Điều tra được tiến hành trên 863 trại gà thịt và gà đẻ thuộc địa bàn 5 tỉnh Tiền Giang, Long An, Bến Tre, Đồng Nai và Bà Rịa Vũng Tàu (BRVT) bằng phương pháp phỏng vấn trực tiếp thông qua bảng câu hỏi được thiết kế sẵn. Điều tra nhằm đánh giá tổng thể thực trạng bệnh ORT, các thiệt hại của bệnh, cũng như ghi nhận các biện pháp phòng trị ORT mà các trại đang áp dụng. Kết quả cho thấy bệnh ORT đang được quan tâm rất nhiều hiện nay (80,76%) với 64,19% trại đã từng có bệnh. Trong đó, Đồng Nai và Tiền Giang có tỷ lệ cao nhất. Đặc biệt, bệnh thường xảy ra ở giai đoạn từ 310 tuần tuổi. Quy mô đàn càng lớn, nguy cơ bệnh ORT nổ ra càng cao. Bệnh thường xảy ra quanh năm với tỉ lệ bệnh cao, dễ lây lan trong đàn. Bệnh xảy ra trên mọi lứa tuổi và thường xuất hiện quanh năm chiếm (41,4%) Bên cạnh đó tỷ lệ bệnh ORT xảy ra cao nhất ở quy mô từ >10.000 con (70,59%) . Có 34% trại có câu trả lời tỉ lệ bệnh lên tới 100% gà trong đàn. Các ca bệnh thường ở thể nhiễm ghép với các biểu hiện triệu chứng hô hấp phức hợp cũng như đa bệnh tích trên gà bệnh. Khi bệnh xảy ra, cần mất nhiều thời gian để điều trị: thời gian điều trị trên 7 ngày chiếm 40%. Chi phí điều trị giao động tùy vào lứa tuổi của gà và trung bình để điều trị cho 2.460 đồngcon. Ngoài ra, mặc dù có can thiệp điều trị nhưng vẫn có tỉ lệ chết sau điều trị. Các trại vẫn sử dụng thuốc kháng sinh để phòng và điều trị bệnh ORT là chủ yếu (69,96%) dẫn tới việc dễ dàng đề kháng kháng sinh.
Trang 10KHẢO SÁT TÌNH HÌNH BỆNH, THIỆT HẠI VÀ PHƯƠNG PHÁP PHÒNG, TRỊ BỆNH
ORNITHOBACTERIUM RHINOTRACHEALE (ORT) TRÊN GÀ TẠI CÁC TỈNH
PHÍA NAM VIỆT NAM SURVEYING THE DISEASE SITUATION, ECONOMIC LOSS, PREVENTION AND
TREATMENT REGIMEN FOR ORNITHOBACTERIUM RHINOTRACHEALE (ORT) IN
CHICKENS IN THE SOUTH OF VIETNAM
Vo Chi Nhan
Phone: 0978.109.120
Email: 15112342@st.hcmuaf.edu.vn
Dinh Thuy Phuong Thao
Phone: 0868.189.496
Email: 17111133@st.hcmuaf.edu.vn
Derpartment: Animal science and Veterinary medicine
ABSTRACT
The survey was conducted on 863 layer and broiler chicken farms in 5 provinces including Tien Giang, Long An, Ben Tre, Dong Nai and Ba Ria Vung Tau (BRVT) by directly interviewing farmers using dedicated questionnaires The aims of the survey were to overall evaluate the current ORT epidemiology and losses caused by this disease, as well as ORT treatment regimens applied Results from the farm's answers showed that currently, ORT disease was known in 80.76% of the farms and outbreaks were reported in 64.19% of the farms Dong Nai and Tien Giang provinces had particularly high rates of ORT disease Especially, this disease occurs popular at 3 - 10 weeks of age The larger population is, the higher ORT occurs The disease outbreaks all year long in 41.4% of the farms and 34%
of farms reported morbidity rate of up to 100% Many case reports of O rhinotracheale infection report a concomitant infection with other respiratory pathogens and that the severity of lesions is enhanced When the disease occurs, it took long time to treat this disease The duration of treatment ranged from 3-7 days in 45% of the farms to over 7 days in 40% Treatment costs depend on the age of the chickens and the average expense treatment for one chicken was VND 2,460 In addition, despite treatment interventions, birds continued to suffer and die causing heavy loss to the farms In 69.96% of the farms, preventive treatment still mainly based on antibiotics and thus creating high chance of antibiotic resistant development.
