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Lipopolysaccharide (LPS) has been reported to contribute to a ruminal acidosis of cattle by affecting ruminal bacteria. The goal of this study was to determine how LPS affects the growth of pure cultures of ruminal bacteria, including those that contribute to ruminal acidosis. We found that dosing LPS (200,000 EU) increased the maximum specific growth rates of four ruminal bacterial species (Streptococcus bovis JB1, Succinivibrio dextrinosolvens 24, Lactobacillus ruminis RF1, and Selenomonas ruminantium HD4). Interestingly, all the species ferment sugars and produce lactate, contributing to acidosis. Species that consume lactate or ferment fiber were not affected by LPS. We found that S. bovis JB1 failed to grow in LPS as the carbon source in the media; growth of S. bovis JB1 was increased by LPS when glucose was present. Growth of Megasphaera elsdenii T81, which consumes lactate, was not different between the detoxified (lipid A delipidated) and regular LPS. However, the maximum specific growth rate of S. bovis JB1 was greater in regular LPS than detoxified LPS. Mixed bacteria from a dual-flow continuous culture system were collected to determine changes of metabolic capabilities of bacteria by LPS, and genes associated with LPS biosynthesis were increased by LPS. In summary, LPS was not toxic to bacteria, and lipid A of LPS stimulated the growth of lactate-producing bacteria. Our results indicate that LPS not only is increased during acidosis but also may contribute to ruminal acidosis development by increasing the growth of lactic acid-producing bacteria.IMPORTANCE Gram-negative bacteria contain lipopolysaccharide (LPS) coating their thin peptidoglycan cell wall. The presence of LPS has been suggested to be associated with a metabolic disorder of cattle-ruminal acidosis-through affecting ruminal bacteria. Ruminal acidosis could reduce feed intake and milk production and increase the incidence of diarrhea, milk fat depression, liver abscesses, and laminitis. However, how LPS affects bacteria associated with ruminal acidosis has not been studied. In this study, we investigated how LPS affects the growth of ruminal bacteria by pure cultures, including those that contribute to acidosis, and the functional genes of ruminal bacteria. Thus, this work serves to further our understanding of the roles of LPS in the pathogenesis of ruminal acidosis, as well as providing information that may be useful for the prevention of ruminal acidosis and reducetion of economic losses for farmers.

Aflatoxin B1 (AFB1) is a mycotoxin known to impair human and animal health. It is also believed to have a deleterious effect on ruminal nutrient digestibility under in vitro batch culture systems. The objective of this study was to evaluate the effects of increasing the dose of AFB1 on ruminal dry matter and nutrient digestibility, fermentation profile, and N flows using a dual-flow continuous culture system fed a diet formulated for lactating dairy cows. Eight fermenter vessels were used in a replicated 4 × 4 Latin square design with 10 d periods (7 d adaptation and 3 d sample collection). Treatments were randomly applied to fermenters on diet DM basis: (1) 0 μg of AFB1/kg of DM (Control); (2) 50 μg of AFB1/kg of DM (AF50); (3) 100 μg of AFB1/kg of DM (AF100); and (4) 150 μg of AFB1/kg of DM (AF150). Treatments did not affect nutrient digestibility, fermentation, and N flows. Aflatoxin B1 concentration in ruminal fluid increased with dose but decreased to undetectable levels after 4 h post-dosing. In conclusion, adding incremental doses of AFB1 did not affect ruminal fermentation, digestibility of nutrients, and N flows in a dual-flow continuous culture system fed diets formulated for lactating dairy cows. [ABSTRACT FROM AUTHOR]

