Micro-pressure promotes endogenous phosphorus release in a deep reservoir by favouring microbial phosphate mineralisation and solubilisation coupled with sulphate reduction.

Deep reservoirs vary in their hydrostatic pressure owing to artificial water level control. The potential migration of phosphorus (P) in reservoir sediments raises the risk of harmful algal blooms. To ascertain the mechanisms of endogenous P release in reservoirs, we characterised aquatic microbial communities associated with coupled iron (Fe), P and sulphur (S) cycling at the sediment-water interface. The responses of microbial communities to hydrostatic pressures of 0.2-0.7 mega pascals (MPa; that is, micro-pressures) were investigated through a 30-day simulation experiment. Our findings unravelled a potential mechanism that micro-pressure enhanced the solubilisation of Fe/aluminium (Al)-bound P caused by microbially-driven sulphate reduction, leading to endogenous P release in the deep reservoir. Although the vertical distribution of labile Fe was not affected by pressure changes, we did observe Fe resupply at sediment depths of 2-5 cm. Metagenomic analysis revealed increased abundances of functional genes for P mineralisation (phoD, phoA), P solubilisation (pqqC, ppx-gppA) and sulphate reduction (cysD, cysC) in sediments subjected to micro-pressure, which contrasted with the pattern of S oxidation gene (soxB). There was a tight connection between P and S cycling-related microbial communities, based on significant positive correlations between labile element (P and S) concentrations and functional gene (phoD, cysD) abundances. This provided strong support that Fe-P-S coupling processes were governed by micro-pressure through modulation of P and S cycling-related microbial functions. Key taxa involved in P and S cycling (for example, Bradyrhizobium, Methyloceanibacter) positively responded to micro-pressure and as such, indirectly drove P release from sediments by facilitating P mineralisation and solubilisation coupled with sulphate reduction.

Effect of controlling nitrogen and phosphorus release from sediment using a biological aluminum-based P-inactivation agent (BA-PIA).

A biological aluminum-based P-inactivation agent (BA-PIA) has been developed and demonstrated to effectively remove nitrogen and phosphorus; however, whether it can control the release of nitrogen and phosphorus in sediment still needs study. This study aimed to examine the effect of BA-PIA on controlling sediment nitrogen and phosphorus release. BA-PIA was prepared by artificial aeration. The use of BA-PIA in controlling nitrogen and phosphorus release was studied using water and sediment from a landscape lake in static simulation experiments. The sediment microbial community was analyzed using high-throughput sequencing. Static simulation showed that the reduction rates of total nitrogen (TN) and total phosphorus (TP) by BA-PIA were 66.8 ± 1.46% and 96.0 ± 0.98%, respectively. In addition, capping of BA-PIA promotes the conversion of easily released nitrogen (free nitrogen) in the sediment to stable nitrogen (acid-hydrolyzable nitrogen). The content of weakly adsorbed phosphorus and iron-adsorbed phosphorus in the sediment was reduced. The relative abundance of nitrifying bacteria, denitrifying bacteria, and microorganisms carrying phosphatase genes (such as Actinobacteria) in the sediment increased by 109.78%. The capping of BA-PIA not only effectively removed the nitrogen and phosphorus in water but greatly reduced the risk of nitrogen and phosphorus release from sediment. BA-PIA was able to make up for the deficiency of the aluminum-based phosphorus-locking agent (Al-PIA) that only removes phosphorus, giving it improved application prospects.

Removal efficacy and mechanism of nitrogen and phosphorus by biological aluminum-based P-inactivation agent (BA-PIA).

