Accumulation of trans C18:1 fatty acids in the rumen after dietary algal supplementation is associated with changes in the Butyrivibrio community

Rumen metagenome reveals the mechanism of mitigation methane emissions by unsaturated fatty acid while maintaining the performance of dairy cows

Dietary fat content can reduce the methane production of dairy cows; however, the relevance fatty acid (FA) composition has towards this inhibitory effect is debatable. Furthermore, in-depth studies elucidating the effects of unsaturated fatty acids (UFA) on rumen function and the mechanism of reducing methane (CH4) production are lacking. This study exposed 10 Holstein cows with the same parity, similar milk yield to two total mixed rations: low unsaturated FA (LUFA) and high unsaturated FA (HUFA) with similar fat content. The LUFA group mainly added fat powder (C16:0 > 90%), and the HUFA group mainly replaced fat powder with extruded flaxseed. The experiment lasted 26 d, the last 5 d of which, gas exchange in respiratory chambers was conducted to measure gas emissions. We found that an increase in the UFA in diet did not affect milk production (P > 0.05) and could align the profile of milk FAs more closely with modern human nutritional requirements. Furthermore, we found that increasing the UFA content in the diet lead to a decrease in the abundance of Methanobrevibacter in the rumen (|linear discriminant analysis [LDA] score| > 2 and P < 0.05), which resulted in a decrease in the relative abundance of multiple enzymes (EC:1.2.7.12, EC:2.3.1.101, EC:3.5.4.27, EC:1.5.98.1, EC:1.5.98.2, EC:6.2.1.1, EC:2.1.1.86 and EC:2.8.4.1) during methanogenesis (P < 0.05). Compared with the LUFA group, the pathway of CH4 metabolism was inhibited in the HUFA group (|LDA| > 2 and P < 0.05), which ultimately decreased CH4 production (P < 0.05). Our results illustrated the mechanism involving decreased CH4 production when fed a UFA diet in dairy cows. We believe that our study provides new evidence to explore CH4 emission reduction measures for dairy cows.

INVITED REVIEW: Research on ruminal biohydrogenation: Achievements, gaps in knowledge, and future approaches from the perspective of dairy science

Scientific knowledge about ruminal biohydrogenation (BH) has improved greatly since this metabolic process was empirically confirmed in 1951. For years, BH had mostly been perceived as a process to be avoided to increase the post-ruminal flow of UFA from the diet. Two milestones changed this perception and stimulated great interest in BH intermediates themselves: In 1987, the in vitro anticarcinogenic properties of CLA were described, and in 2000, the inhibition of milk fat synthesis by trans-10 cis-12 CLA was confirmed. Since then, numerous BH metabolites have been described in small and large ruminants, and the major deviation from the common BH pathway (i.e., the trans-10 shift) has been reasonably well established. However, there are some less well-characterized alterations, and the comprehensive description of new BH intermediates (e.g., using isotopic tracers) has not been coupled with research on their biological effects. In this regard, the low quality of some published fatty acid profiles may also be limiting the advance of knowledge in BH. Furthermore, although BH seems to no longer be considered a metabolic niche inhabited by a few bacterial species with a highly specific metabolic capability, researchers have failed to elucidate which specific microbial groups are involved in the process and the basis for alterations in BH pathways (i.e., changes in microbial populations or their activity). Unraveling both issues may be beneficial for the description of new microbial enzymes involved in ruminal lipid metabolism that have industrial interest. From the perspective of diary science, other knowledge gaps that require additional research in the coming years are evaluation of the relationship between BH and feed efficiency and enteric methane emissions, as well as improving our understanding of how alterations in BH are involved in milk fat depression. Addressing these issues will have relevant practical implications in dairy science.

Dietary supplementation with live or autolyzed yeast: Effects on performance, nutrient digestibility, and ruminal fermentation in dairy cows

This study was conducted to evaluate the effects of live or autolyzed yeast supplementation on dairy cow performance and ruminal fermentation. Two experiments were conducted to evaluate performance, feed sorting, total-tract apparent digestibility of nutrients, purine derivatives excretion, N utilization, ruminal fermentation, and the abundance of specific bacterial groups in the rumen. In experiment 1, 39 Holstein cows (171 ± 40 DIM and 32.6 ± 5.4 kg/d milk yield) were blocked according to parity, DIM, and milk yield and randomly assigned to the following treatments: control (CON); autolyzed yeast fed at 0.625 g/kg DM (AY; Levabon, DSM-Firmenich); or live yeast fed at 0.125 g/kg DM (LY; Vistacell, AB Vista). Cows were submitted to a 2-wk adaptation period followed by a 9-wk trial. In experiment 2, 8 ruminal cannulated Holstein cows (28.4 ± 4.0 kg/d milk yield and 216 ± 30 DIM), of which 4 were multiparous and 4 were primiparous, were blocked according to parity and enrolled into a 4 × 4 Latin square experiment with 21-d periods (the last 7 d for sampling). Cows within blocks were randomly assigned to treatment sequences: control (CON), LY (using the same product and dietary concentration as described in experiment 1), AY, or autolyzed yeast fed at 0.834 g/kg DM (AY2). In experiments 1 and 2, nutrient intake and total-tract apparent digestibility were not affected by treatments. Sorting for long feed particles (>19 mm) tended to be greater in cows fed yeast supplements than CON in experiment 1. Efficiency of N conversion into milk N was increased when feeding yeast supplements in experiment 1, and 3.5% FCM yield tended to be greater in cows fed yeast supplements than CON. Feed efficiency was increased when yeast supplements were fed to cows in relation to CON in experiment 1. In experiment 2, yield of FCM and fat were greater in cows fed yeast supplements compared with CON. Uric acid concentration and output in urine were increased when feeding yeast supplements when compared with CON. Neither ruminal pH nor total VFA were influenced by treatments. The current study did not reveal treatment differences in ruminal abundance of Anaerovibrio lipolytica, the genus Butyrivibrio, Fibrobacter succinogenes, Butyrivibrio proteoclasticus, or Streptococcus bovis. Yeast supplementation can increase feed efficiency without affecting nutrient intake and digestibility, ruminal VFA concentration, or ruminal abundance of specific bacterial groups. Supplementing live or autolyzed yeast, regardless of the dose, resulted in similar performance.

Potential Role of Lauric Acid in Milk Fat Synthesis in Chinese Holstein Cows Based on Integrated Analysis of Ruminal Microbiome and Metabolome

The composition and metabolic profile of the ruminal microbiome have an impact on milk composition. To unravel the ruminal microbiome and metabolome affecting milk fat synthesis in dairy cows, 16S rRNA and internal transcribed spacer (ITS) gene sequencing, as well as ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS/MS) methods were used to investigate the significant differences in ruminal bacterial and fungal communities as well as metabolome among Chinese Holstein cows with contrasting milk fat contents under the same diet (H-MF 5.82 ± 0.41% vs. L-MF 3.60 ± 0.12%). Another objective was to culture bovine mammary epithelial cells (BMECs) to assess the effect of metabolites on lipid metabolism. Results showed that the acetate-to-propionate ratio and xylanase activity in ruminal fluid were both higher in H-MF. Microbiome sequencing identified 10 types of bacteria and four types of fungi differently abundant at the genus level. Metabolomics analysis indicated 11 different ruminal metabolites between the two groups, the majority of which were lipids and organic acids. Among these, lauric acid (LA) was enriched in fatty acid biosynthesis with its concentration in milk fat of H-MF cows being greater (217 vs. 156 mg per 100 g milk), thus, it was selected for an in vitro study with BMECs. Exogenous LA led to a marked increase in intracellular triglyceride (TG) content and lipid droplet formation, and it upregulated the mRNA abundance of fatty acid uptake and activation (CD36 and ACSL1), TG synthesis (DGAT1, DGAT2 and GPAM), and transcriptional regulation (SREBP1) genes. Taken together, the greater relative abundance of xylan-fermenting bacteria and fungi, and lower abundance of bacteria suppressing short-chain fatty acid-producing bacteria or participating in fatty acid hydrogenation altered lipids and organic acids in the rumen of dairy cows. In BMECs, LA altered the expression of genes involved in lipid metabolism in mammary cells, ultimately promoting milk fat synthesis. Thus, it appears that this fatty acid plays a key role in milk fat synthesis.

Effects of Supplementing Tributyrin on Meat Quality Characteristics of Foreshank Muscle of Weaned Small-Tailed Han Sheep Lambs

This experiment aimed to evaluate the effects of supplementing tributyrin (TB) on the meat quality characteristics of foreshank muscle of weaned lambs. A total of 30 healthy weaned Small-Tailed Han female lambs with body weights ranging from 23.4 to 31.6 kg were selected and randomly divided into five groups, and each group consisted of 6 lambs. The control group was fed a basic total mixed ration, while other groups were fed the same ration supplemented with 0.5, 1.0, 2.0, and 4.0 g/kg TB, respectively. The experiment lasted 75 d, including 15 d of adaptation. Foreshank muscle obtained at the same position from each lamb was used for chemical analysis and sensory evaluation. The results showed that supplementing TB increased the muscle contents of ether extract (p = 0.029), calcium (p = 0.030), phosphorus (p = 0.007), and intermuscular fat length (p = 0.022). Besides, TB increased the muscle pH (p = 0.001) and redness (p < 0.001) but reduced the lightness (p < 0.001), drip loss (p = 0.029), cooking loss (p < 0.001), shear force (p = 0.001), hardness (p < 0.001), cohesiveness (p < 0.001), springiness (p < 0.001), gumminess (p < 0.001), and chewiness (p < 0.001). In addition, TB increased the muscle content of inosine-5'-phosphate (p = 0.004). Most importantly, TB increased the muscle contents of essential amino acids (p < 0.001). Furthermore, TB increased the saturated fatty acids level in the muscle (p < 0.001) while decreasing the unsaturated fatty acids content (p < 0.001). In conclusion, supplementing TB could influence the meat quality of foreshank muscle of weaned lambs by modifying the amino acid and fatty acid levels.