The utilization of microencapsulated organic acids and pure botanicals (mOAPB) is widely used in the monogastric livestock industry as an alternative to antibiotics; in addition, it can have gut immunomodulatory functions. More recently, an interest in applying those compounds in the ruminant industry has increased; thus, we evaluated the effects of mOAPB on ruminal fermentation kinetics and metabolite production in an in vitro dual-flow continuous-culture system. For this study, two ruminal cannulated lactating dairy Holstein cows were used as ruminal content donors, and the inoculum was incubated in eight fermenters arranged in a 4 × 4 Latin square design. The basal diet was formulated to meet the nutritional requirements of a 680-kg Holstein dairy cow producing 45 kg/d of milk and supplemented with increasing levels of mOAPB (0; 0.12; 0.24; or 0.36% of dry matter [ DM ]), which contained 55.6% hydrogenated and refined palm oil, 25% citric acid, 16.7% sorbic acid, 1.7% thymol, and 1% vanillin. Diet had 16.1 CP, 30.9 neutral detergent fiber (NDF), and 32.0 starch, % of DM basis, and fermenters were fed 106 g/d split into two feedings. After a 7 d adaptation, samples were collected for 3 d in each period. Samples of the ruminal content from the fermenters were collected at 0, 1, 2, 4, 6, and 8 h postmorning feeding for evaluation of the ruminal fermentation kinetics. For the evaluation of the daily production of total metabolites and for the evaluation of nutrient degradability, samples from the effluent containers were collected daily at days 8 to 10. The statistical analysis was conducted using MIXED procedure of SAS and treatment, time, and its interactions were considered as fixed effects and day, Latin square, and fermenter as random effects. To depict the treatment effects, orthogonal contrasts were used (linear and quadratic). The supplementation of mOAPB had no major effects on the ruminal fermentation, metabolite production, and degradability of nutrients. The lack of statistical differences between control and supplemented fermenters indicates effective ruminal protection and minor ruminal effects of the active compounds. This could be attributed to the range of daily variation of pH, which ranged from 5.98 to 6.45. The pH can play a major role in the solubilization of lipid coat. It can be concluded that mOAPB did not affect the ruminal fermentation, metabolite production, and degradability of dietary nutrients using an in vitro rumen simulator. [ABSTRACT FROM AUTHOR]

Climate change may have an adverse effect on feed production. Hydroponic fodders produced in controlled environments are alternative feeds that may be used for dairy cattle. The objective of this study was to evaluate in-situ dry matter ruminal degradability of hydroponic fodders and corn silage. Two rumen-canulated lactating Holstein cows were used in a complete randomized block design with four treatments and 9 times (0, 2, 4, 8, 12, 24, 48, 72, and 240 h). Treatments were corn silage (CS), hydroponic sprouts of barley, wheat, and triticale. Quadruplicate samples were placed in Dacron bags (10 x 20 cm, 50 μm porosity) and incubated in the rumen. After incubation, samples were washed and dried in an air-forced oven set at 60°C for 48 h and DM recovery was weighted. Ingredients nutrient composition were CS (32.3% NDF, 8.4% CP, and 41.6% starch, 1.3% WSC; % of DM), barley (34.3% NDF, 17.1% CP, and 4.2% starch, 32.9% WSC; % of DM), wheat (23.7% NDF, 23.3% CP, and 8.5% starch, 32.7% WSC; % of DM), triticale (20.0% NDF, 16.2% CP, and 21.7% starch, 33.2% WSC; % of DM). Model included fixed effects of treatment and random effects of cow and replicate(cow). Data were analyzed using PROC MIXED of SAS. Degradation fractions were calculated based on DM disappearance. There were treatment effects (P < 0.01) on fraction A (degradable), fraction B (potentially degradable), fraction C (undegradable), effective ruminal degradability (ERD), and rate of degradation (kd: %/h). Fraction A was greater for triticale (74.1%) compared with wheat (70.2%), CS (63.1%), and barley (55.0%). Fraction B was greater for barley (28.5%) compared with CS (23.2%), wheat (19.1%), and triticale (13.9%). Fraction C was less for wheat (10.6%) than triticale (12.0%), CS (13.7%), and barley (16.4%). The ERD was greater for wheat (90.8%) compared with triticale (89.0%), CS (88.0%), and barley (85.6%). The kd for barley (2.4%) was less than triticale (4.9%). The kd for CS (1.8%) was less than triticale (4.9%). Overall, triticale had the greatest fraction A, barley had the greatest fraction B, and wheat had the least fraction C and the greatest ERD and kd. [ABSTRACT FROM AUTHOR]

