The present study was carried out during the period from November 2008 to October, 2009. Large intestines of goats were collected from slaughter houses at Mymensingh town and Kamal Ranjit market of Bangladesh Agricultural University (BAU), Mymensingh. Parasites collection, identification, recovery of (O. columbianum) eggs and their incubation were done by following the techniques.
Female parasites were crushed by using mortar and pestle containing necessary amount of phosphate buffer solution (PBS). Eggs were counted by modified McMaster technique (Thienpont et al., 1979) by using Mcmaster counting chember. Total number of eggs/ml = (Total eggs×10)/ 0.3.
Study of the effects of temperature: To study the effects of temperature, eggs were incubated at various temperature gradients that is 370 C, 260 C, 170 C and 90 C. The pre-counted numbers of eggs were suspended in a petri dish containing culture media. The petri dishes were kept in an aluminium tray covered with a thin layer of moist tissue paper to prevent the evaporation of culture media. Then they were incubated in an incubator separately at above mentioned temperature gradients upto 5 days and examined regularly at 24 hours interval by using dissecting microscope. A drop of culture media was examined for the detection of development of eggs. To study the effect of 40 C temperature, the culture media were kept in refrigerator. After 15 days of observation the culture media were replaced in room temperature to record the further development described by Soulsby (1982) and Rahman et al. (1996).
Study of the effects of pH
To study the effects of pH, the different pH levels (2, 3, 4, 5.5, 6.5, 7.5, 9.5 and 11.5) of the culture media were adjusted by adding glacial acetic acid or by adding sodium hydroxide in PBS drop by drop with the help of dropper and stirred the media. The pH was detected by pH meter. Observations were made by dissecting microscope in every 24 hours up to 7 days.
Study of the effects of pH
To study the effects of pH, the different pH levels (2, 3, 4, 5.5, 6.5, 7.5, 9.5 and 11.5) of the culture media were adjusted by adding glacial acetic acid or by adding sodium hydroxide in PBS drop by drop with the help of dropper and stirred the media. The pH was detected by pH meter. Observations were made by dissecting a microscope in every 24 hours up to 7 days.
Study of the effects of light
There were two groups of samples and each containing three media to identify the light effect on those groups. Pre-counted number of eggs counting culture media was covered with hard paper to make dark condition having facilities for air exchange keeping in room temperature. Then observation was made in similar manner up to 8 days.
Study of the effects of different media
To find out a suitable media for the cultivation of eggs of O. columbianum, pre-counted eggs were cultured in phosphate buffer solution (PBS), normal saline (NS) and tap water (TW) and incubated at room temperature and observed in similar procedure.
Study of the effects of different nutrients on the hatching of eggs
For the preparation of different nutrient media 5%, 10%, 15% serum and 5%, 10% and 15% liver extract were added separately to the PBS. A pre-counted number of eggs were suspended in each and every culture medium mentioned above and all were incubated at room temperature up to 8 days. Then the percentage of hatching eggs was calculated at every 24 hours.
Statistical analysis
Student t-test was used to determine the significance among the different variables (Steel and Torrie, 1980).