Quantification of ruminalClostridium proteoclasticumby real-time PCR using a molecular beacon approach

Bioefficiency of microencapsulated hemp leaf phytonutrient-based extracts to enhance in vitro rumen fermentation and mitigate methane production

The objective was to assess the supplementation with microencapsulation of hemp leaf extract (mHLE) utilized as a rumen enhancer on in vitro rumen fermentation and to enhance the bioavailability of active compounds for antimicrobial action, particularly in protozoa and methanogen populations. The feed treatments were totally randomized in the experimental design, with different levels of mHLE diet supplemented at 0, 4, 6 and 8% of total DM substrate and added to an R:C ratio of 60:40. During fermentation, gas kinetics production, nutrient degradability, ammonia nitrogen concentration, volatile fatty acid (VFA) profiles, methane production, and the microbial population were measured. The supplemented treatment at 6% of total DM substrate affected reductions in gas kinetics, cumulative gas production, and volatile fatty acid profiles, especially the acetate and acetate to propionate ratio. Whereas propionate proportion and total volatile fatty acid concentration were enhanced depending on the increase of nutrients in vitro dry matter degradability (IVDMD) after 12 h of post-fermentation at a R:C ratio of 60:40 (P < 0.05). Consequently, mHLE addition resulted in optimal ruminal pH and increased nutrient degradability, followed by ammonia nitrogen concentrations (P < 0.05), which were enhanced by dominant cellulolytic bacteria, particularly Ruminococcus albus and Ruminococcus flavefaciens, which showed the highest growth rates in the rumen ecology. Therefore, mHLE, a rich phytonutrient feed additive, affected the methanogen population, reduced the calculated methane production and can be a potential supplement in the ruminant diet.

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.

Producing natural functional and low-carbon milk by regulating the diet of the cattle-The fatty acid associated rumen fermentation, biohydrogenation, and microorganism response

Conjugated linoleic acid (CLA) has drawn significant attention in the last two decades for its various potent beneficial effects on human health, such as anticarcinogenic and antidiabetic properties. CLA could be generally found in ruminant products, such as milk. The amount of CLA in ruminant products mainly depends on the diet of the animals. In general, the fat content in the ruminant diet is low, and dietary fat supplementation can be provided to improve rumen activity and the fatty acid (FA) profile of meat and milk. Especially, dietary 18-carbon polyunsaturated FA (C18 PUFA), the dominant fat source for ruminants, can modify the milk FA profile and other components by regulating the ruminal microbial ecosystem. In particular, it can improve the CLA in milk, intensify the competition for metabolic hydrogen for propionate producing pathways and decrease methane formation in the rumen. Therefore, lipid supplementation appears to be a promising strategy to naturally increase the additional nutritional value of milk and contribute to lower methane emissions. Meanwhile, it is equally important to reveal the effects of dietary fat supplementation on rumen fermentation, biohydrogenation (BH) process, feed digestion, and microorganisms. Moreover, several bacterial species and strains have been considered to be affected by C18 PUFA or being involved in the process of lipolysis, BH, CLA, or methane emissions. However, no review so far has thoroughly summarized the effects of C18 PUFA supplementation on milk CLA concentration and methane emission from dairy cows and meanwhile taken into consideration the processes such as the microorganisms, digestibility, rumen fermentation, and BH of dairy cattle. Therefore, this review aims to provide an overview of existing knowledge of how dietary fat affects rumen microbiota and several metabolic processes, such as fermentation and BH, and therefore contributes to functional and low-carbon milk production.

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.

Effect of Saccharomyces cerevisiae culture mitigates heat stress-related dame in dairy cows by multi-omics

The effect of heat stress on ruminants is an important issue. In recent years, the growth of the Chinese dairy industry has rapidly increased, generating RMB 468,738 million revenue in 2021. A decreased milk yield is the most recognized impact of heat stress on dairy cows and results in significant economic loss to dairy producers. Heat stress also lowers immunity and antioxidant capacity and changes the bacterial composition and metabolites of the rumen. The purpose of this study was to investigate the effect of addition Saccharomyces cerevisiae culture on heat-stressed cows. The impact of S. cerevisiae culture on microbiota composition, functional profiles, and metabolomics was assessed in heat-stressed cows. A total of 45 Holstein cows in mid-lactation were selected and randomly divided into three groups (15 cows per group). Groups D-C, D-A, and D-B were fed with the basal diet, the basal diet + first S. cerevisiae culture 100 g/day, and the basal diet + second S. cerevisiae culture 30 g/day, respectively. The trial lasted 60 days. There was an increased abundance of the Phylum Firmicutes in the rumen of heat-stressed dairy cows fed with S. cerevisiae, of which four genera had significantly higher abundance, Ruminococcus_gauvreauii_group, Butyrivibrio_2, Moryella, and Ruminiclostridium_6. At the functional level, ten pathways differed significantly between the three groups (P < 0.05), with an increase in fatty acid biosynthesis, fatty acid metabolism, PPAR signaling pathway, ferroptosis, and biotin metabolism in the treatment groups. More differential metabolites were found in the D-C and D-A groups than in the D-C and D-B groups. These results indicate that S. cerevisiae cultures can influence the health status of heat-stressed cows by modulating rumen microbial composition, function, and metabolites, thereby improving rumen cellulolytic capacity. This study can provide or offer suggestions or recommendations for the development and utilization of feed additives.

