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Ruminant animals constitute major contributors to greenhouse gas (GHG) emissions and play an important part in sustainable agricultural systems. A bioactive compound (BC) with antibacterial properties was utilized to inhibit rumen methanogens and decrease ruminant methane emissions. The bio efficacy of ruminant nutrition was frequently employed using a new technology through microencapsulation technique to produce stable products. The microencapsulated banana flower powder pellet (mBAFLOP) powder was used as a BC in the diets. Consequently, this study aimed to evaluate the effects of mBAFLOP supplementation on in vitro gas production kinetics, rumen fermentation, microbial population, and methane production. A completely randomized design (CRD) was used to randomly assign respective treatments at 0, 1, 2, and 3% of the total dry matter (DM) substrate. Ruminal pH, in vitro dry matter degradability and volatile fatty acid profile both at 12, and 24 h were not negatively affected by supplementation with mBAFLOP. The supplemented mBAFLOP (3% of total DM substrate) resulting in ruminal ammonia-nitrogen concentrations was linearly increased (P < 0.01) different among treatments, while methane production was reduced when compared with other treatment (quadratic effect, P < 0.05). Moreover, Ruminococcus flavefaciens was increased when the proportion of mBAFLOP supplement was increased. Furthermore, there was a linear effect (P < 0.05) of decreasing Methanobacteriales in the rumen with increased levels of mBAFLOP supplementation. Based on this study, the use of mBAFLOP at 3% could enhance NH 3 N concentration and cellulolytic bacteria especially Ruminococcus flavefaciens was increased. Furthermore, supplementation with mBAFLOP decreased methane production. Therefore, a possible dietary plant-based bioactive compound, mBAFLOP supplementation cloud enhances rumen fermentation and mitigates methane production., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

Microplastics (MPs), recognized as an emerging environmental menace, have been extensively investigated in both marine and terrestrial fauna. This study is comprehensive to investigate how polystyrene (PS) affects ruminant animals. The experimental design comprised 24 individually housed lambs, divided into a CON group (diet without PS) and three PS-exposed (25 μm, 50 μm, 100 μm) groups, each with six lambs, the exposure of PS was 100 mg/day, and the duration of exposure was 60 days. The study yielded noteworthy results: (ⅰ) PS leads to a decrease in average daily gain along with an increase in feed conversion rate. (ⅱ) PS decreases rumen ammonia nitrogen. The rumen microbiota diversity remains consistent. However, the relative abundance of Bacteroidetes and Actinobacteria increased in the PS-exposed groups, while the relative abundance of Coriobacteriales&#95;incertae&#95;Sedis and Prevotellaceae&#95;YAB2003&#95;group decreased. (ⅲ) PS leads to decrease in hemoglobin, thrombocytocrit, and albumin levels in lamb blood, thus triggering oxidative stress accumulation, along with swelling of the kidneys and liver. (ⅳ) PS inflicts severe damage to jejunum, consequently impacting digestion and absorption. (ⅴ) PS reduces meat quality and the nutritional value. In conclusion, PS-exposure inhibited lambs' digestive function, adversely affects blood and organs' health status, reducing average daily gain and negatively influencing meat quality. PS particles of 50-100 μm bring worse damage to lambs. This research aims to fill the knowledge void concerning MPs' influences on ruminant animals, with a specific focus on the meat quality of fattening lambs., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Ruminal fermentation is a natural process involving beneficial microorganisms that contribute to the production of valuable products and efficient nutrient conversion. However, it also leads to the emission of greenhouse gases, which have detrimental effects on the environment and animal productivity. Phytobiotic additives have emerged as a potential solution to these challenges, offering benefits in terms of rumen fermentation modulation, pollution reduction, and improved animal health and performance. This updated review aims to provide a comprehensive understanding of the specific benefits of phytobiotic additives in ruminant nutrition by summarizing existing studies. Phytobiotic additives, rich in secondary metabolites such as tannins, saponins, alkaloids, and essential oils, have demonstrated biological properties that positively influence rumen fermentation and enhance animal health and productivity. These additives contribute to environmental protection by effectively reducing nitrogen excretion and methane emissions from ruminants. Furthermore, they inhibit microbial respiration and nitrification in soil, thereby minimizing nitrous oxide emissions. In addition to their environmental impact, phytobiotic additives improve rumen manipulation, leading to increased ruminant productivity and improved quality of animal products. Their multifaceted properties, including anthelmintic, antioxidant, antimicrobial, and immunomodulatory effects, further contribute to the health and well-being of both animals and humans. The potential synergistic effects of combining phytobiotic additives with probiotics are also explored, highlighting the need for further research in this area. In conclusion, phytobiotic additives show great promise as sustainable and effective solutions for improving ruminant nutrition and addressing environmental challenges., (© 2024. The Author(s).)

This study aimed to evaluate the effects of essential oils (EOs) extracted from Cannabis sativa L. and Cannabis indica Lam. on in vitro ruminal fermentation characteristics, selected rumen microbial populations, and methane production. GC-MS analyses allowed us to identify 89 compounds in both EOs. It was found that E -β-caryophyllene predominated in C. sativa (18.4%) and C. indica (24.1%). An in vitro (Ankom) test was performed to analyse the control and monensin groups, as well as the 50 µL or 100 µL EOs. The samples for volatile fatty acids (VFAs), lactate, and microbiological analysis were taken before incubation and after 6 and 24 h. The application of EOs of C. indica resulted in an increase in the total VFAs of acetate and propionate after 6 h of incubation. The applied EOs had a greater impact on the reduction in methane production after 6 h, but no apparent effect was noted after 24 h. Lower concentrations of C. sativa and C. indica had a more pronounced effect on Lactobacillus spp. and Buryrivibrio spp. than monensin. The presented findings suggest that C. sativa and C. indica supplementation can modify ruminal fermentation, the concentrations of specific volatile fatty acids, and methane production.

Background: Rubber seed kernel is a by-product derived from rubber tree plantations. It is rich in C18 unsaturated fatty acids (UFA) and has the potential to be used as a protein source for ruminant diets. This investigation has been conducted to determine the influence of rubber seed kernel pellet (RUSKEP) supplementation on in vitro rumen fermentation characteristics and fatty acid profiles in swamp buffalo. Using a completely randomized design (CRD) and supplementation of RUSKEP at 0, 2, 4, 6, 8, and 10% dry matter (DM) of substrate., Results: The supplementation with RUSKEP had no effect on gas kinetics, cumulative gas production, or degradability. Ruminal pH decreased linearly (P < 0.01) and ammonia-nitrogen (NH 3 -N) concentration decreased quadratically (P < 0.01) by RUSKEP supplementation. The proportion of acetate (C2) decreased linearly (P < 0.01), but propionate (C3) and butyrate (C4) increased linearly (P < 0.01), resulting in a decrease in the acetate to propionate ratio (C2:C3) (P < 0.01) by RUSKEP supplementation. With an increasing level of dietary RUSKEP, there was a slight increase in UFA in the rumen by increasing the oleic acid (OA; C18:1 cis-9 + trans-9), linoleic acid (LA; C18:2 cis-9,12 + trans-9,12), and α-linolenic acid (ALA; C18:3 cis-9,12,15) concentrations (P < 0.01)., Conclusions: Adding up to 10% of RUSKEP could improve in vitro rumen fermentation and C18 unsaturated fatty acids, especially ALA, in swamp buffalo., (© 2024. The Author(s).)

Emulsifiers are essential for achieving a homogenous distribution of lipophilic supplements in in vitro rumen fluid incubations. Since emulsifiers can alter rumen fermentation, it is crucial to select one that minimally impacts fermentation parameters to reduce potential biases. This study aimed to evaluate seven emulsifiers' impact on in vitro ruminal fermentation using the Hohenheim Gas Test in order to identify the most inert emulsifier. Rumen fluids were collected from three non-lactating Original Brown-Swiss cannulated cows before morning feeding and incubated for 24 h with a basal diet in triplicates. The emulsifiers tested were ethanol, ethyl acetate, propylene glycol, glycerol, ethylene glycol, soy lecithin, and Tween® 80, each in two dosages (0.5% or 1% v/v). The untreated basal diet served as control. Compared to control, in vitro organic matter digestibility was enhanced by ethyl acetate (by 36.9 and 48.2%), ethylene glycol (by 20.6 and 20.1%), glycerol (by 46.9 and 56.8%) and soy lecithin (by 19.7 and 26.8%) at 0.5 and 1% dosage, respectively. Additionally, the 24-h methane production increased for ethanol (by 41.9 and 46.2%), ethylene glycol (by 50.5 and 51.5%), and glycerol (by 63.1 and 65.4%) for the 0.5 and 1% dosage, respectively, and 0.5% dosage for ethyl acetate (by 31.6%). The acetate molar proportion was 17.2%pt higher for ethyl acetate, and 25.5%pt lower for glycerol at 1% dosage, compared to the control. The propionate concentration was 22.1%pt higher 1% glycerol, and 15.2%pt and 15.1%pt higher for 0.5 and 1% propylene glycol, respectively, compared to the control. In summary, Tween® 80 did not significantly affect in vitro rumen fermentation parameters, making it the most suitable choice for in vitro incubations involving lipophilic substances in rumen fluid. Ethanol may be considered as an alternative emulsifier if methane production is not the variable of interest., (© 2024 The Authors. Journal of Animal Physiology and Animal Nutrition published by Wiley‐VCH GmbH.)

