hatching identification cannot be done. Follow-up research was needed.

The Master technique was used for quantitative analysis (Hu et al., 2016). Faecal samples (2 g) were suspended in 58-mL sodium nitrate saturated solution (specific gravity 1.2) and stirred continuously for 20 min to homogenise the mixture. Large plant debris were removed via 0.18-mm mesh. The remaining homogenised aliquot of the filtrate was transferred into both McMaster counting chambers (Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences). Counting was performed under a light-optical microscope at 100 × magnification, started 5 min after loading the slide. The eggs per gram were calculated as: Eggs per gram = [n/(0.15 × 2)] × V/m, where n is the mean number of eggs or oocysts in the two counting chambers, 0.15 is the volume of each counting chamber, and there are two chambers, and V and m are the volume of the homogenised faecal sample and weight of the faeces, respectively; in this case V = 60 mL and m = 2 g (Hu et al., 2016) . The faecal egg density was estimated using a modified McMaster technique with a sensitivity of 100 eggs per gram.