Dietary cardoon meal modulates rumen biohydrogenation and bacterial community in lambs

Cardoon meal is a by-product of oil extraction from the seeds of Cynara cardunculus and can serve as a novel alternative feedstuff for ruminants. This study examined the rumen fermentation, biohydrogenation of fatty acids (FA) and microbial community in lambs fed a concentrate diet containing 15% dehydrated lucerne (CON, n = 8) or cardoon meal (CMD, n = 7) for 75 days pre-slaughter. Diets did not influence rumen fermentation characteristics and the abundance of bacteria, methanogens, fungi, or protozoa. Rumen digesta in CMD-fed lambs displayed a higher concentration of total saturated FA and lower total odd- and branched-chain FA and monounsaturated FA. Feeding CMD decreased total trans-18:1 isomer and the ratio of trans-10 to trans-11 C18:1, known as the "trans-10 shift". Amplicon sequencing indicated that the rumen bacterial community in CMD-fed lambs had lower diversity and a higher relative phyla abundance of Proteobacteria at the expense of Bacteroidetes and Fibrobacteres. At the genus level, CMD mediated specific shifts from Prevotella, Alloprevotella, Solobacterium and Fibrobacter to Ruminobacter, suggesting that these genera may play important roles in biohydrogenation. Overall, these results demonstrate that cardoon meal can be used as a feedstuff for ruminants without negatively affecting rumen fermentation and microbiota but its impact on biohydrogenation may influence the FA composition in meat or milk.

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.

Meta-analysis of the effect of glycerin inclusion in dairy cattle diet on milk fatty acid profile

The use of glycerin in diets for dairy cows initially emerged as an alternative for the prevention and control of ketosis. However, despite some controversy, there are still several studies associating glycerin with increases in daily milk yield, with possible changes in its constituents. Therefore, the objective of this study was to evaluate, using a meta-analysis approach, the effect of glycerin inclusion in dairy cow diets on milk fatty acid. Twenty-two peer-reviewed publications with 66 treatment means were included in data set. The effect of glycerin inclusion in diet (treatment) were evaluated using random-effect models to examine the weighted mean differences (WMD) between a control diet (without glycerin in the diet) and the treatment diet. Heterogeneity was explored by meta-regression and subgroup analysis performed for: genetic type; days in milk; experimental period; glycerin in diet; glycerin type and concentrate in diet. Inclusion of glycerin in the diet increased the digestibility of dry matter and protein, as well as ruminal propionate. It did not affect dry matter intake (P = 0.351) and milk yield (P = 0.730). The effect of glycerin inclusion on the milk fat yield is dependent on the genetic group, in which Holstein (WMD = −0.04 kg/d; P = 0.010) and Holstein-crossbreed (WMD = −0.10 kg/d; P < 0.0001) cows produced less fat in milk compared to Jersey cows, when glycerin was included in the diets. Glycine inclusions of up to 100 g/kg in the diet of dairy cows did not negatively affect milk production and composition. However, inclusions above 150 g/kg of glycerin in the diet reduced the concentration of fat, and of unsaturated, monounsaturated, polyunsaturated fatty acids and conjugated linoleic acid (CLA C18: 2 cis-9 and trans-11) in milk. The results reported in our meta-analysis does not demonstrate the effectiveness of glycerin in improving the composition of milk and a group of fatty acids of importance for human health such as C18: 2 cis-9, trans-11 CLA.

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.

