This study was carried out for investigation of an outbreak in Karachi. A disease outbreak in poultry was reported during April, 2000 in Karachi. The main symptoms included respiratory distress, sneezing and gasping. Autopsy of dead birds showed tracheitis, air-sacculitis and involvement of lungs. The morbid material was collected for processing in the laboratory. During the investigation for isolation of pathogenic bacteria or virus, Ornithobacterium rhinotracheale was isolated on 5% sheep blood agar plates in an atmosphere containing 5-10% CO2 at 37 degree C and identified through biochemical and fermentation tests. A Lasota like virus was also isolated from the same material which showed HA activity but was found negative to Avian Influenza virus against known Avian Influenza serum. The isolated virus was sent to Central Veterinary Laboratory, Weybridge, U.K. which confirmed it to be Lasota virus having comparatively high Intracerebral Pathogenicity Index (ICPI) as 0.90. Attempts for the transmission of the disease in susceptible healthy broiler chicks was successful through aerosol route using combination of inoculum of the isolated bacteria and virus. On post-mortem of infected birds air- sacculitis, tracheitis and unilateral pneumonia were noticed. Again ORT and NDV were isolated from the material harvested from these chicks. According to the observations of these experiments, it was concluded that the isolated ORT had a triggering effect on Lasota virus or vice versa. The environmental temperature and other stress factors might have aggravated the disease problem.

In this study ELISA was standardized for detecting antibodies against Hydropericardium Syndrome Virus. Factors like Antigen, Conjugate and incubation time were studied. Standardization was carried out by checker board titration method. Optimum incubation time for colour development was found to be 15 minutes while 50 mug/ml of antigen gave better results than 100 mug/ml. The conjugate dilution of 1:500 was observed to give satisfactory results as determined by regression analysis. Cut off value was determined by adding 2SDs and 3SDs in the mean optical density (OD) values of negative serum samples. It was found that mean OD+2SD (0.0684) resulted in better diagnostic sensitivity) and diagnostic specificity than mean OD+3SDs (0.0741).

The effects of melatonin and Light treatments on the reproductive performance of yearling Suffolk rams were investigated. The two groups (A, n = 8; B, n = 8) were given a priming period of long days (18 h Light (L): 6 h dark (D) during 1st February to 14th March. During 14th March to 9th September, group A was exposed to local light + melatonin Implants (Regulin) at 5 weekly intervals, group B was exposed to local light + melatonin Fed (M- 5250) alongwith the feed. The group (C, n = 8) in the local light during 1st February to 14th March and during 14th March to 9th September remained on local light + melatonin implants (Regulin) at 5-weekly intervals. However, the group (D, n=8) was treated as control and kept on local light environment (Lat. 51 degree 43'N) throughout the experiment. Testis diameter, sexual behaviours and semen quality were used to assess reproductive performances. The treatment to group A & B resulted in a significant advancement in high reproductive performance. The treatment to group C indicated that the abrupt application of melatonin in mid March resulted in a weak response in terms of all the criteria of assessment. The investigation indicated that seasonal fluctuations in reproductive behaviour and semen quality may be rephrased by the application of light and melatonin treatments and that these treatments may be considered for the preparation of rams for out of season breeding.

The quick diagnosis of Newcastle disease requires known serum against the disease. In this study, an attempt was made to raise anti- Newcastle disease virus hyperimmune serum in rabbits. Three different inoculum were prepared to inoculate in the rabbits; (i) Fresh harvested allantoic fluid containing Newcastle disease virus (NDV) Mukteswar vaccine strain; (ii) Freshly harvested ND virus pelletted through centrifuging at 40,000 rpm for two hours and resuspended in normal saline and (iii) Pelletted virus (centrifuged and suspended as in ii) with addition of incomplete Freund's adjuvant. It was observed during the monitoring of haemagglutination inhibition (HI) titre that the serum collected after series of inoculation of 1st and 2nd inoculum provided maximum titre upto 1:256. However, the serum collected after series of injection of 3rd inoculum gave maximum HI titre 1:1024. This study suggested that antigen containing incomplete Freund's adjuvant provided better immune response against Newcastle disease virus in rabbits.

This trial was conducted to study effect of freezing on quality of broiler meat after freezing. Meat samples were taken from two sites such as breast and thigh. The weight, moisture, protein, fat and ash contents were analyzed before and after freezing at -25 degree centigrade for 15 days using methods given in AOAC, (1990). It was observed that protein, fat and ash contents were not changed consequent to freezing. There was loss (P less than 0.05) in weight which can be attributed to drip loss when meat is thawed. This study provided evidence that there is no change in nutrients when meat is subjected to freezing.

This study was conducted to examine comparative productive performance of different varieties of Desi chickens identified from group of Desi flock procured from rural field conditions of Mianwali and Bhakkar districts of Punjab province (Pakistan). A total of five varieties of Desi chickens viz., dark brown, medium brown, light brown, black and mixed colour were identified on the basis of their plumage colour and uniformity of body characters. Four hundred and eighty birds (96 of each variety) were selected for further study. The birds of each variety were randomly divided into 3 equal replicates. They were maintained in 15 separate pens on deep litter system under optimal managemental conditions and were fed a balanced layers ration ad-libitum. The birds were provided 16 hours light per day. The experiment was conducted for 8 weeks. The results indicated that varieties differed significantly in egg production, feed conversion efficiency and egg mass, whereas, no difference was observed in feed intake and egg weight between them. Based on the findings of this study, it appeared that different varieties of Desi chickens identified and selected during the course of this study on phenotypic basis differed in their productive potential on the basis of better productive potentials in terms of egg yield, FCR and egg mass, dark brown, and black varieties of Desi chickens could be used to carry out further selective breeding work to study possibility of improving their productive potentials.