Determination and Occurrence of Histamine in Rumen Liquor of Sheep

Methods for the determination of histamine in rumen liquor and different feeds are described. The procedures involve adsorption of histamine on Amberlite IRC-50 columns and biological determination of the histamine content of eluates from the ion-exchange resin. By these methods 70—80 % of added histamine were recovered and histamine concentrations as low as 0.01 μg histamine diphosphate per ml of rumen liquor could usually be estimated.Occurrence and formation of histamine in rumen contents of sheep have been examined with the following results:

1. Feeding invariably increased the concentration of histamine in the rumen, the increments being related to the histamine content of the feed.
2. A small formation of histamine seemed to take place in rumen content both in vivo and in vitro after feeding hay or concentrates.
3. The in vitro formation of histamine in rumen contents was greatly increased when L-histidine (10 mg/ml) was added. The formation of histamine varied widely from day to day and was further related to the time of feeding.
4. Pyridoxal-5-phosphate increased the in vitro formation of histamine in rumen content.