Andrographolide restored production performances and serum biochemical indexes and attenuated organs damage in Mycoplasma gallisepticum-infected broilers

1. This study aimed to study the preventive and therapeutic effects of andrographolide (Andro) during Mycoplasma gallisepticum HS strain (MG) infection in ArborAcres (AA) broilers.2. The minimum inhibitory concentration (MIC) of Andro against MG was measured. Broiler body weight, feed efficiency, morbidity, cure rate and mortality were recorded during the experiment. Air sac lesion scores and immune organ index were calculated. Expression of pMGA1.2 in lung tissue and serum biochemical indices were examined. Histopathological examinations of immune organs, liver, trachea and lung tissue were conducted by Haematoxylin and Eosin stain.3. MIC was 3.75 μg/mL and Andro significantly inhibited the expression of pMGA1.2 (P ≤ 0.05). Compared with control MG-infected group, Andro low-dose and high-dose prevention reduced the morbidity of chronic respiratory disease in 40.00% and 50.00%, respectively. Mortality of C, D and E group was 16.67%, 10.00% and 6.67%, respectively. Cure rate of E, F, G and H group was 92.00%, 92.86%, 93.33% and 100.0%, respectively. Compared with control MG-infected group, Andro treatment significantly increased average weight gain (AWG), relative weight gain rate (RWG) and feed conversion rate (FCR) at 18 to 24 days (P ≤ 0.05). Compared with control group, Andro alone treatment significantly increased AWG in broilers (P ≤ 0.05).4. Compared with control MG-infected group, Andro significantly attenuated MG-induced air sac lesion, immune organs, liver, trachea and lung damage in broilers. Andro alone treatment did not induce abnormal morphological changes in these organs in healthy broilers. Serum biochemical analysis results showed, comparing with control MG-infected group, Andro significantly decreased the content of total protein, albumin, globulin, alanine aminotransferase, aspartate aminotransferase, total bilirubin, urea, creatinine, uric acid, total cholesterol, and increased the albumin/globulin ratio and content of alkaline phosphatase, apolipoprotein B and apolipoprotein A-I in a dose-dependent manner (P ≤ 0.05).5. Andro could act as a potential agent against MG infection in broilers.