Investigating the effect of supplementing different levels of Isochrysis galbana on in vitro rumen fermentation parameters

This study aimed to investigate the effect of supplementing Isochrysis galbana (I. galbana) at levels of 0 (control), 1, 2, 3, 4, and 5 (g/100 g DM) of the diet on the gas production kinetics, methane production, rumen fermentation parameters, and relative microbial population in vitro. Supplementation of I. galbana at high level (5 g/100 g DM) caused a significant decrease in total gas production (p < 0.05). High supplementation rates (4 and 5 g/100 g DM) decreased CH4 production relative to the control by 18.4% and 23.2%, respectively. Although rumen ammonia nitrogen (N-NH3) and total volatile fatty acids (VFA) concentrations were affected by dietary treatments, but the VFA profile did not changed. The relative proportion of protozoa and methanogenic archaea as well as Anaerovibrio lipolytica, Prevotella spp., Ruminococcus flavefaciens, and Fibrobacter succinogenes were decreased significantly as a result of microalgae supplementation. However, the relative abundance of Ruminococcus albus, Butyrivibrio fibrisolvens and Selenomonas ruminantium were significantly increased (p < 0.05), related to the control group. As well, the pH was not affected by dietary treatments. It was concluded that I. galbana reduced in vitro CH4 production and methanogenic archaea that its worth to be investigated further in in vivo studies.

Effects of different feeding patterns on the rumen bacterial community of tan lambs, based on high-throughput sequencing of 16S rRNA amplicons

Introduction

The mutton quality of Chinese Tan lambs (Ovis aries) has declined as feeding patterns have shifted from pasturing to pen rationing. While pen-fed can enhance the growth performance of sheep, it falls short in terms of meat quality attributes such as meat color and tenderness. Furthermore, compared to pen-fed, pasture-fed husbandry increases the proportion of oxidative muscle fibers, decreases the proportion of glycolytic muscle fibers, and reduces LDH (lactate dehydrogenase) activity. Mutton quality is affected by fatty acids, and rumen microorganisms play a role in the synthesis of short-chain fatty acids, long-chain fatty acids, and conjugated linoleic acids.

Methods

We used 16S rRNA sequencing to analyze the effects of two feeding patterns on the rumen bacteria of Tan lambs. In a randomized block design with 24 newborn Tan lambs, 12 lambs were fed by ewes in pasture and 12 were fed by pen-fed ewes. At 2 months, the biceps femoris and the longissimus dorsi were analyzed by gas chromatography for intramuscular fat content and fatty acids composition, and DNA in the rumen contents was extracted and used to analyze the structure of the bacterial community.

Results

Different feeding patterns had no significant effect on the intramuscular fat content of the biceps femoris and longissimus dorsi of the lambs, but there was a significant effect on fatty acids composition. The fatty acids c18:3n3 and c20:5n3 were significantly higher in the biceps femoris and longissimus dorsi of the pasture group than the pen-ration group. The alpha diversity of rumen bacteria was significantly greater in the pasture group compared to the pen-ration group. The ACE index, Chao1 index, Shannon index, and Simpson index were all notably higher in the pasture group than in the pen-ration group. Utilizing beta diversity analysis to examine the differences in rumen bacteria between the pasture group and pen-ration group, it was observed that the homogeneity of bacteria in the pasture group was lower than that in the pen-ration group. Furthermore, the diversity of rumen bacteria in the pasture group was greater than that in the pen-ration group. Twenty-one phyla were identified in the pasture group, and 14 phyla were identified in the pen-ration group. The dominant phyla in the pasture group were Bacteroidetes and Fibrobacteres; the dominant phyla in the pen-ration group were Proteobacteria and Bacteroidetes. The relative abundance of Proteobacteria was significantly higher in the pen-ration group than in the pasture group (p < 0.01). Diversity at the genus level was also higher in the pasture group, with 176 genera in the pasture group and 113 genera in the pen-ration group. The dominant genera in the pasture group were Prevotella_1, Rikenellaceae_RC9_gut_group, and Bacteroidales_BS11_gut_group_Na; the dominant genera in the pen-ration group were Prevotella_1, Prevotella_7, Succinivibrionaceae_UCG-001, and Succinivibrionaceae_NA.

Discussion

The rumen bacterial community of Tan sheep is significantly influenced by pen-ration and pasture-fed conditions, leading to variations in fatty acid content in the muscle, which in turn affects the flavor and nutritional value of the meat to some extent. Pasture-fed conditions have been shown to enhance the diversity of rumen bacterial community structure in Tan sheep, thereby increasing the nutritional value of their meat.

Effects of Phlorotannins from Sargassum on In Vitro Rumen Fermentation, Microbiota and Fatty Acid Profile

The fatty acid profiles of ruminant-derived products are closely associated with human health. Ruminal microbiota play a vital role in modulating rumen biohydrogenation (BH). The aim of this study was to assess the influence of dietary supplementation with phlorotannins (PTs) extracted from Sargassum on rumen fermentation, fatty acid composition and bacterial communities by an in vitro culture study. The inclusion of PTs in the diet increased dry matter digestibility and gas production, and reduced ammonia-N concentration and pH. PT extract inhibited rumen BH, increasing the content of trans-9 C18:1, cis-9 C18:1, trans-9 and trans-12 C18:2 and reducing C18:0 concentration. 16S rRNA sequencing revealed that PTs caused an obvious change in rumen bacterial communities. The presence of Prevotella decreased while carbohydrate-utilizing bacteria such as Prevotellaceae_UCG-001, Ruminococcus, Selenomonas, Ruminobacter and Fibrobacter increased. Correlation analysis between rumen FA composition and the bacterial microbiome revealed that Prevotellaceae_UCG-001, Anaerovorax, Ruminococcus, Ruminobacter, Fibrobacter, Lachnospiraceae_AC2044_group and Clostridia_UCG-014 might have been involved in the BH process. In conclusion, the results suggest that the inclusion of PTs in the diet improved rumen fermentation and FA composition through modulating the rumen bacterial community.

Microbiota-host crosstalk in the newborn and adult rumen at single-cell resolution

BACKGROUND

The rumen is the hallmark organ of ruminants, playing a vital role in their nutrition and providing products for humans. In newborn suckling ruminants milk bypasses the rumen, while in adults this first chamber of the forestomach has developed to become the principal site of microbial fermentation of plant fibers. With the advent of single-cell transcriptomics, it is now possible to study the underlying cell composition of rumen tissues and investigate how this relates the development of mutualistic symbiosis between the rumen and its epithelium-attached microbes.

RESULTS

We constructed a comprehensive cell landscape of the rumen epithelium, based on single-cell RNA sequencing of 49,689 high-quality single cells from newborn and adult rumen tissues. Our single-cell analysis identified six immune cell subtypes and seventeen non-immune cell subtypes of the rumen. On performing cross-species analysis of orthologous genes expressed in epithelial cells of cattle rumen and the human stomach and skin, we observed that the species difference overrides any cross-species cell-type similarity. Comparing adult with newborn cattle samples, we found fewer epithelial cell subtypes and more abundant immune cells, dominated by T helper type 17 cells in the rumen tissue of adult cattle. In newborns, there were more fibroblasts and myofibroblasts, an IGFBP3+ epithelial cell subtype not seen in adults, while dendritic cells were the most prevalent immune cell subtype. Metabolism-related functions and the oxidation-reduction process were significantly upregulated in adult rumen epithelial cells. Using 16S rDNA sequencing, fluorescence in situ hybridization, and absolute quantitative real-time PCR, we found that epithelial Desulfovibrio was significantly enriched in the adult cattle. Integrating the microbiome and metabolome analysis of rumen tissues revealed a high co-occurrence probability of Desulfovibrio with pyridoxal in the adult cattle compared with newborn ones while the scRNA-seq data indicated a stronger ability of pyroxidal binding in the adult rumen epithelial cell subtypes. These findings indicate that Desulfovibrio and pyridoxal likely play important roles in maintaining redox balance in the adult rumen.

CONCLUSIONS

Our integrated multi-omics analysis provides novel insights into rumen development and function and may facilitate the future precision improvement of rumen function and milk/meat production in cattle.