The transition of courses from in-person to an online format due to the COVID-19 pandemic could have potentially affected overall student performance in lecture-based courses. The objective of this case study was to determine the impact of course format, as well as the effects of student sex, time of year at which the course was taken, and the institution it was taken at on student performance in an undergraduate animal science course. The course used for this study was taught at two institutions (University of Florida; UF and University of Nevada, Reno; UNR) over 7 yr (2014–2017 at UNR and 2018–2021 at UF). Student's performance (n  = 911) was evaluated using both quizzes and exams from 2014 through the spring semester 2020 and only exams were used for summer and fall semesters of 2020 and the spring and summer semesters of 2021. The final score (out of 100%) for each student was used to evaluate student's performance. In addition, students were classified as high-performing students, if they scored ≥95% and low-performing students, if they scored ≤70%. The variables evaluated were the effects of semester (spring, summer, or fall), institution (UF or UNR), sex (male or female), number of teaching assistants (TAs; 0–13), and course format (online or in-person). The course was taught in-person at UNR and in-person and online at UF. The spring semester of 2020 was taught in-person until March but was switched to online approximately 9 wk after the semester started and was considered an online semester for this analysis. As the course was only taught online at UF, the variable course format was assessed using UF records only. Data were analyzed using both linear models and logistic regressions. The probability that students were high performing was not affected by sex or institution. Interestingly, both fall semester and the online format had a positive, desirable effect on the probability that students were high performing. The probability that students were low performing was not affected by sex. However, if a student performed poorly in the class, they were more likely to have taken the course at UNR, or at UF with many TAs. Thus, student's performance was impacted by changing the course format, as well as institution, the number of TAs, and the semester in which the course was taken. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the effects of different sources of cobalt in a lactating dairy cow diet on in vitro ruminal fermentation. All diets provided the same amount of supplemental Co (1 mg per kg of diet DM) included in a premix with a targeted inclusion level of 2.5% of diet DM. Treatments were cobalt carbonate (CON), and three alternative Co sources; alternative source 1 (AS1), alternative source 2 (AS2), and alternative source 3 (AS3). Eight dual-flow continuous culture fermenters were used in a replicated 4 × 4 Latin square. Experimental periods were 10 d (7 d adaptation and 3 d sample collection). Composite samples of daily effluents were collected and analyzed for NH3-N, lactate, and VFA concentration as well as for nutrient digestibility. Samples of ruminal content were collected from each fermenter at 0, 1, 2, 4, 6, and 8 h after feeding to determine lactate, NH3-N, and pH kinetics. All data were analyzed using PROC MIXED of SAS and the repeated variable of time was included for pH, lactate, and NH3-N. There were neither treatment effects nor interactions between treatment and time for pH, NH3-N, and lactate concentrations, indicating a similar Co kinetics across treatments. With regards to lactate pool, we did not observe treatment effects for L-lactate; however, we observed treatment effects for D-lactate and total-lactate as seen in Table 1. Analyses of total and individual VFA, N utilization, and nutrient degradation are still undergoing, hence, it is possible that Co sources have effects on ruminal fermentation. