Clinicopathological Indications of Resilience of Swamp Buffaloes to Infection with Fasciola gigantica
Fasciolosis caused by Fasciola gigantica is a common disease among livestock such as swamp buffaloes (Bubalus bubalis) in rice-producing areas in humid tropical regions. It causes a significant reduction in meat and milk production, growth rate, fertility and draught power in infected animals (Dargie, 1987). However, the extent to which infection adversely affects the production of infected animals depends on several factors, among which is the breed of susceptible animals. Different breeds of animals and individuals within the same breed manifest varying responses and resilience to infection (Spithill et at., 1999). For instance, differences in response to infection with F. gigantica were seen in Bali, Ongole and buffalo calves in terms of weight gain (E. Wiedosari, personal communication, 1997). This information demonstrates breed differences in response to F. gigantica infection and shows that swamp buffaloes are more resilient than cattle to F. gigantica. The clinicopathological responses of swamp buffaloes naturally infected with F. gigantica were evaluated in this study to determine whether these parameters would indicate resilience to natural infection with parasites.
Primary experimental infection of riverine buffaloes with Fasciola gigantica.
The clinical course of the primary experimental Fasciola gigantica infection was investigated in riverine buffalo calves of the Murrah breed. Nine male calves aged 12-15 months were randomly assigned to two groups of five (Group I) and four (Group II) animals. Each animal in Group I, was orally infected with 1000 metacercariae (mc) of F. gigantica, whereas Group II animals did not receive any infection dose and served as uninfected controls. No clinical signs of fasciolosis were observed until the sixth week post-infection (PI). Group I animals, however, developed recognised symptoms of acute fasciolosis, comprising apyrexic inappetance, anemia, poor weight gain, diarrhoea and sub-mandibular and facial oedema, respectively, from 5, 6, 8, 16 and 17 weeks PI. The signs were intermittent in nature and of variable duration. The prepatent period was of 92-97 days (mean 95.2 +/- 3.1). One of the five infected animals died on Day 147 PI. At necropsy, 36.8 +/- 11.0% of the infection dose was recovered as adult fluke population. The gross lesions were primarily biliary in nature. Group II, the uninfected controls, throughout the study period of 165 days PI, did not show any symptom and were negative for F. gigantica. The study demonstrated that the onset of adverse effects of F. gigantica on the growth and health of the infected host was mainly noted during late prepatency much before coprological prediction and diagnosis. The significance of preventive therapy against fasciolosis during prepatency has been stressed in endemic areas.
Investigations on the rôle of organic matter in plant nutrition
1. As the result of decomposition of green manure in a swamp soil, the coarse fractions (including coarse and fine sand) of the surface layer (first 3 inches) decreased by 11·2 per cent. while the fine ones (silt+clay) increased by 9·8 per cent. in the course of 43 days. The effect was less pronounced in the manured soil maintained at 60 per cent. saturation, while no alteration was to be noticed in the case of the unmanured specimens. 2. Treatment with dilute hydrochloric acid prior to dispersion had no appreciable effect on the estimates of mechanical composition obtained in the different cases. Loss in solution was also comparatively small. 3. The silica-sesquioxide ratio increased slightly as the result of decomposition of green manure in swamp soil. The composition of the fine fractions was also altered, the total percentages of the oxides of iron, aluminium and silicon increasing from 90·5 to 99·3 in the course of 71 days. 4. The practical significance of the above and related observations has been discussed.