Effects of supplemental plant oils on rumen bacterial community profile and digesta fatty acid composition in a continuous culture system (RUSITEC)

Lipid supplementation of ruminant diets may trigger changes in the ruminal microbiota and in anaerobic digestion. Changes in the bacterial community composition and in the fatty acid hydrogenation caused by the addition of different supplemental plant oils to a high concentrate diet were investigated in vitro using RUSITEC (rumen simulation technique) fermenters. The control (CTR) diet was a high-concentrate total mixed ration for dairy sheep, with no supplementary oil. The other experimental diets were supplemented with olive (OLV), sunflower (SFL) or linseed (LNS) oils at 6% (dry matter basis). Four RUSITEC fermenters were used for each experimental diet, all inoculated with rumen digesta of sheep. Extent of dry matter and fat degradation, composition of the bacterial community and long-chain fatty acids in digesta were determined. The addition of plant oils increased (P < 0.001) apparent degradation of fat in the fermenters, whereas fermentation kinetics (gas production and average fermentation rate) were lower (P < 0.05) with the LNS than with the CTR diet. Hydrogenation of C18 unsaturated fatty acids (P < 0.05), in particular that of oleic acid (P < 0.001), and stearic acid proportion (P < 0.001) were reduced, and oleic acid proportion was increased (P < 0.001) with all oil supplements. Addition of OLV decreased linoleic and LNS increased α-linolenic (P < 0.001), whereas conjugated linoleic was increased with SFL oil (P = 0.025) and vaccenic increased with both SFL and LNS oils (P = 0.008). Addition of 6% OLV and LNS reduced (P < 0.05) microbial community diversity and quantity of total bacteria relative to the control. Some specific microbial groups were affected (P < 0.001) by oil addition, with less relative abundance of Clostridiales and Actinobacteria and increased Bacteroidales, Aeromonadales and Lactobacillales species. In conclusion, the supplementation of high-concentrate ruminant diets with plant oils, in particular from sunflower or linseed, causes shifts in the rumen microbiota and fatty acid hydrogenation in the rumen increasing the formation of vaccenic and conjugated linoleic acids.

Comparative Genomics of Rumen Butyrivibrio spp. Uncovers a Continuum of Polysaccharide-Degrading Capabilities

Feeding a global population of 8 billion people and climate change are the primary challenges facing agriculture today. Ruminant livestock are important food-producing animals, and maximizing their productivity requires an understanding of their digestive systems and the roles played by rumen microbes in plant polysaccharide degradation. Members of the genera Butyrivibrio and Pseudobutyrivibrio are a phylogenetically diverse group of bacteria and are commonly found in the rumen, where they are a substantial source of polysaccharide-degrading enzymes for the depolymerization of lignocellulosic material. Our findings have highlighted the immense enzymatic machinery of Butyrivibrio and Pseudobutyrivibrio species for the degradation of plant fiber, suggesting that these bacteria occupy similar niches but apply different degradation strategies in order to coexist in the competitive rumen environment.

Plant polysaccharide breakdown by microbes in the rumen is fundamental to digestion in ruminant livestock. Bacterial species belonging to the rumen genera Butyrivibrio and Pseudobutyrivibrio are important degraders and utilizers of lignocellulosic plant material. These bacteria degrade polysaccharides and ferment the released monosaccharides to yield short-chain fatty acids that are used by the ruminant for growth and the production of meat, milk, and fiber products. Although rumen Butyrivibrio and Pseudobutyrivibrio species are regarded as common rumen inhabitants, their polysaccharide-degrading and carbohydrate-utilizing enzymes are not well understood. In this study, we analyzed the genomes of 40 Butyrivibrio and 6 Pseudobutyrivibrio strains isolated from the plant-adherent fraction of New Zealand dairy cows to explore the polysaccharide-degrading potential of these important rumen bacteria. Comparative genome analyses combined with phylogenetic analysis of their 16S rRNA genes and short-chain fatty acid production patterns provide insight into the genomic diversity and physiology of these bacteria and divide Butyrivibrio into 3 species clusters. Rumen Butyrivibrio bacteria were found to encode a large and diverse spectrum of degradative carbohydrate-active enzymes (CAZymes) and binding proteins. In total, 4,421 glycoside hydrolases (GHs), 1,283 carbohydrate esterases (CEs), 110 polysaccharide lyases (PLs), 3,605 glycosyltransferases (GTs), and 1,706 carbohydrate-binding protein modules (CBM) with predicted activities involved in the depolymerization and transport of the insoluble plant polysaccharides were identified. Butyrivibrio genomes had similar patterns of CAZyme families but varied greatly in the number of genes within each category in the Carbohydrate-Active Enzymes database (CAZy), suggesting some level of functional redundancy. These results suggest that rumen Butyrivibrio species occupy similar niches but apply different degradation strategies to be able to coexist in the rumen.

