Long-term and combined effects of N-[2-(nitrooxy)ethyl]-3-pyridinecarboxamide and fumaric acid on methane production, rumen fermentation, and lactation performance in dairy goats

BACKGROUND

In recent years, nitrooxy compounds have been identified as promising inhibitors of methanogenesis in ruminants. However, when animals receive a nitrooxy compound, a high portion of the spared hydrogen is eructated as gas, which partly offsets the energy savings of CH₄ mitigation. The objective of the present study was to evaluate the long-term and combined effects of supplementation with N-[2-(nitrooxy)ethyl]-3-pyridinecarboxamide (NPD), a methanogenesis inhibitor, and fumaric acid (FUM), a hydrogen sink, on enteric CH₄ production, rumen fermentation, bacterial populations, apparent nutrient digestibility, and lactation performance of dairy goats.

RESULTS

Twenty-four primiparous dairy goats were used in a randomized complete block design with a 2 × 2 factorial arrangement of treatments: supplementation without or with FUM (32 g/d) or NPD (0.5 g/d). All samples were collected every 3 weeks during a 12-week feeding experiment. Both FUM and NPD supplementation persistently inhibited CH₄ yield (L/kg DMI, by 18.8% and 18.1%, respectively) without negative influence on DMI or apparent nutrient digestibility. When supplemented in combination, no additive CH₄ suppression was observed. FUM showed greater responses in increasing the molar proportion of propionate when supplemented with NPD than supplemented alone (by 10.2% vs. 4.4%). The rumen microbiota structure in the animals receiving FUM was different from that of the other animals, particularly changed the structure of phylum Firmicutes. Daily milk production and serum total antioxidant capacity were improved by NPD, but the contents of milk fat and protein were decreased, probably due to the bioactivity of absorbed NPD on body metabolism.

CONCLUSIONS

Supplementing NPD and FUM in combination is a promising way to persistently inhibit CH₄ emissions with a higher rumen propionate proportion. However, the side effects of this nitrooxy compound on animals and its residues in animal products need further evaluation before it can be used as an animal feed additive.

Active dry yeast supplementation improves the growth performance, rumen fermentation, and immune response of weaned beef calves

The objective of this experiment was to investigate the potential benefits of active dry yeast (ADY) on the growth performance, rumen fermentation, nutrient digestibility, and serum parameters of weaned beef calves. Thirty Simmental crossbred male calves (body weight = 86.47 ± 4.41 kg and 70 ± 4 d of age) were randomly divided into 2 groups: control (CON) (fed basal ration) and ADY (fed basal ration and 5 g/d ADY per calf). The dietary concentrate-to-roughage ratio was 35:65. All the calves were regularly provided rations 3 times a day at 07:00, 13:00, and 19:00 and had free access to water. The experiment lasted for 60 d. The average daily gain of ADY group was higher (P = 0.007) than that of the CON group, and the ratio of feed intake to average daily gain in the ADY group was reduced (P = 0.022) as compared to the CON group. The concentration of ruminal ammonia-N was higher (P = 0.023) in the CON group than that in the ADY group, but an opposite trend of microbial protein was found between the 2 groups. Also, the ruminal concentrations of propionate and butyrate were higher (P < 0.05) in the ADY group than those in the CON group. Calves fed ADY exhibited higher (P < 0.05) crude protein and neutral detergent fiber digestibility. Supplementation of ADY increased (P < 0.05) the contents of glucose, glutathione peroxidase, superoxide dismutase, immunoglobulin A, immunoglobulin M, and interleukin 10 in the serum of calves, but an opposite trend was observed in malondialdehyde, interleukin 1 beta, and tumor necrosis factor alpha contents between the 2 groups. In conclusion, dietary supplementation with ADY could improve the growth performance, rumen fermentation, nutrient digestibility, antioxidant ability, and immune response of weaned beef calves.

Effects of riboflavin supplementation on performance, nutrient digestion, rumen microbiota composition and activities of Holstein bulls

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.

Adding polyethylene glycol to steer ration containing sorghum tannins increases crude protein digestibility and shifts nitrogen excretion from feces to urine

The objectives of the experiment were to study the effects of adding polyethylene glycol (PEG) to steer ration containing high sorghum tannins on rumen fermentation, nutrient digestion, nitrogen (N) balance and plasma biochemical parameters. Eight growing steers at 16 months of age were allotted to a replicated 4 × 4 Latin square design with 4 treatments and 4 periods (19 d each). Polyethylene glycol at 0, 1.75, 3.50 and 7.00 g/kg dry matter (DM) were added to a basal ration containing 27.82% DM of sorghum grain (total tannins 3.3 g/kg DM) as the treatments. The results indicated that adding PEG quadratically increased the ruminal pH (P = 0.049), tended to linearly increase the ruminal concentration of total volatile fatty acids (P = 0.070), increased the molar proportion of acetate (P = 0.016), linearly decreased the molar proportion of butyrate (P = 0.015), and tended to increase the molar proportion of iso-valerate (P = 0.061) and the ruminal concentration of ammonia N (P = 0.092). Adding PEG tended to quadratically decrease the relative abundance of methanogenic archaea (P = 0.082), linearly decreased the relative abundance of Fibrobacter succinogenes (P = 0.008) and decreased the relative abundance of Butyrivibrio fibrisolvens (P = 0.048) at 7.00 g/kg DM. Dietary addition with PEG increased the crude protein (CP) digestibility (P < 0.001) and tended to increase the neutral detergent fiber digestibility (P = 0.066) in a linear manner. Adding PEG to basal ration also increased the plasma globulin concentration (P = 0.029) and tended to linearly increase the plasma total protein concentration (P = 0.069). Adding PEG linearly decreased the fecal N excretion (P < 0.001) and the fecal N-to-total N excretion ratio (P = 0.004) and increased the urinary N-to-total N excretion ratio (P = 0.004) and urinary urea excretion (P = 0.010) without affecting the urinary N and total N excretions (P > 0.05). It was concluded that adding PEG effectively improved the CP digestibility of the ration containing high sorghum tannins but increased the urinary urea excretion without improving the N retention and N retention rate in steers.