Trang 2TÓM TẮT
Điều tra được tiến hành trên 863 trại gà thịt và gà đẻ thuộc địa bàn 5 tỉnh Tiền Giang, Long
An, Bến Tre, Đồng Nai và Bà Rịa Vũng Tàu (BRVT) bằng phương pháp phỏng vấn trực tiếp thông qua bảng câu hỏi được thiết kế sẵn Điều tra nhằm đánh giá tổng thể thực trạng bệnh ORT, các thiệt hại của bệnh, cũng như ghi nhận các biện pháp phòng trị ORT mà các trại đang áp dụng Kết quả cho thấy bệnh ORT đang được quan tâm rất nhiều hiện nay (80,76%) với 64,19% trại đã từng
có bệnh Trong đó, Đồng Nai và Tiền Giang có tỷ lệ cao nhất Đặc biệt, bệnh thường xảy ra ở giai đoạn từ 3-10 tuần tuổi Quy mô đàn càng lớn, nguy cơ bệnh ORT nổ ra càng cao Bệnh thường xảy
ra quanh năm với tỉ lệ bệnh cao, dễ lây lan trong đàn Bệnh xảy ra trên mọi lứa tuổi và thường xuất hiện quanh năm chiếm (41,4%) Bên cạnh đó tỷ lệ bệnh ORT xảy ra cao nhất ở quy mô từ
>10.000 con (70,59%) Có 34% trại có câu trả lời tỉ lệ bệnh lên tới 100% gà trong đàn Các ca bệnh thường ở thể nhiễm ghép với các biểu hiện triệu chứng hô hấp phức hợp cũng như đa bệnh tích trên gà bệnh Khi bệnh xảy ra, cần mất nhiều thời gian để điều trị: thời gian điều trị trên 7 ngày chiếm 40% Chi phí điều trị giao động tùy vào lứa tuổi của gà và trung bình để điều trị cho 2.460 đồng/con Ngoài ra, mặc dù có can thiệp điều trị nhưng vẫn có tỉ lệ chết sau điều trị Các trại vẫn sử dụng thuốc kháng sinh để phòng và điều trị bệnh ORT là chủ yếu (69,96%) dẫn tới việc
dễ dàng đề kháng kháng sinh.
Trang 3Up until January 2018, some provinces in the south of Vietnam, such as Tien Giang, Long An, Ben Tre, Ba Ria – Vung Tau (BRVT) and Dong Nai have had the largest number of total chickens raised in the southern area, reaching over 43 million chickens (Statistical Department, 2018) Along with the fast development in the total number of chicken raised as well as farm infrastructures, diseases, especially respiratory problems, have been constantly troubling the poultry industry throughout the whole country There are many different causes for respiratory diseases; they could be due to microorganism factors such as viruses, bacteria, and fungi, or they could be due to farms’ management
Among those, bacteria Ornithobacterium rhinotracheale (ORT) plays an important part in causing complex respiratory syndromes with high mortality (Umali et al, 2018) Duration of the disease O rhinotracheale is not only cause sudden death, rapid transmission but also causes severe respiratory
symptoms (van Ampel và Hafez, 2010)
Until now in Vietnam, there have only been a few researches regarding ORT, namely Nguyễn Thị Bích Liên et al (2014), Nguyễn Thị Lan et al (2016, 2017), and there is no official study regarding the circulation of ORT in southern provinces in Vietnam
Therefore, it is extremely necessary to investigate and evaluate the status of the disease as well as the ability to prevent and treat chicken disease caused by ORT This study’s aim is to build up data which could be utilized for analyzing and diagnosing the disease in order to form a better procedure for prevention and treatment of ORT disease
MATERIALS AND METHODS
Research subjects
The research was conducted on farm with a questionaire in chicken farms with the scale of at least
500 chickens in some districts of 5 provinces: Tien Giang, Long An, Ben Tre, Đong Nai and BRVT
Contents and research methods
All data regarding the total number of chickens raised as well as chicken farms were gathered from the 2018 annual statistical results of Tien Giang, Ben Tre, Long An, Đong Nai and BRVT According to those results, around 10-20% of total chicken farms were surveyed based on the farm scale of over 500 chickens per farm by a questionaire (Table 1)
Trang 4Table 1 Number of expected surveyed chicken farms
Province Number of surveyed chickens Number of expected surveyed chicken
farms