In this study, aluminum-based P-inactivation agent (Al-PIA) was used as a high-efficiency microbial carrier, and the biological Al-PIA (BA-PIA) was prepared by artificial aeration. Laboratory static experiments were conducted to study the effect of BA-PIA on reducing nitrogen and phosphorus contents in water. Physicochemical characterization and isotope tracing method were applied to analyze the removal mechanism of nitrogen and phosphorus. High-throughput techniques were used to analyze the characteristic bacterial genus in the BA-PIA system. The nitrogen and phosphorus removal experiment was conducted for 30 days, and the removal rates of NH4+-N, TN and TP by BA-PIA were 81.87%, 66.08% and 87.97%, respectively. The nitrogen removal pathways of BA-PIA were as follows: the nitrification reaction accounted for 59.0% (of which denitrification reaction accounted for 56.4%), microbial assimilation accounted for 18.1%, and the unreacted part accounted for 22.9%. The characteristic bacteria in the BA-PIA system were Streptomyces, Nocardioides, Saccharopolyspora, Nitrosomonas, and Marinobacter. The loading of microorganisms only changed the surface physical properties of Al-PIA (such as specific surface area, pore volume and pore size), without changing its surface chemical properties. The removal mechanism of nitrogen by BA-PIA is the conversion of NH4+-N into NO2--N and NO3--N by nitrifying bacteria, which are then reduced to nitrogen-containing gas by aerobic denitrifying bacteria. The phosphorus removal mechanism is that metal compounds (such as Al) on the surface of BA-PIA fix phosphorus through chemisorption processes, such as ligand exchange. Therefore, BA-PIA overcomes the deficiency of Al-PIA with only phosphorus removal ability, and has better application prospects.

Three kinds of active thin-layer capping materials for reducing the phosphorus load in eutrophic water body: comparison in dynamic experiment.

In this article, dynamic simulation experiments have studied the effects of three capping materials, quartz sand (QS), aluminum-based phosphorus-locking agent (Al-PIA), and lanthanum-modified bentonite (LMB) in reducing phosphorus load in eutrophic water bodies. The changes of various forms of phosphorus in Al-PIA and sediment before and after the test were analyzed, and the mechanism of phosphorus migration and transformation in different capping systems was described. The dynamic simulation test lasted 95 days. The results showed that when the initial concentration of total phosphorus (TP) was 3.55 mg/L, the capping strength was 2 kg/m2 and the hydraulic retention time of water circulation was 0.5 days, indicating that the average reduction rates of TP by LMB, Al-PIA and QS systems were 74.66%, 69.54%, and 3.64%, respectively, compared with the control system. The analysis of variance showed that there were significant differences (P < 0.05) in the TP concentration of the overlying water between the LMB, Al-PIA capping system, and the control system. Lanthanum ions in LMB can fix phosphorus. Al-PIA reduces the phosphorus concentration in water by means of ion exchange, adsorption, complexation, etc. LMB and Al-PIA promoted the migration of phosphorus in sediment. Among them, the phosphorus fixed by Al-PIA was mainly in the form of non-apatite inorganic phosphorus (NAIP) in inorganic phosphorus (IP), which can be seen; Al-PIA can effectively reduce the phosphorus load of eutrophic water.

Variation, distribution, and diversity of canonical ammonia-oxidizing microorganisms and complete-nitrifying bacteria in highly contaminated ecological restoration regions in the Siding mine area.

Canonical ammonia-oxidizing archaea (AOA), ammonia-oxidizing bacteria (AOB) and complete-nitrifying bacteria (comammox) exist in a variety of ecosystems. However, little is known about AOA, AOB and comammox or their contributions to nitrification in the soils of heavily degraded and acidic mine regions. In the present study, the activity, richness, diversity and distribution patterns of AOA, AOB and comammox in the Siding mine area were investigated. Nemerow's multifactor pollution index (PN) values indicated that the soil in all three areas in the Siding mine area was highly contaminated by Cd, Pb, Zn, Mn and Cu. The AOA, AOB and comammox amoA gene copy numbers exhibited significant positive correlations with Pb and Zn levels and PN values, which indicated that the populations of AOA, AOB and comammox underwent adaptation and reproduction in response to pollution from multiple metals in the Siding mine area. Among them, the abundance of AOA was the highest, and AOA may survive better than AOB and comammox under such severely pollution-stressed and ammonia-limited conditions. The phyla Thaumarchaeota and Crenarchaeota may play vital roles in the soil ammonia oxidation process. Unlike AOA, AOB may use soil available phosphorus to help them compete for NH3 and other limiting nutrients with AOA and heterotrophs. Moreover, soil organic matter was the main factor influencing the species diversity of AOB, the ß-diversity of AOB and comammox, and the community composition of AOA, AOB and comammox. Our research will help to explain the role and importance of AOA, AOB and comammox in the different ecological restoration regions in the Siding mine area.