IMPORTANCE Feeding a global population of 8 billion people and climate change are the primary challenges facing agriculture today. Ruminant livestock are important food-producing animals, and maximizing their productivity requires an understanding of their digestive systems and the roles played by rumen microbes in plant polysaccharide degradation. Members of the genera Butyrivibrio and Pseudobutyrivibrio are a phylogenetically diverse group of bacteria and are commonly found in the rumen, where they are a substantial source of polysaccharide-degrading enzymes for the depolymerization of lignocellulosic material. Our findings have highlighted the immense enzymatic machinery of Butyrivibrio and Pseudobutyrivibrio species for the degradation of plant fiber, suggesting that these bacteria occupy similar niches but apply different degradation strategies in order to coexist in the competitive rumen environment.

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.

Comparative aspects of plant tannins on digestive physiology, nutrition and microbial community changes in sheep and goats: A review

Comparative aspects of plant tannins on digestive physiology, nutrition and microbial community in sheep and goats are discussed in the context of differences due to feed intake, digestibility, utilization of nutrients and microbial community. The purpose of this review was to present an overview of the potential benefits of tannin-containing diets for sheep and goats and specie differences in their response to tannins. It is well established that moderate level of tannins in the diet (3%-4% tannins DM) can precipitate with soluble proteins and increase protein supply to the sheep, but comparative aspects of tannin-containing diets in sheep and goats on animal performance, digestive physiology, rumen microbial changes and potential benefits to sustainable animal production by those compounds have received little attention. In addition, developing plant-based tannin-containing diets for control of rumen microbiota and rumen fermentation (e.g., methane gas) would be expected to have a greater impact on the ruminant health, productivity and emission of greenhouse gasses. The positive impacts of the plant tannin compounds mainly depend on their influence on the gut microbiome diversity and ability to generate fermentation end products (short-chain fatty acids) that have diverse biological roles. Diets which contain optimal levels of tannins have potential benefits for sustainability of small ruminant production systems. However, there is a need for an improved understanding of the utilization of tannin-containing forages to improve their management. This implies investigations of animal responses to tannin-containing forages or browse species and, in particular, a better understanding of the interactions that can arise between sheep and goats on digestion, DMD, rumen fermentation and microbial community changes. This knowledge could help to improve current feeding systems in terms of efficiency of feed use and environmental impacts (reduce methane gas production) and thus contribute to the development of a sustainable sheep and goat production.

Does intra-ruminal nitrogen recycling waste valuable resources? A review of major players and their manipulation

Nitrogenous emissions from ruminant livestock production are of increasing public concern and, together with methane, contribute to environmental pollution. The main cause of nitrogen-(N)-containing emissions is the inadequate provision of N to ruminants, leading to an excess of ammonia in the rumen, which is subsequently excreted. Depending on the size and molecular structure, various bacterial, protozoal and fungal species are involved in the ruminal breakdown of nitrogenous compounds (NC). Decelerating ruminal NC degradation by controlling the abundance and activity of proteolytic and deaminating microorganisms, but without reducing cellulolytic processes, is a promising strategy to decrease N emissions along with increasing N utilization by ruminants. Different dietary options, including among others the treatment of feedstuffs with heat or the application of diverse feed additives, as well as vaccination against rumen microorganisms or their enzymes have been evaluated. Thereby, reduced productions of microbial metabolites, e.g. ammonia, and increased microbial N flows give evidence for an improved N retention. However, linkage between these findings and alterations in the rumen microbiota composition, particularly NC-degrading microbes, remains sparse and contradictory findings confound the exact evaluation of these manipulating strategies, thus emphasizing the need for comprehensive research. The demand for increased sustainability in ruminant livestock production requests to apply attention to microbial N utilization efficiency and this will require a better understanding of underlying metabolic processes as well as composition and interactions of ruminal NC-degrading microorganisms.

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.

The complete genome sequence of the rumen bacterium Butyrivibrio hungatei MB2003

Butyrivibrio hungatei MB2003 was isolated from the plant-adherent fraction of rumen contents from a pasture-grazed New Zealand dairy cow, and was selected for genome sequencing in order to examine its ability to degrade plant polysaccharides. The genome of MB2003 is 3.39 Mb and consists of four replicons; a chromosome, a secondary chromosome or chromid, a megaplasmid and a small plasmid. The genome has an average G + C content of 39.7%, and encodes 2983 putative protein-coding genes. MB2003 is able to use a variety of monosaccharide substrates for growth, with acetate, butyrate and formate as the principal fermentation end-products, and the genes encoding these metabolic pathways have been identified. MB2003 is predicted to encode an extensive repertoire of CAZymes with 78 GHs, 7 CEs, 1 PL and 78 GTs. MB2003 is unable to grow on xylan or pectin, and its role in the rumen appears to be as a utilizer of monosaccharides, disaccharides and oligosaccharides made available by the degradative activities of other bacterial species.

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.

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.

