Abortion and various associated risk factors in dairy cow and sheep in Ili, China.

Huan Zhang,Jinliang Sheng,Zhiran Shao,Shengnan Song,Chuangfu Chen,Buyun Cui,Qin Yang,Zhengfei Liu,Xiaoyu Deng,Zhen Wang,Yong Wang,Yuanzhi Wang,Xiaoli Zhao

doi:10.1371/journal.pone.0232568

Abstract

We studied livestock abortion and various associated risk factors in the Ili region of northwest China. Livestock abortion prevalence was estimated and correlated with infections (Brucellosis, Salmonellosis, Mycoplasma and Chlamydia seropositivity) and management (farming type and contact with other herds/flocks) risk factors. A total of 2996 serum samples (1406 cow, 1590 sheep) were identified by RBPT (Rose Bengal Plate Test) and c-ELISA (competitive-enzyme linked immunosorbent assay), and they showed the overall seroprevalence of brucellosis in the study area was cow 6.76%, sheep 9.50%. The seroprevalence of brucellosis in X county was cow 7.06%, sheep 9.12%; in H county was cow 11.70%, sheep 10.80%; and in Q county was cow 4.22%, sheep 9.11%. The overall seroprevalence of Mycoplasma in the study area was cow 3.20%, sheep 6.42%. The seroprevalence of Mycoplasma in X county was cow 3.39%, sheep 7.98%; in H county was cow 5.26%, sheep 9.97%; and in Q county was cow 2.11%, sheep 4.33%. The Odds ratio of brucellosis for cow and sheep, respectively, were 45.909 [95% CI 26.912–78.317, P<0.001] and 70.507 [95% CI 43.783–113.544, P<0.001] times higher than other abortion-related factors including mixed farming, contact with other flocks and Mycoplasma infection. A total of 54 samples, including aborted cow (22), sheep (30) fetuses and milk samples (2), were identified as Brucella melitensis (B. melitensis) positive. A total of 38 Brucella were isolated from 16 aborted cow, 20 sheep fetuses and 2 milk samples. All of these isolates were identified, and confirmed, as B. melitensis. A phylogenetic tree showed that the Brucella isolates closely matched the B. melitensis biovar 3 isolated in Inner Mongolia, China, and B. melitensis isolated from Norway and India. These results suggest that B. melitensis biovar 3 is the main pathogen responsible for cow and sheep abortion and also pose a human health risk. Additionally, livestock reproduction can also be influenced by Mycoplasma infection and managerial factors (farming type and contact with other herds/flocks), especially in remote areas.

Highlights

Ruminants are a major source of meat production in China and are important for food security
The brucellosis positivity for cows and sheep in X county was cow 7.06%, sheep 9.12%; in H county was cow 11.70%, sheep 10.80%; and in Q county was cow 4.22%, sheep 9.11%, which is much higher than the seroprevalence of other pathogens in these three counties (Table 2)
No aborted fetuses were positive for these pathogens. These results show that B. melitensis biovar 3 is the dominant pathogen responsible for sheep and cow abortion

Summary

Introduction

Ruminants are a major source of meat production in China and are important for food security. Xinjiang Uygur Autonomous Region (XUAR) is located in northwest China and is a major ruminant production province. In 2017, beef production (0.43 million tons) and mutton production (0.58 million tons) in Xinjiang, respectively, accounted for the 6.8% and 12.4% in the total beef and mutton production in China. Ili is located in the western part of XUAR, where the economy is highly dependent on animal production [1, 2]. The combined number of cattle, sheep and goats is approximately 5.88 million in this region, in which the goats only accounted for the 2.1% because of economic value. The sheep, goats and cattle are reared under traditional systems, and confined sheep/goats or cattle ranches are the two main feeding systems

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