The effect of secondary capping on the control of phosphorus release from sediment by activated thin-layer capping with Al-PIA.

It is well-known that the activated thin-layer capping covering by secondary capping of contaminated sediment poses a threat to the inactivation of activated material. In this study, the static simulation experiment was conducted to study the effect of secondary capping thickness by sediment on the control of TP release from the sediment by aluminum-based P-inactivation agent (Al-PIA), and to propose the phosphorus adsorption pathway of Al-PIA. The results showed that Al-PIA could effectively reduce the release of phosphorus pollutants from the sediment at the capping intensity of 2 kg/m2. When the secondary capping thickness of sediment were 0, 2, 4, 7, 10, and 15 mm, the average removal rates of TP were 87.57%, 76.39%, 61.22%, 51.32%, 41.93%, and 32.11%, respectively, indicating that the removal efficiency of phosphorus decreased with the increase of the secondary capping thickness of the sediment. The adsorbed phosphorus by Al-PIA was mainly non-apatite inorganic phosphorus (NAIP) in inorganic phosphorus. With the increase of the secondary capping thickness of sediment, the NAIP proportion of phosphorus adsorbed by Al-PIA increased. Meanwhile, the removal rate of phosphorus in the activated capping system showed a first increase and then decrease trend, and the removal rates of total phosphorus (TP), inorganic phosphorus (IP), and organic phosphorus (OP) were obvious except for that of organic phosphorus (OP).

Effect of anti-inflammatory compounds or antibiotic administration on receiving performance and physiological responses of transported heifers.

The objectives of this experiment was to evaluate the effects of products with anti-inflammatory properties (yeast product [YEA; 20 g/heifer daily] or astragalus polysaccharide [APS; 20 g/heifer daily]) or an antibiotic (TUL, tulathromycin; 0.025 mL/kg body weight [BW]) on receiving performance and stress responses of transported heifers. Angus heifers (n = 80) were ranked by BW (315 ± 6 kg) and assigned to one of four treatments (five pens per treatment, four heifers per pen) 7 d before shipping 1,400 km (day -7): 1) fed a basal diet of ad libitum hay and concentrate supplement (CON) from day -7 to day 29; 2) YEA in supplemental concentrate from day -7 to day 7 (YEA); 3) APS in supplemental concentrate from day -7 to day 7 (APS); 4) administration of TUL at loading for shipping (day 0; TUL). Upon arrival at the receiving facility (day 1), heifers within each treatment were ranked by BW and assigned to 20 feedlot pens in the same manner as pre-transport. Daily dry matter intake (DMI) was recorded from day 1 to day 28. Full BW was recorded on days -7, -1, 0, 1, 28, and 29. Blood samples were collected on days -7, -1, 1, 4, 7, 14, and 28. Over the receiving period, average daily gain (ADG) and gain: feed did not differ (P ≥ 0.19) for YEA, APS, and TUL, which were greater (P ≤ 0.01) than CON. Average daily gain was also lower (P < 0.01) for CON vs. YEA, APS, and TUL from day -7 to day 28. During the first week of receiving, hay, concentrate, and total DMI were lower (P < 0.01) in CON than the YEA, APS, and TUL, but did not differ (P ≥ 0.13) among these three groups. Hay and total DMI were still lower (P < 0.01) in CON vs. TUL in the second week. Total DMI was greater (P = 0.01) for TUL vs. YEA, and greater (P < 0.01) for YEA vs. CON. Serum nonesterified fatty acid concentrations were greater (P ≤ 0.05) for CON and TUL vs. YEA and APS on day 1. Plasma cortisol concentrations were greater (P ≤ 0.05) for YEA and CON vs. APS and TUL on day 1. Serum tumor necrosis factor-α concentrations were lower (P ≤ 0.05) for APS vs. CON, YEA, and TUL on days 1 and 4. Plasma haptoglobin concentrations were greater (P ≤ 0.05) for CON vs. YEA, APS, and TUL on days 1 and 4, greater (P ≤ 0.05) for YEA, APS vs. TUL on day 1, and greater (P = 0.03) for YEA vs. TUL on day 4. Plasma ceruloplasmin concentrations were greater (P ≤ 0.05) for CON vs. YEA, APS and TUL vs. APS on days 1, 4, and 7. In conclusion, YEA, APS, and TUL modulated the physiological stress responses and alleviated the performance losses caused by long-distance transportation.