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the immunopotential of mixed ruminal lipopolysaccharides (LPS) on cultured primary bovine ruminal epithelial cells (RECs). Primary bovine RECs were isolated from 6 yearling steers and grown in culture for 3 experiments. In Exp. 1 the objective was to determine the immunopotential of ruminal LPS, in Exp. 2 the objective was to assess tolerance to chronic LPS exposure, and the objective of Exp. 3 was to evaluate antagonistic interactions between ruminal and E.coli LPS. In exp. 1 & 2, RECs were exposed to nonpyrogenic water (CON), 20 μg/mL of E. coli LPS (E. COLI), 10 μg/mL of mixed ruminal-LPS (RUM10), 20 μg/mL of mixed ruminal-LPS (RUM20) and 40 μg/mL of mixed ruminal-LPS (RUM40) either continuously or intermittently. For the continuous exposure, RECs underwent a 6 h exposure, while for the intermittent exposure, the procedure was 1) a 12 h continuous exposure to treatments followed by LPS removal for 24 h and then another 12 h of exposure (RPT), and 2) a 12 h continuous exposure to treatments followed by LPS removal and a recovery period of 36 h (RCV). In exp 3, RECs were exposed to nonpyrogenic water (0:0), 1 μg/mL E. coli LPS (0:1), 1 μg/mL mixed ruminal-LPS:1 μg/mL E. coli LPS (1:1), 10 μg/mL mixed ruminal-LPS :1 μg/mL E. coli LPS (10:1) and 50 μg/mL mixed ruminal-LPS :1 μg/mL E. coli LPS (50:1). Each experiment was done as a complete randomized block design with 6 REC donors. The REC donor was used as a blocking factor. Each treatment had 2 technical replicates, and treatment responses for all data were analyzed with the MIXED procedure of SAS. For all exp., total RNA was extracted from RECs and real-time quantitative PCR was performed to determine the relative expression of genes for toll-like receptors (TLR2 & TLR4), proinflammatory cytokines (TNFa, IL1ß, and IL6), chemokines (CXCL2 & CXCL8), growth factor-like cytokines (CSF2 & TGFß), and a lipid mediator (PTGS2). In exp. 1, the targeted genes were upregulated in response to E. COLI (P < 0.01), while all ruminal LPS treatments resulted in a lower transcript abundance (P < 0.01). Regarding RPT and RCV condition, in Exp. 2, the expression of targeted genes was downregulated or not affected in response to ruminal LPS treatments. Lastly, in Exp. 3 all targeted genes resulted in decreased transcript abundance on all ruminal LPS ratios (P < 0.01). Overall, our results indicate that ruminal LPS have a limited capacity to activate the TLR4/NF-κB pathway and to induce the expression of inflammatory genes. [ABSTRACT FROM AUTHOR]

The objectives of this study were: 1) to compare the effects of live yeast (LY), yeast fermentation product (YFP), a mix of Lactobacillus acidophilus and Propionibacterium freudenreichii (MLP), and Lactobacillus plantarum included as additives in dairy cows' diets on in vitro ruminal fermentation and gas production (GP); and 2) to evaluate the effects of L. plantarum as direct-fed microbials (DFM) in dairy cows' diets on in vitro ruminal fermentation, GP, nutrient digestibility, and N metabolism. Three experiments were carried out: Exp. 1 had the objective to compare all additives regarding ruminal fermentation parameters: an Ankom GP system was used in a completely randomized design, consisting of four 48 h incubations, and eight replications per treatment. There were eight treatments: a basal diet without additive (CTRL) or with one of the following additives: LY, YFP, MLP, or L. plantarum at four levels (% of diet Dry Matter (DM)): 0.05% (L1), 0.10% (L2), 0.15% (L3), and 0.20% (L4). In Exp. 2, a batch culture was used to evaluate ruminal fermentation, and CO2 and CH4 production using the same treatments and a similar experimental design, except for having 16 replications per treatment. Based on Exp. 1 and 2 results, Exp. 3 aimed at evaluating