Effects of captive and primate-focused tourism on the gut microbiome of Tibetan macaques

Documenting the effects of anthropogenic activities on the gut microbiome of wild animals is important to their conservation practices. Captivity and ecotourism are generally considered two common anthropogenic disturbances on the health of nonhuman primates. Here, we examined the divergences of gut microbiome in different environments of Tibetan macaques. Our results showed that there were no significant differences in the alpha diversity, predominant families and genera of gut microbiomes between wild and tourist groups. However, these indexes decreased significantly in the captive individuals. In addition, the significant differences of beta diversity and community compositions between wild and tourism groups also were detected. In particular, higher potential pathogenic and predicted KEGG pathway of drug resistance (antimicrobial) were detected in the gut microbiome of individuals in captive environment. Our results indicated that living in the wild are beneficial to maintaining gut microbial diversity of Tibetan macaques, while captivity environment is harmful to the health of this macaque. Exploring ways to restore the native gut microbiome and its diversity of captive individual should pay more attention to in the future studies.

Metagenomic Characterization and Volatile Compounds Determination in Rumen from Saanen Goat Kids Fed Olive Leaves

The accumulation and disposal of by-products deriving from the agro-food industry represents a problem both from an economic and environmental point of view. The use of these matrices in zootechnical nutrition could represent a feasible solution. The aim of the study was to examine the effect of a diet containing olive leaves (OL), a by-product of the olive industry, on the ruminal microbial community of Saanen goat kids and on volatile organic compounds (VOCs) produced during the digestion. Twenty goat kids were randomly divided into two groups of ten goat kids each. The control group (CTR) was fed with a standard diet, while the experimental group (OL+) received a custom-formulated diet containing 10 % OL on a dry matter (DM) basis. After 30 days of trial, genomic DNA was extracted from the rumen liquor and prepared for 16S rRNA-gene sequencing to characterize the rumen microbiota; furthermore, rumen VOCs were also characterized by solid-phase microextraction coupled with gas chromatography-mass spectrometry. The Shannon’s alpha index was not significantly different between the two groups, on the contrary, Bray-Curtis (p < 0.01) and Jaccard (p < 0.01) distances evidenced that feed affected microbial community. Eleven genera were influenced by OL supplementation, with a significant increase (p < 0.05) in Paludibacter, Fibrobacter, Sphaerochaeta Christensenella, Rikenella, Oligosphaera, Candidatus Endomicrobium, Anaerovorax, and Atopobium was observed, while the percentages of Bacteroides and Selenomonas were reduced (p < 0.05). Differences were also observed between the two groups at the family level (p < 0.004). Fibrobacteriaceae, Christensenellaceae, Coriobacteriaceae, Oligosphaeraceae, Candidatus Endomicrobium, and Planctomycetaceae were significantly higher (p < 0.05) in goat kids fed OL diet compared to CTR, while the levels of other identified families, Succinivibrionaceae and Bifidobacteriaceae, were opposite (p < 0.05). Finally, results showed that the main phyla in both groups were Bacteroidetes and Firmicutes; however, no significant differences in the relative abundance of any phyla were observed between the two groups. In addition to what has been reported, the analysis of VOCs at the rumen level showed the ability of the OL integration to induce an increase in hexanoic acid and a parallel decrease in decanal. Furthermore, only in OL+ samples there was the accumulation of α-terpineol to which a wide range of interesting biological properties is attributed. The presence of VOCs associated with health status suggests a favorable role of OL in preserving and improving animal welfare.

Altering Methane Emission, Fatty Acid Composition, and Microbial Profile during In Vitro Ruminant Fermentation by Manipulating Dietary Fatty Acid Ratios

This study evaluated the effects of different dietary n-6/n-3 polyunsaturated fatty acid (PUFA) ratios on in vitro ruminant fermentation. Methane production, fatty acid composition, and microbial profiles were compared after the in vitro fermentation of rumen fluid collected from cows that had been fed isoenergetic and isoproteic experimental diets at three different n-6/n-3 ratios: 3.04 (HN6, high n-6 source), 2.03 (MN6, medium n-6 source), and 0.8 (LN6, low n-6 source). The fermented rumen fluid pH and total volatile fatty acid (VFA) levels were significantly decreased (p < 0.05) in the HN6 group as compared with those in the MN6 and LN6 groups. Additionally, the HN6 group produced a significantly lower (p < 0.05) proportion of methane than the MN6 group during in vitro fermentation. The MN6 and LN6 groups had significantly increased (p < 0.05) levels of C18:2n6 and C18:3n3 in the fermented rumen fluid, respectively, as compared with the HN6 group. The Chao 1 diversity index value was lower (p < 0.05) in the HN6 group than in the MN6 and LN6 groups. The observed species richness was significantly lower (p < 0.05) in the HN6 group than in the MN6 group. The reduced relative abundances of Lachnospiraceae UCG-006 and Selenomonas in the HN6 group resulted in lower pH and VFA levels (i.e., acetate, propionate, butyrate, and total VFA) during in vitro fermentation. Furthermore, n-6 and n-3 PUFAs were toxic to Butyrivibrio_2 growth, resulting in high levels of incomplete biohydrogenation. Taken together, the study findings suggest that supplementation of high-forage diets with high levels of n-6 PUFAs could reduce methane emissions, whereas both VFA concentration and pH are reduced.

Exploring the relationship between bacterial genera and lipid metabolism in bovine rumen

The rumen is characterised by a complex microbial ecosystem, which is particularly active in lipid metabolism. Several studies demonstrated a role of diet and breed on bacterial community profile, with the effect on metabolic pathways. Despite the knowledge achieved on metabolism and the bacterial profile, little is known about the relationship between individual bacteria and metabolic pathways. Therefore, a multivariate approach was used to search for possible relationships between bacteria and products of several pathways. The correlation between rumen bacterial community composition and rumen lipid metabolism was assessed in 40 beef steers (20 Maremmana and 20 Aubrac) reared with the same system and fed the same diet. A canonical discriminant analysis combined with a canonical correlation analysis (CCA) was performed to explore this correlation. The variables showing a Pearson correlation higher than 0.6 as absolute value and significant were retained for CCA considering the relationship of bacterial composition with several metabolic pathways. The results indicated that some bacterial genera could have significant impacts on the presence of several fatty acids. However, the relationship between genera and fatty acid changes according to the breed, demonstrating that the metabolic pathways change according to the host genetic background, related to breed evolution, although there is also an intra-breed genetic background which should not be ignored. In Maremmana, Succiniclasticum and Rikenellaceae_RC9_gut_group showed a high positive correlation with dimethylacetals (DMAs) DMA_C13:0, DMA_C14:0, DMA_C14:0iso, DMA_C15:0, DMA_C15:0iso, and DMA_C18:0. Prevotellaceae_UCG-003 correlates with C18:3c9c12c15 and C18:1t11, while Fibrobacter and Succiniclasticum correlate with C18:2c9t11 and Lachnospiraceae_NK3A20_group correlates with C18:1c12. Prevotellaceae_UCG-003, Ruminococcaceae_UCG-010, and Oribacterium showed a positive correlation with C13:0iso, and C17:0. Conversely, in Aubrac, Treponema_2 and Rikenellaceae_RC9_gut_group correlated with DMA_C14:0iso, DMA_C16:0iso, DMA_C17:0iso, while Ruminococcaceae_UCG-010, Christensenellaceae_R-7_group and Ruminococcaceae_NK4A214_group correlated with DMA_C18:1t11, DMA_C14:0, DMA_C18:1c12. Acetitomaculum correlated with C18:2c9c12, C18:1c12, C18:1c13, C18:1t12 and Lachnospiraceae_NK3A20_group with C18:1t6-8 and C18:1t9. Saccharofermentas, Ruminococcaceae_UCG-010 and Rikenellaceae_RC9_gut_group correlated with C18:2c9t11 while, Prevotellaceae_UCG-001 and Ruminococcus_1 correlated with C14:0iso, C15:0, C15:0iso, C17:0. Saccharofermentans, Rikenellaceae_RC9_gut_group, Ruminococcaceae_NK4A214_group, and Ruminococcaceae_UCG-010 correlated with C13:1c12 and C16:0iso. These results lead to hypothesise a possible association between several metabolic pathways and one or a few bacterial genera. If these associations are confirmed by further investigations that verify the causality of a bacterial genus with a particular metabolic process, it will be possible to deepen the knowledge on the activity of the rumen population in lipid metabolism. This approach appears to be a promising tool for uncovering the correlation between bacterial genera and products of rumen lipid metabolism.

DHA-Rich Aurantiochytrium Biomass, a Novel Dietary Supplement, Resists Degradation by Rumen Microbiota without Disrupting Microbial Activity

We first sought to evaluate the effect of dietary supplementation with the docosahexaenoic acid (DHA)-rich microalgae, Aurantiochytrium limacinum (AURA), on rumen fermentation and the resistance of DHA to degradation and biohydrogenation by rumen microbes through ex vivo fermentation experiments. Subsequently, we sought to quantify the diet-derived DHA content of milk and the impact of AURA on microbial composition and metabolism in a pilot feeding trial with rumen-cannulated dairy cows. To achieve our aims, rumen fluid from cannulated cows was used as inoculum, and the effect of AURA inclusion on fermentation ex vivo was examined. At doses corresponding to the amount of AURA recommended for commercial production animals, only ~10% of DHA was degraded or biohydrogenated by rumen microorganisms. The results show that feeding with AURA had no effect on either total bacterial density or short-chain fatty acid production. Real-time quantitative PCR analysis of the rumen fluid samples collected during a seven-week in vivo trial revealed that microbes related to lactic acid metabolism and methanogenesis were significantly suppressed by the AURA-supplemented diet. The DHA concentration in milk increased over 25-fold with the AURA-supplemented diet and dropped by 30–40% within one week of washout. The addition of A. limacinum biomass to dairy cow diets resulted in positive effects on rumen microbial composition with no adverse effect on fermentation activity. AURA-derived DHA was stable, with only modest degradation in the rumen, and was successfully deposited in milk. This is the first study to investigate the effect of supplementing the diet of dairy cows with a protist-based biomass, namely, on important rumen fermentation parameters and on DHA deposition in milk, using a combination of ex vivo and in vivo approaches.