Incorporating Curcumin into animal diets holds significant promise for enhancing both animal health and productivity, with demonstrated positive impacts on antioxidant activity, anti-microbial responses. Therefore, this study aimed to determine whether adding Curcumin to the diet of dairy calves would influence ruminal fermentation, hematologic, immunological, oxidative, and metabolism variables. Fourteen Jersey calves were divided into a control group (GCON) and a treatment group (GTRA). The animals in the GTRA received a diet containing 65.1 mg/kg of dry matter (DM) Curcumin (74% purity) for an experimental period of 90 days. Blood samples were collected on days 0, 15, 45, and 90. Serum levels of total protein and globulins were higher in the GTRA group (P < 0.05) than the GCON group. In the GTRA group, there was a reduction in pro-inflammatory cytokines (IL-1ß and IL-6) (P < 0.05) and an increase in IL-10 (which acts on anti-inflammatory responses) (P < 0.05) when compared to the GCON. There was a significantly higher (P < 0.05) concentration of immunoglobulin A (IgA) in the serum of the GTRA than the GCON. A Treatment × Day interaction was observed for haptoglobin levels, which were higher on day 90 in animals that consumed Curcumin than the GCON (P < 0.05). The catalase and superoxide dismutase activities were significantly higher (P < 0.05) in GTRA, reducing lipid peroxidation when compared to the GCONT. Hematologic variables did not differ significantly between groups. Among the metabolic variables, only urea was higher in the GTRA group when compared to the GCON. Body weight and feed efficiency did not differ between groups (meaning the percentage of apparent digestibility of dry matter, crude protein, and acid detergent fiber (ADF) and neutral detergent fiber (NDF). There was a tendency (P = 0.09) for treatment effect and a treatment x day interaction (P = 0.05) for levels of short-chain fatty acids in rumen fluid, being lower in animals that consumed curcumin. There was a treatment vs. day interaction (P < 0.05) for the concentration of acetate in the rumen fluid (i.e., on day 45, had a reduction in acetate; on day 90, values were higher in the GTRA group when compared to the GCON). We conclude that there was no evidence in the results from this preliminary trial that Curcumin in the diet of dairy calves interfered with feed digestibility. Curcumin may have potential antioxidant, anti-inflammatory, and immune effects that may be desirable for the production system of dairy calves., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

The objective of this study was to evaluate various wheat supplementation levels on rumen microbiota and fermentation parameter in Tibetan sheep. A total of ninety ram with an average 12.37 ± 0.92 kg at the age of 2 months were randomly allocated to three treatments: 0% wheat diet (CW, N = 30), 10% wheat diet (LW, N = 30), and 15% wheat diet (HW, N = 30) on a dry matter basis. The experiment was conducted over a period of 127 days, including 7 days of adaption to the diets. Our results showed that sheep fed 10% wheat exhibited optimal average daily gain and feed gain ratio compared with HW group (p < 0.05). The serum alkaline phosphatase concentration was the lowest when fed the 10% wheat diet (p < 0.05), whereas serum aspartate aminotransferase concentration was the highest (p < 0.05). Both acetate and propionate increased with increase in dietary wheat ratio (p < 0.05), while a greater decrease in concentrations of NH 3 -N was observed (p < 0.05). In rumen fluid, 3413 OTUs were obtained with 97% consistency. Phylum Firmicutes was the predominant bacteria and accounted for 49.04%. The CW groups supported significantly increased the abundance of Bacteroidetes (p < 0.05), as compared with the HW group. The abundance of Bacteroidales&#95;UCG-001, Ruminococcus, and Mitsuokella possessed a higher relative abundance in HW group (p < 0.05). No differences in the bacterial community and fermentation parameters were observed between the sheep fed 0% and 10% wheat (p > 0.05). Ruminal bacterial community structure was significantly correlated with isobutyrite (r 2  = 0.4878, p = 0.035) and valerate (r 2  = 0.4878, p = 0.013). In conclusion, supplementation of 10% wheat in diet promoted the average daily gain and never altered microbial community structure and fermentation pattern, which can be effectively replace partial corn in Chinese Tibetan Sheep., (© 2023 Wiley-VCH GmbH. Published by John Wiley & Sons Ltd.)

Background: In this study, we investigated the effects of alpine meadow in different phenological periods on ruminal fermentation, serum biochemical indices, and gastrointestinal tract microbes in grazing yak on the Qinghai-Tibetan Plateau. A total of eighteen female freely grazing yaks with an average age of 3 years old and a body weight of 130 ± 19 kg were selected. According to the plant phenological periods, yaks were randomly allocated to one of three treatments: (1) regreen periods group (RP, n = 6); (2) grassy periods group (GP, n = 6); and (3) hay periods group (HP, n = 6). At the end of the experiment, the blood, rumen fluids, and rectal contents were collected to perform further analysis., Results: The concentrations of total volatile fatty acid (TVFA), acetate, glucose (GLU), triglyceride (TG), cholesterol (CHO), high density lipoprotein (HDL), and low density lipoprotein (LDL) were higher in the GP group than in the HP group (P < 0.05). However, compared with the RP and GP groups, the HP group had higher concentrations of isobutyrate, isovalerate, valerate, and creatinine (CREA) (P < 0.05). The abundance of Prevotella in the rumen, and the abundances of Rikenellaceae&#95;RC9&#95;gut&#95;group, Eubacterium&#95;coprostanoligenes&#95;group, and Prevotellaceae&#95;UCG-004 in the gut were higher in the GP group compared with the HP group (P < 0.05). The HP had higher abundance of Eubacterium&#95;coprostanoligenes&#95;group in the rumen as well as the abundances of Romboutsia and Arthrobacter in the gut compared with the RP and GP groups (P < 0.05)., Conclusions: Based on the results of rumen fermentation, serum biochemical, differential biomarkers, and function prediction, the carbohydrate digestion of grazing yak would be higher with the alpine meadow regreen and grassy due to the gastrointestinal tract microbes. However, the risk of microbe disorders and host inflammation in grazing yak were higher with the alpine meadow wither., (© 2024. The Author(s).)

Rumen microorganisms can efficiently degrade lignocellulosic wastes to produce volatile fatty acids (VFAs). pH is a key factor in controlling the type and yield of VFAs by affecting the microorganisms involved in rumen fermentation. However, the effects of different pH on rumen microbial diversity, communities, and mechanisms are unclear. In this study, the hydrolysis and acidogenesis of corn straw and diversity, communities, and mechanisms of rumen microorganisms were explored at different initial pHs. Results showed that the highest hemicellulose, cellulose, and lignin degradation efficiency of corn straw was 55.2 %, 38.3 %, and 7.01 %, respectively, and VFA concentration was 10.2 g/L at pH 7.0. Low pH decreased the bacterial diversity and increased the fungal diversity. Rumen bacteria and fungi had different responses to initial pHs, and the community structure of bacteria and fungi had obviously differences at the genus level. The core genera Succiniclasticum, Treponema, and Neocallimastix relative abundance at initial pH 7.0 samples were significantly higher than that at lower initial pHs, reaching 6.01 %, 1.61 %, and 5.35 %, respectively. The bacterial network was more complex than that of fungi. pH, acetic acid, and propionic acid were the main factors influencing the bacterial and fungal community structure. Low pH inhibited the expression of functional genes related to hydrolysis and acidogenesis, explaining the lower hydrolysis and acidogenesis efficiency. These findings will provide a better understanding for rumen fermentation to produce VFAs., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

The objectives of this study were to evaluate the levels of supplemental salt on low-quality forage intake, water intake, dry matter (DM) digestibility, and rumen fermentation. Six ruminally cannulated, Angus crossbred heifers (14 mo of age; 449 kg ± 24 kg body weight [BW]) were used in a dual 3 × 3 Latin square design. The heifers were housed in individual stalls with 2 animals assigned to each treatment per period. Salt treatments were mixed into a protein supplement of 50% cracked corn and 50% soybean meal and fed at 0.3% of shrunk BW. Salt treatments consisted of 1) control, no salt (CON), 2) 0.05% of BW salt (LOW), and 3) 0.1% of BW salt (HIGH). Chopped, low-quality (CP = 7.4%; NDF = 64.2%), grass hay was used as the base ration and was provided daily at 120% of the average daily intake of the previous 3 d. Each period included a 14-d diet adaptation, 6 d of sample collection, 1 d collection of rumen fluid samples for ruminal and microbial profiles. Individual forage dry matter intake, water intake, and DM digestibility were measured during the 6-d collection period. Rumen pH, ammonia levels, and volatile fatty acid (VFA) concentrations were measured during the 1-d ruminal profile. Rumen DM and liquid fill were determined with a 5-h post-feeding rumen evacuation. Supplemental salt had no influence on forage intake (P = 0.19) expressed on a kg/d basis yet tended to decrease linearly (P = 0.06) with increasing levels of salt when expressed on a grams/kg BW basis. DM digestibility was not influenced by salt levels (P > 0.05), but DM fill tended to increase linearly with increasing salt levels (P = 0.06). Water intake and liquid fill, however, increased linearly with increasing levels of salt (P < 0.01) with an 18.9% increase in water intake and 17.0% increase in liquid fill compared to control animals. Ruminal pH and ammonia levels both decreased linearly with increasing salt (P < 0.01). Acetate concentration and acetate: propionate ratio increased linearly with increasing levels of salt (P < 0.01). In contrast, isobutyrate and butyrate concentrations decreased linearly with increasing levels of salt (P < 0.01). Our research suggests that increasing levels of salt tends to influence dry matter intake, DM fill, liquid kinetics, and rumen fermentation characteristics. Results from this research provide additional information on how salt-limited supplements may impact beef cattle consuming low-quality forage diets., (© The Author(s) 2024. Published by Oxford University Press on behalf of the American Society of Animal Science.)

The objectives of this study were to evaluate the nutritional characteristics of bakery by-products (castella, pancake, baumkuchen) and their effect on rumen fermentation in vitro as compared with steam-flaked corn and barley as human-edible grains. The fermentation pattern of sugar and starch as pure components was also investigated. Additionally, rumen pH was evaluated using a low-capacity buffer. Bakery by-products contained high sugar (212-590 g/kg DM) and starch (262-545 g/kg DM). Castella exhibited the highest sugar content, whereas pancake and baumkuchen were rich in starch and ether extract within bakery by-products, respectively. The gas production rate at the early phase of incubation was higher in bakery by-products than in grains, and the highest in castella among all feeds. Bakery by-products produced higher total organic acids and propionate than grains. Bakery by-products also exhibited a lower rumen pH than grains during twenty-four hours of incubation with a low-capacity buffer. As pure components, sucrose showed a higher gas production rate and lower pH than starch. Overall, compared with grains, bakery by-products have the potential not only to supply more energy to ruminants but also decrease rumen pH because sugar and starch in bakery by-products ferment rapidly and produce higher organic acids in the rumen., (© 2024 The Author(s). Animal Science Journal published by John Wiley & Sons Australia, Ltd on behalf of Japanese Society of Animal Science.)

The utilization of polyphenol-modified starch in ruminants has not undergone extensive exploration. This study aimed to investigate the impact of the complex formed between starch and Melastoma candidum D. Don fruit extract on physicochemical properties, phenol release kinetics in various buffers simulating the gastrointestinal tract, methane production, and post-rumen digestibility. The interaction between starch and M. candidum D. Don fruit extract significantly (p < 0.001) increased resistant starch and particle size diameter. The maximum phenolic release from complex between starch and M. candidum D. Don fruit extract, due to gastrointestinal tract-simulated buffers, ranged from 22.96 to 34.60 mg/100 mg tannic acid equivalent. However, rumen and abomasum-simulated buffers released more phenolic content, whereas the intestine-simulated buffer showed higher antioxidant activity (ferric ion-reducing antioxidant power). Furthermore, complex between starch and M. candidum D. Don fruit extract significantly decreased dry matter rumen digestibility (p < 0.001) and maximum methane gas production (p < 0.001)., (© 2024 Japanese Society of Animal Science.)

Short-chain fatty acids (SCFAs) produced in the rumen are key factors affecting dairy cows' energy balance (EB). This study aimed to quantitatively evaluate the effects of SCFAs production on EB in dairy cows. Primiparous dairy cows were divided into high non-esterified fatty acid (NEFA; group H) and low NEFA (group L) groups based on their blood NEFA levels at week 3 postpartum, which served as an indicator of EB. The amounts of SCFAs produced in the rumen, including acetate, propionate, and butyrate (SCFAsP), were calculated using the predicted rumen volume. Because there were no differences between the groups in SCFAsP/dry matter intake, whereas 4% fat-corrected milk (FCM)/SCFAsP was significantly higher in group H, it was suggested that more body fat was mobilized for milk production in group H. However, group L, which showed better EB, had propionate dominant and lower FCM/SCFAsP and milk energy/SCFAs energy at 3 and 7 weeks postpartum, indicating that group L had a better energy supply for milk production. These results suggest that SCFAsP produced by rumen fermentation and the composition of SCFAs in the rumen affect milk production and EB., (© 2024 Japanese Society of Animal Science.)

