The Evaluation of Anthelmintic on Prevention of Ascariasis in Pig Farms and Study of Gene Expression of Swine Milk Spot Liver

• Main Author: 黃威祺
• Other Authors: Dan-Yuan Lo
• Format: Others
• Language: zh-TW
• Online Access: http://ndltd.ncl.edu.tw/handle/43793094361061084971

碩士 === 國立嘉義大學 === 獸醫學系研究所 === 102 === Ascaris suum is a nematode parasite of pig. Ascariasis reduces the feed efficiency and growth rate of pigs and causes liver condemnations at slaughterhouse, thereby seriously affecting the pig industry’s economy. There are two main purposes in this study: 1. To improve the high discarding percentage of milk spot livers in Taiwan’s slaughterhouse. 2. To explore the relationship between the formation of milk spot liver and the expression of cytokines. The first part was a six month field trial that took place from May 2011 to Oct 2011. We selected 8 commercial pig farms from the yun-chia-nan area as field farms of this study, and categorized the farms into group A (used) and B (unused), based on whether or not the farmers used sodium hydroxide solution to clean the environment. The program we used to deworm the farms was the addition of 30 ppm flubendazole in feed for 7 days, every two months, during the trial period. To explore the effect of usage of sodium hydroxide solution to clean environment on anthelmintic treatment for prevent ascariasis in pig farms. Finally, we used the percentage of discarding livers per month of each farm and percentage of ascaris eggs detected in fecal analysis, as a basis for assessing the effectiveness of prevention of the ascariasis in pig farms. Second, we collected milk spot livers and normal livers from pig slaughterhouses in yun-chia-nan area. According to tissue type, the samples were divided: group 1 is normal liver tissue; group 2 is tissue in the lesion of milk spot liver; group 3 is normal tissue of milk spot liver. A total of 30 samples were collected, with 10 samples in each group. We used the relative quantitative real time polymerase chain reaction (relative quantitative rt-PCR) to confirm the difference of expressions of transforming growth factor-β1 (TGF-β1), tumor necrosis factor-α (TNF-α) and vascular endothelial growth factor A (VEGFA) between the various groups. With the use of histopathological exams, the pathological changes of 30 milk spot liver samples were examined monthly, from Jan 2011 to Dec 2012. Our results showed that, after the usage of antihelmintics, the percentage of discarded livers decreased from 7.90 ± 4.37 % to 4.61 ± 1.30 % in group A, and decreased from 29.86 ± 14.63 % to 13.15 ± 3.96 % in group B. However, there was no significant difference between post-test and pretest. The average detected percentage of ascaris eggs decreased from 2.19 ± 2.95 % to 0.38 ± 0.75 % in group A, and decreased from 13.44 ± 6.40 % to 6.88 ± 10.68 % in group B. Furthermore, the high positive correlation between the two assessment projects, the percentage of discarded livers and percentage of ascaris eggs detected in fecal analysis, showed that the former was about 2.7 times higher than the latter. In economic efficiency of deworming program, the profit of deworming program in group A is NT 0.54/pig and in group B is NT 99.32/pig. In second part, the gene expression of TNF-α and VEGFA in the lesion of milk spot liver was significantly lower than other groups (p < 0.01), and TGF-β1 had no significant difference in all groups (p > 0.05). Histopathological lesions of milk spot livers, eosinophil infiltration (100 %, 720/720) had the highest occurrence, followed by biliary hyperplasia (96.39 %, 694/720), bridge fibrosis (95.28 %, 686/720), connective tissue hyperplasia (84.72 %, 610/720), focal necrosis (48.33 %, 348/720), hemorrhage (25.28 %, 182/720), granulomatous inflammation (3.75 %, 27/720) and pyogranulomatous inflammation (1.53 %, 11/720). In conclusion, the addition of anthelmintic into feed every two months and the usage of 3 % sodium hydroxide solution to clean the environment are beneficial for the prevention of ascariasis in pig farms. The percentage of ascaris eggs detected in fecal analysis can be used to estimate the percentage of discarded livers in pig farm, and to act as a reference for ascaris prevention. The gene expression of TNF-α and VEGFA may be associated with the formation of milk spot lesions. However, the amount of cytokine producing cells probably decreased due to the ascaris migrating larvae induced immunosuppression of host or increase of connective tissue thereby causing the milk spot lesion’s gene expression of cytokines to become significantly reduced or show no significant difference from normal liver. In the future, to further explore the differences of gene expressions between the milk spot liver and normal liver, a microarray can be used to simultaneously measure the expression levels of many different genes.