Freeze-dried Nannochloropsis oceanica biomass protects eicosapentaenoic acid (EPA) from metabolization in the rumen of lambs

Eicosapentaenoic acid (EPA) from freeze-dried biomass of Nannochloropsis oceanica microalgae resists ruminal biohydrogenation in vitro, but in vivo demonstration is needed. Therefore, the present study was designed to test the rumen protective effects of N. oceanica in lambs. Twenty-eight lambs were assigned to one of four diets: Control (C); and C diets supplemented with: 1.2% Nannochloropsis sp. oil (O); 12.3% spray-dried N. oceanica (SD); or 9.2% N. oceanica (FD), to achieve 3 g EPA /kg dry matter. Lambs were slaughtered after 3 weeks and digestive contents and ruminal wall samples were collected. EPA concentration in the rumen of lambs fed FD was about 50% higher than lambs fed SD or O diets. Nevertheless, the high levels of EPA in cecum and faeces of animals fed N. oceanica biomass, independently of the drying method, suggests that EPA was not completely released and absorbed in the small intestine. Furthermore, supplementation with EPA sources also affected the ruminal biohydrogenation of C18 fatty acids, mitigating the shift from the t10 biohydrogenation pathways to the t11 pathways compared to the Control diet. Overall, our results demonstrate that FD N. oceanica biomass is a natural rumen-protected source of EPA to ruminants.

Analysis of bacterial community in rumen fluid of cattle supplemented with different protein and energy sources

Context Source and composition of feed influence rumen microbial community, which determines efficiency of feed digestion and thus productivity in ruminants. Therefore, changes in the structure, function and diversity of the rumen microbial populations in response to changes in diet provide an understanding in the rumen fermentation process. Aims The present study, consisting of two experiments, was conducted to determine the effects of supplementing different protein and energy sources on the rumen bacterial community in cattle. Methods The dietary treatments of the first experiment, which evaluated the effect of protein sources, were as follows: (i) Hymenachne acutigluma grass, rice straw and rice bran (1.5 kg/head.day; C1), (ii) C1 plus 120 g urea/head.day (C1 + U), (iii) C1 plus 720 g soybean/head.day (C1 + SM), and (iv) C1 plus 720 g of blood and feather meal (in 1:1 ratio)/head.day (C1 + BFM). The treatments in the second experiment were (i) Hymenachne acutigluma grass, rice straw and concentrate (1.5 kg/head.day; C2), (ii) C2 plus 250 g fish oil/head.day (C2 + FO) and (iii) C2 + 250 g soybean oil/head.day (C2 + SO). At the end of the 90-day feeding trial, rumen fluids were extracted for microbial DNA isolation to identify the microbe species by the polymerase chain reaction–denaturing gradient gel electrophoresis method and sequencing of the 16S rRNA region. Key results The sequences of some DNA bands were closely related to the bacteria strains of the Prevotella, Cytophaga, Capnocytophaga, Cyanobacterium, Catonella, Faecalibacterium, Lachnospiraceae, Ruminococcaceae, Propionivibrio, Galbibacter, Moorellaglycerin, Escherichia coli and Klebsiella alba groups, with similarity levels ranging from 73% to 96%. In addition, the Prevotella species was found in both the protein and the energy supplement trials, and irrespective of diet supplements, the Firmicutes and Bacteroidetes were the prominent groups in the rumen. Conclusions Firmicutes and Bacteroidetes are the two dominant groups of rumen microflora, and Bacteroidia and Clostridia classes together with the Prevotella genus are predominant in the rumen irrespective of protein and energy sources. Implications Our findings provided evidence on the effect of diet on the interaction of rumen microbial community and have important implications in establishing optimal diets for cattle.

Rumen bacteria and meat fatty acid composition of Sunit sheep reared under different feeding regimens in China

BACKGROUND

Rumen bacteria play a critical role in feed degradation and productivity. This study evaluated the impact of feeding regimen on the rumen microbial populations and fatty acid composition of the meat of sheep. Twenty-four Sunit sheep were raised on a grass pasture from birth to 9 months of age, at which time they were randomly divided into two feeding groups: pasture feeding (PF) and barn feeding (BF). Sheep in the PF group were allowed to graze freely on wild grassland for 3 months. Sheep in the BF group were confined for 3 months to a dry barn, in which they roamed freely with corn straw and corn.

RESULTS

Sheep in the PF group had greater rumen bacteria diversity. The relative abundances of the genera Butyrivibrio_2, Saccharofermentans and Succiniclasticum were increased, and that of the genus RC9_gut_group was decreased, in the PF compared to the BF sheep. The n-3 polyunsaturated fatty acid contents were greater in meat from PF sheep than from BF sheep. In addition, the α-linolenic acid (C18:3 n-3, ALA) and conjugated linoleic acid (CLA) contents were positively correlated with the abundance of Butyrivibrio_2.

CONCLUSION

Grazing may improve the diversity of rumen bacteria and increase the proportion of ALA and CLA in sheep meat. © 2020 Society of Chemical Industry.

Untargeted and Targeted Metabolomics Profiling of Muscle Reveals Enhanced Meat Quality in Artificial Pasture Grazing Tan Lambs via Rescheduling the Rumen Bacterial Community

Tan is a local fat-tail sheep that is famous for its great eating quality but with little attention to its meat metabolome. The aim of this study was to investigate Tan-lamb meat metabolome as well as the key rumen bacteria related to the beneficial compound deposition in the muscle using untargeted and targeted metabolomics under different feeding regimes: indoor feeding (F), artificial pasture grazing with indoor feeding (GF), and pure artificial pasture grazing (G). The untargeted metabolome was detected by ultraperformance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry. Ruminal bacterial communities were detected by 16S rRNA sequencing. Using untargeted metabolomics, the main three altered metabolic pathways in the lamb, including amino acid, lipid, and nucleotide metabolisms, were found in the G group compared to the GF and F groups. Increased N-acetyl-l-aspartic acid, N-acetylaspartylglutamate, acetylcarnitine, and l-carnitine, but decreased carnosine and creatinine, were the main newly found G group-associated metabolites, which might contribute to the improved lamb meat functional quality. Compared to the F group, the G group feeding increased the contents of sweet amino acids (e.g., glycine, alanine, serine, and threonine) and umami amino acids (e.g., glutamic acid and aspartic acid) in the muscle, and G and GF groups increased the level of meat polyunsaturated fatty acid (PUFA), especially the concentration of n3 PUFA, and reduced n6/n3 in the muscle by targeted metabolomics. The abundance of ruminal Moryella was decreased, and Schwartzia and Anaeroplasma were increased in the G group, which were both strongly correlated with the n3 PUFA and other functional compounds in the muscle of lambs. In conclusion, artificial pasture grazing modified the meat amino acid and fatty acid composition as well as the related biological pathways through rescheduling the rumen bacterial community, which would be a better selection for production of healthier lamb meat products.

Effects of the substitution of soybean meal by spirulina in a hay-based diet for dairy cows on milk composition and sensory perception

The demand for protein sources alternative to soybean meal for supplementing forages low in metabolizable protein is large. The suitability of spirulina (Arthrospira platensis), a fast growing and resource-efficient blue-green microalga, as a source of metabolizable protein for dairy cows is known, but its effects on milk antioxidants and sensory properties were never investigated. Twelve cows were allocated to 2 groups and fed hay-based diets complemented with sugar beet pulp and wheat flakes in individual feeding troughs. The N content per kilogram of DM was equivalent between the 2 diets. Diet of 1 group was supplemented with 5% spirulina; the second group was supplemented with 6% soybean meal (control). After an adaptation period of 15 d, data were collected, and feed, milk, blood, and rumen fluid were sampled. Feeds were analyzed for proximate contents, and blood plasma was analyzed for total antioxidant capacity and antioxidant contents (tocopherol, phenols). Milk samples were analyzed for fatty acid profile, coagulation properties, color, and contents of fat, protein, lactose, total phenols, lipophilic vitamins, and provitamins (e.g., β-carotene). Triangle tests were performed by a trained sensory panel on 6 homogenized and pasteurized bulk milk samples per treatment. The substitution of soybean meal by spirulina in the diet did not affect feed intake, milk yield, milk fat, protein, or lactose contents compared with the control group. However, the milk from the spirulina-fed cows had a higher content of β-carotene (0.207 vs. 0.135 μg/mL) and was more yellow (b* index: 14.9 vs. 13.8). Similar to the spirulina lipids but far less pronounced, the milk fat from the spirulina-fed cows had a higher proportion of γ-linolenic acid (0.057 vs. 0.038% of fatty acid methyl esters) compared with milk fat from soybean meal-fed cows. Also trans-11 C18:1 (vaccenic acid) and other C18:1 trans isomers were elevated, but otherwise the fatty acid profile resembled that of cows fed the control diet. No sensory difference was found between milk from the 2 experimental groups. Furthermore, we observed no effects of substituting soybean meal by spirulina on total antioxidant capacity, α-tocopherol and total phenols in blood and milk. Effects on rumen fluid characteristics were minor. In conclusion, spirulina seems to be a promising protein source for dairy cows with certain improvements in nutritionally favorable constituents in milk and without side-effects on animal performance in the short term.