Dose and time response of ruminally infused algae on rumen fermentation characteristics, biohydrogenation and Butyrivibrio group bacteria in goats

BACKGROUND

Micro-algae could inhibit the complete rumen BH of dietary 18-carbon unsaturated fatty acid (UFAs). This study aimed to examine dose and time responses of algae supplementation on rumen fermentation, biohydrogenation and Butyrivibrio group bacteria in goats.

METHODS

Six goats were used in a repeated 3 × 3 Latin square design, and offered a fixed diet. Algae were infused through rumen cannule with 0 (Control), 6.1 (L-Alg), or 18.3 g (H-Alg) per day. Rumen contents were sampled on d 0, 3, 7, 14 and 20.

RESULTS

H-Alg reduced total volatile fatty acid concentration and acetate molar proportion (P < 0.05), and increased propionate molar proportion (P < 0.05), whereas L-Alg had no effect on rumen fermentation. Changes in proportions of acetate and propionate in H-Alg were obvious from d 7 onwards and reached the largest differences with the control on d 14. Algae induced a dose-dependent decrease in 18:0 and increased trans-18:1 in the ruminal content (P < 0.05). H-Alg increased the concentrations of t9, t11-18:2 and t11, c15-18:2 (P < 0.05). L-Alg only seemed to induce a transient change in 18-carbon isomers, while H-Alg induced a rapid elevation, already obvious on d 3, concentrations of these fatty acid rose in some cases again on d 20. Algae had no effect on the abundances of Butyrivibrio spp. and Butyrivibrio proteoclasticus (P > 0.10), while H-Alg reduced the total bacteria abundance (P < 0.05). However, this was induced by a significant difference between control and H-Alg on d 14 (-4.43 %). Afterwards, both treatments did not differ as increased variation in the H-Alg repetitions, with in some cases a return of the bacterial abundance to the basal level (d 0).

CONCLUSIONS

Changes in rumen fermentation and 18-carbon UFAs metabolism in response to algae were related to the supplementation level, but there was no evidence of shift in ruminal biohydrogenation pathways towards t10-18:1. L-Alg mainly induced a transient effect on rumen biohydrogenation of 18-carbon UFAs, while H-Alg showed an acute inhibition and these effects were not associated with the known hydrogenating bacteria.

Impairment of rumen biohydrogenation and bacteria of the Butyrivibrio group in the rumen of goats through a 20:5 n-3 (EPA) rich supplement

BACKGROUND

Marine products can inhibit biohydrogenation in the rumen, but the mechanism is not clear. This study investigated a 20:5 n-3 rich supplement effects on rumen biohydrogenation, microbial change and fermentation characteristics in goats.

RESULTS

The supplementation decreased 18:0 proportions in rumen fatty acids (P < 0.001), while it increased cis-9, trans-11 conjugated linoleic acid (CLA) (P < 0.001) and trans-10, cis-12 CLA proportions (P < 0.001). The supplement reduced the number of Butyrivibrio spp. and B. proteoclasticus (P < 0.01). Denaturing gradient gel electrophoresis redundancy analysis indicated that some species, mainly from the rumen of goats receiving the 2.5 and 5.0 g d(-1) supplement, were positively correlated with cis-9, trans-11 CLA proportions; some species, mainly from the rumen of control goats, were positively correlated with 18:0 proportions. The supplement reduced the NH3 -N concentrations and acetate molar proportions in the rumen (P < 0.05), but increased propionate and butyrate molar proportions (P < 0.01), and had no effect on total volatile fatty acid concentration.

CONCLUSION

The supplement rich in 20:5 n-3 reduced the biohydrogenation of 18-carbon unsaturated fatty acids with a significant reduction of the 18:0 proportion and this was coupled with the suppression of the abundance of biohydrogenating bacteria and unknown bacteria.

The Cytosolic Oligosaccharide-Degrading Proteome of Butyrivibrio Proteoclasticus

The growth and productivity of ruminants depends on a complex microbial community found in their fore-stomach (rumen), which is able to breakdown plant polysaccharides and ferment the released sugars. Butyrivibrio proteoclasticus B316T is a Gram-positive polysaccharide-degrading, butyrate-producing bacterium that is present at high numbers in the rumen of animals consuming pasture or grass silage based diets. B316T is one of a small number of rumen fibrolytic microbes capable of efficiently degrading and utilizing xylan, as well as being capable of utilizing arabinose, xylose, pectin and starch. We have therefore carried out a proteomic analysis of B316T to identify intracellular enzymes that are implicated in the metabolism of internalized xylan. Three hundred and ninety four proteins were identified including enzymes that have potential to metabolize assimilated products of extracellular xylan digestion. Identified enzymes included arabinosidases, esterases, an endoxylanase, and β-xylosidase. The presence of intracellular debranching enzymes indicated that some hemicellulosic side-chains may not be removed until oligosaccharides liberated by extracellular digestion have been assimilated by the cells. The results support a model of extracellular digestion of hemicellulose to oligosaccharides that are then transported to the cytoplasm for further digestion by intracellular enzymes.