Effects of vegetable oil supplementation on rumen fermentation and microbial population in ruminant: a review

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.

Comparative study of growth performance, nutrient digestibility, and ruminal and fecal bacterial community between yaks and cattle-yaks raised by stall-feeding

The experiment was conducted to compare the growth performance, rumen fermentation, nutrient digestibility, and ruminal and fecal bacterial community between yaks and cattle-yaks. Ten male yaks (36-month-old) were used as the yak (YAK) group and 10 male cattle-yaks with similar age were selected as the cattle-yak (CAY) group. All the animals were fed same ration and the experiment lasted for 60 days. The results showed that the average daily gain and dry matter intake of CAY group were higher (P < 0.05) than those of YAK group. The ruminal concentrations of total volatile fatty acids, acetate, and butyrate were higher (P < 0.05) in CAY group than those in YAK group. However, the neutral detergent fiber and acid detergent fiber digestibility exhibited an opposite between two groups. In the rumen, the relative abundances of Prevotella 1 and Prevotellaceae UCG-001 were higher (P < 0.05) and Succiniclasticum and Butyrivibrio 2 were lower (P < 0.05) in YAK group compared to CAY group. In the feces, the unclassified Lachnospiraceae, Lachnospiraceae NK4A136 group, and Lachnospiraceae AC2044 group were significantly enriched (P < 0.05) in YAK group, whereas the Ruminococcaceae UCG-010, Ruminococcaceae UCG-013, and Succiniclasticum were significantly enriched (P < 0.05) in CAY group. Overall, under the same diet, the yaks have higher fiber utilization and cattle-yaks have higher energy utilization.

Effects of faba bean, blue lupin and rapeseed meal supplementation on nitrogen digestion and utilization of dairy cows fed grass silage-based diets

There is increasing interest in using locally produced protein supplements in dairy cow feeding. The objective of this experiment was to compare rapeseed meal (RSM), faba beans (FBs) and blue lupin seeds (BL) at isonitrogenous amounts as supplements of grass silage and cereal based diets. A control diet (CON) without protein supplement was included in the experiment. Four lactating Nordic Red cows were used in a 4 × 4 Latin Square design with four 21 d periods. The milk production increased with protein supplementation but when expressed as energy corrected milk, the response disappeared due to substantially higher milk fat concentration with CON compared to protein supplemented diets. Milk protein output increased by 8.5, 4.4 and 2.7% when RSM, FB and BL were compared to CON. The main changes in rumen fermentation were the higher propionate and lower butyrate proportion of total rumen volatile fatty acids when the protein supplemented diets were compared to CON. Protein supplementation also clearly increased the ruminal ammonia N concentration. Protein supplementation improved diet organic matter and NDF digestibility but efficiency of microbial protein synthesis per kg organic matter truly digested was not affected. Flow of microbial N was greater when FB compared to BL was fed. All protein supplements decreased the efficiency of nitrogen use in milk production. The marginal efficiency (amount of additional feed protein captured in milk protein) was 0.110, 0.062 and 0.045 for RSM, FB and BL, respectively. The current study supports the evidence that RSM is a good protein supplement for dairy cows, and this effect was at least partly mediated by the lower rumen degradability of RSM protein compared to FB and BL. The relatively small production responses to protein supplementation with simultaneous decrease in nitrogen use efficiency in milk production suggest that economic and environmental consequences of protein feeding need to be carefully considered.

Dynamics of rumen bacterial composition of yak (Bos grunniens) in response to dietary supplements during the cold season

This study aimed to explore the rumen bacterial community of yak in response to dietary supplements during the cold season. In addition, the rumen fermentation products were also analyzed. Twenty-one female domestic yaks were randomly divided into three groups i.e., pure grazing (GG) group, grazing plus oats hay supplement (OG) group, and grazing plus concentrate supplement group (CG). Rumen contents were collected after 90 days to assess rumen fermentation parameters and bacterial community. The GC group presented higher concentrations of ammonia nitrogen (P < 0.001), and total volatile fatty acids (TVFA) (P < 0.001), and lower rumen pH (P < 0.001) compared to other experimental groups. The CG group displayed higher proportions of propionate, butyrate, isobutyrate, and isovalerate while lower A/P ratio compared to other experimental groups. Shannon, Chao1, and ACE values were significantly lower in the OG group compared to GG and CG groups. Anosim test showed significant differences in bacterial community structure between groups but the PCA plot was not very informative to see these differences. Bacteroidetes, Proteobacteria, and Firmicutes were the three dominant phyla in all groups. The genera Oscillospira was more abundant in GG and OG groups. Higher relative abundance of Ruminococcus and Clostridium was observed in the GG group, while Ruminobacter, Corynebacterium, and Selenomonas were more abundant in the CG group. These findings will help in improving our understanding of rumen bacteria in yaks in response to changes in diet.