Effect of steam explosion of oil palm frond and empty fruit bunch on nutrient composition and ruminal fermentation characteristics.

In this study, we evaluated the effect of steam explosion of oil palm frond (OPF) and oil palm empty fruit bunch (EFB) on nutrient composition and ruminal fermentation characteristics in vitro. The results showed that steam explosion decreased NDF (P < 0.01), ADF (P < 0.01), and hemicellulose content (P < 0.01) in OPF and EFB. Steam explosion improved the effective energy value of OPF and EFB. In vitro fermentation results revealed that 72-h gas production capacity of OPF and EFB increased by 12.60and 85.06% (P < 0.01), respectively, after steam explosion. Steam explosion had a tendency to improve the concentration of total volatile fatty acids (TVFA) (P = 0.082). In conclusion, steam explosion of OPF and EFB reduced NDF, ADF, and hemicellulose content and increased gas production and TVFA concentration.

Manganese accumulation and plant physiology behavior of Camellia oleifera in response to different levels of nitrogen fertilization.

Manganese (Mn) pollution in soil, especially around the mining areas, is a severe problem in China. Seeking for effective remediation methods for Mn-contaminated soil is therefore urgent and necessary. Camellia oleifera (C. oleifera) is one of the world's four major woody oil plants, which is widely cultivated in subtropical acidic soils for oil production and has become an important economic and ecological resource in Guangxi Province. Nitrogen (N) is one of the most common limiting factors for plant growth and development in soils. We carried out this study to evaluate the effects of different N fertilization levels (0, 100, 300 and 500 mg kg-1) on the morphological and physiological characteristics of C. oleifera in two soils with different Mn-contamination degrees. The results indicate that N fertilization affected the plant growth and the content of photosynthetic pigments, while C. oleifera accumulated great amounts of Mn in both soils. However, the plant biomass reduced significantly at the high-level N fertilization (≥300 mg kg-1), and the oxidative stress was stimulated under Mn contamination. As a comparison, the plant biomass remained unaffected at the low-level N fertilization (100 mg kg-1), and the ascorbate peroxidase (APX) activity in C. oleifera leaves were enhanced to alleviate the oxidative stress and therefore protecting the plant from Mn contamination. Meanwhile, plants supplemented with a low-level of N fertilizer (100 mg kg-1) had appropriate antioxidant enzyme and nonenzymatic antioxidant activities, which indicates that this was favorable growth conditions for C. oleifera. Thus, the recommended N fertilization level for maintaining plant biomass and increasing Mn accumulation in plant is 100 mg kg-1 N; at which level the efficiency of Mn phytoremediation by C. oleifera can be further enhanced.

Characterizing the correlation between dephosphorization and solution pH in a calcined water treatment plant sludge.

This study focused on characterizing the correlation between the dephosphorization process of calcined water treatment plant sludge (C-WTPS) and the solution initial pH in batch experiments. The specific aim was to illustrate the effect of different initial pH on the adsorption and desorption of phosphorous in C-WTPS. In addition, the effects of solution initial pH on the release of ammonia nitrogen and total organic carbon (TOC) from C-WTPS and the change of pH after adsorption were also investigated. The results demonstrated that the initial pH significantly influenced the adsorption of phosphorus on C-WTPS. When initial pH was increased from 3 to 10, the phosphorous absorption capacity reduced by 76.5%. Especially, when the initial pH reached to 11, the phosphorus adsorption capacity became a negative value, indicating that C-WTPS released phosphorus into the solution. The addition of C-WTPS to the solution had little impact on the initial pH of the solution. The absorbed phosphorous on C-WTPS was relatively stable in the pH range of 3 to 10. Nevertheless, when the solution pH was higher than 11, it can be easily released into the solution. Furthermore, by comparison with WTPS, C-WTPS released less ammonia nitrogen and TOC into the solution and adsorbed more phosphorus from the solution in the experimental pH range. Therefore, C-WTPS is more suitable to serve as a cost-effective sorbent for phosphorus removal.

Improvement of cadmium phytoremediation by Centella asiatica L. after soil inoculation with cadmium-resistant Enterobacter sp. FM-1.