High rumen degradable starch decreased goat milk fat via trans-10, cis-12 conjugated linoleic acid-mediated downregulation of lipogenesis genes, particularly, INSIG1

Background

Starch is an important substance that supplies energy to ruminants. To provide sufficient energy for high-yielding dairy ruminants, they are typically fed starch-enriched diets. However, starch-enriched diets have been proven to increase the risk of milk fat depression (MFD) in dairy cows. The starch present in ruminant diets could be divided into rumen-degradable starch (RDS) and rumen escaped starch (RES) according to their different degradation sites (rumen or intestine). Goats and cows have different sensitivities to MFD. Data regarding the potential roles of RDS in milk fat synthesis in the mammary tissue of dairy goats and in regulating the occurrence of MFD are limited.

Results

Eighteen Guanzhong dairy goats (day in milk = 185 ± 12 d) with similar parity, weight, and milk yield were selected and randomly assigned to one of three groups (n = 6), which were fed an LRDS diet (Low RDS = 20.52%), MRDS diet (Medium RDS = 22.15%), or HRDS diet (High RDS = 24.88%) for 5 weeks. Compared with that of the LRDS group, the milk fat contents in the MRDS and HRDS groups significantly decreased. The yields of short-, medium- and long-chain fatty acids decreased in the HRDS group. Furthermore, increased RDS significantly decreased ruminal B. fibrisolvens and Pseudobutyrivibrio abundances and increased the trans-10, cis-12 conjugated linoleic acid (CLA) and trans-10 C18:1 contents in the rumen fluid.

A multiomics study revealed that the HRDS diet affected mammary lipid metabolism down-regulation of ACSS2, MVD, AGPS, SCD5, FADS2, CERCAM, SC5D, HSD17B7, HSD17B12, ATM, TP53RK, GDF1 and LOC102177400. Remarkably, the significant decrease of INSIG1, whose expression was depressed by trans-10, cis-12 CLA, could reduce the activity of SREBP and, consequently, downregulate the downstream gene expression of SREBF1.

Conclusions

HRDS-induced goat MFD resulted from the downregulation of genes involved in lipogenesis, particularly, INSIG1. Specifically, even though the total starch content and the concentrate-to-fiber ratio were the same as those of the high-RDS diet, the low and medium RDS diets did not cause MFD in lactating goats.

Corn oil supplementation enhances hydrogen use for biohydrogenation, inhibits methanogenesis, and alters fermentation pathways and the microbial community in the rumen of goats

Enteric methane (CH4) emissions are not only an important source of greenhouse gases but also a loss of dietary energy in livestock. Corn oil (CO) is rich in unsaturated fatty acid with >50% PUFA, which may enhance ruminal biohydrogenation of unsaturated fatty acids, leading to changes in ruminal H2 metabolism and methanogenesis. The objective of this study was to investigate the effect of CO supplementation of a diet on CH4 emissions, nutrient digestibility, ruminal dissolved gases, fermentation, and microbiota in goats. Six female goats were used in a crossover design with two dietary treatments, which included control and CO supplementation (30 g/kg DM basis). CO supplementation did not alter total-tract organic matter digestibility or populations of predominant ruminal fibrolytic microorganisms (protozoa, fungi, Ruminococcus albus, Ruminococcus flavefaciens, and Fibrobacter succinogenes), but reduced enteric CH4 emissions (g/kg DMI, -15.1%, P = 0.003). CO supplementation decreased ruminal dissolved hydrogen (dH2, P < 0.001) and dissolved CH4 (P < 0.001) concentrations, proportions of total unsaturated fatty acids (P < 0.001) and propionate (P = 0.015), and increased proportions of total SFAs (P < 0.001) and acetate (P < 0.001), and acetate to propionate ratio (P = 0.038) in rumen fluid. CO supplementation decreased relative abundance of family Bacteroidales_BS11_gut_group (P = 0.032), increased relative abundance of family Rikenellaceae (P = 0.021) and Lachnospiraceae (P = 0.025), and tended to increase relative abundance of genus Butyrivibrio_2 (P = 0.06). Relative abundance (P = 0.09) and 16S rRNA gene copies (P = 0.043) of order Methanomicrobiales, and relative abundance of genus Methanomicrobium (P = 0.09) also decreased with CO supplementation, but relative abundance (P = 0.012) and 16S rRNA gene copies (P = 0.08) of genus Methanobrevibacter increased. In summary, CO supplementation increased rumen biohydrogenatation by facilitating growth of biohydrogenating bacteria of family Lachnospiraceae and genus Butyrivibrio_2 and may have enhanced reductive acetogenesis by facilitating growth of family Lachnospiraceae. In conclusion, dietary supplementation of CO led to a shift of fermentation pathways that enhanced acetate production and decreased rumen dH2 concentration and CH4 emissions.

Dietary composition and yeast/microalgae combination supplementation modulate the microbial ecosystem in the caecum, colon and faeces of horses

Starchy diets can induce hindgut dysbiosis in horses. The present study evaluated the impact of a yeast (Saccharomyces cerevisiae) and microalgae (Aurantiochytrium limacinum) supplementation on caecal, colonic and faecal microbial ecosystem and on blood inflammatory parameters of horses fed high-fibre or high-starch diets. Six fistulated geldings in a 2 × 2 Latin-square design were alternatively supplemented and received during each period 100 % hay (4 weeks) followed by a 56/44 hay/barley diet (3 weeks). Caecal, colonic and faecal samples were collected 4 h after the morning meal three times per diet, at 5-d intervals, to measure bacterial composition and microbial end products. Blood was simultaneously collected for measuring inflammatory markers. The starchy diet clearly modified the microbial ecosystem in the three digestive segments, with an increase of the amylolytic function and a decrease of the fibrolytic one. However, no effect of the diet was observed on the blood parameters. When horses were supplemented, no significant change was found in lipopolysaccharides, PG-E2, serum amyloid A concentrations and complete blood count neither in cellulose-utilising, starch-utilising and lactate-utilising bacteria concentrations nor in the volatile fatty acids and lactate concentrations and pH. Under supplementation, relative abundance of Family XIII Clostridiales increased in caecum and faeces irrespective of diet and relative abundance of Veillonellaceae was higher during the hay/barley diet in colon and faeces. Most variations of faecal bacterial taxa under supplementation were not observed in the hindgut. However, all variations suggested that supplementation could increase fibrolytic function whatever the diet and limit dysbiosis when the horses' diet changed from high fibre to high starch.

Rumen bacterial community responses to DPA, EPA and DHA in cattle and sheep: A comparative in vitro study

The role of marine lipids as modulators of ruminal biohydrogenation of dietary unsaturated fatty acids may be explained by the effects of their n-3 polyunsaturated fatty acids (PUFA) on the bacterial community. However, the impact of individual PUFA has barely been examined, and it is uncertain which bacteria are truly involved in biohydrogenation. In addition, despite interspecies differences in rumen bacterial composition, we are not aware of any direct comparison of bovine and ovine responses to dietary PUFA. Therefore, rumen fluid from cannulated cattle and sheep were used as inocula to examine in vitro the effect of 20:5n-3 (EPA), 22:5n-3 (DPA), and 22:6n-3 (DHA) on the bacterial community. Amplicon 16 S rRNA sequencing suggested that EPA and DHA had a greater contribution to the action of marine lipids than DPA both in cattle and sheep. Certain effects were exclusive to each ruminant species, which underlines the complexity of rumen microbial responses to dietary fatty acids. Based on changes in bacterial abundance, Barnesiella, Prevotella, Paraprevotella, Hallela, Anaerovorax, Succiniclasticum, Ruminococcus and Ruminobacter may be involved in the ruminal response in biohydrogenation to the addition of marine lipids, but further research is necessary to confirm their actual role in ruminal lipid metabolism.

The parasitic worm product ES-62 normalises the gut microbiota bone marrow axis in inflammatory arthritis

The human immune system has evolved in the context of our colonisation by bacteria, viruses, fungi and parasitic helminths. Reflecting this, the rapid eradication of pathogens appears to have resulted in reduced microbiome diversity and generation of chronically activated immune systems, presaging the recent rise of allergic, autoimmune and metabolic disorders. Certainly, gastrointestinal helminths can protect against gut and lung mucosa inflammatory conditions by modulating the microbiome and suppressing the chronic inflammation associated with dysbiosis. Here, we employ ES-62, an immunomodulator secreted by tissue-dwelling Acanthocheilonema viteae to show that helminth-modulation of the gut microbiome does not require live infection with gastrointestinal-based worms nor is protection restricted to mucosal diseases. Specifically, subcutaneous administration of this defined immunomodulator affords protection against joint disease in collagen-induced arthritis, a mouse model of rheumatoid arthritis, which is associated with normalisation of gut microbiota and prevention of loss of intestinal barrier integrity.