Garlic skin induces shifts in the rumen microbiome and metabolome of fattening lambs

Garlic (Allium sativum L.) and its constituents have been shown to modify rumen fermentation and improve growth performance. Garlic skin, a by-product of garlic processing, contains similar bioactive components as garlic bulb. This study aimed to investigate the effects of garlic skin supplementation on growth performance, ruminal microbes, and metabolites in ruminants. Twelve Hu lambs were randomly assigned to receive a basal diet (CON) or a basal diet supplemented with 80 g/kg DM of garlic skin (GAS). The experiment lasted for 10 weeks, with the first 2 weeks serving as the adaptation period. The results revealed that the average daily gain and volatile fatty acid concentration were higher (P < 0.05) in lambs fed GAS than those in the CON group. Garlic skin supplementation did not significantly (P > 0.10) affect the α-diversity indices, including the Chao1 index, the abundance-based coverage estimator value, and the Shannon and Simpson indices. At the genus level, garlic skin supplementation altered the ruminal bacterial composition by increasing (P < 0.05) the relative abundances of Prevotella, Bulleidia, Howardella, and Methanosphaera and decreasing (P < 0.05) the abundance of Fretibacterium. Concentrations of 139 metabolites significantly differed (P < 0.05) between the GAS and the CON groups. Among them, substrates for rumen microbial protein synthesis were enriched in the GAS group. The pathways of pyrimidine metabolism, purine metabolism, and vitamin B6 metabolism were influenced (P < 0.05) by garlic skin supplementation. Integrated correlation analysis also provided a link between the significantly altered rumen microbiota and metabolites. Thus, supplementation of garlic skin improved the growth performance of lambs by modifying rumen fermentation through shifts in the rumen microbiome and metabolome.

Association of fibre degradation with ruminal dissolved hydrogen in growing beef bulls fed with two types of forages

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.

Ensiling sorghum with unsalable pumpkin improves feed digestibility with minimal influence on the rumen microbial population using the rumen simulation technique

This study aimed to determine the influence of sorghum ensiled with unsalable pumpkin at 20 or 40% dry matter (DM) basis on rumen fermentation characteristics and rumen microbial communities using the rumen simulation technique (RUSITEC). The experiment used a completely randomised design including silages comprising (1) 100% sorghum; (2) 80% sorghum + 20% DM pumpkin; or (3) 60% sorghum + 40% DM pumpkin. Each RUSITEC run (n = 2) was 15 d long, including 6 d of adaptation and 9 d of sampling. Dry matter digestibility (DMD) was measured on d 8 and 10-13. Gas production was measured daily, whereas methane and volatile fatty acids (VFA) production were measured from d 7-15. Solid-associated microbes (SAM) were collected on d 5, 10 and 15, whereas liquid-associated microbes (LAM) were collected after 15-d incubation. The V4 region of the 16S rRNA gene and the ITS1 region were sequenced to identify archaeal, bacterial and fungal communities. Ensiling 40% DM pumpkin with sorghum increased DMD and decreased the ratio of acetate to propionate (P ≤ 0.01). Both bacterial SAM and LAM communities were dominated by Megasphaera, and had the highest relative abundance (P = 0.03) with 40% DM pumpkin after 5 d incubation in the SAM community, while species of the Aspergillus genus dominated fungal SAM and LAM communities with 20 or 40% DM unsalable pumpkin. Therefore, ensiling up to 40% DM unsalable pumpkin with sorghum produces a high-quality ruminant feed with minimal influence on the rumen microbial population. KEY POINTS: • Including 40% DM unsalable pumpkin decreased acetate:propionate • Ensiling unsalable pumpkin with sorghum increases digestibility in a RUSITEC • Rumen microbial communities were slightly influenced by unsalable pumpkin inclusion.

Digestion, ruminal metabolism, and feeding behavior of buffaloes fed diets supplemented with soybean oil, whole and raw soybean, and calcium salts of fatty acids