The current study was conducted to investigate the feasibility of high concentration diet (HCD) supplementation with Dimethyl Silicone Oil (DSO) to prevent frothy rumen bloat in goats. The treatments were control group (group C, feeding HCD) and test group (group T, feeding HCD supplemented with 0.1%DSO). The results showed that compared with the group C, the ruminal pH value, Microbial Crude Protein content of group T was extremely significantly higher ( p  < 0.01), the levels of acetic acid and propionic acid were significantly ( p  < 0.05) and extremely significantly ( p  < 0.01) lower in group T, respectively. The foam production and foam strength of the rumen fluid in the group T was extremely significantly lower ( p  < 0.01), the viscosity was extremely significantly ( p  < 0.01) higher than those of group C. The total gastrointestinal apparent digestibility of various nutrients, the rumen microbial relative abundance at the phylum level and genus level were not significantly different ( p  > 0.05). The results indicated that the supplementation of 0.1% DSO in HCD can significantly eliminate foam of the rumen fluid, and didn't disturb the ruminal microorganisms, no negatively affect on digestibility of nutrients in goats, thereby has the application prospect of preventing frothy rumen bloat.

The rumen ecosystem harbours a galaxy of microbes working in syntrophy to carry out a metabolic cascade of hydrolytic and fermentative reactions. This fermentation process allows ruminants to harvest nutrients from a wide range of feedstuff otherwise inaccessible to the host. The interconnection between the ruminant and its rumen microbiota shapes key animal phenotypes such as feed efficiency and methane emissions and suggests the potential of reducing methane emissions and enhancing feed conversion into animal products by manipulating the rumen microbiota. Whilst significant technological progress in omics techniques has increased our knowledge of the rumen microbiota and its genome (microbiome), translating omics knowledge into effective microbial manipulation strategies remains a great challenge. This challenge can be addressed by modelling approaches integrating causality principles and thus going beyond current correlation-based approaches applied to analyse rumen microbial genomic data. However, existing rumen models are not yet adapted to capitalise on microbial genomic information. This gap between the rumen microbiota available omics data and the way microbial metabolism is represented in the existing rumen models needs to be filled to enhance rumen understanding and produce better predictive models with capabilities for guiding nutritional strategies. To fill this gap, the integration of computational biology tools and mathematical modelling frameworks is needed to translate the information of the metabolic potential of the rumen microbes (inferred from their genomes) into a mathematical object. In this paper, we aim to discuss the potential use of two modelling approaches for the integration of microbial genomic information into dynamic models. The first modelling approach explores the theory of state observers to integrate microbial time series data into rumen fermentation models. The second approach is based on the genome-scale network reconstructions of rumen microbes. For a given microorganism, the network reconstruction produces a stoichiometry matrix of the metabolism. This matrix is the core of the so-called genome-scale metabolic models which can be exploited by a plethora of methods comprised within the constraint-based reconstruction and analysis approaches. We will discuss how these methods can be used to produce the next-generation models of the rumen microbiome., (Copyright © 2023 The Author(s). Published by Elsevier B.V. All rights reserved.)

This study evaluated the effects of high concentrate diets (HCD) on the rumen fermentation and the digestibility of nutrients in different sites of the gastrointestinal tract (GIT) in goats. Four goats were used in a crossover design. The goats were fitted with a ruminal cannula and flexible T-cannulae proximal duodenum and terminal ileum. Treatments were as follows: low concentrate group (LCG) and high concentrate group (HCG). Duodenal flow and forestomach digestibility of starch were significantly higher in the HCG than those in the LCG ( p   <   0.05); There was no significant difference in ileum flow and digestibility of starch in the small intestine, large intestine and total GIT ( p   >   0.05). The digestibility of crude protein (CP) in the forestomach was significantly higher in the HCG than in the LCG ( p   <   0.05); the flow of the duodenum and ileum of CP, and the CP digestibility of the small intestine, large intestine and total GIT were not significantly different between groups ( p   >   0.05). The duodenal and ileal flow of neutral detergent fiber (NDF), the NDF digestibility of the different segments and total GIT were not significantly different between groups ( p   0.05) than the LCG. The foam strength, foam production and viscosity of the rumen fluid in the HCG were higher than the LCG (   0.05). Compared to the LCG, the ruminal pH of the HCG was significantly lower ( p 0.01). These results showed that when the goats were fed with HCD, the digestibility of nutrients was not significantly impaired, but the risk of frothy rumen bloat increased. ImplicationsDue to a serious shortage of high-quality roughage in China, producers commonly used a high-concentrate diet in ruminants, which can improve animal production performance.Gastrointestinal digestive function plays a vital role in the absorption of nutrients and the healthy growth of animals.Therefore, this research evaluated the digestibility of various nutrients in different segments of the gastrointestinal tract (GIT) under HCD feeding by using three-site cannula goats as experimental animals.The results indicated that the GIT of goats could fully digest nutrients such as starch and protein under HCD feeding conditions.  <   0.05). The HCG concentrations of microbial crude protein, ammonia nitrogen and isovaleric acid were significantly higher ( p   <   0.05) than the LCG. The foam strength, foam production and viscosity of the rumen fluid in the HCG were higher than the LCG ( p   <   0.01). These results showed that when the goats were fed with HCD, the digestibility of nutrients was not significantly impaired, but the risk of frothy rumen bloat increased. ImplicationsDue to a serious shortage of high-quality roughage in China, producers commonly used a high-concentrate diet in ruminants, which can improve animal production performance.Gastrointestinal digestive function plays a vital role in the absorption of nutrients and the healthy growth of animals.Therefore, this research evaluated the digestibility of various nutrients in different segments of the gastrointestinal tract (GIT) under HCD feeding by using three-site cannula goats as experimental animals.The results indicated that the GIT of goats could fully digest nutrients such as starch and protein under HCD feeding conditions.

Background: Previous studies have discussed the effects of grazing and house feeding on yaks during the cold season when forage is in short supply, but there is limited information on the effects of these feeding strategies on Jersey cows introduced to the Tibetan Plateau. The objective of this study was to use genomics and metabolomics analyses to examine changes in rumen microbiology and organism metabolism of Jersey cows with different feeding strategies., Methods: We selected 12 Jersey cows with similar body conditions and kept them for 60 days under grazing ( n  = 6) and house-feeding ( n  = 6) conditions. At the end of the experiment, samples of rumen fluid and serum were collected from Jersey cows that had been fed using different feeding strategies. The samples were analyzed for rumen fermentation parameters, rumen bacterial communities, serum antioxidant and immunological indices, and serum metabolomics. The results of the study were examined to find appropriate feeding strategies for Jersey cows during the cold season on the Tibetan plateau., Results: The results of rumen fermentation parameters showed that concentrations of acetic acid, propionic acid, and ammonia nitrogen in the house-feeding group (Group B) were significantly higher than in the grazing group (Group G) ( P  < 0.05). In terms of the rumen bacterial community 16S rRNA gene, the Chao1 index was significantly higher in Group G than in Group B ( P  = 0.038), while observed species, Shannon and Simpson indices were not significantly different from the above-mentioned groups ( P  > 0.05). Beta diversity analysis revealed no significant differences in the composition of the rumen microbiota between the two groups. Analysis of serum antioxidant and immune indices showed no significant differences in total antioxidant capacity between Group G and Group B ( P  > 0.05), while IL-6, Ig-M , and TNF- α were significantly higher in Group G than in Group B ( P  < 0.05). LC-MS metabolomics analysis of serum showed that a total of 149 major serum differential metabolites were found in Group G and Group B. The differential metabolites were enriched in the metabolic pathways of biosynthesis of amino acids, protein digestion and absorption, ABC transporters, aminoacyl-tRNA biosynthesis, mineral absorption, and biosynthesis of unsaturated fatty acids. These data suggest that the house-feeding strategy is more beneficial to improve the physiological state of Jersey cows on the Tibetan Plateau during the cold season when forages are in short supply., Competing Interests: The authors declare there are no competing interests., (©2023 Yuan et al.)

Fibrobacter succinogenes is a cellulolytic bacterium that plays an essential role in the degradation of plant fibers in the rumen ecosystem. It converts cellulose polymers into intracellular glycogen and the fermentation metabolites succinate, acetate, and formate. We developed dynamic models of F. succinogenes S85 metabolism on glucose, cellobiose, and cellulose on the basis of a network reconstruction done with the automatic reconstruction of metabolic model workspace. The reconstruction was based on genome annotation, five template-based orthology methods, gap filling, and manual curation. The metabolic network of F. succinogenes S85 comprises 1,565 reactions with 77% linked to 1,317 genes, 1,586 unique metabolites, and 931 pathways. The network was reduced using the NetRed algorithm and analyzed for the computation of elementary flux modes. A yield analysis was further performed to select a minimal set of macroscopic reactions for each substrate. The accuracy of the models was acceptable in simulating F. succinogenes carbohydrate metabolism with an average coefficient of variation of the root mean squared error of 19%. The resulting models are useful resources for investigating the metabolic capabilities of F. succinogenes S85, including the dynamics of metabolite production. Such an approach is a key step toward the integration of omics microbial information into predictive models of rumen metabolism. IMPORTANCE F. succinogenes S85 is a cellulose-degrading and succinate-producing bacterium. Such functions are central for the rumen ecosystem and are of special interest for several industrial applications. This work illustrates how information of the genome of F. succinogenes can be translated to develop predictive dynamic models of rumen fermentation processes. We expect this approach can be applied to other rumen microbes for producing a model of rumen microbiome that can be used for studying microbial manipulation strategies aimed at enhancing feed utilization and mitigating enteric emissions., Competing Interests: The authors declare no conflict of interest.

