Chemotaxis toward carbohydrates and peptides by mixed ruminal protozoa when fed, fasted, or incubated with polyunsaturated fatty acids

Abstract

In contrast to the well-characterized chemotaxis and migratory behavior between the dorsal and ventral locations of the rumen by isotrichids, we hypothesized that chemotaxis toward soluble nutrients maintains entodiniomorphid protozoa in the particulate fraction. The objectives of these experiments were to compare the dose-responsive chemotaxis (1) toward different glucose concentrations when ruminal samples were harvested from fed versus fasted cows; (2) toward increasing concentrations of glucose compared with xylose when protozoa were harvested from a fed cow; (3) toward peptides of bacterial, protozoal, and soy origin; and (4) toward glucose when mixed ruminal protozoa were previously incubated for 0, 3, or 6h in the presence of emulsified polyunsaturated fatty acids (PUFA; Liposyn II, Hospira, Lake Forest, IL). In experiment 1, isotrichid protozoa decreased chemotaxis toward increasing glucose concentration when cows were fasted. Entodiniomorphids exhibited chemotaxis to similar concentrations of glucose as did isotrichids, but to a lesser magnitude of response. In experiment 2, xylose was chemotactic to both groups. Xylose might draw fibrolytic entodiniomorphid protozoa toward newly ingested feed. In contrast, even though isotrichids should not use xylose as an energy source, they were highly chemoattracted to xylose. In experiment 3, entodiniomorphids were not selectively chemoattracted toward bacterial or protozoal peptides compared with soy peptides. In experiment 4, despite isotrichid populations decreasing in abundance with increasing time of incubation in PUFA, chemotaxis to glucose remained unchanged. In contrast, entodiniomorphids recovered chemotaxis to glucose with increased time of PUFA incubation. Current results support isotrichid chemotaxis to sugars but also our hypothesis that a more moderate chemotaxis toward glucose and peptides explains how they swim in the fluid but pass from the rumen with the potentially digestible fraction of particulates.

An Investigation into Rumen Fungal and Protozoal Diversity in Three Rumen Fractions, during High-Fiber or Grain-Induced Sub-Acute Ruminal Acidosis Conditions, with or without Active Dry Yeast Supplementation

“…A meta-analysis of S. cerevisiae supplementation indicated that it would increase protozoal growth (Desnoyers et al, 2009 ). Isotrichids have been shown to associate with plant particles due to chemotaxis toward a variety of sugars (Orpin and Letcher, 1978 ; Diaz et al, 2014a , b ), thus their increase in the present study with ADY treatment may result from the associated improvement in fiber digestion and availability of sugars (AlZahal et al, 2014 ).…”

Relationship between rumen ciliate protozoa and biohydrogenation fatty acid profile in rumen and meat of lambs

“…It seems that the retention of ciliates in rumen is not similar for every protozoa group[8]. While Holotrichs have a strong chemotaxis toward sugars and after a meal migrate to the ventral reticulo-rumen, avoiding to be washed out, Entodiniomorphids have a moderate chemotaxis toward glucose and peptides and are uniformly distributed in ruminal content do not show the same affinity to the rumen wall as Holotrichs, and thus flow out of the rumen with the particulate matter [8, 45, 46]. The results of the present study are compatible with that dynamics of protozoa in rumen.…”

Accumulation of Reserve Carbohydrate by Rumen Protozoa and Bacteria in Competition for Glucose

“…Still, concentrations of ϳ5 mM can be reached after feeding unadapted animals large amounts of grain (6,30), and soluble sugar concentrations of 69 mM have been recorded after feeding beet pulp (31). Furthermore, concentrations of soluble sugars may be high around feed particles due to the accumulation of hydrolysis products from primary colonizers (28,32), and protozoa (both isotrichids and ophryoscolecids) display chemotaxis toward sugars (33). In our experiments, we intensified carbohydrate excess by removing N (by washing cells with N-free buffer).…”