This study aimed to evaluate the effects of the inclusion of unsaturated fatty acid (UFA) sources on the nutrient intake, apparent digestibility, ruminal fermentation, and feeding behavior in diets for buffaloes. Four castrated Murrah buffaloes with approximately 24 months of age and an initial average body weight of 351 ± 15 kg were randomly assigned to a 4 × 4 Latin square experiment, containing the following diets: (1) control (CON): control diet based on soybean meal and ground corn, (2) soybean oil (SO): dietary inclusion of 2.20% (DM basis), (3) whole raw soybean (WRS): dietary inclusion of 16.0%, and (4) calcium salts of FA (CSFA): dietary inclusion of 2.60%. There was an effect of diets in ether extract intake among buffaloes fed UFA and CON diets, and among buffaloes fed CSFA and WRS diets (P < 0.05). Diets containing UFA sources provided higher EE digestibility (P < 0.05). Buffaloes fed WRS had higher rumen pH values than animals fed the CSFA diet (P < 0.05). Supplementation of UFA sources decreased the molar concentrations of short-chain fatty acids (P < 0.05). Diets influenced the times spent in chewing, idling, and the rumination efficiencies of DM and NDF (P < 0.05). The supplementation with WRS, SO, and CSFA does not negatively affect intake, digestion, ruminal metabolism, and feeding behavior. The WRS as a fat supplement source decreases dietary costs by replacing ground corn and soybean meal simultaneously compared to other fat sources used. Nevertheless, whole and raw soybean in buffaloes' diet can reduce chewing and rumination activity.

Evaluation of dietary addition of 2 essential oils from Achillea moschata, or their components (bornyl acetate, camphor, and eucalyptol) on in vitro ruminal fermentation and microbial community composition

This study investigated the effects of 2 Achillea moschata essential oils extracted from plants collected in 2 different valleys of the Italian Alps and 3 pure compounds of oils - bornyl acetate (BOR), camphor (CAM), and eucalyptol (EUCA) - on in vitro ruminal fermentation and microbiota. An in vitro batch fermentation experiment (Exp. 1) tested the addition of all of the substances (2 essential oils and 3 compounds) in fermentation bottles (120 mL) at 48 h of incubation, whereas a subsequent in vitro continuous culture experiment (Exp. 2) evaluated the pure compounds added to the fermenters (2 L) for a longer incubation period (9 d). In both experiments, total mixed rations were incubated with the additives, and samples without additives were included as the control (CTR). Each treatment was tested in duplicate and was repeated in 3 and 2 fermentation runs in Exp. 1 and 2, respectively. Gas production (GP) in Exp. 1 was similar for all of the treatments, and short chain volatile fatty acid (SCFA) production was similar in both experiments except for a decrease of SCFA produced (P = 0.029) due to EUCA addition in Exp. 2. Compared to CTR, BOR and CAM reduced the valerate proportion (P = 0.04) in Exp. 1, and increased (P < 0.01) the acetate proportion in Exp. 2. All treatments increased (P < 0.01) total protozoa counts (+36.7% and +48.4% compared to CTR on average for Exp. 1 and 2, respectively). In Exp. 1, all of the treatments lowered the Bacteroidetes and Firmicutes and increased the Proteobacteria relative abundances (P < 0.05), whereas in Exp. 2, the EUCA addition increased (P = 0.012) the Ruminococcus. In Exp. 1, methane (CH4) as a proportion of the GP was lowered (P = 0.004) by the addition of CAM and EUCA compared to CTR, whereas in Exp. 2, EUCA reduced the amount of stoichiometrically calculated CH4 compared to CTR. Overall, essential oils extracted from A. moschata and the pure compounds did not depress in vitro rumen fermentation, except for EUCA in Exp. 2. In both experiments, an increase of the protozoal population occurred for all the additives.

Effects of different levels of rapeseed cake containing high glucosinolates in steer ration on rumen fermentation, nutrient digestibility and the rumen microbial community

This trial was conducted to study the effects of dietary rapeseed cake (RSC) containing high glucosinolates (GLS) on rumen fermentation, nutrient digestion and the rumen microbial community in steers. Eight growing steers and four rations containing RSC (GLS 226·1 μmol/g DM) at 0·00, 2·65, 5·35 and 8·00 % DM were assigned in a replicate 4 × 4 Latin square design. The results indicated that increasing RSC levels increased the ruminal concentration of thiocyanate (SCN) (P < 0·01), decreased the ruminal concentration of ammonia nitrogen (NH3-N) and the molar proportion of isovalerate (P < 0·05), did not affect the ruminal concentration of total volatile fatty acids (P > 0·05), decreased the crude protein (CP) digestibility (P < 0·05) and increased the ether extract (EE) digestibility (P < 0·01). Increasing RSC levels tended to decrease the abundances of ruminal Ruminobacter amylophilus (P = 0·055) and Ruminococcus albus (P = 0·086) but did not affect methanogens, protozoa, fungi and other bacteria (P > 0·05). Increasing RSC levels in the ration did not affect the ruminal bacterial diversity (P > 0·05), but it increased the operational taxonomic units and the bacterial richness (P < 0·05) and affected the relative abundances of some bacteria at the phylum level and genus level (P < 0·05). In conclusion, RSC decreased the ruminal concentration of NH3-N and the CP digestibility, increased the EE digestibility and partly affected the ruminal bacterial community. SCN, as the metabolite of GLS, could be a major factor affecting these indices.

