Improved in vitro procedure for maintaining stock cultures of three genera of rumen protozoa.

To maintain stock cultures of rumen protozoa, studies were initiated to explore possible methods for keeping the protozoa viable without feeding every day. Cultures of Entodinium caudatum, Epidinium caudatum, Enoploplastron triloricatum, and Entodinium exiguum were used to study the effect of not feeding for 1 or 2 d. The study lasted 88 d, and although bacterial concentrations decreased when cultures were not fed for 2 d (over the weekend), they recovered quickly with subsequent daily feedings. The exception was Enoploplastron triloricatum, which showed a gradual decline over the entire study. Addition of streptomycin to the media had little effect on maintaining bacterial concentrations in all cultures except Entodinium caudatum, in which the overall mean concentration was greater (P < 0.01). No differences in pH or bacterial concentrations were found between cultures fed daily and those held without feed for 2 d, with or without streptomycin. For maintaining protozoal cultures (10-mL volumes) over a long period without feeding on weekends, the following schedule is proposed: transfer and feed 0.12 mL of 1.5% ground wheat-1% orchardgrass on Monday; feed 0.12 mL of 1.5% ground wheat-1% orchardgrass on Tuesday, Wednesday, and Thursday; transfer and feed 0.5 mL of 1.5% ground wheat-1% orchardgrass on Friday; do not feed on Saturday and Sunday.