Investigation On The Contamination Of Worm Larvae In Pen And The Comparative Study On The Killing Effect Of Commonly Used Disinfectants

Nematode disease in livestock is one of the most common chronic wasting diseases in farming.Most nematodes have a short life cycle,do not require an intermediate host and are soil-derived parasites,therefore,livestock have a high chance of being infected.The following pilot study was conducted to investigate the current nematode infection situation in various areas of Uttar Pradesh,and to provide effective control of the disease at a later stage and reduce the risk of repeated nematode infections in sheep due to larval contamination in enclosures.Firstly,an epidemiological survey of sheep and cattle digestive nematode disease was conducted during the "spring tide" period in the Wushen banner.The study was conducted from April to May 2022 to investigate the prevalence of digestive nematode disease in sheep in the region by using qualitative and quantitative faecal egg examination techniques according to different administrative areas and pasture types,and to understand the predominant species of nematodes prevalent in the region,so as to provide a basis for subsequent experiments.The survey found that the highest nematode infection rate in sheep in Wushen banner was 34.8 %(931/2 675),with 28.9 %(773/2675)of the Hemonchus contortus;the highest nematode infection rate was 55.8 %(249/446)in Wushenzhao town among the different administrative region;The highest nematode infection rate among the different pasture types was 44.8 %(1432/3 196).Digestive nematode larvae were then cultured under laboratory conditions and disinfected with each of the six disinfectants and observed to kill the larvae to determine the level of disinfection.Faeces and soil were collected from selected sheep enclosures and placed in a thermostat for 7 d.The larvae were collected by separation,diluted and grouped together and inhaled into bottles at the doses indicated for the different disinfectants.Larval mortality was recorded at 30 min,1 h,3 h,5 h and 24 h and analysed for comparison.The results showed that povidone-iodine,calcium chloride and sodium hydroxide had a strong killing effect on GI nematode larvae,with larval mortality reaching 100 % at 1 h,24 h and 24 h after administration,respectively.Finally,a comparative study of the efficacy of the disinfectants screened in advance in killing digestive nematode larvae was carried out under natural conditions.The disinfection was carried out in areas of nematode-infected sheep enclosures,using the depth of longitudinal distribution of larvae in the soil as a dose indicator,and faeces and soil were collected at 30 min,1 h,3 h,12 h and 24 h.The larvae were separated by the Bellman larval isolation method to compare the killing effect of the different disinfectants on the larvae under natural conditions.The results showed that povidone-iodine was the most effective in killing GI nematode larvae in their natural environment.The above results provide important basic information for research on reducing the rate of repeated infections of nematodes in livestock and mitigating the development of drug resistance,and have practical implications for herders to reduce economic losses.