This study examined the potential of a cadmium-resistant Enterobacter sp. FM-1 to promote plant growth and assist in cadmium accumulation in both mine-type C. asiatica L. and non-mine type C. asiatica L. tissues in highly cadmium-polluted soils. The results indicated that Enterobacter sp. FM-1 significantly promoted growth and alleviated metal toxicity in both types of C. asiatica L. Meanwhile, inoculation with Enterobacter sp. FM-1 in contaminated soil can increased cadmium bioavailability in soil. Furthermore, it will increase plant uptake and the accumulation of cadmium in C. asiatica L. leaves, stems and roots compared to that in an uninoculated plant. However, mine-type C. asiatica L. had better cadmium tolerance than the non mine-type C. asiatica L. Because of its native metal-tolerant ability, which could easily grow and proliferate, and had a better performance under cadmium-contamination conditions. Additionally, inoculation with Enterobacter sp. FM-1 significantly enhanced the bioaccumulation factor (BAF) and the translocation factor (TF) values in both types of C. asiatica L. even under high cadmium concentration soil condition. Hence, based on higher BAF and TF values and strong cadmium accumulation in the leaves and stems, we concluded that inoculation with Enterobacter sp. FM-1 is potentially useful for the phytoremediation of cadmium-contaminated sites by Centella asiatica L.

Nitrate decreases ruminal methane production with slight changes to ruminal methanogen composition of nitrate-adapted steers.

BACKGROUND: This study was conducted to examine effects of nitrate on ruminal methane production, methanogen abundance, and composition. Six rumen-fistulated Limousin×Jinnan steers were fed diets supplemented with either 0% (0NR), 1% (1NR), or 2% (2NR) nitrate (dry matter basis) regimens in succession. Rumen fluid was taken after two-week adaptation for evaluation of in vitro methane production, methanogen abundance, and composition measurements. RESULTS: Results showed that nitrate significantly decreased in vitro ruminal methane production at 6 h, 12 h, and 24 h (P < 0.01; P < 0.01; P = 0.01). The 1NR and 2NR regimens numerically reduced the methanogen population by 4.47% and 25.82% respectively. However, there was no significant difference observed between treatments. The alpha and beta diversity of the methanogen community was not significantly changed by nitrate either. However, the relative abundance of the methanogen genera was greatly changed. Methanosphaera (PL = 0.0033) and Methanimicrococcus (PL = 0.0113) abundance increased linearly commensurate with increasing nitration levels, while Methanoplanus abundance was significantly decreased (PL = 0.0013). The population of Methanoculleus, the least frequently identified genus in this study, exhibited quadratic growth from 0% to 2% when nitrate was added (PQ = 0.0140). CONCLUSIONS: Correlation analysis found that methane reduction was significantly related to Methanobrevibacter and Methanoplanus abundance, and negatively correlated with Methanosphaera and Methanimicrococcus abundance.

Growth performance and development of internal organ, and gastrointestinal tract of calf supplementation with calcium propionate at various stages of growth period.

To investigate the effects of calcium propionate (CaP) supplementation on performance, the development of the internal organ, and gastrointestinal tract of calves at various stages of growth period, 54 male Jersey calves (age = 7 ± 1 d, body weight(BW) = 23.1 ± 1.2 kg) were randomly allocated to three treatment groups. While control calves were fed basis dietary with no additives (0CaP), other treatment calves were fed basis dietary supplementation with CaP at 50 (5CaP) or 100 (10CaP) g kg-1 dry matter. The experiment lasted 160 d and was divided into three feeding stages: Stage 1 (d 0 to 30), Stage 2 (d 31 to 90), and Stage 3 (d 91 to160). Six calves from each group were randomly selected and slaughtered on days 30, 90, and 160 when at the conclusion of each experimental feeding stage. The BW of calves increased with 10CaP after feeding 90 d, whereas it increased with 5CaP and 10CaP at feeding 120d and 160d compared to 0CaP. The 10CaP group improved average daily gain (ADG) of calves at stage 2, and d120-160 of stage 3 compared with the 0CaP group. The ADG of 5CaP was greater than the 0CaP group only at 120-160 d of stage 3 compared with the 0CaP group. The results of feed efficiency were in agreed with ADG as no dry matter intake difference at all stages of growth period. The 10CaP treatment exhibited the greatest spleen weight among the treatment at the end of the experiment; the liver weight of the 5CaP and 10CaP calves at feeding 90 d and of the 10CaP calves at feeding 160 d and were greater than those of the 0CaP animals. The CaP at the tested doses increased the rumen weight after feeding 90d of Jersey calves, and also improved the development of intestine. In conclusion, dietary supplementation with calcium propionate at the tested doses caused a beneficial effect in the growth performance and gastrointestinal tract traits of Jersey calves, thus to add 10% CaP before feeding 90 days was better and 5% CaP supplementation was expected at the period for feeding 90 to160 d.

