Substrates enriched by the fungusCunninghamella echinulata: anin vitrostudy of nutrient composition, sheep rumen fermentation and lipid metabolism

Abstract

Aims: Enrichment of wheat bran (WB), corn meal (CM) and barley flakes (BF) with the oleaginous fungus Cunninghamella echinulata (CE) might lead to effective use of these by-products in ruminant nutrition. We examined their effects on rumen fermentation and lipid metabolism. Methods and Results: WB, CM and BF substrates without or with brewer's grains (WBG, CMG, BFG) and enriched with CE were incubated with meadow hay (MH, 500 : 500, w/w) in rumen fluid in vitro for 24 h. The dry matter of the CE-enriched substrates increased (by 2-4%); however, digestibility decreased (P < 0Á01). Adverse effects of CE-enriched substrates on the rumen ciliate population were observed. Little effect on the rumen eubacterial population was detected by the 16S-polymerase chain reaction/denaturizing gradient gel electrophoresis method. The increase in c-linolenic acid output in the MH + BFGCE diet (800 : 200, w/w) was accompanied by an increase in rumen biohydrogenation of polyunsaturated fatty acids. Conclusion: The diet substrates enriched with the fungus CE were less digestible than the untreated cereal substrates; no appreciable positive effect was observed on rumen fermentation patterns or the eubacterial and ciliate populations. Significance and Impact of the Study: The in vitro study showed that adding CE-enriched substrates to ruminant diets is not effective for improving rumen fermentation.

The possible application of fungal enriched substrates in ruminant nutrition. A review

“…In addition, the direct supplementation of purified microbial oil (GLA-enriched oil; 30 g · kg −1 DM) into diets decreased the protozoal population in RUSITEC effluent (Kišidayová et al, 2006). This observation suggests that the specific antiprotozoal fungal effects of PCS or GLA-enriched microbial oil do not interfere with hydrogenesis, since methane production in experiments was not reduced (Laho et al, 2011a,b;Wencelová et al, 2014). However, it is known that PUFA sources distinctly inhibit the ruminal protozoal population, but they do not suppress bacterial activity (Hristov et al, 2004), although the reduction in the protozoal population may also lead to a decrease in the methanogen population (Toprak, 2015;Szczechowiak et al, 2016).…”

“…However, HAP bacteria are capable of utilizing certain substrates and thereby producing ammonia on various substrates (Eschenlauer et al, 2002). Based on the 16S-PCR-DGGE (denaturing gradient gel electrophoresis) method, the species C. echinulata is uncapable to produce sufficient concentrations of bioactive compounds that will have an impact on the eubacterial community (Wencelová et al, 2014). However, the DGGE method indicates species richness, but not individual population size, and this limitation of the 16S-PCR-DGGE method may point to the changes at least in the population of ammoniaproducing bacteria (Wencelová et al, 2014).…”

“…Based on the 16S-PCR-DGGE (denaturing gradient gel electrophoresis) method, the species C. echinulata is uncapable to produce sufficient concentrations of bioactive compounds that will have an impact on the eubacterial community (Wencelová et al, 2014). However, the DGGE method indicates species richness, but not individual population size, and this limitation of the 16S-PCR-DGGE method may point to the changes at least in the population of ammoniaproducing bacteria (Wencelová et al, 2014). When diets are supplemented with lipids, no effect (Jalc et al, 2005) or mostly a reducing effect (Doreau et al, 1991;Machmüller et al, 1998;Messana et al, 2013) of supplemented fats on ammonia concentrations are found.…”

“…When diets are supplemented with lipids, no effect (Jalc et al, 2005) or mostly a reducing effect (Doreau et al, 1991;Machmüller et al, 1998;Messana et al, 2013) of supplemented fats on ammonia concentrations are found. Interestingly, it seems that PCS with BSG produces higher concentrations of ammonia when compared with PCS without BSG (Wencelová et al, 2014). Studies have shown that BSG, as a partial replacement of concentrates in the diet of cows, increase the concentration of ammonia 2 h after feeding (Cozzi and Polan, 1994;Miyazawa et al, 2007).…”

“…PCS are mainly used for ruminant diet supplementing. In recent studies (Laho et al, 2011a;Wencelová et al, 2014;Čertík et al, 2017) it was shown that PCS enriched with GLA effectively enhanced the output of GLA in an artificial rumen (RUSITEC) without detectable differences in rumen fermentation patterns or microorganism populations.…”