The interview process was conducted directly at the farm with a prepared questionnaire to record the information which is provided the necessary requirements of the experiment (Appendix attached) Each farm filled in the questionaire with information about their own farm, then, those information would be collected and statistically analyzed in order to evaluate the ORT disease status, damages caused by the disease as well as methods to prevent and treat ORT in 863 chickens farms of Tien Giang, Long An, Ben Tre, BRVT and Dong Nai Accordingly, the farms were identified by: (1) Some mild respiratory symptoms such as: transient nasal discharge, dyspnea, coughing, sneezing, neck lift (Roepke
et al., 1998) And the common particular lesions include pneumonia, pleuritis, tracheitis and (casein)fibrinosuppurative airsacculitis, (Van Empel et al., 1997), (2) Veterinarian's diagnosis, (3) Test results (if any)
Data analysis methods
After gathering information in the questionair, all data were digitalized, then analyzed using descriptive statistics method by Excel 2010 and Minitab 16
RESULTS AND DISCUSSION
1 ORT status by surveyed areas
1.1 Level of concern and awareness of ORT
Table 2 Level of concern and awareness about ORT
According to Table 2, farms that are concerned and aware of ORT accounted for a really high percentage of 80.76%, equaling to 697/863 farms; whereas, only 19.23% of farms were not aware of the
Trang 5disease This result clearly showed that ORT has always been one of the most concerned problems for chicken farms in the surveyed areas
1.2 ORT status by provinces
Table 3 Number of farms with suspected ORT clinical signs by different provinces
Number of farms Percent (%)
There were 554 out of 863 farms (64.19%) said that their farms suffered from ORT before This result indicated that ORT has often occurred in the surveyed areas The result from comparing the
disease percentages of 5 provinces showed that there was a significant difference found (P<0,001) with
Dong Nai and Tien Giang taking the highest disease percentages of 81.37% and 66.67%, respectively
1.3 ORT status by the scale of chicken flocks
Chicken farm scales were classified into 3 large groups: scale of over 2000 chickens was considered as industrial rearing, scale of 500-2000 considered as semi-industrial rearing, and scale of lower than 500 chickens considered as household rearing (Farming Institute, 2004) In this study, the status of ORT was evaluated by each scale shown in Table 4
Table 4 ORT status by the scale of chicken flocks
N=863
Total
ORT
Trang 6Out of 554 farms suspected of ORT, there were 12 farms that could not be collected precise data from, therefore, they were omitted According to Table 4, farms with the scale of over 10,000 chickens had the highest percentage of being infected with ORT (70.59%), while only 50,38% of farms with the scale of < 2000 chickens reported of being infected with the disease, which was the lowest There was a significant difference between the 500-2000 chickens group compared to others regarding the frequency
of being infected with ORT (P<0,05) It could be concluded that the inadequate management of the farms as well as ORT treatment and prevention could be one of the contributing factors for increasing the probability of ORT in farms with larger scales
1.3 ORT status by age groups
According to the result, there were 554 farms reported of being infected with ORT before Out
of these farms, data about ORT status by age groups were collected from 476 farms, which are shown in Table 5
Table 5 Percent of ORT by age groups
According to Table 5, the age group of 3-10 weeks old was most commonly seen being infected with ORT It was probably due to the fact that when chickens reached this age, their maternal immunity has started to degrade while the acquired immunity from vaccination has not developed fully Therefore, they were more prone to different diseases, including ORT (tai liệu tham khảo?)