Background: Stevia straw is a byproduct of sugar crop stevia. It is a good feed material because of richness in nutrients and active substances (steviosides and flavonoids). However, due to improper utilization such as piling, burning and so on, it became a large amount of wasted straw resources and lead to environmental pollution., Methods: We added 0%, 0.2%, 0.4%, 0.6%, 0.8%, 1.0% and 1.5% of stevia stalk to study the effects of different stevia stalk concentrations on nutrient utilization and rumen fermentation in sheep (based on sheep diet). In vitro fermentation method was used, with 17 repetitions for each treatment. All fermentation substrate based on sheep diet with different stevia stalk concentrations were fermented for 2 h, 6 h, 12 h, 24 h and 48 h, then the gas production, dry matter degradability (DMD), crude protein degradability (CPD), neutral detergent fiber degradability (NDFD), acid detergent fiber degradability (ADFD), pH, ammonia nitrogen (NH 3 -N) and volatile fatty acids (VFAs) were determined., Results: The results showed that at different fermentation time, the change trend of gas production in each teatment was basically same, but the maximum occurred in 1.0% treatment at 48 h. The DMD, CPD, NDFD and ADFD of sheep diets increased with fermentation time increasing, especially the CPD 48h , NDFD 48h and ADFD 48h of diets in 0.8%, 1.0% and 1.5% treatments were significantly higher than those in control ( P < 0.05). The pH of fermentation substrate in each treatment remained within the normal range of 6.21∼7.25. NH 3 -N 24h-48h in 0.8%, 1.0% and 1.5% treatments were higher than that in control. At 6 h-12 h, the total acid content of 0.8% and 1.0% treatments were significantly higher than those of other treatments ( P < 0.05), it reached the highest in 1.0% treatment. According to overall evaluation, effect ranking of stevia stalk on sheep nutrient utilization was as follows: 1.0% >0.8% >1.5% >0.4% >0.6% >0.2%. Overall, 1.0% stevia stalk could promote nutrient degradation and sheep rumen fermentation., Competing Interests: The authors declare there are no competing interests., (©2023 Zhang et al.)

Medium chain fatty acid (MCFA) treatment (0.75% C6, hexanoic; C8, octanoic; C10, decanoic; or equal proportion mixtures of C6:C8:C10:C12 or C8:C10/g; C12 = dodecanoic acid) of aerobically-exposed corn silage on spoilage and pathogenic microbes and rumen fermentation were evaluated in vitro . After 24 h aerobic incubation (37 °C), microbial enumeration revealed 3 log 10 colony-forming units (CFU)/g fewer ( P  = 0.03) wild-type yeast and molds in C8:C10-treated silage than controls. Compared with controls, wild-type enterococci decreased ( P  < 0.01) in all treatments except the C6:C8:C10:C12 mixture; lactic acid bacteria were decreased ( P  < 0.01) in all treatments except C6 and the C6:C8:C10:C12 mixture. Total aerobes and inoculated Staphylococcus aureus or Listeria monocytogenes were unaffected by treatment ( P  > 0.05). Anaerobic incubation (24 h at 39 °C) of ruminal fluid (10 mL) with 0.02 g overnight air-exposed MCFA-treated corn silage revealed higher hydrogen accumulations ( P  = 0.03) with the C8:C10 mixture than controls. Methane, acetate, propionate, butyrate, or estimates of fermented hexose were unaffected. Acetate:propionate ratios were higher ( P  < 0.01) and fermentation efficiencies were marginally lower ( P  < 0.01) with C8- or C8:C10-treated silage than controls. Further research is warranted to optimize treatments to target unwanted microbes without adversely affecting beneficial microbes.

This study aimed to evaluate the effect of the inclusion of coconut fruit pulp by-product (CPB) on the intake, apparent digestibility, nitrogen balance, and ruminal parameters of sheep. Five intact, male, non-descript lambs with a mean initial body weight of 25.5 ± 1.68 kg were assigned to a Latin square design (5 × 5) of five treatments consisting of CPB inclusion levels, in five proportions of 0%, 5%, 10%, 15%, and 20% dry matter (DM), in diets consisting of sugarcane bagasse as forage, with corn and soybean meal. Each period lasted 15 days for adaptation followed by 6 days for data collection. The inclusion of CPB linearly decreased (P < 0.05) the intake of DM, crude protein, non-fibre carbohydrates, neutral detergent fibre (NDF), and DM digestibility. The inclusion of CPB linearly increased (P < 0.05) the ether extract digestibility, but did not influence (P > 0.05) the NDF digestibility. There was a linear reduction (P < 0.05) in the absorbed nitrogen (N) and retained N (g/day); however, a quadratic increase (P < 0.05) for N absorbed (% consumed) as well as ammonia nitrogen was observed. There was a quadratic increase (P < 0.05) for propionate (mMol/L and %) and the ratio of acetate, propionate and butyrate (mMol/L and %) with the inclusion of CPB in the diet. Based on these findings, it was recommended to incorporate CPB up to the level of 5% in the diet of sheep., (© 2022. The Author(s), under exclusive licence to Springer Nature B.V.)

Background: Abnormal or stereotyped behaviours in dairy cows are common in large-scale indoor farms and are usually accompanied by high physiological stress levels. Feed tossing is an abnormal behaviour commonly seen in cows while being fed, making farm management difficult. However, the reasons behind this behaviour have not been sufficiently reported. The objective of this study was to explore the changes in rumen fermentation, serum indicators, inflammatory conditions and the performance of cows with feed tossing behaviour. Holstein cows with similar lactation stages in the same barn were subjected to behaviour observations two times per day for 21 consecutive days. Ten cows with feed tossing behaviour (FT) and ten cows without abnormal behaviours (CON) were selected for further sampling. Plasma samples, rumen fluid, milk yield data of cows, and an indoor environment temperature-humidity index (THI) were collected., Results: There was no significant difference in average daily milk yield during the observation period between feed-tossing cows (n = 68) and the other cows (n = 112). The number of cows showing FT behaviour had a moderately strong negative linear correlation with the THI of the environment. Compared to the CON cows, the FT cows had higher cortisol, norepinephrine and urea nitrogen levels in plasma, as well as higher plasma levels of inflammatory indicators, including total protein, lactate dehydrogenase, albumin, aspartate aminotransferase levels, and the ratio of aspartate aminotransferase to alanine aminotransferase. The FT cows had no significant variations from the CON cows regarding their rumen fermentation indicators, such as pH, ammonia nitrogen, and volatile fatty acids. In addition, 16S rRNA analysis revealed that there might be no clear association between the diversity and abundance of rumen bacteria and feed tossing behaviour., Conclusions: Our findings suggested that cows might have suffered from high levels of physiological stress and immune state for a long period when they exhibited FT behaviour. The environmental THI could affect the FT behaviour of cows; as the THI increases, the willingness of cows to throw decreases. This work provided the first evidence that feed tossing might be a response associated with high levels of physiological stress and immune. It also explored our insights into a commonly observed behavioural response to cow welfare traits., (© 2022. The Author(s).)

Distiller’s grain is rich in natural active ingredients and can be used as an excellent antioxidant feed for goats. The current study aimed to assess the feeding value of four different types of distiller’s grains with an in vitro gas production trial. The chemical composition, total phenols, total anthocyanins, dry matter degradability, methane, hydrogen, and rumen fermentation parameters were evaluated. The results indicated that red distiller’s grain and glutinous rice distiller’s grain had higher (p < 0.05) levels of crude protein than the other two types. There were significantly (p < 0.05) higher concentrations of dry matter, ether extract, hemicellulose, and total carbohydrate in corn distiller’s grain than in the other three types of distiller’s grain. In addition, red distiller’s grain showed a higher (p < 0.05) gas production rate constant (c) and ruminal outflow rate, as well as higher (p < 0.05) concentrations of total phenol, total anthocyanins and 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity, than the other three types of distiller’s grains. In contrast, red distiller’s grain displayed the lowest (p < 0.05) immediately soluble fraction (a) and half the time of maximum gas production relative to the other samples. In particular, the levels of methane (%) in white distiller’s grain and glutinous rice distiller’s grain were greater (p < 0.05) than that in red distiller’s grain. Moreover, the ammonia nitrogen content in red distiller’s grain was greater (p < 0.05) than that in white distiller’s grain and corn distiller’s grain. In contrast, red distiller’s grain exhibited a lower (p < 0.05) level of ruminal fluid acetic acid relative to that found in white distiller’s grain and corn distiller’s grain. Taken together, the results showed that red distiller’s grain and glutinous rice distiller’s grain could be used as protein feed, red distiller’s grain had higher levels of total phenols and total anthocyanins and a high DPPH scavenging activity; corn distiller’s grain might be considered as an alternative energy source feed, and white distiller’s grain exhibited higher total gas production.

In recent years, whole-plant corn silage has been widely used in China. Roughage is an important source of nutrition for ruminants and has an important effect on rumen microbiota, which plays an important role in animal growth performance and feed digestion. To better understand the effects of different silages on rumen microbiota, the effects of whole-plant corn silage or corn straw silage on growth performance, rumen fermentation products, and rumen microbiota of Simmental hybrid cattle were studied. Sixty healthy Simmental hybrid cattle were randomly divided into 2 groups with 6 replicates in each group and 5 cattle in each replicate. They were fed with whole-plant corn silage (WS) diet and corn straw silage (CS) diet respectively. Compared with corn straw silage, whole-plant corn silage significantly increased daily gain and decreased the feed intake-to-weight gain ratio (F/G) of beef cattle. Whole-plant corn silage also decreased the acetic acid in the rumen and the acetate-to-propionate ratio (A/P) compared with corn straw silage. On the genus level, the relative abundance of Prevotella&#95;1 was significantly increased while the relative abundance of Succinivibrionaceae&#95;UCG-002 was decreased in cattle fed whole-plant corn silage compared with those fed corn straw silage. Prevotella&#95;1 was positively correlated with acetic acid and A/P. Succinivibrionaceae&#95;UCG-002 was positively correlated with propionic acid and butyric acid, and negatively correlated with pH. Feeding whole-plant corn silage improved amino acid metabolism, nucleotide metabolism, and carbohydrate metabolism. Correlation analysis between rumen microbiota and metabolic pathways showed that Succinivibrionaceae&#95;UCG-002 was negatively correlated with glycan biosynthesis and metabolism, metabolism of co-factors and vitamins, nucleotide metabolism, and translation while Prevotellaceae&#95;UCG-003 was positively correlated with amino acid metabolism, carbohydrate metabolism, energy metabolism, genetic information processing, lipid metabolism, membrane transport, metabolism of cofactors and vitamins, nucleotide metabolism, replication and repair, and translation. Ruminococcus&#95;2 was positively correlated with amino acid metabolism and carbohydrate metabolism. Feeding whole-plant corn silage can improve the growth performance and rumen fermentation of beef cattle by altering rumen microbiota and regulating the metabolism of amino acids, carbohydrates, and nucleotides. KEY POINTS: • Feeding whole-plant corn silage could decrease the F/G of beef cattle • Feeding whole-plant corn silage improves rumen fermentation in beef cattle • Growth performance of beef cattle is related to rumen microbiota and metabolism., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Palm kernel cake, the main by-product of the palm kernel oil extraction process, is a highly available and low-priced agro-industrial by-product. However, several concerns exist to arriving at a safe inclusion level, especially for buffaloes. Two experiments were conducted to evaluate the effects of feeding de-oiled palm kernel cake (DPKC) to tropical buffaloes. In trial I, four fistulated Murrah buffaloes arranged in a 4 × 4 Latin square design were fed diets containing DPKC inclusions at 0, 15, 30, and 45% levels of compound feed to study their effects on rumen fermentation parameters. Trial II involves feeding twelve lactating buffaloes with DPKC inclusion levels at 0 or 15% of the compound feed to evaluate the effect of DPKC on the nutrient digestibility, serum biochemical constituents, rumen fermentation patterns, and lactation profile. The DPKC diets did not affect rumen pH, TCA-ppt nitrogen, and TVFA proportion; nevertheless, the NH 3 -N data revealed a decreased trend (P = 0.076). The acetate fraction decreased linearly (P < 0.05) with increased DPKC diets. Replacing the conventional protein sources with DPKC at a 15% level did not influence the nutrient intake and digestibility coefficients. No significant effects were observed for serum biochemical and mineral profiles of the lactating buffaloes fed the DPKC diet. Neither milk yield nor milk constituents (SNF, total solids, density, lactose, protein) were altered with the diets fed, except for milk fat%, which tended to increase (P = 0.092) on feeding DPKC diets. All the lactation parameters varied with time of collection, and diet × time interactions were noticed for fat, density, protein, 6% FCM yield, and butterfat yield. The feed efficiency tended to increase (P = 0.070) in the buffaloes fed DPKC diets. The profit margins were ₹6.07 and ₹1.63 for the DPKC included diets and feed cost per Kg 6% FCMY, respectively. In  conclusion, the inclusion of DPKC in the diet decreases feed cost without affecting the nutrient intakes, digestibility coefficients, serum biochemical and mineral profile, and lactation parameters., (© 2022. The Author(s), under exclusive licence to Springer Nature B.V.)

