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ThesisItem Open Access Susceptibility of ducks to newcastle disease virus (NDV) and their role in the transmission of the disease to chicken(Department of veterinary and Animal Sciences, College of Veterinary and Animal Sciences, Mannuthy, 1981) Sudharma, D; KAU; Sulochana, SThe susceptibility of ducks to Newcastle disease virus and their possible role in the epizootiology of this disease were investigated. Cloacal and throat swabs and sera were collected from clinically normal as well as diseased ducks from different parts of Kerala. The swabs were tested for virus excertion by inoculating into the allantoic cavity of 10 day embryonated chicken eggs and the sera were examined for the presence of haemagglutination inhibition antibodies. Eight and one week – old ducklings were infected experimentally by different routes or methods to find out their susceptibility to this virus. A virulent strain of the virus received from Veterinary Biological Institute, Palode was employed for all experimental infection studies. Two week – old chickens were used for determining contact transmission. Inoculation of processed cloacal and throat swabs into the allantoic cavity of 10 day embryonated eggs resulted in the isolation of eleven haemagglutinating viruses from a total of 151 samples. The agglutination produced by these viruses were inhibited by specific ND antiserum, thereby confirming their identity as Newcastle disease virus. Out of a total of 226 serum samples collected from ducks, 34 showed HI antibodies ranging from 1:20 to 1:160 in the titre. Eight week – old ducklings infected intranasally and intraocularly showed symptoms of ND by third day of infection but recovered by the seventh day. All of them excreted the virus either through trachea, cloaca or by both the routes. Haemagglutination inhibition antibodies were demonstrable within two weeks of infection. The chickens kept in contact with the infected ducklings died after showing specific symptoms of newcastle disease. Postmortem examination revealed specific lesions and virus could be isolated from pooled tissue samples. Week – old ducklings could successfully be infected by intranasal/intraocular, subcutaneous, intramuscular or by contact infection. All the ducklings exposed to infection died after showing symptoms of pneumoencephalitis and diarrhoea. Virus was isolated from seventeen out of twenty five cases. Chickens placed in contact with subcutaneously infected ducklings died showing specific symptoms and lesions in ND and virus could be isolated from all the cases. The eight week – old ducklings although showed a clinical infection they could eventually recover following the development of antibodies in the system. Hence ducklings of eight weeks and above could be considered as resistant to newcastle disease virus infection. On the contrary week – old ducklings readily succumbed to the infection indicating their grater susceptibility. Contact transmission to chickens was possible from both age group of ducklings. The isolation of virus from clinically normal and diseased ducks showed that ducks excrete the virus without showing any clinical symptoms. It is also possible that some ducklings may show symptoms of the disease, but the development of antibody in the system leads to complete elimination of the virus. The results and the observation of the present study indicate that ducks can play an important role in the epizootiology of Newcastle disease by contracting infection from infected chicken or from other susceptible species and transmitting it to the incontact susceptible chicken.ThesisItem Open Access Bio-climatological studies on dry matter intake and water consumption of growing livestock(Department of Animal Management, College of Veterinary and Animal Sciences, Mannuthy, 1980) Somanathan, V L; KAU; Rajagopalan, T GThe present work was undertaken to study the distribution of climate at Mannuthy and to study the effect of the prevailing ambient temperature and relative humidity on the performance of growing crossbred cattle. The meterological data over a period of five years (1974 – 1978) were analysed to study the climatic picture of this locality. The rectal temperature, respiration rate, dry matter intake, water consumption and growth rate of eleven male and five female calves were observed for a period of twelve months. The climatic picture showed that there are two distinct seasons prevailing in this locality, namely, the dry and the rainy seasons, which are further sub divided into ‘Warm and dry’, ‘Hot and dry’, ‘Cold and wet’ and ‘Warm and wet’ seasons, respectively. The rectal temperature of the animals remained fairly constant throughout the year, inspite of wide variations in the ambient temperature. It showed negative correlation with ambient temperature (-0.357 in males and -0.207 in females) and positive correlation with relative humidity which was significantly only in males (0.416). The respiration rate varied from 30.973 per minute during July (lowest) to 49.230 per minute during April (highest). It showed positive correlation with ambient temperature (0.638 in males and 0.561 in females). Significant negative correlation between respiration rate and relative humidity was observed in males only (-0.253). The percentage dry matter intake was found to have a strong negative correlation with ambient temperature (-0.652 in males and -0.685 in females). Whereas with the relative humidity, the correlation was positive and was significant only in males (0.514). Highly significant positive correlation between ambient temperature and daily water consumption (0.763 in males and o.748 in females) and negative correlation between relative humidity and water consumption (-0.725 in males and -0.503 in females) were obtained in this study. There was negative correlation between ambient temperature and monthly weight gain and positive correlation between relative humidity and monthly weight gain, but was significant only in males. The negative correlation obtained in this case can be attributed to the poor quality of the roughage during the summer months rather than the direct effect of ambient temperature.