Ruminal fermentation and duodenal flow following progressive inoculations of fauna-free wethers with major individual species of ciliate protozoa or total fauna

Naturally fauna-free (FF) wethers, equipped with luminal and duodenal cannu las, were used in two groups of eight (Group A) and seven (Group B) animals in six consecutive experimental periods, each lasting for 28 d. The object ive was to measure ruminal fermentation traits, and flows of nonammonia nit rogen (NAN), total amino acid (TAA), and bacterial nitrogen (BN) from the s tomach after inoculation with individual ciliate protozoa species in each p eriod. The wethers in both groups were fed a diet based on corn silage, hay lage, and soybean meal, and they remained FF during the first period. At th e beginning of each other period, the wethers were progressively inoculated intraruminally with one individual major species of ruminal ciliate protoz oa or total fauna (TF). Thus, Group A was progressively inoculated (+) with Dasytricha ruminantium (DS), Polyplastron multivesiculatum (PP), Isotricha intestinalis (IS), Entodinium caudatum (EN) and TF-type A. Also, Group B w as progressively inoculated (+) with IS, DS, Epidinium ecaudatum (EP), Eudi plodinium maggi (EU), and EN. Duodenal digesta and ruminal fluid were colle cted and sampled in each period on d 26 and 28, respectively, and subjected to chemical analyses. A significantly higher (P < .05) pH (6.4) in ruminal fluid of the Group A wethers was obtained when each DS, DS+PP, DS-PP-IS+EN , and TF population was present in the rumen than when the wethers were FF (6.2). In the Group B wethers, pH (6.1) was lower (P < .05) for the populat ion of IS-DS-EP+EU than for other populations (6.2 to 6.3). The concentrati on of total VFA in ruminal fluid was higher (P < .05) in the Group B wether s when IS, IS+DS, or IS-DS+EP populations were present in the rumen than wh en the wethers were FF. The flow of NAN, TAA, and BN from the stomach to th e intestinal tract was generally lower for different protozoa populations t han for the FF period. Largest decreases (P < .05) in the flow of NAN, TAA, and BN occurred when EN was added into the rumen of wethers in the A and B groups, which already contained populations of DS-PP+IS and IS-DS-EP+EU, r espectively. Holotrich protozoa had very little effect on the protein metab olism in the rumen, but cellulolytic protozoa (PP, EP, and EU) and EN decre ased the efficiency of protein utilization by the ruminant host.