Effects of levamisole dilutions on HA of Newcastle Disease virus were studied in vitro and the findings are: 1. Treatment period 4 hours (at room temperature) - 1.1 When levamisole were mixed up to make final dilutions of 0.02 and 0.05% with NDV, no effect on HA was apparent; 1.2 When the final dilutions were 0.1, 0.25, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5 and 4.0%, the HA dropped significantly; 1.3 When the final dilution were 4.5 and 5.0% all HA activities of the NDV were destroyed. 2. At final dilution 0.02% levamisole did not affect the HA when the NDV were treated for 24 hours at room temperature. 3. HA activities of NDV was usually affected when NDV were treated longer than 4 hours when the final dilutions of levamisole were higher than 2.0%. Levamisole dilution should not exceed 0.1% when it is used as ND Vaccine diluent.

Six outbreaks of Aujeszky's disease in pigs have been confirmed by the Department of Pathology, Faculty of Veterinary Science, Chulalongkorn University since December, 1977. The clinically ill piglets were submitted and diagnosed by several laboratory methods. F.A. tests applied on brain impression smears and cryostat tonsil sections were rapid and gave an accurate results. Taking more time, histopathology of brains, tonsils and other organs of the infected pigs and the rabbit inoculation with the isolated virus were found reliable to support the F.A. tests. In this study, 21 out of 22 piglets from the 6 outbreaks of Aujeszky's Disease had non-suppurative encephalitis associated with Cowdry tape A intranuclear inclusion bodies in nerve and glial cells. Focal necrosis on livers, lungs, spleens, lymph nodes and tonsils were common. Rabbits developed intense pruritus at the site of injection at 2-4 days after inoculation of the virus. Clinically, the affected pigs, in all 6 outbreaks, exhibited nervous and respiratory signs and the pregnant swine had a high rate of abortions during the outbreaks.

Culture of the giant freshwater prawn in three different systems were comparatively studied. These culture systems are: 1) a large earthen pond; 2) nylon cages submerged in an irrigation canal; and 3) a longitudinal ditch located in an orchard. Each culture system was initially stocked with juvenile prawns at 5 prawns/m2. The prawns were fed with a compound diet at the same ratio for the experimental period of six months. The results showed a significant difference on growth among these three systems. The prawns reared in cages exhibited the poorest growth while those of the other two systems exhibited better and comparable growth. Nevertheless, the prawn reared in cages showed the best survival (52.5%). Survival of prawn reared in the earthen pond and the longitudinal ditch were 48.0% and 35.2%, respectively. The yield per rai (0.16 ha) per crop (six months) of these three systems were 210 kg, 138 kg, and 74 kg, respectively. The factors affecting growth, survival, and production of the prawn are discussed.

Fish feed, in general, contains protein content not less than 35%. At present, the use of the fish meal as a source of protein is facing problem since the price of fish meal has been increasing and often unavailable. Thus, there is a need to replace fish meal with another source of protein. Since the brewers' yeast contains 38-42% protein it might be possible to produce fish feed.

Some observations before, during and after parturition were reported in 20 swamp buffalo cows (Bubalus bubalis) all together. Preparturient changes concerning labia, pelvis and udder were described. The rectal temperature in one cow was recorded every morning and evening for 11 days before parturition. During parturition the appearance and the rupture of the fetal membranes were observed. The expulsion of the calf took 28 min. in average. The placenta was expelled 3 hours and 24 min. after the expulsion of the fetus.

Three groups of 20 chickens Were given Lasota strain of Newcastle disease vaccine when they were 11 days old via eye dropping. Chickens of the first group were also inoculated subcutaneously with levamisole 4.5 mg/bird and 6.75 mg/bird (10.0 mg/lb. and 15.0 mg/lb.). Serum samples were serially collected and hemagglutination inhibition (HI) titres were assay. HI titres in sera from levamisole inoculated birds were higher than those in sera collected from control birds.

The main objective of this study is to identify the socio-economic factors influencing farmers decision making regarding the adoption of high yielding varieties of rice and the impact on farming and farmers of Suphan Buri. Two hundreds farm households were randomized from Don Chedi of Suphan Buri for interview. The adoption of high yielding varieties of rice is largely determined by the degree of water control. The adoption has been accompanied by a sharp rise in demand for labor and farm mechanization. This resulted in raising farm productivity and reducing seasonal unemployment.