Effects of chitosan and whole raw soybeans on ruminal fermentation and bacterial populations, and milk fatty acid profile in dairy cows

The objective of this study was to evaluate whether providing chitosan (CHI) to cows fed diets supplemented with whole raw soybeans (WRS) would affect the nutrient intake and digestibility, ruminal fermentation and bacterial populations, microbial protein synthesis, N utilization, blood metabolites, and milk yield and composition of dairy cows. Twenty-four multiparous Holstein cows (141 ± 37.1 d in milk, 38.8 ± 6.42 kg/d of milk yield; mean ± SD) were enrolled to a 4 × 4 Latin square design experiment with 23-d periods. Cows were blocked within Latin squares according to milk yield, days in milk, body weight, and rumen cannula (n = 8). A 2 × 2 factorial treatment arrangement was randomly assigned to cows within blocks. Treatments were composed of diets with 2 inclusion rates of WRS (0 or 14% diet dry matter) and 2 doses of CHI (0 or 4 g/kg of dry matter, Polymar Ciência e Nutrição, Fortaleza, Brazil). In general, CHI+WRS negatively affected nutrient intake and digestibility of cows, decreasing milk yield and solids production. The CHI increased ruminal pH and decreased acetate to propionate ratio, and WRS reduced NH3-N concentration and acetate to propionate in the rumen. The CHI reduced the relative bacterial population of Butyrivibrio group, whereas WRS decreased the relative bacterial population of Butyrivibrio group, and Fibrobacter succinogenes, and increased the relative bacterial population of Streptococcus bovis. No interaction effects between CHI and WRS were observed on ruminal fermentation and bacterial populations. The CHI+WRS decreased N intake, microbial N synthesis, and N secreted in milk of cows. The WRS increased N excreted in feces and consequently decreased the N excreted in urine. The CHI had no effects on blood metabolites, but WRS decreased blood concentrations of glucose and increased blood cholesterol concentration. The CHI and WRS improved efficiency of milk yield of cows in terms of fat-corrected milk, energy-corrected milk, and net energy of lactation. The CHI increased milk concentration [g/100 g of fatty acids (FA)] of 18:1 trans-11, 18:2 cis-9,cis-12, 18:3 cis-9,cis-12,cis-15, 18:1 cis-9,trans-11, total monounsaturated FA, and total polyunsaturated FA. The WRS increased total monounsaturated FA, polyunsaturated FA, and 18:0 to unsaturated FA ratio in milk of cows. Evidence indicates that supplementing diets with unsaturated fat sources along with CHI negatively affects nutrient intake and digestibility of cows, resulting in less milk production. Diet supplementation with CHI or WRS can improve feed efficiency and increases unsaturated FA concentration in milk of dairy cows.

Oil supplementation improved growth and diet digestibility in goats and sheep fed fattening diet

OBJECTIVE

This study evaluated the growth, digestibility and rumen fermentation between goats and sheep fed a fattening diet fortified with linseed oil.

METHODS

Twelve 3 to 4 months old male goats and sheep were randomly allocated into two dietary treatment groups in a 2 (species)×2 (oil levels) factorial experiment. The treatments were: i) goats fed basal diet, ii) goats fed oil-supplemented diet, iii) sheep fed basal diet, and iv) sheep fed oil-supplemented diet. Each treatment group consisted of six animals. Animals in the basal diet group were fed with 30% alfalfa hay and 70% concentrates at a rate equivalent to 4% of their body weight. For the oil treatment group, linseed oil was added at 4% level (w:w) to the concentrate portion of the basal diet. Growth performance of the animals was determined fortnightly. Digestibility study was conducted during the final week of the feeding trial before the animals were slaughtered to obtain rumen fluid for rumen fermentation characteristics study.

RESULTS

Sheep had higher (p<0.01) average daily weight gain (ADG) and better feed conversion ratio (FCR) than goats. Oil supplementation did not affect rumen fermentation in both species and improved ADG by about 29% and FCR by about 18% in both goats and sheep. The above enhancement is consistent with the higher dry matter and energy digestibility (p<0.05), as well as organic matter and neutral detergent fiber digestibility (p<0.01) in animals fed oil- supplemented diet. Sheep had higher total volatile fatty acid production and acetic acid proportion compared to goat.

CONCLUSION

The findings of this study suggested that sheep performed better than goats when fed a fattening diet and oil supplementation at the inclusion rate of 4% provides a viable option to significantly enhance growth performance and FCR in fattening sheep and goats.

Effects of naturally-produced lovastatin on feed digestibility, rumen fermentation, microbiota and methane emissions in goats over a 12-week treatment period

Twenty male Saanen goats were randomly assigned to four levels of lovastatin supplementation and used to determine the optimal dosage and sustainability of naturally produced lovastatin from fermentation of palm kernel cake (PKC) with Aspergillus terreus on enteric methane (CH₄) mitigation. The effects on ruminal microbiota, rumen fermentation, feed digestibility and health of animal were determined over three measuring periods (4-, 8- and 12-weeks) and the accumulation of lovastatin in tissues was determined at the end of the experiment. The diets contained 50% rice straw, 22.8% concentrates and 27.2% of various proportions of untreated or treated PKC to achieve the target daily intake level of 0 (Control), 2, 4 or 6 mg lovastatin/kg body weight (BW). Enteric CH₄ emissions per dry matter intake (DMI), decreased significantly (P<0.05) and equivalent to 11% and 20.4%, respectively, for the 2 and 4 mg/kg BW groups as compared to the Control. No further decrease in CH₄ emission thereafter with higher lovastatin supplementation. Lovastatin had no effect on feed digestibility and minor effect on rumen microbiota, and specifically did not reduce the populations of total methanogens and Methanobacteriales (responsible for CH₄ production). Similarly, lovastatin had little effect on rumen fermentation characteristics except that the proportion of propionate increased, which led to a decreasing trend (P<0.08) in acetic: propionate ratio with increasing dosage of lovastatin. This suggests a shift in rumen fermentation pathway to favor propionate production which serves as H⁺ sink, partly explaining the observed CH₄ reduction. No adverse physiological effects were noted in the animals except that treated PKC (containing lovastatin) was less palatable at the highest inclusion level. Lovastatin residues were detected in tissues of goats fed 6 mg lovastatin/kg BW at between 0.01 to 0.03 μg/g, which are very low.

Alteration of Rumen Bacteria and Protozoa Through Grazing Regime as a Tool to Enhance the Bioactive Fatty Acid Content of Bovine Milk

Rumen microorganisms are the origin of many bioactive fatty acids (FA) found in ruminant-derived food products. Differences in plant leaf anatomy and chemical composition between cool- and warm-season pastures may alter rumen microorganisms, potentially enhancing the quantity/profile of bioactive FA available for incorporation into milk. The objective of this study was to identify rumen bacteria and protozoa and their cellular FA when cows grazed a warm-season annual, pearl millet (PM), in comparison to a diverse cool-season pasture (CSP). Individual rumen digesta samples were obtained from five Holstein cows in a repeated measures design with 28-day periods. The treatment sequence was PM, CSP, then PM. Microbial DNA was extracted from rumen digesta and sequence reads were produced with Illumina MiSeq. Fatty acids (FA) were identified in rumen bacteria and protozoa using gas-liquid chromatography/mass spectroscopy. Microbial communities shifted in response to grazing regime. Bacteria of the phylum Bacteroidetes were more abundant during PM than CSP (P < 0.05), while protozoa of the genus Eudiplodinium were more abundant during CSP than PM (P < 0.05). Microbial cellular FA profiles differed between treatments. Bacteria and protozoa from cows grazing CSP contained more n-3 FA (P < 0.001) and vaccenic acid (P < 0.01), but lower proportions of branched-chain FA (P < 0.05). Microbial FA correlated with microbial taxa and levels of vaccenic acid, rumenic acid, and α-linolenic acid in milk. In conclusion, grazing regime can potentially be used to alter microbial communities shifting the FA profile of microbial cells, and subsequently, alter the milk FA profile.