Milk fatty acid composition, rumen microbial population, and animal performances in response to diets rich in linoleic acid supplemented with chestnut or quebracho tannins in dairy ewes

The aim of the study was to evaluate milk fatty acid (FA) profile, animal performance, and rumen microbial population in response to diets containing soybean oil supplemented or not with chestnut and quebracho tannins in dairy ewes. Eighteen Comisana ewes at 122±6 d in milking were allotted into 3 experimental groups. Diets were characterized by chopped grass hay administered ad libitum and by 800 g/head and day of 3 experimental concentrates containing 84.5 g of soybean oil/kg of dry matter (DM) and 52.8 g/kg of DM of bentonite (control diet), chestnut tannin extract (CHT diet), or quebracho tannin extract (QUE diet). The trial lasted 4 wk. Milk yield was recorded daily, and milk composition and blood parameters were analyzed weekly. At the end of the experiment, samples of rumen fluid were collected to analyze pH, volatile fatty acid profile, and the relative proportions of Butyrivibrio fibrisolvens and Butyrivibrio proteoclasticus in the rumen microbial population. Hepatic functionality, milk yield, and gross composition were not affected by tannin extracts, whereas milk FA composition was characterized by significant changes in the concentration of linoleic acid (CHT +2.77% and QUE +9.23%), vaccenic acid (CHT +7.07% and QUE +13.88%), rumenic acid (CHT -1.88% and QUE +24.24%), stearic acid (CHT + 8.71% and QUE -11.45%), and saturated fatty acids (CHT -0.47% and QUE -3.38%). These differences were probably due to the ability of condensed versus hydrolyzable tannins to interfere with rumen microbial metabolism, as indirectly confirmed by changes in the relative proportions of B. fibrisolvens and B. proteoclasticus populations and by changes in the molar proportions of volatile fatty acids. The effect of the CHT diet on the milk FA profile and microbial species considered in this trial was intermediate between that of QUE and the control diet, suggesting a differential effect of condensed and hydrolyzable tannins on rumen microbes. Compared with control animals, the presence of B. fibrisolvens increased about 3 times in ewes fed CHT and about 5 times in animals fed QUE. In contrast, the abundance of B. proteoclasticus decreased about 5- and 15-fold in rumen liquor of ewes fed CHT and QUE diets, respectively. The use of soybean oil and a practical dose of QUE or CHT extract in the diet of dairy ewes can be an efficient strategy to improve the nutritional quality of milk.

Diversity of butyrivibrio group bacteria in the rumen of goats and its response to the supplementation of garlic oil

This study aimed to investigate the diversity of the Butyrivibrio group bacteria in goat rumen and its response to garlic oil (GO) supplementation as revealed by molecular analysis of cloned 16S rRNA genes. Six wethers fitted with ruminal fistulas were assigned to two groups for a cross-over design with 28-d experimental period and 14-d interval. Goats were fed a basal diet without (control) or with GO ruminal infusion (0.8 g/d). Ruminal contents were used for DNA extraction collected before morning feeding on d 28. A total bacterial clone library was firstly constructed by nearly full-length 16S rRNA gene cloned sequences using universal primers. The resulting plasmids selected by Butyrivibrio-specific primers were used to construct a Butyrivibrio group-specific bacterial clone library. Butyrivibrio group represented 12.98% and 10.95% of total bacteria in control and GO group, respectively. In libraries, clones were classified to the genus Pseudobutyrivibrio, Butyrivibrio and others within the family Lachnospiraceae. Additionally, some specific clones were observed in GO group, being classified to the genus Ruminococcus and others within the family Ruminococcaceae. Based on the criterion that the similarity was 97% or greater with database sequences, there were 29.73% and 18.42% of clones identified as known isolates (i.e. B. proteoclasticus and Ps. ruminis) in control and GO groups, respectively. Further clones identified as B. fibrisolvens (5.41%) and R. flavefaciens (7.89%) were specifically found in control and GO groups, respectively. The majority of clones resembled Ps. ruminis (98% to 99% similarity), except for Lachnospiraceae bacteria (87% to 92% similarity) in the two libraries. The two clone libraries also appeared different in Shannon diversity index (control 2.47 and GO group 2.91). Our results indicated that the Butyrivibrio group bacteria had a complex community with considerable unknown species in the goat rumen.