Rumen microbiome structure and metabolites activity in dairy cows with clinical and subclinical mastitis

Background

Due to the high prevalence and complex etiology, bovine mastitis (BM) is one of the most important diseases to compromise dairy cow health and milk quality. The shift in milk compositions has been widely investigated during mastitis, but recent studies suggested that gastrointestinal microorganism also has a crucial effect on the inflammation of other peripheral tissues and organs, including the mammary gland. However, research focused on the variation of rumen inner-environment during mastitis is still limited. Therefore, the ruminal microbial profiles, metabolites, and milk compositions in cows with different udder health conditions were compared in the present study. Furthermore, the correlations between udder health status and ruminal conditions were investigated. Based on the somatic cell counts (SCC), California mastitis test (CMT) parameters and clinical symptoms of mastitis, 60 lactating Holstein dairy cows with similar body conditions (excepted for the udder health condition) were randomly divided into 3 groups (n = 20 per group) including the healthy (H) group, the subclinical mastitis (SM) group and the clinical mastitis (CM) group. Lactation performance and rumen fermentation parameters were recorded. And rumen microbiota and metabolites were also analyzed via 16S rRNA amplicon sequencing and untargeted metabolomics, respectively.

Results

As the degree of mastitis increased, rumen lactic acid (LA) (P < 0.01), acetate, propionate, butyrate, valerate (P < 0.001), and total volatile fatty acids (TVFAs) (P < 0.01) concentrations were significantly decreased. In the rumen of CM cows, the significantly increased bacteria related to intestinal and oral inflammation, such as Lachnospiraceae (FDR-adjusted P = 0.039), Moraxella (FDR-adjusted P = 0.011) and Neisseriaceae (FDR-adjusted P = 0.036), etc., were accompanied by a significant increase in 12-oxo-20-dihydroxy-leukotriene B4 (FDR-adjusted P = 5.97 × 10^− 9) and 10beta-hydroxy-6beta-isobutyrylfuranoeremophilane (FDR-adjusted P = 3.88 × 10^− 10). Meanwhile, in the rumen of SM cows, the Ruminiclostridium_9 (FDR-adjusted P = 0.042) and Enterorhabdus (FDR-adjusted P = 0.043) were increased along with increasing methenamine (FDR-adjusted P = 6.95 × 10^− 6), 5-hydroxymethyl-2-furancarboxaldehyde (5-HMF) (FDR-adjusted P = 2.02 × 10^− 6) and 6-methoxymellein (FDR-adjusted P = 2.57 × 10^− 5). The short-chain fatty acids (SCFAs)-producing bacteria and probiotics in rumen, including Prevoterotoella_1 (FDR-adjusted P = 0.045) and Bifidobacterium (FDR-adjusted P = 0.035), etc., were significantly reduced, with decreasing 2-phenylbutyric acid (2-PBA) (FDR-adjusted P = 4.37 × 10^− 6).

Conclusion

The results indicated that there was a significant shift in the ruminal microflora and metabolites associated with inflammation and immune responses during CM. Moreover, in the rumen of cows affected by SM, the relative abundance of several opportunistic pathogens and the level of metabolites which could produce antibacterial compounds or had a competitive inhibitory effect were all increased.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40104-020-00543-1.

Milk production and composition efficiency as influenced by feeding Pennisetum purpureum cv. Mahasarakham with Tiliacora triandra, Diels pellet supplementation

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.

Influence of yeast on rumen fermentation, growth performance and quality of products in ruminants: A review

This review aims to give an overview of the efficacy of yeast supplementation on growth performance, rumen pH, rumen microbiota, and their relationship to meat and milk quality in ruminants. The practice of feeding high grain diets to ruminants in an effort to increase growth rate and weight gain usually results in excess deposition of saturated fatty acids in animal products and increased incidence of rumen acidosis. The supplementation of yeast at the right dose and viability level could counteract the acidotic effects of these high grain diets in the rumen and positively modify the fatty acid composition of animal products. Yeast exerts its actions by competing with lactate-producing (Streptococcus bovis and Lactobacillus) bacteria for available sugar and encouraging the growth of lactate-utilising bacteria (Megasphaera elsdenii). M. elsdenii is known to convert lactate into butyrate and propionate leading to a decrease in the accumulation of lactate thereby resulting in higher rumen pH. Interestingly, this creates a conducive environment for the proliferation of vaccenic acid-producing bacteria (Butyrivibrio fibrisolvens) and ciliate protozoa, both of which have been reported to increase the ruminal concentration of trans-11 and cis-9, trans-11-conjugated linoleic acid (CLA) at a pH range between 5.6 and 6.3. The addition of yeast into the diet of ruminants has also been reported to positively modify rumen biohydrogenation pathway to synthesise more of the beneficial biohydrogenation intermediates (trans -11 and cis -9, trans -11). This implies that more dietary sources of linoleic acid, linolenic acid, and oleic acid along with beneficial biohydrogenation intermediates (cis-9, trans-11-CLA, and trans-11) would escape complete biohydrogenation in the rumen to be absorbed into milk and meat. However, further studies are required to substantiate our claim. Therefore, techniques like transcriptomics should be employed to identify the mRNA transcript expression levels of genes like stearoyl-CoA desaturase, fatty acid synthase, and elongase of very long chain fatty acids 6 in the muscle. Different strains of yeast need to be tested at different doses and viability levels on the fatty acid profile of animal products as well as its vaccenic acid and rumenic acid composition.