1.4 ORT status by seasons
Out of 554 farms suspected of ORT, there were 10 farms that could not be collected precise data from regarding the ORT status by seasons, therefore, they were omitted From the results shown in Table 3, it could be clearly seen that there was a significant difference of ORT status by different seasons, in which the all year round group accounted for the highest percentage of ORT infection (41.36%) According to Lopes et al (2002), ORT infection often occurred in winter, spring and in-between season where the temperature fluctuated regularly However, with the current industrial rearing
Trang 7system of chickens with a high density while biosecurity is not secured, ORT infection could happen all year round
Table 6 ORT status by different seasons in a year
3 Investigate pathological characteristics
Through the survey, the clinical signs and typical lesions of ORT were collected through the answers of 110 farms that had appeared ORT Of these, 94 farms had detailed answers for clinical signs and 16 had answers about typical lesions which is showed in Tables 7a and 7b
Table 7a Clinical signs of ORT
B
% 1.06 10.63 4.25 5.31 7.44 31.91 9.57 12.76 1.06 1.06 14.89 100
Table 7b Lesions of ORT
(*) Note: A (Nasal discharge), B (Neck lifting), C (wheezing), D (Prostration)
I (Pleuritis), II (tracheal casein accumulation), III (Airsacculitis with casein accumulation), IV (Casein accumulation near bronchi branching), V (Nasal mucus), VI (Trachea hemorrhage) The clinical signs and lesions of ORT in report are consistent with the description of Van Empel (1997); Roepke et al (1998) such as watery nose, wheezing and neck lift when they breathing or pneumonia, air sacs, tracheal casein accumulation In addition, the majority of cases are complicated transplant expression Among them, dyspnea + neck lift are quite common (31.91%) in cases
2 Damages caused by ORT in surveyed farms
Trang 8Bệnh <5%; 15.31%
Bệnh 5% - <10%; 6.12%
Bệnh 10% - <15%; 7.14%
Bệnh 15% - <20%; 1.02%
Bệnh 20% - <30%; 5.10%
Bệnh 30% - <40%; 7.14%
Bệnh 40% - <60%; 18.37%
Bệnh 60% - < 80%; 4.08%
Bệnh 80% -100%; 35.71%
Figure 1 Percentage of ORT in farms 2.1 Disease percentage
When asked about the percentage of chickens infected with ORT, only 98 farms were capable of providing an answer, with 34% said 100% while 15% answered 50% of the flock The remaining answers are shown in Figure 1 This result indicated that once a chicken is infected with ORT, there would be a high chance that the whole flock would be affected as well
2.2 Mortality after treating
When ORT clinical signs were observed in a flock, farms were provided with a diagnosis as well
as a treatment plan However, there was still mortality recorded, which is shown in Figure 2 Out of 119 farms able to give an answer about flock mortality, 55% said that the mortality was only under 5%, 16% said from 5-10%, and 13% said from 10-15% The survey still recorded that ORT made high mortality, decrease in body weight and performance at infected flocks So the increasing of condemnation rate in farms infected ORT
According to Goovaerts et al (1998), ORT mortality could reach up to 20%, whereas Van Veen et
al (2000) stated that ORT mortality could occur to 50% or over in a flock due to damages caused by the disease In this survey,some case reports of O rhinotracheale infection report a concomitant infection
with other respiratory diseases, such as ND, IB, Coryza or Candidosis According to Chu et al (2017),
when chickens infected Chlamydia psittaci and fungi that caused by Aspergillus spp and ORT, the
Trang 9mortality is about 20% Meanwhile, infection between Chlamydia psittaci, Aspergillus spp., H9N2 and
ORT resulted in up to 40% mortality in chickens
chết <5%; 54.62%
chết 5% - <10%; 15.97%
chết 10% - <15%;
13.45%
chết 15% - <20%; 2.52%chết 20% - <30%; 5.88%
chết 30% - <40%; 3.36%
chết 40% - <60%; 1.68% chết 60% - < 80%; 1.68% chết 80% -100%; 0.84%
Figure 2 Chickens’ mortality 2.3 ORT treatment time
14.99%
44.97%
23.13%
16.92%
< 3 ngày 3-7 ngày 7-14 ngày Kéo dài (>14 ngày)
Figure 3 ORT treatment time
There were a total of 467 farms infected with ORT giving an answer for an effective ORT treatment plan The results in Figure 3 showed that a treatment plan of over 7 days accounted for 40%,
Trang 10whereas a treatment plan of 3-7 days took up to 45% (Figure 3) Therefore, it could be concluded that ORT needs to be treated for a long time in order to be effectively eliminated
2.4 ORT treatment cost
Table 7 ORT treatment cost
Age groups
Number of farms Total number of treated
chickens Average cost/chicken (VND) (weeks old)
(*): thousand VND
According to Table 4, 374 infected farms were able to give an answer regarding to ORT treatment cost by age groups The results showed that the highest treatment cost was for the group from 11-15 weeks old with 4,071 VND/chicken, and the group from 7-10 weeks old took the second place with the average cost of 2,885 VND/chicken The average treatment cost for 1,248,600 ORT infected chickens from 374 farms was 2,460 VND, equaling to 3,071,495,000 VND in total while the average cost for medication and vaccination of a cycle of that broiler is 2,000 – 2,500VND, layer is 7,000-10,000VND according to the record from the surveyed farms
3 Investigation of methods to prevent and treat ORT infected chickens in surveyed farms
3.1 Methods to prevent ORT
There were only 90/863 farms that employed methods in order to prevent ORT, which were equivalent to 10.43% The most commonly seen method that farms utilized to prevent ORT was using antibiotics with 76.67%; the other methods such as supplements, ILT vaccine and antibiotics combination, or antibiotics and supplements combination accounted for a very small percentage, which were all shown in Table 8
Table 8 Methods to prevent ORT