젖소농가의 소 바이러스성 설사 바이러스 유발 지속 감염우 분석에 관한 연구 = Studies on the Analysis of Persistently Infected Bovine Viral Diarrhea Virus in Dairy Cattle Farms

다국어 초록 (Multilingual Abstract)

Bovine Viral Diarrhoea Virus (BVDV), is one of the most
important pathogenic viruses in cattle. The objective of this study was
to evaluate the prevalence of BVDV infection in dairy cattle in
Gyeunggi province in Korea and use this data as the basis for
establishing an effective eradication program for this virus in both beef
and dairy cattle.
A total of 2,194 samples were tested for BVDV antibodies using
bulk milk samples from 2,194 farms. A total of 55,263 samples were
tested for BVDV antigens using ear notch samples from 842 farms
from Mar to Nov 2009. The test method used was the IDEXX ELISA
kit specifically targeted for this purpose. The methods used to confirm
and identify PI (persistently infected) positive cattle comprised
RT-PCR and immunohistochemistry(IHC). Somatic cell counts were
also measured in the milk samples for all cattle. Other information
gathered included milk volumes, calving intervals and open day
intervals.
Out of a total of 2,194 bulk milk samples, 2,007 samples (91.5%)
were BVDV antibody positive and 187 samples (8.5%) were antibody
negative. BVDV PI cattle were detected at 387 farms out of 842 farms
(46%). There was a total of 669 out of 55,263 heads of cattle (1.2%)
identified as being BVDV PI positive. The distribution of these PI
positive cattle by age, were: 178 head (65.4%) less than 14 months
and 94 head (34.6%) more than 14 months of age - in total 272 PI
positive cattle. Most of these PI positive cattle were older than 14
months and 80.9% of them less than 23 months. 4 BVDV antigen
positive samples (taken from ear notches) which were confirmed by
and all shown to be positive using RT-PCR. The same samples were
tested using IHC and gave clear positive results when examining
ketatin cells and epidermal hair follicles.
The average milk volume produced per animal on farms with
some PI positive cattle in the herd was 9,630ℓ which was 211ℓ
(2.15%) lower as compared to 9,841.6ℓ on negative farms. When
taking results for PI positive and non PI cattle separately, the average
annual milk volume from PI positive cattle per head was 7,328.4ℓ and
for non PI cattle 9,735.8 ℓ.
This represents a lower annual milk volume from PI positive cows
of 2,407.4ℓ (24.7%) less than that from non PI cattle. Average milk
fat yield was 3.81% from PI positive farms which was 0.26% lower as
compared to 3.82% on negative farms. There is no significant
difference between the two groups. The milk fat and milk protein
figures from PI positive cattle alone were 3.75% and 3.03%
respectively. These results are lower when compared to the 3.91%
and 3.09% figures obtained from non PI cattle. Average calving
interval per animal was 452 days on farms with some PI positive
cattle which is 7 days more as compared to 445 days on farms with
all negative animals. The calving interval as taken from PI positive
cattle alone was 491 days which is 44 days longer compared to 447
days for non PI cattle. In addition, the open day intervals between the
two groups with PI positive cattle showing 193 days and non PI cattle
11 days shorter at 182 days. The average somatic cell count per
animal on farms with some PI positive cattle in the herd was
251,000/ml. This is 18,000/ml (7.7%) greater than the average count
of 233,000/ml on negative farms. The average somatic cell count per
animal in milk taken from PI positive cattle alone was 286,000/ml
which is 39,000/ml more (15.8%) than the average figure of 247,000/ml
for non PI cattle.
In summary, the majority of milk samples taken from cows at the
farm tested positive for BVDV antibodies. PI positive cows were
widely distributed across the farms at a rate of 1.2% of all individual
cattle tested. PI positive cattle yielded lower milk fat, milk protein and
had longer open day intervals compared to PI negative cattle. The
somatic cell counts in their milk were also greater. The IDEXX ELISA
kit proved to be a successful method to detect BVDV antibodies in
milk and detecting BVDV antigens from ear notch samples. RT PCR
with IHC was equally successful in confirming results. This study has
met its objective of evaluating the prevalence of BVDV infection in
the bovine dairy population in Gyeunggi province. It forms the
foundation and basis on which to build a nationwide BVDV PI
eradication program. Although the scope of this study was dairy
cattle, it is also crucial to evaluate the situation in beef cattle to
minimize economic loss on farms in Korea.

목차 (Table of Contents)

• ABSTRACT
• List of Tables ⅰ
• List of Figures ⅱ
• List of Abbreviations ⅱ
• Ⅰ. 서론 1
• Ⅱ. 재료 및 방법 6
• 1. 우유 채취 6
• 2. 귀조직 채취 6
• 3. ELISA(enzyme-linked immunosorbent assay)를 이용한 BVDV 항체가 분석 7
• 4. Enzyme-linked immunosorbent assay(ELISA)를 이용한 BVDV 항원가 분석 9
• 5. RT- PCR에 의한 BVDV검출 11
• 1) RNA 추출 11
• 2) Reverse Transcription-Polymerase Chain
• Reaction(RT-PCR) reaction 12
• 6. 귀 조직 면역염색(Immunohistochemistry) 14
• 7. 유성분 분석 14
• 8. 공태일수 14
• Ⅲ. 결과 및 고찰 15
• 1. 냉각기 우유에서 BVDV 항체가 검출 15
• 2. BVDV 항체 검출율에 따른 PI 목장분포도 17
• 3. 지속감염우 분포 현황 19
• 4. 지속감염우 귀 조직 RT-PCR 분석 21
• 5. 귀 조직 면역염색(immunohistochemistry) 25
• 6. 검정목장 별 우유분석, 분만간격 및 공태일수 28
• 7. 체세포 및 세균 수 비교 31
• 8. 질병치료비 분석 34
• 9. 사육두수가 분만간격에 미치는 영향 36
• 10. 유량이 분만간격에 미치는 영향 38
• Ⅴ. 결론 40
• 참고문헌 43