A comparative study of artificial cow and sheep rumen fermentation of corn straw and food waste: Batch and continuous operation

To optimize the artificial rumen microorganism sources and develop a stable artificial rumen system, batch and continuous operation were investigated with corn straw and food waste as substrates. The batch trials evaluated the volatile fatty acid (VFA) yield, biogas production, and lignocellulose degradation efficiency. The continuous test evaluated the performance of the artificial cow and sheep rumen systems using a dynamic membrane bioreactor (DMBR) with a stepwise organic loading rate at mesophilic temperature. The anaerobic digestion (AD) of the lignocellulose biomass after rumen fermentation pretreatment and of the permeate from the artificial rumen system were also evaluated for CH₄ production. The results indicated that the cow rumen microorganisms were more suitable than sheep rumen microorganisms for lignocellulosic biomass pretreatment and maximized the CH₄ yield through the AD process without inhibition. After approximately four months of continuous operation, a stable and continuous artificial rumen system for lignocellulosic biomass degradation was achieved with cow rumen fluid as inoculum. Based on analysis of the core lignocellulose-degrading enzyme levels and gel filtration chromatography, the cow rumen microorganisms could secrete more extracellular multienzyme complexes to hydrolyze lignocellulosic biomass than the sheep rumen microorganisms in vitro. During the batch and continuous operations, a high diversity and similar richness of bacteria and fungi demonstrated that the cow rumen microorganisms can be used as a preferred inoculum for the artificial rumen system. The use of an artificial cow rumen system with a DMBR is a promising way to construct a stable and continuous artificial rumen system to biodegrade lignocellulosic biomass for biogas production.

Assessment of potato peel and agro-forestry biochars supplementation on in vitro ruminal fermentation

Background

The awareness of environmental and socio-economic impacts caused by greenhouse gas emissions from the livestock sector leverages the adoption of strategies to counteract it. Feed supplements can play an important role in the reduction of the main greenhouse gas produced by ruminants—methane (CH₄). In this context, this study aims to assess the effect of two biochar sources and inclusion levels on rumen fermentation parameters in vitro.

Methods

Two sources of biochar (agro-forestry residues, AFB, and potato peel, PPB) were added at two levels (5 and 10%, dry matter (DM) basis) to two basal substrates (haylage and corn silage) and incubated 24-h with rumen inocula to assess the effects on CH₄ production and main rumen fermentation parameters in vitro.

Results

AFB and PPB were obtained at different carbonization conditions resulting in different apparent surface areas, ash content, pH at the point of zero charge (pHpzc), and elemental analysis. Relative to control (0% biochar), biochar supplementation kept unaffected total gas production and yield (mL and mL/g DM, p = 0.140 and p = 0.240, respectively) and fermentation pH (p = 0.666), increased CH₄production and yield (mL and mL/g DM, respectively, p = 0.001) and ammonia-N (NH₃-N, p = 0.040), and decreased total volatile fatty acids (VFA) production (p < 0.001) and H₂ generated and consumed (p ≤ 0.001). Biochar sources and inclusion levels had no negative effect on most of the fermentation parameters and efficiency. Acetic:propionic acid ratio (p = 0.048) and H₂ consumed (p = 0.019) were lower with AFB inclusion when compared to PPB. Biochar inclusion at 10% reduced H₂ consumed (p < 0.001) and tended to reduce total gas production (p = 0.055). Total VFA production (p = 0.019), acetic acid proportion (p = 0.011) and H₂ generated (p = 0.048) were the lowest with AFB supplemented at 10%, no differences being observed among the other treatments. The basal substrate affected most fermentation parameters independently of biochar source and level used.

Discussion

Biochar supplementation increased NH₃-N content, iso-butyric, iso-valeric and valeric acid proportions, and decreased VFA production suggesting a reduced energy supply for microbial growth, higher proteolysis and deamination of substrate N, and a decrease of NH₃-N incorporation into microbial protein. No interaction was found between substrate and biochar source or level on any of the parameters measured. Although AFB and PPB had different textural and compositional characteristics, their effects on the rumen fermentation parameters were similar, the only observed effects being due to AFB included at 10%. Biochar supplementation promoted CH₄ production regardless of the source and inclusion level, suggesting that there may be other effects beyond biomass and temperature of production of biochar, highlighting the need to consider other characteristics to better identify the mechanism by which biochar may influence CH₄ production.

Effects of dietary supplementation with different concentration of molasses on growth performance, blood metabolites and rumen fermentation indices of Nubian goats

Background

Molasses is a potential energy supplement; extensively used to improve growth performance, milk and meat characteristics in goats at relatively low concentrations of 5–40% of the diet. Few data are available concerning feeding molasses to goat kids; therefore, the current study aimed to investigate the effects of dietary supplementation with higher concentrations of molasses on growth performance, blood metabolites and rumen fermentation indices. Twenty male Nubian goat kids (4–6 months old; 9–10 kg BW) were randomly assigned to 4 groups receiving different concentration of molasses: 0% (M-0), 30% (M-30), 40% (M-40) and 45% (M-45) for 5 weeks. Feed (DFI) and water intake (DWI) were measured daily, while the blood and rumen liquor samples were collected weekly.