Clay minerals, such as bentonite, are used as feed additives capable of adsorbing mycotoxins and heavy metals and have been related to many positive effects on animal health and productivity. However, these compounds seem to induce also side effects and to interact with the intestinal and ruminal microbiota. The present in vitro study is aimed at evaluating the effects of different doses of bentonite on ruminal fermentations, metabolome and mineral content. Five doses of bentonite (0, 2.5, 5, 10 and 50 mg in 150 mL total volume) were incubated (39 °C for 24 h) with a dairy cow Total Mixed Ratio (TMR) and the ruminal fluid obtained from one healthy Holstein lactating cow. The kinetics of gas production (GP) continuously monitored during the incubation evidenced no significant differences in either cumulative GP (mL/g DM) or GP rate (mL/g DM/h) between the treatment groups. After the incubation, metabolome and mineral content of treated ruminal fluids were studied in pooled replicate samples by 1 H NMR spectroscopy and Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES), respectively. The NMR analysis led to the identification of 20 metabolites and suggested a clear metabolic differentiation among treatments. The ICP-OES analysis suggested that the addition of bentonite affected the concentration of Al, Ba, Ca, Cr, Mn, Mo and Sr. It is conceivable that bentonite administration does not affect gross ruminal fermentations, while it seems to modify the ruminal metabolome and the concentrations of few minerals in ruminal fluid., (Copyright © 2022. Published by Elsevier Ltd.)

Early development of the rumen, rumination, and fermentation is highly important in dairy calves. Yet, common rearing practices with feeding of concentrate-rich starters may jeopardize them because of lacking physically effective fiber (peNDF). The main objective of this study was to establish the influence of the composition of the calf starter feed (only forage with 2 different qualities or concentrate-rich starter diet) on chewing behavior, rumen development, rumen and hindgut fermentation, and selected systemic health and stress variables of dairy calves. The experiment was carried out with 40 newborn Holstein-Friesian calves, randomly assigned to 4 different solid feed treatments: MQH = 100% medium-quality hay (9.4 MJ metabolizable energy, 149 g of crude protein, and 522 g of neutral detergent fiber/kg of dry matter); HQH = 100% high-quality hay (11.2 MJ of metabolizable energy, 210 g of crude protein, 455 g of neutral detergent fiber/kg of dry matter); MQH+C = 30% MQH + 70% starter concentrate; HQH+C = 30% HQH + 70% starter concentrate). All calves were up to 14 wk in the trial and received acidified whole milk ad libitum in the first 4 wk of life, thereafter in reduced quantity until weaning on 12 wk of age. Water and the solid feed treatments were available ad libitum throughout the trial. Chewing activity was measured in wk 4, 6, 10, and 12 using RumiWatch halters. Until wk 3, rumen fluid, feces and blood were sampled weekly, thereafter every 2 wk. Rumen mucosal thickness (RMT) was measured on the same days with rumen fluid samples. Data showed that calves fed the HQH diet consumed more peNDF and this was associated with longer rumination time (591 min/d) and more ruminating boli (709 boli/d) than calves fed concentrate-rich diets (MQH+C: 430 min/d, 518 boli/d; HQH+C: 430 min/d, 541 boli/d), whereas the MQH group was intermediate (539 min/d, 644 boli/d). Ruminal and fecal pH were higher in calves fed only hay (especially MQH) compared with calves with concentrate supplementation. In both hay-fed groups, ruminal and fecal short-chain fatty acids were shifted toward acetate, whereas only the HQH diet increased the butyrate proportion in the ruminal short-chain fatty acids profile. Ruminal ammonia concentration was at a high level only in the first 3 wk and decreased thereafter. Feeding HQH tended to increase ruminal ammonia, likely because of its high crude protein content and ruminal degradability as well as lower assimilation from rumen microbes. The RMT similarly, though nonlinearly, increased in all groups over the course of the experiment. When using RMT as an indicator of rumen development in dairy calves in the practice, our data suggest an RMT of 1.7 mm and >2 mm at wk 5 and 10 of life, respectively. Feeding did not affect the blood levels of aspartate aminotransferase, gamma glutamyl transferase, glutamate dehydrogenase, and cortisol. In conclusion, feeding high-quality hay, instead of concentrate-rich starter feeds, resulted in improved rumination and ruminal fermentation profile, without affecting ruminal pH and systemic and stress health variables., (The Authors. Published by Elsevier Inc. and Fass Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)

Aims: This study aims to investigate the effect of hydroxy-selenomethionine supplementation on the in vitro rumen fermentation characteristics and microorganisms of Holstein cows., Methods and Results: Five fermentation substrates, including control (without selenium supplementation, CON), sodium selenite supplementation (0.3 mg kg -1 DM, SS03), and hydroxy-selenomethionine supplementation (0.3, 0.6 and 0.9 mg kg -1 DM, SM03, SM06 and SM09, respectively) were incubated with rumen fluid in vitro. The results showed that in vitro dry matter disappearance and gas production at 48 h was significantly higher in SM06 than SM03, SS03 and CON; propionate and total volatile fatty acid (VFA) production was higher in SM06 than CON. Moreover, higher species richness of rumen fluid was found in SM06 than others. Higher relative abundance of Prevotella and Prevotellaceae-UCG-003 and lower relative abundance of Ruminococcus-1 were detected in SM06 than CON. Besides, higher relative abundance of Ruminococcaceae&#95;UCG-005 was found in CON than other treatments., Conclusions: It is observed that 0.6 mg kg -1 DM hydroxy-selenomethionine supplementation could increase cumulative gas production, propionate, and total VFAs production by altering the relative abundance of Prevotella, Prevotellaceae-UCG-003, Ruminococcaceae&#95;UCG-005 and Ruminococcus-1, so that it can be used as a rumen fermentation regulator in Holstein cows., Significance and Impact of the Study: This study provides an optimal addition ratio of hydroxy-selenomethionine on rumen fermentation and bacterial composition via an in vitro test., (© 2021 The Authors. Journal of Applied Microbiology published by John Wiley & Sons Ltd on behalf of Society for Applied Microbiology.)

The objective of this study was to evaluate the effects of feeding gallic acid on the growth, nutrient digestibility, plasma metabolites, rumen fermentation, and bacterial community in the rumen fluid and feces of preweaning calves. Thirty-six female Holstein calves with similar ages (means ± SD; 3.1 ± 1.39 d) and body weights (40.8 ± 2.87 kg) were randomly assigned to receive 3 treatments. Calves were fed 1 of 3 treatments as follows: basal diet with no gallic acid (control), 0.5 g/kg gallic acid in starter diet (low), and 1 g/kg gallic acid in starter diet (high). The results showed that feeding gallic acid increased growth by improving the starter intake and average daily gain of the calves. The fecal score tended to decrease in a linear manner with the addition of gallic acid. Total-tract apparent protein digestibility tended to increase linearly with feeding gallic acid. Feeding gallic acid led to a linear increase in the plasma total protein and β-hydroxybutyrate levels. In addition, feeding gallic acid linearly increased catalase and total antioxidant capacity levels and decreased malondialdehyde and tumor necrosis factor-α concentrations. The concentrations of total volatile fatty acids, propionate, butyrate, and valerate in the rumen fluid increased linearly with the addition of gallic acid, resulting in a linear pH reduction. Feeding gallic acid linearly increased the relative abundances of Prevotella&#95;1, Saccharofermentans, and Prevotellaceae&#95;UCG-001 and linearly decreased the relative abundance of Prevotella&#95;7 in the rumen fluid. The Shannon index of ruminal bacterial communities linearly increased by feeding gallic acid. Feeding gallic acid linearly increased the relative abundances of Ruminococcaceae&#95;UCG-005, Bacteroides, and Christensenellaceae&#95;R-7&#95;group in the feces. In summary, feeding gallic acid improved growth, antioxidant function, and rumen fermentation and altered the bacterial community in the rumen fluid and feces of preweaning dairy calves., (The Authors. Published by Elsevier Inc. and Fass Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)

This study aimed to investigate the effects of compound probiotics (consisting of 10 8 cfu/g of Lactobacillus plantarum, 10 8 cfu/g of Pediococcus acidilactici, 10 8 cfu/g of Pediococcus pentosaceus, 10 7 cfu/g of and Bacillus subtilis) on growth performance, rumen fermentation, bacteria community, blood parameters, and health status of Holstein calves at the first 3 mo of age. Forty-eight newborn calves were randomly divided into the following 3 groups: control group (milk replacer with no compound probiotics), low compound probiotics group (milk replacer + 0.12 g of compound probiotics per head per day), and high compound probiotics group (HP; milk replacer + 1.2 g of compound probiotics per head per day). Starter pellets of the low compound probiotics and HP groups were coated with 0.05% compound probiotics. Milk replacer was provided from 2 to 63 d of age (6 L at 2-10 d, 8 L at 11-42 d, 6 L at 43-49 d, 4 L at 50-56 d, and 2 L at 57-63 d), and starter pellets were provided ad libitum from 7 to 90 d of age. Body weight and body size (d 1, 30, 60, and 90), blood (d 40 and 80), and rumen fluid (d 90) were analyzed using the one-way ANOVA procedure; fecal score was recorded daily and analyzed as repeated measures using the mixed model procedure. Results showed that diet supplemented with compound probiotics had no effects on the body weight, average daily gain, dry matter intake, and feed efficiency. At 90 d of age, diet supplemented with compound probiotics decreased the withers height. Immunity activities increased in the HP group, supported by the increased concentrations of serum total protein and immunoglobulins at 40 d of age, and by the increased activity of superoxide dismutase at 80 d of age. Diet supplemented with compound probiotics altered rumen fermentation, indicated by the decreased rumen acetic acid and propionic acid, and the increased butyric acid concentrations. Diet supplemented with compound probiotics improved the health status of calves, indicated by the decreased fecal score at 3 wk of age and the decreased medicine treatments. In summary, although diet supplemented with HP decreased the withers height, this level of probiotics is recommended to improve rumen development and health status of newborn Holstein calves., (The Authors. Published by Elsevier Inc. and Fass Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)

