산란계의 혈액화학치 측정에 의한 지방간 출혈 증후군의 조기 진단

Abstract

국내 실용 산란계 농장에서 FLHS 병력을 지닌 계군과 정상계군에 대한 특정 혈액화학치를 비교 측정하여 다음과 같은 결과를 얻었다. FLHS 계군의 간의 지방 함량과 vacuolation score가 Non-FLHS 계군보다 높게 나타났으며, FLHS를 확인하는데 간의 지방 함량과 조직 병리학적 소견을 평가하는 것이 유의성이 있음을 확인할 수 있었다(p<0.05). 또한, FLHS 계군과 Non-FLHS계군이 실험군으로서 명확하게 구분이 되었다. Non-FLHS와 FLHS 계군의 다섯 가지의 혈액화학치를 측정한 결과, cholesterol, AST, LDH의 평균 수치가 Non- FLHS 계군보다 FLHS 계군이 높았으며, FLHS를 확인하는데 cholesterol, AST, LDH가 유의성 있는 항목임을 알 수 있었다(p<0.05). FLHS 계군은 Non-FLHS 계군보다 CK는 높지 않으면서, AST가 높게 나타났으며, FLHS를 진단하기 위해 AST를 측정할 때, CK를 비교 항목으로 이용하는 것이 유용하다는 것을 확인할 수 있었다. Serum AST는 케이지에서 사육되는 산란계에서 FLHS 발생시 현저하게 상승되는 항목으로, FLHS 계군 중에는 250 IU/L 이상을 보이는 개체가 있었으나, Non-FLHS 계군에는 250 IU/L 이상을 보이는 개체가 없었다. MINITAB을 이용하여 판별 분석을 실시한 결과, AST의 판별 추정 계수가 cholesterol이나 LDH보다 큰 수치를 나타내어, AST가 FLHS의 판별에 더 큰 의미를 부여하는 유용한 항목임을 다시 확인할 수 있었다. Fatty liver-hemorrhagic syndrome (FLHS) is a common nutritional disease in commercial layers and breeders. The most important clinical sign of FLHS is a sudden drop in egg production and increased mortality which causes significant economic loss in the poultry industry. However, the current diagnostic method for FLHS is based on the gross findings at necropsy which is not helpful to reduce the economic loss because of lateness of diagnosis. Therefore, we need early diagnosis and diagnostic methods before chickens were affected by FLHS. In this study we tried to evaluate the effectiveness of clinical pathology including blood chemistry as an early diagnostic method for FLHS in commercial chickens. Profiles of blood biochemistry were compared between two flocks selected in the same commercial layer farm based on the presence of FLHS clinical sings. A flock with clinical signs of FLHS was designated as FLHS and other flock without clinical signs of FLHS as Non-FLHS. Several parameters of blood biochemistry were selected and compared between FLHS and Non-FLHS to evaluate the possibility of early diagnosis. Average concentrations of serum cholesterol, serum calcium, aspartate aminotransferase (AST), lactate dehydrogenase (LDH) and creatine kinase (CK) were <TEX>$139.4\;{\pm}\;87.2$</TEX> (mg/dL), <TEX>$24.5\;{\pm}\;5.4$</TEX> (mg/dL), <TEX>$153.6\;{\pm}\;23.1$</TEX> (IU/L), <TEX>$1238.3\;{\pm}\;475.2$</TEX> (IU/L) and <TEX>$1107.3\;{\pm}\;422.8$</TEX> (IU/L) in Non-FLHS flock, respectively, and <TEX>$210.2\;{\pm}\;173.2$</TEX> (mg/dL), <TEX>$25.2\;{\pm}\;4.1$</TEX> (mg/dL), <TEX>$174.3\;{\pm}\;53.5$</TEX> (IU/L), <TEX>$1694.9\;{\pm}\;691.3$</TEX> (IU/L) and <TEX>$1104.9\;{\pm}\;472.9$</TEX> (IU/L) in FLHS flock, respectively. The activities of serum cholesterol, AST and LDH except CK, were significantly higher in FLHS than those in Non-FLHS flock (p<0.05). Some birds of FLHS flock showed 2~17 times greater than in Non-FLHS flock. For the definitive diagnosis of FLHS in the flocks tested for blood chemistry, we analyzed fat content and histological lesion score in the liver sampled from both FLHS and Non-FLHS flock. Average liver fat contents based on dry weight were <TEX>$16.1\;{\pm}\;0.4$</TEX> (%) in Non-FLHS flock and were <TEX>$21.6\;{\pm}\;16.0$</TEX> (%) in FLHS flock. These result confirmed that FLHS flock was definitely affected by FLHS. The above results suggest that selected parameters of blood biochemistry, particularly AST, could be useful to diagnose FLHS before significant liver damage occurred in commercial layers.