Identification of GH10 xylanases in strains 2 and Mz5 of Pseudobutyrivibrio xylanivorans

Genes encoding glycosyl hydrolase family 11 (GH11) xylanases and xylanases have been identified from Pseudobutyrivibrio xylanivorans. In contrast, little is known about the diversity and distribution of the GH10 xylanase in strains of P. xylanivorans. Xylanase and associated activities of P. xylanivorans have been characterized in detail in the type strain, Mz5. The aim of the present study was to identify GH10 xylanase genes in strains 2 and Mz5 of P. xylanivorans. In addition, we evaluated degradation and utilization of xylan by P. xylanivorans 2 isolated from rumen of Creole goats. After a 12-h culture, P. xylanivorans 2 was able to utilize up to 53% of the total pentose content present in birchwood xylan (BWX) and to utilize up to 62% of a ethanol-acetic acid-soluble fraction prepared from BWX. This is the first report describing the presence of GH10 xylanase-encoding genes in P. xylanivorans. Strain 2 and Mz5 contained xylanases which were related to GH10 xylanase of Butyrivibrio sp. Identifying xylanase-encoding genes and activity of these enzymes are a step toward understanding possible functional role of P. xylanivorans in the rumen ecosystem and contribute to providing an improved choice of enzymes for improving fiber digestion in ruminant animals, agricultural biomass utilization for biofuel production, and other industries.

Application of Molecular Beacons in Real-Time PCR

Real-time PCR or quantitative PCR (QPCR) is a powerful technique that allows measurement of PCR product while the amplification reaction proceeds. It incorporates the fluorescent element into conventional PCR as the calculation standard to provide a quantitative result. In this sense, fluorescent chemistry is the key component in QPCR. Till now, two types of fluorescent chemistries have been adopted in the QPCR systems: one is nonspecific probe and the other is specific. As a brilliant invention by Kramer et al. in 1996, molecular beacon is naturally suited as the reporting element in real-time PCR and has been adapted for many molecular biology applications. In this chapter, we briefly introduce the working principle of QPCR and overview different fluorescent chemistries, and then we focus on the applications of molecular beacons-like gene expression study, single-nucleotide polymorphisms and mutation detection, and pathogenic detection.

Effect of forage conservation method on ruminal lipid metabolism and microbial ecology in lactating cows fed diets containing a 60:40 forage-to-concentrate ratio

The effect of forage conservation method on ruminal lipid metabolism and microbial ecology was examined in 2 complementary experiments in cows. Treatments comprised fresh chopped grass, barn-dried hay, or untreated (UTS) or formic acid-treated silage (FAS) prepared from the same grass sward. Preparation of conserved forages coincided with the collection of samples from cows offered fresh grass. In the first experiment, 5 multiparous Finnish Ayrshire cows (229 d in milk) were used to compare the effects of feeding diets based on grass followed by hay during 2 consecutive 14-d periods separated by a 5-d transition during which extensively wilted grass was fed. In the second experiment, 5 multiparous Finnish Ayrshire cows (53 d in milk) were assigned to 1 of 2 blocks and allocated treatments according to a replicated 3×3 Latin square design with 14-d periods to compare the effects of hay, UTS, and FAS. Cows received 7 or 9 kg/d of the same concentrate in experiments 1 and 2, respectively. Conservation of grass by drying, but not ensiling, decreased forage fatty acid content primarily due to losses of 18:2n-6 and 18:3n-3. Compared with grass, feeding hay had no effect on dry matter intake (DMI), rumen pH, or fermentation characteristics, other than increasing ammonia content, but lowered whole-tract organic matter and fiber digestibility (experiment 1). Relative to hay, silage increased DMI, rumen volatile fatty acid (VFA) concentrations, and molar proportions of butyrate, and decreased molar acetate proportions (experiment 2). Compared with UTS, FAS increased DMI, had no effect on rumen ammonia or VFA concentrations, but tended to lower rumen pH and the molar ratio of lipogenic to glucogenic VFA. Conservation method had no substantial effect on ruminal or whole-tract digestibility coefficients. Compared with fresh grass and silages, hay decreased lipolysis and biohydrogenation (BH) of dietary unsaturates in the rumen, resulting in similar flows of 18:2n-6 and 18:3n-3, but lower amounts of trans-11 18:1 and Δ11,13 18:2 at the omasum. The extent of silage fermentation had minimal influence on ruminal lipid metabolism. Treatments were not associated with changes in the relative abundance of specific bacteria known to be capable of BH or rumen protozoal numbers. In conclusion, conservation method altered forage lipids, the extent of lipolysis and BH in the rumen, and the flow of fatty acids at the omasum, in the absence of substantial changes in ruminal Butyrivibrio populations.