Heat stress influences rumen fermentative processes with effects on the physiology and production of dairy cows. However, the underlying relationship between rumen microbiota and its associated metabolism with heat tolerance in cows have not been extensively described yet. Therefore, the main objective of this study was to investigate differential heat resistance in Holstein cows using rumen bacterial and metabolome analyses. We performed both principal component analysis and membership function analysis to select seven heat-tolerant (HT) and seven heat-sensitive (HS) cows. Under heat stress conditions, the HT cows had a significantly (P < 0.05) higher propionic acid content than the HS cows; while measures of the respiratory rate, acetic, and butyric acid in the HT cows were significantly (P < 0.05) lower compared with the HS cows. Also, the HT cows showed lower (P < 0.01) rectal temperature and acetic acid to propionic acid ratio than the HS group of cows. Omics sequencing revealed that the relative abundances of Muribaculaceae, Rikenellaceae, Acidaminococcaceae, Christensenellaceae, Rikenellaceae&#95;RC9&#95;gut&#95;group, Succiniclasticum, Ruminococcaceae&#95;NK4A214&#95;group and Christensenellaceae&#95;R-7&#95;group were significantly (P < 0.01) higher in the HT cows; whereas Prevotellaceae, Prevotella&#95;1, Ruminococcaceae&#95;UCG-014, and Shuttleworthia were significantly (P < 0.01) lower in HT cows compared to HS cows. Substances mainly involved in carbohydrate metabolism, including glycerol, mannitol, and maltose, showed significantly higher content in the HT cows (P < 0.05) compared to that in the HS cows. Simultaneously, distinct metabolites were significantly correlated with differential bacteria, suggesting that glycerol, mannitol, and maltose could serve as potential biomarkers for determining heat resistance that require further study. Overall, distinct changes in the rumen microbiota and metabolomics in the HT cows may be associated with a better adaptability to heat stress. These findings suggest their use as diagnostic tools of heat tolerance in dairy cattle breeding schemes., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 The Author(s). Published by Elsevier B.V. All rights reserved.)

Pre-weaning nutrition has significant influence on post-weaning performance of lambs. Strategic weaning management on milk replacer allowance at this phase can be a promising approach for harvesting desired carcass trait in finisher phase. Therefore, present experiment aimed economizing pre-weaning weight gain in lambs by feeding milk replacer and subsequently minimizing weaning age. A study of 90 days duration was conducted to determine the production performance, nutrient utilization and rumen fermentation of lambs on milk replacer allowance at different weaning age. Sixty-six Malpura lambs (10 days of age) were randomly divided into 3 equal groups. Lambs in control group were allowed conventional free suckling of dam up to 90 day of age, whereas lambs in the two treatment groups, that is W60 and W90 were offered milk replacer and weaned at 60 and 90 days, respectively. Lambs in all groups were offered ad-libitum creep mixture, Ziziphus nummularia leaves, Vigna unguiculata hay and fresh Ailanthus excelsa leaves. Overall weight gain was 12.7 per cent higher (p < 0.05) in W90 than control whereas in W60 group it was statistically comparable with both control and W90 groups. Overall average daily gain was 12.1 per cent higher (p < 0.05) in W90 group as compared to control. In case of nutrient digestibility, there was significant depression of dry matter (DM), organic matter (OM), crude protein (CP) and neutral detergent fibre (NDF) by 16.9, 17.2, 9.3 and 32.0 per cent in W60 than control; however, in W90, CP digestibility was higher (p < 0.05) than control and W60. Considering economic analysis, the net return obtained from W90 (90 days weaning plus milk replacer allowance) was more 20.0 per cent higher than control. Therefore, it can be concluded that lamb rearing on milk replacer and weaning at 90 days have a sustained positive effect on lambs' production performance and is more profitable than the practice of milk replacer allowance and early weaning in semiarid conditions., (© 2021 Wiley-VCH GmbH.)

The physiological function of the reticulorumen plays an essential role in ruminant nutrition, and detailed knowledge of rumen motility can further advance understanding of ruminant nutrition and physiology. Rumen motility was simulated by setting different stirrer rotation speeds in a rumen simulation technique (RUSITEC) system. The aim of this study was to investigate the effects of rotation speeds on rumen fermentation, saturation factor of dissolved gases, hydrogen (H 2 ) and methane (CH 4 ) emissions, microbial protein synthesis, and selected microbial population using RUSITEC. The experiment was performed according to a balanced 3 × 3 Latin square design, and each period included 7 d for adaptation and 3 d for sampling. Three motility treatments included 5, 15, and 25 rpm rotation speeds. Daily total gas and H 2 and CH 4 emissions had quadratic responses to the increasing rotation speed and were highest at 15 rpm. Quadratic and linear responses (highest at 5 rpm) to increasing rotation speed were observed for saturation factors of H 2 and CH 4 , liquid-dissolved H 2 and CH 4 concentrations, and headspace concentration of H 2 in the gas phase, whereas increasing rotation speed linearly decreased saturation factors of CO 2 and liquid-dissolved CO 2 concentration. Quadratic and linear responses to increasing rotation speed were observed for molar percentages of acetate, ammonia, and microbial protein concentration, whereas increasing rotation speed quadratically increased pH and decreased total volatile fatty acid concentration and acetate-to-propionate ratio. The 15-rpm rotation speed had the highest values of total volatile fatty acids, acetate molar percentage, and microbial protein concentration. Quadratic and linear responses to increasing rotation speed were observed for copy numbers of solid-associated fungi and fluid-associated bacteria, fungi, and protozoa, while increasing rotation speed linearly increased copy numbers of solid-associated protozoa. Rotation at 15 rpm increased populations of fungi and protozoa in the solid rumen contents and the population of bacteria and fungi in the liquid rumen contents. In summary, this study provides insights on the biofunction of proper rumen motility (i.e., at a rotation speed of 15 rpm), such as improving feed fermentation, increasing gas emissions with decreased dissolved gas concentrations and saturation factors, and promoting microbial colonization and microbial protein synthesis, although further increase in rotation speed (i.e., to 25 rpm) decreases feed fermentation and microbial protein synthesis., (© 2022, The Authors. Published by Elsevier Inc. and Fass Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)

The aim of this research was to evaluate the influence of forage species adapted to the tropical region of Ecuador on gas production, enteric methane, digestion, and ruminal fermentation. The tree forage evaluated were C. arborea, E. fusca, B. forficata, E. poeppigiana, C. argentea, G. sepium, C. tora, and F. macrophylla. Ruminal fluid of four adult sheep fistulated with permanent cannulas in the rumen was used in the in vitro gas production technique. The in vitro gas production parameters were lower (P < 0.05) in the C. arborea (A = 41.68 mL gas/g DM, c = 0.044%/h and Lag = 1.654 h) and the average gas production rate for B. forficata was 1.017 mL/h (P < 0.05). C. arborea presented higher (P = 0.0001) effective degradation and real DM digestibility (40.461 g/kg and 82.51 mg/g, respectively). With respect to VFA, the highest (P < 0.05) proportion of acetic, propionic, and butyric was observed in C. arborea, G. sepium, and E. poeppigiana (72.52, 23.09, and 7.44 mol/100 mol, respectively) and the lowest (P = 0.0001) ratio: acetic/propionic was observed in G. sepium (2.92 mol/100 mol). The content of NH 3 -N (mg/L) showed no difference. The lowest (P = 0.0001) methane production was observed in C. arborea (1.23 mL CH 4 /g DM). The use of forage species of tropical climate rich in secondary metabolites in ruminant diets has the capacity to reduce the gas production and enteric methane; however, this is at the expense of the reduction of the fermentation of organic matter in the rumen., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

To investigate the influences of dietary riboflavin (RF) addition on nutrient digestion and rumen fermentation, eight rumen cannulated Holstein bulls were randomly allocated into four treatments in a repeated 4 × 4 Latin square design. Daily addition level of RF for each bull in control, low RF, medium RF and high RF was 0, 300, 600 and 900 mg, respectively. Increasing the addition level of RF, DM intake was not affected, average daily gain tended to be increased linearly and feed conversion ratio decreased linearly. Total tract digestibilities of DM, organic matter, crude protein (CP) and neutral-detergent fibre (NDF) increased linearly. Rumen pH decreased quadratically, and total volatile fatty acids (VFA) increased quadratically. Acetate molar percentage and acetate:propionate ratio increased linearly, but propionate molar percentage and ammonia-N content decreased linearly. Rumen effective degradability of DM increased linearly, NDF increased quadratically but CP was unaltered. Activity of cellulase and populations of total bacteria, protozoa, fungi, dominant cellulolytic bacteria, Prevotella ruminicola and Ruminobacter amylophilus increased linearly. Linear increase was observed for urinary total purine derivatives excretion. The data suggested that dietary RF addition was essential for rumen microbial growth, and no further increase in performance and rumen total VFA concentration was observed when increasing RF level from 600 to 900 mg/d in dairy bulls.