Rumen Biohydrogenation and Microbial Community Changes Upon Early Life Supplementation of 22:6n-3 Enriched Microalgae to Goats

Dietary supplementation of docosahexaenoic acid (DHA)-enriched products inhibits the final step of biohydrogenation in the adult rumen, resulting in the accumulation of 18:1 isomers, particularly of trans(t)-11 18:1. Occasionally, a shift toward the formation of t10 intermediates at the expense of t11 intermediates can be triggered. However, whether similar impact would occur when supplementing DHA-enriched products during pregnancy or early life remains unknown. Therefore, the current in vivo study aimed to investigate the effect of a nutritional intervention with DHA in the early life of goat kids on rumen biohydrogenation and microbial community. Delivery of DHA was achieved by supplementing DHA-enriched microalgae (DHA Gold) either to the maternal diet during pregnancy (prenatal) or to the diet of the young offspring (postnatal). At the age of 12 weeks, rumen fluid was sampled for analysis of long-chain fatty acids and microbial community based on bacterial 16S rRNA amplicon sequencing. Postnatal supplementation with DHA-enriched microalgae inhibited the final biohydrogenation step, as observed in adult animals. This resulted particularly in increased ruminal proportions of t11 18:1 rather than a shift to t10 intermediates, suggesting that both young and adult goats might be less prone to dietary induced shifts toward the formation of t10 intermediates, in comparison with cows. Although Butyrivibrio species have been identified as the most important biohydrogenating bacteria, this genus was more abundant when complete biohydrogenation, i.e. 18:0 formation, was inhibited. Blautia abundance was positively correlated with 18:0 accumulation, whereas Lactobacillus spp. Dialister spp. and Bifidobacterium spp. were more abundant in situations with greater t10 accumulation. Extensive comparisons made between current results and literature data indicate that current associations between biohydrogenation intermediates and rumen bacteria in young goats align with former observations in adult ruminants.

Effect of increasing amounts of olive crude phenolic concentrate in the diet of dairy ewes on rumen liquor and milk fatty acid composition

Agro-industrial by-products contain several secondary plant metabolites, such as polyphenols, tannins, saponins, and essential oils. The effects of these compounds on animal metabolism may vary significantly according to the dose, the chemical nature of the molecules, and the overall composition of the diet. In the Mediterranean area, the olive oil extraction is associated with 2 by-products: olive pomace and wastewater, both rich in polyphenols. In particular, wastewater may be further processed to obtain olive crude phenolic concentrate (OCPC). An experiment was carried out aiming to evaluate animal performance, milk fatty acid (FA) profile, diversity of rumen microbial population, and rumen liquor FA profile in dairy ewes fed diets containing extruded linseed (EL) and increasing doses of OCPC. Twenty-eight Comisana ewes in mid lactation were allotted to 4 experimental groups. The experiment lasted 5 wk after 3 wk of adaptation. Diets were characterized by lucerne hay administrated ad libitum and by 800 g/ewe and day of 4 experimental concentrates containing 22% of EL on dry matter and increasing dose of OCPC: 0 (L0), 0.6 (L0.6), 0.8 (L0.8), and 1.2 (L1.2) g of OCPC/kg of dry matter. Milk yield was daily recorded and milk composition was analyzed weekly. At the beginning and at the end of the experiment, samples of rumen liquor were collected to analyze FA profile, changes in rumen microbial population, and dimethylacetal (DMA) composition. The inclusion of OCPC did not affect milk yield and gross composition, whereas milk from L0.8 and L1.2 sheep contained higher concentrations of linoleic (+18%) and α-linolenic acid (+24%) and lower concentration of the rumen biohydrogenation intermediates. A similar pattern was observed for rumen liquor FA composition. No differences were found in the diversity of the rumen microbial population. Total amount of DMA did not differ among treatments, whereas significant differences were found in the concentration of individual DMA; in the diet with a higher amount of OCPC, DMA 13:0, 14:0, 15:0, and 18:0 increased, whereas DMA 16:0 decreased. Probably the presence of polyphenols in the diet induced a rearrangement of bacteria membrane phospholipids as a response to the rumen environment stimulus. Overall, the use of OCPC allowed a significant increase in the polyunsaturated FA content of milk, probably due to a perturbation of the rumen biohydrogenation process. Further studies are needed to understand the correlation between diet composition and the pattern of DMA in rumen liquor.

Evidence for the Initial Steps of DHA Biohydrogenation by Mixed Ruminal Microorganisms from Sheep Involves Formation of Conjugated Fatty Acids

Incubation of DHA with sheep rumen fluid resulted in 80% disappearance in 6 h. The products were analyzed as their fatty acid (FA) methyl esters by GC-FID on SP-2560 and SLB-IL111 columns. The GC-online reduction × GC and GC-MS techniques demonstrated that all DHA metabolites retained the C22 structure (no evidence of chain-shortening). Two new transient DHA products were identified: mono-trans methylene interrupted-DHA and monoconjugated DHA (MC-DHA) isomers. Identification of MC-DHA was confirmed by their predicted elution using equivalent chain length differences from C18 FA, their molecular ions, and the 22:5 products formed which were the most abundant at 6 h. The 22:5 structures were established by fragmentation of their 4,4-dimethyloxazoline derivatives, and all 22:5 products contained an isolated double bond, suggesting formation via MC-DHA. The most abundant c4,c7,c10,t14,c19-22:5 appeared to be formed by unknown isomerases. Results suggest that the initial biohydrogenation of DHA was analogous to that of C18 FA.

Effect of Dietary Chestnut or Quebracho Tannin Supplementation on Microbial Community and Fatty Acid Profile in the Rumen of Dairy Ewes

Ruminants derived products have a prominent role in diets and economy worldwide; therefore, the capability to control the rumen microbial ecosystem, for ameliorating their quality, is of fundamental importance in the livestock sector. The aim of this study was to evaluate the effect of dietary supplementation with chestnut and quebracho tannins on microbial community and fatty acid profile, in the rumen fluid of dairy ewes. Multivariate analysis of PCR-DGGE profiles of rumen microbial communities showed a correlation among the presence of chestnut or quebracho in the diet, the specific Butyrivibrio group DGGE profiles, the increase in 18:3 cis9, cis12, and cis15; 18:2 cis9 and cis12; 18:2 cis9 and trans11; 18:2 trans11 and cis15; and 18:1 trans11 content, and the decrease in 18:0 concentration. Phylogenetic analysis of DGGE band sequences revealed the presence of bacteria representatives related to the genera Hungatella, Ruminococcus, and Eubacterium and unclassified Lachnospiraceae family members, suggesting that these taxa could be affected by tannins presence in the diets. The results of this study showed that tannins from chestnut and quebracho can reduce the biohydrogenation of unsaturated fatty acids through changes in rumen microbial communities.

Camelina Seed Supplementation at Two Dietary Fat Levels Change Ruminal Bacterial Community Composition in a Dual-Flow Continuous Culture System

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

Can we improve the nutritional quality of meat?

The nutritional value of meat is an increasingly important factor influencing consumer preferences for poultry, red meat and processed meat products. Intramuscular fat content and composition, in addition to high quality protein, trace minerals and vitamins are important determinants of nutritional value. Fat content of meat at retail has decreased substantially over the past 40 years through advances in animal genetics, nutrition and management and changes in processing techniques. Evidence of the association between diet and the incidence of human non-communicable diseases has driven an interest in developing production systems for lowering total SFA and trans fatty acid (TFA) content and enrichment of n-3 PUFA concentrations in meat and meat products. Typically, poultry and pork has a lower fat content, containing higher PUFA and lower TFA concentrations than lamb or beef. Animal genetics, nutrition and maturity, coupled with their rumen microbiome, are the main factors influencing tissue lipid content and relative proportions of SFA, MUFA and PUFA. Altering the fatty acid (FA) profile of lamb and beef is determined to a large extent by extensive plant and microbial lipolysis and subsequent microbial biohydrogenation of dietary lipid in the rumen, and one of the major reasons explaining the differences in lipid composition of meat from monogastrics and ruminants. Nutritional strategies can be used to align the fat content and FA composition of poultry, pork, lamb and beef with Public Health Guidelines for lowering the social and economic burden of chronic disease.

Production of trans and conjugated fatty acids in dairy ruminants and their putative effects on human health: A review

Consumption of milk and dairy products is important in Western industrialised countries. Fat content is an important constituent contributing to the nutritional quality of milk and dairy products. In order to improve the health of consumers, there is high interest in improving their fatty acid (FA) composition, which depends principally on rumen and mammary metabolism. This paper reviews the lipid metabolism in ruminants, with a particular focus on the production of trans and conjugated linoleic acids (CLA) and conjugated linolenic acids (CLnA) in the rumen. After the lipolysis of dietary lipids, an extensive biohydrogenation of unsaturated FA occurs by rumen bacteria, leading to numerous cis and trans isomers of 18:1, non-conjugated of 18:2, CLA and CLnA. The paper examines the different putative pathways of ruminal biohydrogenation of cis9-18:1, 18:2n-6, 18:3n-3 and long-chain FA and the bacteria implicated. Then mechanisms relative to the de novo mammary synthesis are presented. Ruminant diet is the main factor regulating the content and the composition of milk fat. Effects of nature of forage and lipid supplementation are analysed in cows and small ruminants species. Finally, the paper briefly presents the effects of these FA on animal models and human cell lines. We describe the properties of ruminant trans 18:1, when compared to industrial trans 18:1, CLA and CLnA on human health from meta-analyses of intervention studies and then explore the underlying mechanisms.

