Effect of protozoa on rumen protein degradation in sheep

Abstract

Summary.1. We have studied the contribution of ciliate protozoa to the degradation of dietary protein, utilizing 5 defaunated and 6 faunated sheep. Rumen samples from these animals were used as inocula for in vitro determination of the degradability of different protein sources : lupine grain, peanut and soybean cake, and fish meal. We also applied the in sacco method to measure the digestibility of soybean proteins. Two pore sizes (50 and 100 pm) were used in the in sacco study. The nitrogen degradation curve was constructed according to the mathematical model : P(t) = a + b (1-e-°t l, and the parameters a, b, and c were determined for both faunated and defaunated animals. The proteolytic activity of the rumen contents was also determined using azocasein. 3. The in sacco study showed that neither the protozoa nor bag pore size had any effect on the protein fraction (a) immediately soluble in the rumen juice. However, both factors increased the insoluble, potentially degradable fraction « b » (P < .011. Protozoa had a positive effect on the rate of degradation (c) of the fraction b. This effect was most clear with the 100 jim bags. The significant interaction between protozoa and pore size on factor « c » showed that large ciliate protozoa (100 jim) were directly involved in determining this parameter.4. Taking into account the very soluble azocasein utilized in this study to determine the protease activity of rumen juice, we confirmed the dominant effect of bacteria on the degradation of very soluble proteins. Conversely, protozoa, particularly large Ophryoscolecidae (100 w ml, increased the ruminal degradation of relatively insoluble proteins.Introduction.

Effect of Presence of Large Entodiniomorphid Protozoa on the Rumen Bacterial Flora, Fauna Composition of Small Entodinia and in vitro Cellulolysis and Xylanolysis

“….These values are similar to those calculated theoretically18) .While35%of degraded cellulose carbon was converted into cell materials in the absence of protozoa .These results suggest that microbial synthesis would be more efficient in the defaunated sheep rumen and agree with those obtained in vivo experiments2, 19) .As most protozoa show some preferences for species in the engulfment of bacteria20),modification of bacterial flora in addition to the reduction of population size would be expected .Present results which showed a marked decrease in gram negative cocci ,rods and selenomonads-like large curved rods after inoculation of protozoa can be explained by a selective predation and a nutritional competition between protozoa and bacteria .Changes in Entodinium fauna composition after inoculation of D .affine and P.multivesiculatum is interesting; latter is considered as a carnivorous species which engulfs other protozoa such as Epidinium21 multivesiculatum on the one hand and the importance of substrate particle size in this type of assay on the other hand.…”

Synergism of Cattle and Bison Inoculum on Ruminal Fermentation and Select Bacterial Communities in an Artificial Rumen (Rusitec) Fed a Barley Straw Based Diet

“…Furthermore, the increase in N disappearance from the concentrate corresponded to an increase in NH 3 -N. High ruminal NH 3 -N concentration has been associated with large numbers of protozoa in rumen contents (Veira et al, 1983; Towne et al, 1988), presumably a reflection of the predatory activity of these eukaryotes against bacteria (Belanche et al, 2011, 2012) and their ability to degrade feed protein (Ushida et al, 1986). Previous studies demonstrated greater feed protein degradation of diets with low protein solubility in faunated ruminants compared to protozoa-free ruminants (Ushida and Jouany, 1985, 1986; Ushida et al, 1986). The present study is in agreement with these findings, as the linear increase in total and concentrate N disappearance and daily NH 3 -N production observed with increasing proportions of bison inoculum is consistent with the increase in total protozoa numbers.…”

Repeated inoculation of cattle rumen with bison rumen contents alters the rumen microbiome and improves nitrogen digestibility in cattle

“…Previous studies with faunated and protozoa-free ruminants have documented that the role of protozoa in feed protein degradation becomes more important as diet protein solubility decreases 37, 38 . The increase in diet N digestibility as a result of the bison rumen content transfer is consistent with the increase in total protozoa counts.…”