This study determined feeding behavior, dry matter (DM) intake (DMI), rumen fermentation, and milk production responses of lactating dairy cows fed with kale (Brassica oleracea) or swede (Brassica napus ssp. napobrassica). Twelve multiparous lactating dairy cows (560 ± 22 kg of body weight, 30 ± 4 kg of milk/d, and 60 ± 11 d in milk at the beginning of the experiment; mean ± standard deviation) were randomly allocated to 3 dietary treatments in a replicated 3 × 3 Latin square design. The control diet comprised 10 kg of grass silage DM/d, 4 kg of ryegrass herbage DM/d, and 8.8 kg of concentrate DM/d. Then, 25% of herbage, silage, and concentrate (DM basis) was replaced with either kale or swede. Cows offered kale had decreased total DMI compared with cows fed the control and swede diets, whereas inclusion of swede increased eating time. Milk production, composition, and energy-corrected milk:DMI ratio were not affected. Cows fed with kale had a greater rumen acetate:propionate ratio, whereas swede inclusion increased the relative percentage of butyrate. Estimated microbial N was not affected by dietary treatments, but N excretion was reduced with inclusion of kale, improving N utilization. Cows fed kale tended to have increased nonesterified fatty acids and showed presence of Heinz-Ehrlich bodies, whereas hepatic enzymes such as aspartate aminotransferase, γ-glutamyl transferase, and glutamate dehydrogenase were not affected by dietary treatments. In plasma, compared with the control, swede and kale reduced total saturated fatty acids and increased total polyunsaturated fatty acids and total n-3 fatty acids. Overall, feeding cows with winter brassicas had no negative effect on production responses. However, mechanisms to maintain milk production were different. Inclusion of swede increased the time spent eating and maintained DMI with a greater relative rumen percentage of butyrate and propionate, whereas kale reduced DMI but increased triacylglycerides mobilization, which can negatively affect reproductive performance. Thus, the inclusion of swede may be more suitable for feeding early-lactating dairy cows during winter., (Copyright © 2021 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

Background: Meeting the energy and nitrogen (N) requirements of high-performing ruminants at the same time as avoiding digestive disturbances (i.e. rumen acidosis) is a key priority in ruminant nutrition. The present study evaluated the effect of a cereal ammoniation treatment, in which barley grains are combined with urea and enzymes that catalyze the conversion of urea to ammonia to optimize rumen function. Twelve rumen cannulated sheep were randomly divided into two groups and fed a diet containing 60% of ammoniated barley (AMM) or untreated barley supplemented with urea (CTL) to investigate the impact on rumen fermentation and feed utilization., Results: AMM had higher total N content and effective rumen degradable N than untreated barely. AMM sheep had a consistently higher rumen pH throughout the day (6.31 versus 6.03) and tended to have a lower post-prandial ammonia peak and higher acetate molar proportion (+5.1%) than CTL sheep. The rumen environment in AMM sheep favored the colonization and utilization of agro-industrial by-products (i.e. orange pulp) by the rumen microbes leading to a higher feed degradability. AMM sheep also had higher total tract apparent N digestibility (+21.7%) and urinary excretion of purine derivatives (+34%), suggesting a higher N uptake and microbial protein synthesis than CTL sheep., Conclusion: The inclusion of AMM in the diet of ruminants represents a valid strategy for maintaining rumen pH within a physiological range and improving N utilization by the rumen microbes, which could have positive effects on the health and productivity of animals in intensive production systems. These findings warrant further studies under conventional farm conditions. © 2021 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry., (© 2021 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.)

In our previous studies, we revealed the effect of lactose inclusion in calf starters on the growth performance and gut development of calves. We conducted the present study as a follow-up study to identify the shift in rumen microbiota and its relation to rumen fermentation when calves are fed a lactose-containing starter. Thirty Holstein bull calves were divided into 2 calf starter treatment groups: texturized calf starter (i.e., control; n = 15) or calf starter in which starch was replaced with lactose at 10% (i.e., LAC10; n = 15) on a dry matter basis. All calves were fed their respective treatment calf starter ad libitum from d 7, and kleingrass hay from d 35. Rumen digesta were collected on d 80 (i.e., 3 wk after weaning) and used to analyze rumen microbiota and fermentation products. There was no apparent effect of lactose feeding on the α-diversity and overall composition of rumen microbiota. Amplicon sequencing and real-time PCR quantification of the 16S rRNA gene confirmed that the abundance of butyrate-producing bacteria (i.e., Butyrivibrio group and Megasphaera elsdenii) did not differ between the control and LAC10 groups. Conversely, the relative abundance of Mitsuokella spp., which produce lactate, succinate, and acetate, was significantly higher in the rumen of calves that were fed lactose, whereas the lactate concentration did not differ between the control and LAC10 groups. These findings suggest that the lactate production can be elevated by an increase of Mitsuokella spp. and then converted into butyrate, not propionate, since the proportion of propionate was lower in lactose-fed calves. In addition, we observed a higher abundance of Coriobacteriaceae and Pseudoramibacter-Eubacterium in the LAC10 group. Both these bacterial taxa include acetate-producing bacteria, and a positive correlation between the acetate-to-propionate ratio and the abundance of Pseudoramibacter-Eubacterium was observed. Therefore, the higher abundance of Coriobacteriaceae, Mitsuokella spp., and Pseudoramibacter-Eubacterium in the rumen of lactose-fed calves partially explains the increase in the proportion of rumen acetate that was observed in our previous study., (Copyright © 2021 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

Understanding the nature of ruminant nutrition and digestion is essential to improve feeding management and animal production. Among many approaches, manipulating ruminant nutrition and fermentation through feed supplementation is being practised and researched. Over the last decade, the utilization of vegetable oils in feed formulation and their effects on various aspects of ruminants have been reported by many researchers. It is important to understand the lipid metabolism in ruminants by microorganisms because it affects the quality of ruminant-derived products such as meat and milk. Majority of vegetable oil supplementation could reduce rumen protozoa population in ruminants due to the effects of medium-chain fatty acids (FAs). However, vegetable oil also contains unsaturated FAs that are known to have a negative effect on cellulolytic bacteria which could show inhibitory effects of the fibre digestion. In this paper, the physiology of nutrient digestion of ruminants is described. This paper also provides a current review of studies done on improvement and modification of rumen fermentation and microbial population through vegetable oil supplementation., (© 2021. The Author(s), under exclusive licence to Springer Nature B.V.)

The effects of doses CTL (0 mg), 30, 300 and 3000 mg/L of extracts from Stryphnodendron adstringens (Mart.) Coville (SA), Lafoensia pacari A. St.-Hil (LP), Copaifera spp. (CO) and Pterodon emarginatus Vogel (PE) on ruminal fermentation were investigated in eight experiments conducted in randomized complete block designs. The in vitro system contained four fermentation vessels. Each treatment was allocated in one vessel in each run. Incubation was run four and five times with diets 50:50 and 10:90 (roughage to concentrate ratio) respectively. Incubation vessel was the experimental unit, and each incubation run was a block. All plant extracts negatively affected DM degradation at 3000 mg/L. In diet 50:50, SA-3000 increased the molar proportion of propionate (p < 0.05), yet it decreased the concentration of fermentation products (p < 0.05); LP-300 reduced ruminal ammonia nitrogen (NH 3 -N; 98 vs. 120 mg/dl for LP-300 and average of CTL and LP-30, respectively) and isobutyrate (p < 0.05); CO-300 reduced (p < 0.05) NH 3 -N (98 vs. 123 mg/dl for CO-300 and average of CTL and CO-30, respectively); and P. emarginatus had no positive effects on rumen fermentation (p > 0.05). In diet 10:90, SA-300 reduced (p < 0.001) NH 3 -N and total volatile fatty acids (VFA); LP-30 increased (p < 0.05) total VFA (85 vs. 63 mM for LP-30 and CTL, respectively), molar proportions of acetate and propionate, and had lower C 2 :C 3 than CTL (3.6 vs. 4.3, respectively); CO-300 decreased acetate and increased propionate, reducing C 2 :C 3 (p < 0.001; 2.8 vs. 3.6 for CO-300 and average of other doses, respectively); PE-30 and PE-300 reduced NH 3 -N by 14% and increased total VFA by 29% compared with CTL (p < 0.05). Further in vivo investigations may consider L. pacari (LP-30), Copaifera spp. (CO-300) oleoresin and P. emarginatus oleoresin (PE-30 and PE-300) in diets with high inclusion of concentrate., (© 2021 Wiley-VCH GmbH.)

Subacute ruminal acidosis (SARA) continues to be a common and costly metabolic disorder in high-producing dairy cows worldwide. The objective of this study was to evaluate if increasing the concentration of physically effective neutral detergent fiber (peNDF) in diets can reduce the risk of SARA in cows fed a high-concentrate diet. Thirty second-parity Holstein cows in mid lactation (131 ± 8.3 d in milk) were randomly allocated to 3 dietary treatments (10 dairy cows per group): high (11.3%, high peNDF 8.0 ), medium (10.6%, medium peNDF 8.0 ), or low (9.0%, low peNDF 8.0 ) concentration of peNDF 8.0 . The diets were prepared by mixing the same total mixed ration (57% concentrate and 43% roughages) for 10, 18, or 60 min, respectively. The treatments were fed for 36 d with 21 d for adaptation and 15 d for sampling. The peNDF 8.0 intake was positively correlated with the peNDF 8.0 concentration. Chewing and ruminating times adjusted for dry matter intake and NDF intake were linearly increased with the increased dietary peNDF 8.0 concentration. The high peNDF 8.0 diet decreased the number of meals per day. The increased dietary peNDF 8.0 concentration linearly increased the rumen fluid pH, the molar percentage of acetate and isobutyrate, acetate-to-propionate ratio, and ammonia nitrogen concentration, but linearly decreased the molar percentages of propionate and valerate. The total VFA concentration and the molar percentages of butyrate and isovalerate remained unchanged. Meanwhile, the increase in the peNDF 8.0 concentration of the diet linearly increased the activities of carboxymethyl cellulase, avicelase, β-glucanase, and ferulic acid esterase in rumen fluid, but did not affect the activities of xylanase. Total plasma antioxidant capacity, γ-glutamyl transpeptidase activity, and plasma concentrations of total protein, albumin, creatinine, and malondialdehyde were linearly decreased by the increased dietary peNDF 8.0 concentration. The increase in peNDF 8.0 concentration raised the plasma concentrations of glucose, triglyceride, cholesterol, and blood urea nitrogen. Somatic cell counts in the milk were positively correlated with the dietary peNDF 8.0 concentration. The feed and milk energy efficiencies were unaffected by the treatments. Shortening the total mixed ration mixing time may be a practical strategy to increase the peNDF 8.0 concentration and reduce the risk of SARA in dairy cows fed high-concentrate diets., (Copyright © 2021 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

Background: Plant secondary metabolites, including tannins, saponins and phenolic acids, possess potential methane (CH 4 ) inhibition bioactivity. Caffeic acid (CA), as one of the typical phenolic acids, serves as a promising rumen CH 4 inhibitor, but the underlying mechanisms and investigations with typical formulated rations are still not well documented. Therefore, a batch culture study was conducted to investigate the effects of CA on methanogenesis, rumen fermentation and growth of ruminal microorganisms when high-forage or high-concentrate substrates are fermented., Results: After 48 h incubations, adding CA up to 40 g kg -1 dry matter linearly reduced (P < 0.05) the disappearance of dry matter, neutral detergent fiber (NDFD), total gas, methanogenesis, total volatile fatty acid and 16S rDNA copy numbers of Ruminococcus albus and Butyrivibrio fibrisolvens, and increased 16S rDNA copy numbers of methanogens for the high-forage treatment. For the high-concentrate treatment, CA exerted opposite effects (P < 0.05) on the above variables, except that CA did not affect (P > 0.05)16S rDNA copy numbers of methanogens or R. albus., Conclusion: Caffeic acid inhibited in vitro methanogenesis and rumen fermentation with high-forage substrate incubation. Contrarily, CA benefited in vitro fermentation and enhanced methanogenesis with high-concentrate substrate incubation. It suggests that CA modulates methanogenesis and rumen fermentation mainly by affecting the growth of cellulolytic bacteria in vitro. © 2020 Society of Chemical Industry., (© 2020 Society of Chemical Industry.)