Effect of urea-supplemented diets on the ruminal bacterial and archaeal community composition of finishing bulls.

In this study, we evaluated the effects of urea-supplemented diets on the ruminal bacterial and archaeal communities of finishing bulls using sequencing technology. Eighteen bulls were fed a total mixed ration based on maize silage and concentrate (40:60) and randomly allocated to one of three experimental diets: a basal diet with no urea (UC, 0%), a basal diet supplemented with low urea levels (UL, 0.8% dry matter (DM) basis), and a basal diet supplemented with high urea levels (UH, 2% DM basis). All treatments were iso-nitrogenous (14% crude protein, DM basis) and iso-metabolic energetic (ME = 11.3 MJ/kg, DM basis). After a 12-week feeding trial, DNA was isolated from ruminal samples and used for 16S rRNA gene amplicon sequencing. For bacteria, the most abundant phyla were Firmicutes (44.47%) and Bacteroidetes (41.83%), and the dominant genera were Prevotella (13.17%), Succiniclasticum (4.24%), Butyrivibrio (2.36%), and Ruminococcus (1.93%). Urea supplementation had no effect on most phyla (P > 0.05), while there was a decreasing tendency in phylum TM7 with increasing urea levels (P = 0.0914). Compared to UC, UH had lower abundance of genera Butyrivibrio and Coprococcus (P = 0.0092 and P = 0.0222, respectively). For archaea, the most abundant phylum was Euryarchaeota (99.81% of the sequence reads), and the most abundant genus was Methanobrevibacter (90.87% of the sequence reads). UH increased the abundance of genus Methanobrevibacter and Methanobacterium (P = 0.0299 and P = 0.0007, respectively) and decreased the abundance of vadinCA11 (P = 0.0151). These findings suggest that urea-supplemented diets were associated with a shift in archaeal biodiversity and changes in the bacterial community in the rumen.

Effect of ensiled mulberry leaves and sun-dried mulberry fruit pomace on the fecal bacterial community composition in finishing steers.

BACKGROUND: Here, we aimed to investigate the effects of ensiled mulberry leaves (EML) and sun-dried mulberry fruit pomace (SMFP) on fecal bacterial communities in Simmental crossbred finishing steers. To this end, the steers were reared on a standard TMR diet, standard diet containing EML, and standard diet containing SMFP. The protein and energy levels of all the diets were similar. Illumina MiSeq sequencing of the V4 region of the 16S rRNA gene and quantitative real-time PCR were used to analyze and detect the fecal bacterial community. RESULTS: Most of the sequences were assigned to Firmicutes (56.67%) and Bacteroidetes (35.90%), followed by Proteobacteria (1.87%), Verrucomicrobia (1.80%) and Tenericutes (1.37%). The predominant genera were 5-7 N15 (5.91%), CF231 (2.49%), Oscillospira (2.33%), Paludibacter (1.23%) and Akkermansia (1.11%). No significant differences were observed in the numbers of Firmicutes (p = 0.28), Bacteroidetes (p = 0.63), Proteobacteria (p = 0.46), Verrucomicrobia (p = 0.17), and Tenericutes (p = 0.75) populations between the treatment groups. At the genus level, genera classified with high abundance (more than 0.1%) belonged primarily to Bacteroidetes and Firmicutes. Furthermore, no differences were observed at the genus level: 5-7 N15, CF231, Oscillospira, Paludibacter, and Akkermansia (p > 0.05 in all cases), except that rc4-4 was lower in the CON and SMFP groups than in the EML group (p = 0.02). There were no significant differences in the richness estimate and diversity indices between the groups (p > 0.16), and the different diets did not significantly influence most selected fecal bacterial species (p > 0.06), except for Ruminococcus albus, which was higher in the EML group (p < 0.01) and Streptococcus bovis, which was lower in the CON group (p < 0.01) relative to the other groups. CONCLUSIONS: In conclusion, diets supplemented with EML and SMFP have little influence on the fecal bacterial community composition in finishing steers.