Results

The DFI increased and feed conversion ratio (FCR) decreased in all molasses-supplemented groups (P ≤ 0.05), whereas DWI increased in M-30 and decreased in M-45 (P ≤ 0.05). The final BW and average daily gain (ADG) increased (P < 0.0001) in groups M-30 and M-40 compared to the control and M-45. Blood pH was significantly influenced by dietary molasses concentration (MC) and the duration of molasses supplementation (MD), where it decreased in groups M-30 and M-45 compared to the control and M-40 (P < 0.05). The MC had no significant effect on blood Hb, HCT, TLC, albumin, [K⁺], AST, ALT and total protozoa count (TPC), as well as ruminal-[Na⁺], [K⁺], strong ion difference concentration ([SID₃]) and [NH₃]; however, only [NH₃] was significantly affected by MD and the interaction between MC and MD (MC × MD). Serum TP, globulins, [Na⁺] and [Cl⁻] increased (P ≤ 0.05) in all supplemented groups, while A/G ratio and [SID₃] decreased (P ≤ 0.05). Ruminal pH decreased (P < 0.0001) in M-40 and M-45 compared to the control and M-30. However, [VFAs] increased (P < 0.04) in M-30 and M-40 compared to the control and M-45, while osmolality increased (P ≤ 0.05) in M-30 compared to the other groups.

Conclusions

Dietary supplementation with molasses at a concentration of 30% for 3 weeks improved growth performance, protein metabolism and rumen fermentation without compromising animal health, immunity, and electrolytes and acid-base homeostasis.

Effects of copper sulphate and coated copper sulphate addition on lactation performance, nutrient digestibility, ruminal fermentation and blood metabolites in dairy cows

Coated copper sulphate (CCS) could be used as a Cu supplement in cows. To investigate the influences of copper sulphate (CS) and CCS on milk performance, nutrient digestion and rumen fermentation, fifty Holstein dairy cows were arranged in a randomised block design to five groups: control, CS addition (7·5 mg Cu/kg DM from CS) or CCS addition (5, 7·5 and 10 mg Cu/kg DM from CCS, respectively). When comparing Cu source at equal inclusion rates (7·5 mg/kg DM), cows receiving CCS addition had higher yields of fat-corrected milk, milk fat and protein; digestibility of DM, organic matter (OM) and neutral-detergent fibre (NDF); ruminal total volatile fatty acid (VFA) concentration; activities of carboxymethyl cellulase, cellobiase, pectinase and α-amylase; populations of Ruminococcus albus, Ruminococcus flavefaciens and Fibrobacter succinogenes; and liver Cu content than cows receiving CS addition. Increasing CCS addition, DM intake was unchanged, yields of milk, milk fat and protein; feed efficiency; digestibility of DM, OM, NDF and acid-detergent fibre; ruminal total VFA concentration; acetate:propionate ratio; activity of cellulolytic enzyme; populations of total bacteria, protozoa and dominant cellulolytic bacteria; and concentrations of Cu in serum and liver increased linearly, but ruminal propionate percentage, ammonia-N concentration, α-amylase activity and populations of Prevotella ruminicola and Ruminobacter amylophilus decreased linearly. The results indicated that supplement of CS could be substituted with CCS and addition of CCS improved milk performance and nutrient digestion in dairy cows.

Cosubstrate strategy for enhancing lignocellulose degradation during rumen fermentation in vitro: Characteristics and microorganism composition

To enhance the degradation of wheat straw (WS) and corn straw (CS) in rumen fermentation, characterization of degradation and ruminal microorganisms of monosubstrate (WS/CS) groups and a cosubstrate strategy with food waste (FW) group was performed. The cellulose, hemicellulose, and lignin degradation efficiency of WS and CS; soluble chemical oxygen demand; volatile fatty acid yields; and activity of ligninolytic, cellulolytic, and hemicellulolytic enzymes for the cosubstrate group were improved compared with those for the corresponding monosubstrate groups. An accurate and a good of fit of the Weibull kinetic model, decreased crystallinity index values, and characteristic absorbance bands in the Fourier transform-infrared spectra further confirmed that cosubstrate addition with FW decreased the resistance of cellulose and hemicellulose to biodegradation. High-throughput sequencing results suggested that the bacterial diversity in CS rumen fermentation and fungal diversity and richness in WS rumen fermentation were promoted with FW as a cosubstrate. The cosubstrate addition with FW significantly affected the composition of the ruminal bacteria and fungi in rumen fermentation. The relative abundances (RAs) of rumen bacteria were increased in the cosubstrate CS/WS and FW fermentation conditions, and the enhancement of CS degradation with FW supplementation was stronger than that of WS rumen fermentation with FW supplementation. The RAs of the ruminal fungal genera Ustilago and Fusarium were promoted in CS and WS fermentation with FW, respectively. Moreover, the fermentation properties and rumen flora in the FW rumen fermentation also provided some evidence to suggest an enhancement of the cosubstrate strategy compared with the monosubstrate strategy.