Anti-lipopolysaccharide (LPS) antibody administration has the potential benefits of neutralizing and consequently controlling rumen-derived LPS during subacute ruminal acidosis. Four Holstein bulls were used in this crossover study with a 2-week wash-out period. Anti-LPS antibody (0 or 4 g) was administered once daily for 14 days. Significantly lower ruminal LPS and higher 1-h mean ruminal pH were identified in the 4 g group. However, blood metabolites, acute-phase proteins, cytokines, and hepatic transcriptomes were not different between the two groups. Therefore, anti-LPS antibody administration mitigated ruminal LPS release and pH depression without accompanying responses in acute-phase inflammation or hepatic transcriptomic expression., Competing Interests: The authors declare no conflicts of interest., (© 2021 The Korean Society of Veterinary Science.)

The individual and combined effects of 3-nitrooxypropanol (3-NOP) and canola oil (OIL) supplementation on enteric methane (CH4) and hydrogen (H2) emissions, rumen fermentation and biohydrogenation, and total tract nutrient digestibility were investigated in beef cattle. Eight beef heifers (mean body weight ± SD, 732 ± 43 kg) with ruminal fistulas were used in a replicated 4 × 4 Latin square with a 2 (with and without 3-NOP) × 2 (with and without OIL) arrangement of treatments and 28-d periods (13 d adaption and 15 d measurements). The four treatments were: control (no 3-NOP, no OIL), 3-NOP (200 mg/kg dry matter [DM]), OIL (50 g/kg DM), and 3-NOP (200 mg/kg DM) plus OIL (50 g/kg DM). Animals were fed restrictively (7.6 kg DM/d) a basal diet of 900 g/kg DM barley silage and 100 g/kg DM supplement. 3-NOP and OIL decreased (P < 0.01) CH4 yield (g/kg DM intake) by 31.6% and 27.4%, respectively, with no 3-NOP × OIL interaction (P = 0.85). Feeding 3-NOP plus OIL decreased CH4 yield by 51% compared with control. There was a 3-NOP × OIL interaction (P = 0.02) for H2 yield (g/kg DM intake); the increase in H2 yield (P < 0.01) due to 3-NOP was less when it was combined with OIL. There were 3-NOP × OIL interactions for molar percentages of acetate and propionate (P < 0.01); individually, 3-NOP and OIL decreased acetate and increased propionate percentages with no further effect when supplemented together. 3-NOP slightly increased crude protein (P = 0.02) and starch (P = 0.01) digestibilities, while OIL decreased the digestibilities of DM (P < 0.01) and neutral detergent fiber (P < 0.01) with no interactions (P = 0.15 and 0.10, respectively). 3-NOP and OIL increased (P = 0.04 and P < 0.01, respectively) saturated fatty acid concentration in rumen fluid, with no interaction effect. Interactions for ruminal trans-monounsaturated fatty acids (t-MUFA) concentration and percentage were observed (P = 0.02 and P < 0.01); 3-NOP had no effect on t-MUFA concentration and percentage, while OIL increased the concentration (P < 0.01) and percentage (P < 0.01) of t-MUFA but to a lesser extent when combined with 3-NOP. In conclusion, the CH4-mitigating effects of 3-NOP and OIL were independent and incremental. Supplementing ruminant diets with a combination of 3-NOP and OIL may help mitigate CH4 emissions, but the decrease in total tract digestibility due to OIL may decrease animal performance and needs further investigation., (© Her Majesty the Queen in Right of Canada, as represented by the Minister of Agriculture and Agri-Food Canada, 2021.)

The present study investigated the association between fibre degradation and the concentration of dissolved molecular hydrogen (H2) in the rumen. Napier grass (NG) silage and corn stover (CS) silage were compared as forages with contrasting structures and degradation patterns. In the first experiment, CS silage had greater 48-h DM, neutral-detergent fibre (NDF) and acid-detergent fibre degradation, and total gas and methane (CH4) volumes, and lower 48-h H2 volume than NG silage in 48-h in vitro incubations. In the second experiment, twenty-four growing beef bulls were fed diets including 55 % (DM basis) NG or CS silages. Bulls fed the CS diet had greater DM intake (DMI), average daily gain, total-tract digestibility of OM and NDF, ruminal dissolved methane (dCH4) concentration and gene copies of protozoa, methanogens, Ruminococcus albus and R. flavefaciens, and had lower ruminal dH2 concentration, and molar proportions of valerate and isovalerate, in comparison with those fed the NG diet. There was a negative correlation between dH2 concentration and NDF digestibility in bulls fed the CS diet, and a lack of relationship between dH2 concentration and NDF digestibility with the NG diet. In summary, the fibre of CS silage was more easily degraded by rumen microorganisms than that of NG silage. Increased dCH4 concentration with the CS diet presumably led to the decreased ruminal dH2 concentration, which may be helpful for fibre degradation and growth of fibrolytic micro-organisms in the rumen.

Methane emissions from ruminants enhance global warming and lead to a loss of feed energy. The emissions are low when fed brassica crops, but the factors contributing to low emissions are unknown. A meta-analysis was conducted with individual animal data collected from seven experiments. In these experiments, methane emissions were measured using respiration chambers. Animal characteristics, feed chemical composition and rumen fermentation parameters were included for the analysis using multiple regression models. Feed intake level, animal live weight and age were animal factors that were weakly and negatively related to methane yield (g/dry matter intake). The duration in which sheep were fed brassica crops was a significant contributor in the model, suggesting that the effect on emissions diminishes with time. Among a range of feed chemical composition characters, acid detergent fibre and hot-water-soluble carbohydrate contributed significantly to the model, suggesting that both structural and soluble carbohydrates affect methane formation in the rumen. There was no significant correlation between the concentration of sulphate in brassicas and emissions, but nitrate was moderately and negatively correlated with methane yield (r = -.53). Short-chain fatty acid profiles in the rumen of animals fed brassicas were different from those fed pasture, but these parameters only moderately correlated to methane emissions (r = .42). Feeding forage rape resulted in low rumen pH. The pH before morning feeding was strongly correlated to methane yield (r = .90). Rumen pH, together with microbial communities mediated by pH, might lead to low emissions. Bacteria known to produce hydrogen were relatively less abundant in the rumen contents of brassica-fed animals than pasture-fed animals. In conclusion, animal and feed factors, rumen fermentation and microbial communities all affect methane emissions to some extent. The interactions of these factors with each other thus contribute to methane emissions from brassica-fed sheep., (© 2020 Wiley-VCH GmbH.)

Aims: The effect of increasing dietary cation-anion difference (DCAD) on rumen fermentation and ruminal microbial community in dairy cows under heat stress (HS) conditions were evaluated., Methods and Results: This study was performed as a two-period cross-over design during the summer season, with eight lactating dairy cows randomly distributed to either a control DCAD diet (CON: 33·5 mEq/100 g DM) or high DCAD diet (HDCAD: 50·8 mEq/100 g DM). Throughout the present study, the temperature and humidity index (THI; 80·2 ± 4·29) was generally elevated above the threshold (THI = 72) that is reported to cause HS in lactating dairy cows. Rumen liquid samples were collected on 15 and 21 d during each 21 d-period. The absolute concentration of ruminal total volatile fatty acid (TVFA) in HDCAD treatment was significantly (P < 0·05) higher than those in the control, whilst the ruminal pH, NH 3 -N, and VFA molar percentages were unaffected through increasing DCAD. Furthermore, the copy numbers of the cellulolytic bacteria Ruminococcus albus and Ruminococcus flavefaciens in rumen fluid significantly (P < 0·05) rose along with the increment of DCAD. Although the Alpha diversity indexes and the bacterial microbiota structure were unaffected, increasing DCAD significantly (P < 0·05) enriched the phylum Fibrobacteres and genus Fibrobacter in the microflora of rumen fluid, whilst the genera Flexilinea and Dubosiella were the most differentially abundant taxa in the control., Conclusions: Increasing DCAD under HS conditions resulted in a greater concentration of total VFA without affecting rumen bacteria diversity or structure, although the enrichment of some cellulolytic/hemicellulolytic bacteria was observed., Significance and Impact of the Study: The present study provides information on the modulation of rumen fermentation and microbial community through the increment of DCAD in Holstein dairy cows under HS conditions., (© 2020 The Society for Applied Microbiology.)

Ruminal fermentation efficiency has been shown to be closely related with milk production in dairy cows. This investigation aimed at the utilization of sweet grass and bamboo grass pellet supplementation on ruminal fermentation, feed utilization efficiency, milk quantity, and quality in lactating dairy cows. Four lactating Holstein Friesian crossbreds were randomly assigned in a 2 × 2 factorial arrangement in a 4 × 4 Latin square design to determine the effect of roughage sources and bamboo grass (Tiliacora triandra, Diels) pellet (BP) supplementation on voluntary feed intake, digestibility of nutrients, fermentation characteristics of the rumen, and milk quantity and quality. Sweet grass (SG) (Pennisetum purpureum cv. Mahasarakham) and rice straw (RS) were fed as roughage sources as the first factor, while the second factor was supplementation levels of BP (0 and 150 g/cow/day). The results revealed that SG (P < 0.01) and BP supplementation (P < 0.05) improved feed intake, digestibility of nutrients, especially roughage intake and digestibility of DM and NDF. Ruminal pH (P < 0.05), bacterial (P < 0.01), and fungal population (P < 0.01) were increased with SG feeding, enhancing the concentration of total VFAs (P < 0.01) and propionic acid (P < 0.01), while both SG and BP decreased methane production (P < 0.01). While milk yield (P < 0.01) and milk composition (P < 0.01), especially unsaturated fatty acids including those of conjugated linoleic acid (P < 0.001), were enhanced. Supplementation of BP containing bioactive compounds such as condensed tannins (CT) enhanced rumen bacterial population with increased total VFAs (P < 0.05) and propionic acid (P < 0.05) concentrations, while decreased methane production (P < 0.05). The findings of this study indicate that SG would be beneficial to improved rumen fermentation, feed utilization, and milk production of dairy cows, while bamboo grass pellet supplementation tended to additionally improve rumen fermentation and feed intake without negative effects on milk production.

This study aimed to evaluate the effects of ensiling fruit byproducts on their chemical composition and in vitro ruminal fermentation. Persimmon peel (PP), white grape pomace (WGP), and red grape pomace (RGP) were ensiled for 1, 2, 4, and 8 weeks. Fresh and ensiled PP, WGP, and RGP were used for in vitro rumen fermentation with or without polyethylene glycol (PEG). The non-fiber carbohydrate (NFC) content of the byproducts decreased after ensiling, especially for PP. The total tannin content was not changed after ensiling for up to 4 weeks for all byproducts. However, the soluble tannin content in PP decreased but that in grape pomaces was unaffected by ensiling. Gas production, total volatile fatty acid concentration, and methane production by in vitro rumen fermentation for PP and WGP were reduced by ensiling, and increased by adding PEG, except for gas production from the PP silage. These results indicated that changes in the fractions of carbohydrate and tannins during the ensiling process were different between PP and grape pomace. Even though the insolubilization of tannins in PP during ensiling reduced its inhibitory effect on ruminal fermentability, the ensiling PP seemed to remain the ability to mitigate methanogenesis in the rumen., (© 2021 Japanese Society of Animal Science.)