The effect of calcium propionate on the ruminal bacterial community composition in finishing bulls.

OBJECTIVE: Manipulating the fermentation to improve the performance of the ruminant has attracted the attention of both farmers and animal scientists. Propionate salt supplementation in the diet could disturb the concentration of propionate and total volatile fatty acids in the rumen. This study was conducted to evaluate the effect of calcium propionate supplementation on the ruminal bacterial community composition in finishing bulls. METHODS: Eight finishing bulls were randomly assigned to control group (CONT) and calcium propionate supplementation (PROP) feeding group, with four head per group. The control group was fed normal the total mixed ration (TMR) finishing diet, and PROP group was fed TMR supplemented with 200 g/d calcium propionate. At the end of the 51-day feeding trial, all bulls were slaughtered and rumen fluid was collected from each of the animals. RESULTS: Propionate supplementation had no influence the rumen fermentation parameters (p>0.05). Ruminal bacterial community composition was analyzed by sequencing of hypervariable V3 regions of the 16S rRNA gene. The most abundant phyla were the Firmicutes (60.68%) and Bacteroidetes (23.67%), followed by Tenericutes (4.95%) and TM7 (3.39%). The predominant genera included Succiniclasticum (9.43%), Butyrivibrio (3.74%), Ruminococcus (3.46%) and Prevotella (2.86%). Bacterial community composition in the two groups were highly similar, except the abundance of Tenericutes declined along with the calcium propionate supplementation (p = 0.0078). CONCLUSION: These data suggest that the ruminal bacterial community composition is nearly unchanged by propionate supplementation in finishing bulls.

Effects of Diets Supplemented with Ensiled Mulberry Leaves and Sun-Dried Mulberry Fruit Pomace on the Ruminal Bacterial and Archaeal Community Composition of Finishing Steers.

This study investigated the effects of ensiled mulberry leaves (EML) and sun-dried mulberry fruit pomace (SMFP) on the ruminal bacterial and archaeal community composition of finishing steers. Corn grain- and cotton meal-based concentrate was partially replaced with EML or SMFP. The diets had similar crude protein (CP), neutral detergent fiber (NDF), and metabolizable energy. Following the feeding trial, the steers were slaughtered and ruminal liquid samples were collected to study the ruminal microbiome. Extraction of DNA, amplification of the V4 region of the 16S rRNA gene, and Illumina MiSeq pyrosequencing were performed for each sample. Following sequence de-noising, chimera checking, and quality trimming, an average of 209,610 sequences were generated per sample. Quantitative real-time PCR was performed to examine the selected bacterial species in the rumen. Our results showed that the predominant phyla were Bacteroidetes (43.90%), Firmicutes (39.06%), Proteobacteria (4.31%), and Tenericutes (2.04%), and the predominant genera included Prevotella (13.82%), Ruminococcus (2.51%), Butyrivibrio (2.38%), and Succiniclasticum (2.26%). Compared to the control group, EML and SMFP groups had a higher abundance of total bacteria (p < 0.001); however, the bacterial community composition was similar among the three groups. At the phylum level, there were no significant differences in Firmicutes (p = 0.7932), Bacteroidetes (p = 0.2330), Tenericutes (p = 0.2811), or Proteobacteria (p = 0.0680) levels among the three groups; however, Fibrobacteres decreased in EML (p = 0.0431). At the genus level, there were no differences in Prevotella (p = 0.4280), Ruminococcus (p = 0.2639), Butyrivibrio (p = 0.4433), or Succiniclasticum (p = 0.0431) levels among the groups. Additionally, the dietary treatments had no significant effects on the archaeal community composition in the rumen. Therefore, EML and SMFP supplementation had no significant effects on the ruminal bacterial or archaeal community composition of finishing steers.