Effects of dietary rumen-protected Lys levels on rumen fermentation and bacterial community composition in Holstein heifers

This study aimed to evaluate the effects of partial reducing rumen-protected Lys (RPLys) on rumen fermentation and microbial composition in heifers. Three ruminal fistulated Holstein Friesian bulls were used to determine the effective degradability of RPLys using an in situ method at incubation times of 0, 2, 6, 12, 16, 24, 36, and 48 h. Thereafter, 36 Holstein heifers at 90 days of age were assigned to one of two dietary treatments: a theoretically balanced amino acid diet (PC group; 1.21% Lys, 0.4% Met) or a 30% Lys-reduced diet (PCLys group, 0.85% Lys, 0.4% Met). Rumen fluid samples from five heifers in each group were extracted using esophageal tubing on day 90 to determine pH, microprotein, ammonia, volatile fatty acids, and microbial communities. Results showed that the effective ruminal degradability was 25.76%. Furthermore, differences in rumen fermentation parameters and alpha diversity of the microbiota between the two groups were not significant, but beta diversity was significant. Based upon relative abundance analysis, short-chain fatty acid-producing bacteria, including Sharpea, Syntrophococcus, [Ruminococcus]_gauvreauii_group, Acetitomaculum, and [Eubacterium]_nadotum_group belonging to Firmicutes, were significantly decreased in the PCLys group. Spearman's analysis revealed a positive correlation between the butyrate molar proportion and the relative abundance of butyrate-producing bacteria such as [Eubacterium]_nadotum_group, Coprococcus_1, Ruminococcaceae_UCG_013, Pseudoramibacter, and Lachnospiraceae_UCG_010. Phylogenetic Investigation of Communities by Reconstruction of Unobserved States analysis further validated that RPLys deduction influenced energy metabolism. Together, our findings highlight the role of RPLys or Lys in butyrate-producing bacteria. However, the number of bacteria affected by Lys was very limited and insufficient to alter rumen fermentation. Key Points • Reducing 30% Lys via rumen-protected Lys did not affect rumen fermentation parameters and alpha diversity of microbiota of Holstein heifers. It meant that the ruminal fermentation pattern was not changed. • Reducing 30% Lys via rumen-protected lysine significantly decreased relative abundance of short-chain fatty acid-producing bacteria belonging to Firmicutes. • Functions of microorganisms were changed by reducing 30% Lys via rumen-protected Lys, especially amino acid metabolism. It may affect the amino acid composition of microprotein.

Persistent action of cow rumen microorganisms in enhancing biodegradation of wheat straw by rumen fermentation

Rumen fermentation is known to be effective for lignocellulosic-wastes biodegradation to certain extent but it is still unclear if there exists a termination of the microorganisms' action to further degrade the bio-refractory fractions. In order to illuminate the related microbiological characteristics, experiments were conducted in a prolonged duration of rumen fermentation of mechanically ruptured wheat straw, with inoculation of cow rumen microorganisms in vitro. Although the organic wastes could not be biodegraded quickly, continuous conversion of the lignocellulosic contents to volatile fatty acids and biogas proceeded in the duration of more than three months, resulting in 96-97% cellulose and hemicellulose decomposition, and 42% lignin decomposition. X-ray diffraction and Fourier transform infrared spectroscopy further demonstrated the characteristics of lignocellulosic structure decomposition. Under the actions of cow rumen microorganisms, stable pH was maintained in the fermentation liquid, along with a steady NH₄⁺-N, volatile fatty acids accumulation, and a large buffering ability. It was identified by enzyme analysis and Illumina MiSeq sequencing that the rich core lignocellulolytic enzymes secreted by the abundant and diverse rumen bacteria and fungi contributed to the persistent degradation of lignocellulosic wastes. Members of the Clostridiales order and Basidiomycota phylum were found to be the dominant lignocellulolytic bacteria and fungi, respectively. It could thus be inferred that the main lignocellulose degradation processes were a series of catalytic reactions under the actions of lignocellulolytic enzymes secreted from bacteria and fungi. The dominant hydrogenotrophic methanogens (Methanomassiliicoccus, Methanobrevibacter, Methanosphaera, and Methanoculleus) in the rumen could also assist CH₄ production if the rumen fermentation was followed with anaerobic digestion.

Nutritional status of grazing Lowline Angus crossbred supplemented with fermented cassava starch residue

This study aimed to compare growth performance of Lowline Angus crossbred with Thai native cattle under a grazing system with supplementation of fermented cassava starch residue. Three Ruzi grass sub-fields were used for twenty heads of beef cattle for a 7-month experiment from February to August 2017. Yeast, molasses, and urea-fermented cassava starch residue was offered at 1.50% BW of animal. Blood metabolite and fecal composition were determined for health and nutritional stage assessment. The temperature-humidity index was highest (75.6-84.6) in April. Overall growth rate of beef cattle was not significantly different among breeds except in the first month when the native had greater weight gain than the crossbred. Average daily gain was 353 and 345 g for Thai native and its crossbred with Lowline Angus, respectively. Blood triglyceride concentration sampled at 7 months of the native was higher than that of the crossbred; in contrast, blood cholesterol of the crossbred tended to be higher than that of the native. Other blood metabolites including glucose, cholesterol, urea nitrogen, creatinine, total protein, albumin, and globulin were comparable between breeds. The native and the crossbred were similar in fecal composition, ruminal fermentation end-products (ammonia nitrogen and volatile fatty acids), and microbial population. Therefore, under grazing condition with low-quality feed supplementation, Thai native beef cattle and its Lowline Angus crossbred had similar growth rate, health, and nutritional status.