PURSE 2001

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Browsing PURSE 2001 by Author "Abeynayake, P."

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    A preliminary study to detect antibiotic residues in fresh milk
    (University of Peradeniya, Peradeniya, Sri Lanka, 2001-11-16) Hathurusinghe, M. H.; Piyankarage, R. H.; Abeynayake, P.; Jayaweera, W.
    Due to the wide usage of antibiotics in the treatment and prevention of diseases in dairy cows, there is a likelihood of antibiotic residues occurring in milk. Such residues can cause several adverse effects in humans including hypersensitivity reactions. These residues may also interfere with bacterial starter cultures used for preparing of curd, yoghurt and cheese. This study was designed to screen milk for the presence of antibiotic residues. The study was carried out in 74 dairy cows reared in certain selected areas of the Kandy district. After taking the history of each cow, milk samples from each animal were obtained into sterile bottles at the time of milking. Before performing the screening test, the samples were heated at 100°C for 5 minutes to destroy natural inhibitory substances in raw milk. For negative control, 2 ml of 10 % skimmed milk heated at 110°C for 10 minutes was used. The positive control was a 2 ml milk sample containing 0.006 ug/ml of benzathene benzyl penicillin. A prepared test culture of 0.2 ml of Streptococcus thermophilus strain T.J. containing yeast-extract and bromocresol purple (as pH indicator), were added to each 2 ml of milk sample and placed in a water bath at 45°C ± 0.5 for 2.5 hours. Bromocresol purple is purple at the beginning and turns yellow due to acidification during the growth of the bacteria. Retention of the original purple colour indicates that the bacterial growth has been inhibited and such samples were considered as positive. The samples that gave a yellow colour were considered as negative. Out of the 74 samples tested, 7 samples (9.5 %) were found to be positive and 63 samples (85.1 % ) were negative for chemical inhibitory substance. Four samples (5.4%) gave intermediate colours indicating doubtful results. The positive results could be due to the presence of antibiotic residues or other inhibitory chemicals in raw milk. Serial dilutions of antibiotics prepared in skimmed milk were used to detect the level of sensitivity of the test. Penicillin and oxytetracycline gave the colour change at >0.005 ug/ml. Cloxacillin gave the colour change at 0.5 ug/ml where as gentamycin changed the colour at 0.5j.tg/ml concentrations. Chloramphenicol gave the colour change at 100 ug/ml. Therefore the test was found to be highly sensitive to penicillin and oxytetracycline antibiotics, whereas Chloramphenicol was found to be the least sensitive antibiotic for this test. The results revealed that the fresh milk is not totally devoid of inhibitory substances and further studies are necessary to specify the chemical and to quantitatively determine its concentration.
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    Occurrence and Pathology of Ascites and Right Ventricular Failure in Broilers
    (University of Peradeniya, Peradeniya, Sri Lanka, 2001-11-16) Ekanayake, S.; Horadagoda, N. U.; Jayasekera, M. U.; Abeynayake, P.; Guneratne, S. P.; Ranathunge, L.
    Ascites and Right Ventricular Failure (ARVF) is a metabolic disease of fast growing broiler chicken which is associated with multitude of factors such as genetic selection, high quality feed, high altitude and increased sodium content in feed and water. The disease is clinically evident from the age of one month onwards and is characterized by distension of the abdomen, dispnoea, cynosis, reluctance to move, and a poor growth rate. The mortality in ARVF is variable but it can be as high as 25%. Although cases of ARVF has been observed in Sri Lanka there had been no systematic investigations performed on the occurrence of the disease and the associated lesions. In the present study, these aspects have been examined in a population of adult boilers of 35 to 38 days old reared in the mid-country region of Sri Lanka. A total of 15,116 birds were examined over a two-month period at a broiler processing plant. Birds with gross lesions characterised by abdominal distensions with fluid were collected prior to evisceration. The selected carcasses (de-feathered) were subjected to detailed post- mortem examinations and data were collected on carcase weight, sex, characteristics of the pericardial and ascitic fluid, and changes in the heart, lung and liver. For purposes of comparison, similar data were also obtained from 146 apparently healthy carcasses of adult birds. ARVF was observed in 24 birds (0.16 %). The most prominent lesions were the accumulation of increased quantity of yellow to amber coloured ascitic fluid (14 - 140 ml), which often contained fibrin clots and flakes. The gross lesions in the lungs included severe congestion and oedema. The pericardial cavity was distended with a variable volume of clear to straw coloured fluid (1 - 12 ml) and there was marked dilatation of the right ventricle. The liver of diseased birds was found to be enlarged and fibrinous deposits were present on the capsule. The carcass weight of the affected birds was lower (mean ± sem; 1136 ± 47.1 kg) than the unaffected ones (1295 ± 14.8 kg). Among the affected birds, the occurrence of the disease was significantly high in males (66.6 %) compared with the females (33.3 %). Studies are also in progress to determine the prevalence of the disease at different times of the year and to identify the aetiological factors responsible for ARVF in Sri Lanka.