the effects of the L. plantarum on ruminal true nutrient digestibility and N utilization in order to evaluate the use of L. plantarum as DFM. The treatments CTRL, MLP, L1, and L2 were used in a replicated 4 × 4 Latin square design using a dual-flow continuous culture system. Data were analyzed using linear and nonlinear regression; treatment means were compared through contrasts, and L treatments in Exp. 1 and 2 were tested for linear, quadratic, and cubic effects. In Exp. 1, all treatments containing additives tended to reduce OM digestibility as well as reduced total volatile fatty acids (VFA) concentration and total GP. The YFP had greater OM digestibility than LY, and MLP treatment had greater total VFA concentration compared to L. plantarum treatments. In Exp. 2, additives reduced CO2 production, and there were no major differences in CH4. In Exp. 3, all additives reduced NH3-N concentration. In conclusion, pH and lactate concentration were not affected in all three experiments regardless of additive tested, suggesting that these additives may not improve ruminal fermentation by pH modulation; and L. plantarum may improve ruminal N metabolism when used as DFM in high-producing dairy cows' diets, mainly by reducing NH3-N concentration. [ABSTRACT FROM AUTHOR]

Bovine mammary epithelial cells (MAC‐Ts) are a common cell line for the study of mammary epithelial inflammation; these cells are used to mechanistically elucidate molecular underpinnings that contribute to bovine mastitis. Bovine mastitis is the most prevalent form of disease in dairy cattle that culminates in annual losses of two billion dollars for the US dairy industry. Thus, there is an urgent need for improved therapeutic strategies. Histone deacetylase (HDAC) inhibitors are efficacious in rodent models of inflammation, yet their role in bovine mammary cells remain unclear. HDACs have traditionally been studied in the regulation of nucleosomal DNA, in which deacetylation of histones impact chromatin accessibility and gene expression. Using MAC‐T cells stimulated with tumor necrosis factor α (TNF‐α) as a model for mammary cell inflammation, we report that inhibition of HDACs1 and 2 (HDAC1/2) attenuated TNF‐α‐mediated inflammatory gene expression. Of note, we report that HDAC1/2‐mediated inflammatory gene expression was partly regulated by c‐Jun N‐terminal kinase (JNK) and extracellular signal‐regulated kinase (ERK) phosphorylation. Here, we report that HDAC1/2 inhibition attenuated JNK and ERK activation and thus inflammatory gene expression. These data suggest that HDACs1 and 2 regulate inflammatory gene expression via canonical (i.e., gene expression) and noncanonical (e.g., signaling dependent) mechanisms. Whereas, further studies using primary cell lines and animal models are needed. Our combined data suggest that HDAC1/2‐specific inhibitors may prove efficacious for the treatment of bovine mastitis. Histone deacetylases (HDACs) 1 and 2 regulate extracellular signal‐regulated kinase and c‐Jun N terminal kinase phosphorylation in bovine mammary epithelial (MAC‐T) cells. HDAC1/2‐selective inhibition attenuated mitogen‐activated protein kinase signaling, which contributed to normalization of tumor necrosis factor α‐mediated inflammatory gene expression. [ABSTRACT FROM AUTHOR]

The objectives of this study were to evaluate the effect of reducing dietary CP contents on 1) total and partial nutrient digestion and nitrogen balance and 2) on microbial crude protein (MCP) synthesis and true MCP digestibility in the small intestine obtained with 15N and purine bases (PB) in beef cattle. Eight bulls (4 Nellore and 4 Crossbred Angus × Nellore) cannulated in the rumen and ileum were distributed in duplicated 4 × 4 Latin squares. The diets consisted of increasing CP contents: 100, 120, or 140 g CP/kg DM offered ad libitum, and restricted intake (RI) diet with 120 g CP/kg DM. The experiment lasted four 17-d periods, with 10 d for adaptation to diets and another 7 for data collection. Omasal digesta flow was obtained using Co-EDTA and