~ ~~~~~A container with nylon and stainless steel mesh screens (10 pm and 20 pm pores, respectively), which allowed the passage of bacteria and soluble substrate but restricted the passage of protozoa, was used to investigate the phenomena of sequestration, migration and lysis of protozoa in the rumen of steers. After feeding, the concentration of Isotrichidae in the rumen increased 8-7-fold within 40 min and then decreased 88% by 4 h; however, the concentration of Isotrichidae inside the containers remained almost constant. Fluctuations in concentrations of Isotrichidae were shown to be due to migration and sequestration within the rumen. Ophryoscolecidae did not exhibit the phenomena of sequestration and migration. When steers were fed once a day, about 50% of the decrease in the concentration of Ophryoscolecidae immediately after feeding could be attributed to the dilution effects of feed and water and/or passage out of the rumen. The remaining 50% of the decrease appeared to be from cell lysis, resulting in a wasteful recycling of protozoal protein.In an experiment to determine the effects of feed restriction on concentrations of Ophryoscolecidae, it was shown that decreased concentrations associated with substrage restriction are due to cell lysis rather than to passage out of the rumen.

A quantitative method of analysis for 2-aminoethylphosphonic acid (AEP) was developed using reverse-phase HPLC. The detection limit for AEP was 15 nM, and the detector response (peak area) was linear from AEP levels up to 100 microM (R = .99). Mean recovery of AEP added to strained ruminal fluid from faunated sheep was 98.2%. When AEP was added to a fermentation mixture at a concentration of 22.6 micrograms/ml, 78% disappeared during a 24-h incubation. 2-Aminoethylphosphonic acid was readily detected in preparations of mixed ruminal ciliate protozoa as well as in mixed and pure strains of ruminal bacteria, feedstuffs, and ruminal fluid and duodenal digesta from defaunated sheep. The occurrence of AEP in feed and bacterial hydrolysates was confirmed by organic phosphorus analyses. The concentration of AEP in mixed ruminal protozoa was three times greater than its concentration in mixed ruminal bacteria (4,304 vs 1,383 micrograms/g DM, respectively). The AEP values for pure ruminal bacterial cultures ranged from 733 micrograms/g DM in Bacteroides succinogenes B21a to 1,166 micrograms/g DM in Butyrivibrio fibrisolvens H17c. Ruminal fluid and duodenal digesta from defaunated sheep contained AEP concentrations of 30 micrograms/ml and 90 micrograms/g DM, respectively. The concentration of AEP in feedstuffs ranged from 25 micrograms/g DM in wheat straw to 263 micrograms/g DM in oats. Because AEP occurrence is not limited to ruminal ciliate protozoa, it is of little value as a marker for protozoal presence in or passage out of the rumen.

Trials were conducted to determine effects of defaunation procedures on protozoal concentrations and in situ nutrient disappearance in steers and to determine effects of defaunation and supplemental protein source on performance of lambs. Four ruminally cannulated steers were isolated from other ruminants and fed a dehydrated alfalfa-cracked corn diet for three periods with four replicates (steers) per period. Treatments were as follows: 1) control (no defaunation), 2) dosing fasted steers for two consecutive days with 40 g dioctyl sulfosuccinate (DSS) and 3) daily feeding of 40 g DSS to defaunated, nonfasted steers. Ten days post-dosing with DSS (treatment 2), three steers were free of protozoa but one steer still had a ruminal concentration of .6 x 10(4) protozoa/ml. Compared to steers prior to defaunation, treating steers for 2 d with DSS decreased (P less than .05) both in situ soybean meal (SBM) N disappearance at 3, 6 and 9 h of incubation and in situ orchardgrass DM disappearance at 24 h of incubation. Feeding 40 g of DSS daily for 10 d was not successful in maintaining the rumen free of protozoa. Thirty crossbred Targhee lambs (avg wt, 25 kg) were defaunated with DSS and allotted by BW and sex to five treatments: 1) defaunated, fish meal supplemented at 9.5% dietary CP (FM-9.5% CP), 2) defaunated, SBM-9.5% CP, 3) refaunated, FM-9.5% CP, 4) refaunated, SBM-9.5% CP and 5) refaunated SBM-12% CP. Defaunated lambs remained free of protozoa during the 56-d performance trial that was initiated 24 d after the defaunation procedure.(ABSTRACT TRUNCATED AT 250 WORDS)