For Cytogenetic cultures in buffalo (2N 50),having problem, blood co-agulates after just 1hour of setting up?

In order to study the chromosomal abnormalities in our river buffalo (2N 50) I am trying to establish a protocol for reproducible results however, for the last four months I am encountering a problem that within 1 - 12 the hours cultured samples show a picture where the buffalo blood has co-agulated and forms a jelly like membrane at the botton of the tube of flask. This is to worth mentioning that I have worked extesively on sheep and cattle chromosomes in UK, and have tried different options of using our own reagents, reagent from other labs and a mixture. Only once I had a success during this time when I setup my cultures in a different cytogenetic lab with a very low mitotic index achieved and the quality of chromosomes was not either great. Anybody's feed back would be highly valuable.