Enhancing the DHA content in milk from dairy cows by feeding ALL-G-RICH™

The objective of this study was to evaluate the effect of the dietary inclusion of 6 g/kg dry matter intake of an unextracted Aurantiochytrium limacinum algae (AURA) in mid-lactation Italian Friesian cows under commercial conditions on milk yield, milk composition and docosahexaenoic acid (DHA) content. Cows were allocated to two groups (n = 18; 108.2 ± 66.1 and 104.4 ± 54.6 days in milk, control and treated groups, respectively). Feeding AURA for 84 d had no effect on dry matter intake, body condition score or weight gain, but did improve milk yield by 1.9 kg/cow/d (+5.4%; P < 0.1) over the course of the experiment. Milk fat concentration declined by 12% (P < 0.0001) without any significant change in 4% fat corrected milk, protein or lactose. Supplementing AURA for 12 weeks substantially altered the fatty acid profile of milk compared with milk from CON-fed cows such that the proportion of unsaturated fatty acids increased, omega-3 fatty acid content increased by 73.1% (P < 0.0001) and was accompanied by a favourable increase in the omega-3:6 fatty acid ratio by 75.0% (P < 0.0001). The AURA supplement, during day 7–84, increased the DHA concentration to 0.37 g /100 g milk total fatty acids (P < 0.0001) with a mean transfer efficiency of 18.1% from feed to milk. Together these results indicated that supplementing a dairy cow diet with DHA-rich microalgae is a feasible and efficient means for creating DHA-enriched milk for human consumption.

Effect of Sunflower and Marine Oils on Ruminal Microbiota, In vitro Fermentation and Digesta Fatty Acid Profile

This study using the rumen simulation technique (RUSITEC) investigated the changes in the ruminal microbiota and anaerobic fermentation in response to the addition of different lipid supplements to a ruminant diet. A basal diet with no oil added was the control, and the treatment diets were supplemented with sunflower oil (2%) only, or sunflower oil (2%) in combination with fish oil (1%) or algae oil (1%). Four fermentation units were used per treatment. RUSITEC fermenters were inoculated with rumen digesta. Substrate degradation, fermentation end-products (volatile fatty acids, lactate, gas, methane, and ammonia), and microbial protein synthesis were determined. Fatty acid profiles and microbial community composition were evaluated in digesta samples. Numbers of representative bacterial species and microbial groups were determined using qPCR. Microbial composition and diversity were based on T-RFLP spectra. The addition of oils had no effect on substrate degradation or microbial protein synthesis. Differences among diets in neutral detergent fiber degradation were not significant (P = 0.132), but the contrast comparing oil–supplemented diets with the control was significant (P = 0.039). Methane production was reduced (P < 0.05) with all oil supplements. Propionate production was increased when diets containing oil were fermented. Compared with the control, the addition of algae oil decreased the percentage C18:3 c9c12c15 in rumen digesta, and that of C18:2 c9t11 was increased when the control diet was supplemented with any oil. Marine oils decreased the hydrogenation of C18 unsaturated fatty acids. Microbial diversity was not affected by oil supplementation. Cluster analysis showed that diets with additional fish or algae oils formed a group separated from the sunflower oil diet. Supplementation with marine oils decreased the numbers of Butyrivibrio producers of stearic acid, and affected the numbers of protozoa, methanogens, Selenomonas ruminantium and Streptococcus bovis, but not total bacteria. In conclusion, there is a potential to manipulate the rumen fermentation and microbiota with the addition of sunflower, fish or algae oils to ruminant diets at appropriate concentrations. Specifically, supplementation of ruminant mixed rations with marine oils will reduce methane production, the acetate to propionate ratio and the fatty acid hydrogenation in the rumen.

In vitro response to EPA, DPA, and DHA: Comparison of effects on ruminal fermentation and biohydrogenation of 18-carbon fatty acids in cows and ewes

The modulation of milk fat nutritional quality through fish oil supplementation seems to be largely explained by the action of n-3 very long chain polyunsaturated fatty acids (PUFA) on ruminal biohydrogenation (BH) of C18 fatty acids (FA). However, relationships among this action, disappearance of those PUFA in the rumen, and potential detrimental consequences on ruminal fermentation remain uncertain. This study compared the effect of 20:5n-3 (eicosapentaenoic acid; EPA), 22:5n-3 (docosapentaenoic acid; DPA), and 22:6n-3 (docosahexaenoic acid; DHA) on rumen fermentation and BH of C18 FA and was conducted simultaneously in cows and sheep to provide novel insights into interspecies differences. The trial was performed in vitro using batch cultures of rumen microorganisms with inocula collected from cannulated cows and ewes. The PUFA were added at a dose of 2% incubated dry matter, and treatment effects on ruminal C18 FA concentrations, PUFA disappearances, and fermentation parameters (gas production, ammonia and volatile FA concentrations, and dry matter and neutral detergent fiber disappearances) were examined after 24 h of incubation. A principal component analysis suggested that responses to PUFA treatments explained most of the variability; those of ruminant species were of lower relevance. Overall, EPA and DHA were equally effective for inhibiting the saturation of trans-11 18:1 to 18:0 and had a similar influence on ruminal fermentation in cows and sheep (e.g., reductions in gas production and acetate:propionate ratio). Nevertheless, DHA further promoted alternative BH pathways that lead to trans-10 18:1 accumulation, and EPA seemed to have specific effects on 18:3n-3 metabolism. Only minor variations attributable to DPA were observed in the studied parameters, suggesting a low contribution of this FA to the action of marine lipids. Although most changes due to the added PUFA were comparable in bovine and ovine, there were also relevant specificities, such as a stronger inhibition of 18:0 formation in cows and a greater increase in 18:3n-3 metabolites in sheep. No direct relationship between in vitro disappearance of the incubated PUFA and effect on BH (in particular, inhibition of the last step) was found in either cows or ewes, calling into question a putative link between extent of disappearance and toxicity for microbiota. Conversely, an association between the influence of these PUFA on ruminal lipid metabolism and fermentation may exist in both species. In vivo verification of these findings would be advisable.

Dietary n-6:n-3 Fatty Acid Ratios Alter Rumen Fermentation Parameters and Microbial Populations in Goats

Revealing the ruminal fermentation patterns and microbial populations as affected by dietary n-6:n-3 PUFA ratio would be useful for further clarifying the role of the rumen in the lipid metabolism of ruminants. The objective of the present study was to investigate the effects of dietary n-6:n-3 PUFA ratios on fermentation characteristics, fatty acid (FA) profiles, and microbial populations in the rumen of goats. A total of twenty-one goats were randomly assigned to three dietary treatments with different n-6:n-3 PUFA ratios of 2.27:1 (low ratio, LR), 5.01:1 (medium ratio, MR), and 10.38:1 (high ratio, HR). After 100 days of feeding, all goats were slaughtered. Dietary n-6:n-3 PUFA ratios had no effect (P > 0.05) on rumen pH and NH₃N concentration. Goats fed HR diet had lower (P < 0.05) propionate and total volatile fatty acids and higher (P < 0.05) butyrate compared with those fed the MR and LR diets. The proportion of C18:0 decreased (P < 0.05) as dietary n-6:n-3 PUFA ratios increased. The proportions of C18:1 trans-11, C18:2n-6, cis-9 trans-11 CLA, and C20:4n-6 were greater in the HR goats compared with the MR and LR goats. Lowering dietary n-6:n-3 PUFA ratios enhanced (P < 0.05) the proportion of C18:3n-3 and total n-3 PUFA in the rumen fluid of goats. The populations of R. albus and R. flavefaciens decreased (P < 0.05) as the n-6:n-3 PUFA ratios increased in diet. Diet had no effect (P > 0.05) on the ruminal populations of F. succinogenes, total bacteria, methanogens, total protozoa, Entiodinium, and Holotrich. The population of B. fibrisolvens was lower (P < 0.05) in the LR goats compared with the MR and HR goats. It was concluded that HR would increase the concentration of cis-9 trans-11 CLA and C18:1 trans-11 in the rumen. However, LR whould decrease the B. fibrisolvens population, which is involved in the BH process in the rumen. Further research is needed to evaluate the potential role and contribution of rumen microbiome in the metabolism of FA in the rumen.

In vitro rumen fermentation characteristics of goat and sheep supplemented with polyunsaturated fatty acids

An in vitro gas-production study was conducted to compare differences in rumen fermentation characteristics and the effect of supplementation of 4% linseed oil as a source of polyunsaturated fatty acids on the rumen fermentation profile in rumen fluid collected from goats and sheep. Rumen fluid for each species was obtained from two male goats of ~18 months old and two sheep of similar sex and age fed the similar diet containing 30% alfalfa hay and 70% concentrates. The substrate used for the fermentation was alfalfa hay and concentrate mixture (30:70) without (control) and with addition of linseed oil. The experiment was a two (inoculums) × two (oil levels) factorial experiment, with five replicates per treatment, and was repeated once. Rumen fermentation characteristics, including pH, fermentation kinetics, in vitro organic matter digestibility (IVOMD), volatile fatty acid (VFA) production and microbial population were examined. Results of the study showed that gas-production rate (c), IVOMD, VFA production and population of total bacteria and two cellulolytic bacteria (Ruminococus albus and Butyrivibrio fibrisolvens) from rumen fluid of goat were significantly (P &lt; 0.05) higher than those of samples from sheep. Irrespective of sources of inoculums, addition of oil did not affect fermentation capacity, IVOMD and total VFA production. The higher B. fibrisolvens population (associated with bio-hydrogenation) in rumen fluid of goat seems to suggest that polyunsaturated fatty acids are more prone to bio-hydrogention in the rumen of goat than in sheep. This assumption deserves further investigation.