Effects of dry yeast supplementation on growth performance, rumen fermentation characteristics, slaughter performance and microbial communities in beef cattle.

This study aimed to investigate the effects of active dry yeast (ADY) on growth performance, rumen microbial composition and carcass performance of beef cattle. Thirty-two finishing beef cattle (yak ♂ × cattle-yaks ♀), with an average body weight of 110 ± 12.85 kg, were randomly assigned to one of four treatments: the low plane of nutrition group (control), low plane of nutrition group + ADY 2 g/head daily (ADY2), low plane of nutrition group + ADY 4 g/head daily (ADY4) and the high plane of nutrition group (HPN). Supplementation of ADY increased average daily gain compared to the control group. The neutral detergent fiber and acid detergent fiber apparent digestibility in HPN group was greater than that in control group. The propionic acid concentration in the rumen in ADY2, ADY4, and HPN groups was greater than that in control group. The Simpson and Shannon indexes in control and HPN groups were higher than that in ADY4 group. At the phylum level, the relative abundance of Firmicutes in the HPN group was higher than that in ADY4 group. The relative abundance of Ruminococcaceae UCG-002 in ADY4 group was higher than that in control and HPN groups. In conclusion, supplementation ADY 4 g/head daily shift the rumen microbial composition of beef cattle fed low plane of nutrition to a more similar composition with cattle fed with HPN diet and produce the similar carcass weight with HPN diet.HighlightsThe ADY can improve the utilization of nitrogen and decrease the negative impact on the environment in beef cattle.Cattle fed low plane of nutrition diet supplemented with ADY 4 g/head daily increased growth performance.Supplementation ADY 4 g/head daily in low plane of nutrition diet might be produced comparable carcass weight to HPN diet.

Performances of simultaneous enhanced removal of nitrogen and phosphorus via biological aerated filter with biochar as fillers under low dissolved oxygen for digested swine wastewater treatment.

This study aims to explore the feasibility of biochar as a carrier to improve the simultaneous removal of nitrogen and phosphorus in biological aerated filters (BAFs) for treating low C/N digested swine wastewater (DSW). Two similar BAFs (BAF-A with hydrophobic polypropylene resin as fillers and BAF-B with bamboo biochar as carrier) were developed for DSW treatment. Results showed that the NH4+-N, TN, and TP removal performances in BAF-B were higher than those in BAF-A. Carrier type had an obvious influence on the structures and diversity of the microbial population. The biochar carrier in BAF-B was conducive to the enrichment of the functional microorganisms and the increase of microbial diversity under high NH4+-N conditions. Microbial analysis showed that the genera Rhodanobacter (10.64%), JGI_0001001-h003 (14.24%), RBG-13-54-9 (8.87%), Chujaibacter (11.27%), and Ottowia were the predominant populations involved in nitrogen and phosphorus removal in the later stage of phase III in BAF-B. BAF with biochar as carrier was highly promising for TN and TP removal in low C/N and high NH4+-N DSW treatment.

Responses of Nitrogen and Phosphorus Removal Performance and Microbial Community to Fe3O4@SiO2 Nanoparticles in a Sequencing Batch Reactor.

The responses of total nitrogen (TN) and total phosphorus (TP) removal performance and microbial community to 0-1.2 g/L Fe3O4@SiO2 nanoparticles (NPs) in sequencing batch reactors were investigated. Results showed that an appropriate dose of Fe3O4@SiO2 NPs (0.3 g/L) could promote the removal efficiency of TN and TP. High-throughput sequencing results indicated that microbial richness increased, whereas microbial diversity did not vary upon exposure to 0.1-1.2 g/L Fe3O4@SiO2 NPs. The relative abundances of Alphaproteobacteria, Betaproteobacteria, and Gammaproteobacteria increased from 11.75%, 3.52%, and 6.77%, respectively, at 0 g/L Fe3O4@SiO2 to 27.05%, 7.21%, and 14.77%, respectively, upon exposure to 0.3 g/L Fe3O4@SiO2. At the genus level, 0.3 g/L Fe3O4@SiO2 NPs enriched norank_f_Nitrosomonadaceae, norank_f_Xanthomonadaceae, Amaricoccus, and Shinella. Real-time quantitative polymerase chain reaction results suggested that the gene copy number of ammonium-oxidizing, nitrite-oxidizing, and denitrifying bacteria population remarkably increased, whereas the number of phosphorus-accumulating organisms slightly increased under long-term exposure to 0.3 g/L Fe3O4@SiO2 NPs. Energy-dispersive spectrum analysis showed that the phosphorus content was higher at 0.3 g/L Fe3O4@SiO2 than at 0 g/L Fe3O4@SiO2. Nitrogen removal primarily occurred through a biological mechanism, while most phosphorus in wastewater may be removed by the combination of physicochemical and biological methods.