indigestible NDF (iNDF) as markers, and to estimate ileal digesta flow only iNDF was used. From days 11 to 17 of each experimental period, ruminal infusions of Co-EDTA (5.0 g/d) and 15N (7.03 g of ammonium sulfate enriched with 10% of 15N atoms) were performed. There was no effect of CP contents (linear effect, P = 0.55 and quadratic effect, P = 0.11) on ruminal OM digestibility. Intake of CP linearly increased (P < 0.01) with greater dietary CP. The NH3-N (P < 0.01) and urinary N excretion (P < 0.01) increased in response to dietary CP, whereas retained N increased linearly (P = 0.03). Liquid-associated bacteria (LAB) in the omasum had greater N content (P < 0.05) in relation to the particle-associated bacteria (PAB). There was no difference between LAB and PAB (P = 0.12) for 15N:14N ratio. The 15N:14N ratio was greater (P < 0.01) in RI animals in relation to those fed at voluntary intake. Microbial CP had a quadratic tendency (P = 0.09) in response to CP increase. Microbial efficiency (expressed in relation to apparent ruminally degradable OM and true ruminally degradable OM) had a quadratic tendency (P = 0.07 and P = 0.08, respectively) to CP increasing and was numerically greatest at 120 g CP/kg DM. The adjusted equations for estimating true intestinal digestibility of MCP (Y1) and total CP (Y2) were, respectively, as follows: Y1 =−-16.724(SEM = 40.06) + 0.86X(SEM = 0.05) and Y2 = −43.81(SEM = 49.19) + 0.75X(SEM = 0.05). It was concluded that diets with 120 g/kg of CP optimize the microbial synthesis and efficiency and ruminal ash and protein NDF digestibility, resulting in a better use of N compounds in the rumen. The PB technique can be used as an alternative to the 15N to estimate microbial synthesis. [ABSTRACT FROM AUTHOR]

This experiment aimed to determine the effects of camelina seed (CS) supplementation at different dietary fat levels on ruminal bacterial community composition and how it relates to changes in ruminal fermentation in a dual-flow continuous culture system. Diets were randomly assigned to 8 fermenters (1,200-1,250 mL) in a 2 × 2 factorial arrangement of treatments in a replicated 4 × 4 Latin square with four 10-day experimental periods that consisted of 7 days for diet adaptation and 3 days for sample collection. Treatments were: (1) no CS at 5% ether extract (EE, NCS5); (2) no CS at 8% EE (NCS8); (3) 7.7% CS at 5% EE (CS5); and (4) 17.7% CS at 8% EE (CS8). Megalac was used as a control to adjust EE levels. Diets contained 55% orchardgrass hay and 45% concentrate, and fermenters were equally fed a total of 72 g/day (DM basis) twice daily. The bacterial community was determined by sequencing the V4 region of the 16S rRNA gene using the Illumina MiSeq platform. Sequencing data were analyzed using mothur and statistical analyses were performed in R and SAS. The most abundant phyla across treatments were the Bacteroidetes and Firmicutes, accounting for 49 and 39% of the total sequences, respectively. The bacterial community composition in both liquid and solid fractions of the effluent digesta changed with CS supplementation but not by dietary EE. Including CS in the diets decreased the relative abundances of Ruminococcus spp., Fibrobacter spp., and Butyrivibrio spp. The most abundant genus across treatments, Prevotella, was reduced by high dietary EE levels, while Megasphaera and Succinivibrio were increased by CS supplementation in the liquid fraction. Correlatively, the concentration of acetate was decreased while propionate increased; C18:0 was decreased and polyunsaturated fatty acids, especially C18:2 n-6 and C18:3 n-3, were increased by CS supplementation. Based on the correlation analysis between genera and fermentation end products, this study revealed that CS supplementation could be energetically beneficial to dairy cows by increasing propionate-producing bacteria and suppressing ruminal bacteria associated with biohydrogenation. However, attention should be given to avoid the effects of CS supplementation on suppressing cellulolytic bacteria. [ABSTRACT FROM AUTHOR]