Effects Of Residues Of Ivermectin In Cattle Dung On Soil Nematodes In A Typical Steppe Of Inner Mongolia

Veterinary drug residues in feces and urine of domestic animals will affect non-target organisms,and then affect the structure and function of ecosystem.In order to understand the effects of Ivermectin residues in cattle dung on soil nematode communities,Bos taurus was given a oral Ivermectin treatments in a typical steppe of Inner Mongolia from July 2018 to October2020.The dynamic characteristics of Ivermectin residues in excreted cattle dung and their effects on soil nematode communities in feces were studied.The effect of artificial addition of ivermectin in fresh cattle dung on soil nematode community was also studied.The main results are as follows:1.In typical steppe of Inner Mongolia,the recommended dose(0.2mg/kg body weight)was taken orally.The peak of Ivermectin residue in excreted feces appeared on the 1st day after treatment,and the residual level was reduced to zero on the 3rd day after treatment.2.Ivermectin residue in excreted feces on the 3rd day after treatment significantly decreased the abundance and biomass of nematode community(P<0.05),and the effects lasted for 7 days.The residue of veterinary drugs in excreted feces on the 7th day after treatment significantly reduced the abundance and biomass,and the effects lasted for 3 days.There was no significant effect on the generic number of nematodes.3.Ivermectin residue significantly reduced the abundance of Malenchus and Protorhabditis in cattle dung,which lasted for 1 week.There was no significant effect on Diplogaster and Cephalobus.4.The ivermectin residue excreted in cattle dung on day 3 after treatment significantly reduced the abundance of bacterial-feeding nematodes and plant parasitic nematodes in fecal mass(P<0.05),which was mainly reflected in 3-7days of stacking,but had no significant effect after 7 days.The effect of ivermectin residue in feces on the abundance of bacterial-feeding nematodes in cattle dung was mainly reflected on the 1st day after feces stacking,and had no significant effect after the first day(P>0.05).5.The field stacking experiments of artificial addition of Ivermectin in fresh cattle dung showed that the degradation time of the residual Ivermectin in cattle dung was more than 75 d at two levels of artificial addition(5.0mg/kg fresh weight and 20.0 mg/kg fresh weight).The artificial addition of Ivermectin to cattle dung could reduce the abundance,biomass and diversity of soil nematode community in feces,and the higher the added concentration,the greater the reduction.Therefore,Ivermectin residue in cattle dung had a negative effect on most soil nematode community indices,lasting for about 1 week.In livestock practice,special attention should be paid to the proper disposal of excreted feces within one week of the application of Iermectin.