| Gastrointestinal nematodiasis is a major parasitic disease affecting livestock production performance and economic benefits,and has a huge impact on animal husbandry.Gannan Prefecture is one of the main pastoral areas in Gansu Province.Yak and Tibetan sheep breeding are the main economic sources of the people in this area and play an important role in promoting local social and economic development.However,there are few studies on the rapid,accurate and efficient detection methods,epidemiological investigation and comprehensive prevention and control of digestive tract nematodes in Gannan yaks and Tibetan sheep.In order to study the prevalence of three kinds of gastrointestinal nematodes in Gannan yaks and Tibetan sheep,and the prevention and control strategies of digestive tract nematode disease,the following experiments have been carried out:1.Three pairs of specific primers were designed to target the ribosomal ITS sequences of three kinds of nematodes,and a multiplex PCR detection method was established.The multiplex PCR method established in this study had high specificity,good repeatability,and high sensitivity.The minimum concentrations for the detection of DNA of Ostertagia ostertagi,Haemonchus contortus and Teladorsagia circumcincta were 0.03 ng/μL,0.03 ng/μL,0.02 ng/μL,respectively.This method has high accuracy in detecting clinical samples,and could be used for epidemiological investigation of three nematodes.2.The established multiplex PCR method was used to detect 986 yak fecal samples in Gannan to investigate the prevalence of three digestive tract nematodes in Gannan yak.The results showed that 224 positive samples were detected,with a positive rate of 22.72%.The prevalence rates of Ostertagia ostertagi,Haemonchus contortus and Teladorsagia circumcincta in Gannan yaks were 12.58%,14.30%,11.36%,respectively,and more the rate of polyinfection was 12.98%.In addition,the prevalence of three gastrointestinal nematodes from January to April was significantly higher than that from May to December(p < 0.01),but there was no significant difference between the infection rate in yak aged 0～3 years and over 3 years,and between different cities in Gannan Prefecture.3.The established multiplex PCR detection method was used to detect 767 fecal samples of Gannan Tibetan sheep to investigate the prevalence of three digestive tract nematodes in Gannan Tibetan sheep.The results showed that 201 positive samples were detected,with a positive rate of 26.21%.The prevalence rates of Ostertagia ostertagi,Haemonchus contortus and Teladorsagia circumcincta in Gannan yaks were14.34%,13.34%,14.21%,respectively,and more the rate of polyinfection was13.69%.The infection rate of three kinds of digestive tract nematodes in Gannan Tibetan sheep in summer was significantly higher than that in autumn and winter(p <0.05),the infection rate of the Tibetan sheep age < 1 year was significantly higher than that age > 1 year(p < 0.05),and the positive rate of the samples in Xiahe County of Gannan Prefecture was significantly higher than that in Maqu County and Luqu County(p < 0.05).4.The anthelmintic effect of the repellent "Dilefen"(albendazole and ivermectin)on digestive tract nematodes was evaluated by fecal egg count reduction test(FECRT).The anthelmintic effect of "Dilefen" on nematodes in the digestive tract of Gannan yak and Tibetan sheep was significant,and the average reduction rate of the nematode eggs in the digestive tract of Gannan yaks was 95.61%;The average reduction rate of digestive tract nematode eggs in Gannan Tibetan sheep was 95.73%,which could be used for the prevention and control of gastrointestinal nematodes in Gannan yak and Tibetan sheep.The established multiplex PCR detection method was used to further verify the efficacy of "Dilefen" in the disinfestation of nematodes in the digestive tract of Gannan yak and Tibetan sheep,the positive rate of the samples was significantly lower than that before the disinfestation(p < 0.01).Then,combined with the local actual grazing management,the comprehensive control strategy of digestive tract nematode of Gannan yak and Tibetan sheep was determined.The results of this study showed that the prevalence of three kinds of gastrointestinal nematodes in Gannan yak and Tibetan sheep was high,and the prevention and control of gastrointestinal nematodes could not be ignored.This study provides the latest survey data for the infection status of digestive tract nematodes in Gannan yak and Tibetan sheep,and developed a comprehensive prevention and control strategy to provide reference for improving the local breeding level. |
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