Dietary fish oil supplements modify ruminal biohydrogenation, alter the flow of fatty acids at the omasum, and induce changes in the ruminal Butyrivibrio population in lactating cows

Four lactating cows fitted with ruminal cannulae and fed a grass silage-based diet were used in a 4 × 4 Latin square with 28-d periods to investigate the effects of incremental dietary fish oil (FO) supplementation (0, 75, 150, or 300 g/d) on the flow of fatty acids at the omasum and populations of rumen bacteria capable of biohydrogenation. FO decreased silage intake and ruminal volatile fatty acid concentrations and promoted an increase in molar butyrate and propionate proportions at the expense of acetate. Extensive ruminal biohydrogenation of 20:5(n-3) and 22:6(n-3) resulted in corresponding increases in numerous 20- and 22-carbon unsaturated fatty acids at the omasum. Omasal flow of several 20-, 21-, and 22-carbon all-cis (n-3) PUFA exceeded the intake from FO. Supplements of FO also induced a dose-dependent decrease in 18:0 and increased trans 18:1 and trans 18:2 flow at the omasum. Trans-11 was the major 18:1 intermediate in digesta, while FO induced quadratic increases in trans-10 18:1 flow, reaching a maximum of 300 g/d. FO had no substantial influence on omasal flow of CLA. Results suggest that one or more fatty acids in FO inhibit the reduction of trans-18:1 and trans-18:2 intermediates by ruminal microorganisms. qPCR based on 16S rRNA genes in omasal digesta indicated that key Butyrivibrio spp. declined linearly in response to FO. Dose-dependent increases in ruminal outflow of biohydrogenation intermediates containing one or more trans double bonds in response to FO has major implications for host metabolism and the nutritional quality of ruminant foods.

Effects of ruminal infusion of garlic oil on fermentation dynamics, Fatty Acid profile and abundance of bacteria involved in biohydrogenation in rumen of goats

This study aimed to investigate the effects of ruminal infusion of garlic oil (GO) on fermentation dynamics, fatty acid (FA) profile, and abundance of bacteria involved in biohydrogenation in the rumen. Six wethers fitted with ruminal fistula were assigned to two groups for cross-over design with a 14-d interval. Each 30-d experimental period consisted of a 27-d adaptation and a 3-d sample collection. Goats were fed a basal diet without (control) or with GO ruminal infusion (0.8 g/d). Ruminal contents collected before (0 h) and at 2, 4, 6, 8, and 10 h after morning feeding were used for fermentation analysis, and 0 h samples were further used for FA determination and DNA extraction. Garlic oil had no influence on dry matter intakes of concentrate and hay. During ruminal fermentation, GO had no effects on total VFA concentration and individual VFA molar proportions, whereas GO increased the concentrations of ammonia nitrogen and microbial crude protein (p<0.05). Compared with control, GO group took a longer time for total VFA concentration and propionate molar proportion to reach their respective maxima after morning feeding. The ratio of acetate to propionate in control reduced sharply after morning feeding, whereas it remained relatively stable in GO group. Fatty acid analysis showed that GO reduced saturated FA proportion (p<0.05), while increasing the proportions of C18, t11-18:1 (TVA), c9,t11-conjugated linoleic acid (c9,t11-CLA), t10,c12-CLA, and polyunsaturated FA (p<0.05). The values of TVA/(c9,t11-CLA+TVA) and C18:0/(TVA+ C18:0) were reduced by GO (p<0.05). Real-time PCR showed that GO tended to reduce Butyrivibrio proteoclasticus abundance (p = 0.058), whereas GO had no effect on total abundance of the Butyrivibrio group bacteria. A low correlation was found between B. proteoclasticus abundance and C18:0/(TVA+C18:0) (p = 0.910). The changes of fermentation over time suggested a role of GO in delaying the fermentation process and maintaining a relatively modest change of ruminal environment. The inhibitory effects of GO on the final step of biohydrogenation may be related to its antibacterial activity against B. proteoclasticus and other unknown bacteria involved.

Extracellular polysaccharide-degrading proteome of Butyrivibrio proteoclasticus

Plant polysaccharide-degrading rumen microbes are fundamental to the health and productivity of ruminant animals. Butyrivibrio proteoclasticus B316(T) is a gram-positive, butyrate-producing anaerobic bacterium with a key role in hemicellulose degradation in the rumen. Gel-based proteomics was used to examine the growth-phase-dependent abundance patterns of secreted proteins recovered from cells grown in vitro with xylan or xylose provided as the sole supplementary carbon source. Five polysaccharidases and two carbohydrate-binding proteins (CBPs) were among 30 identified secreted proteins. The endo-1,4-β-xylanase Xyn10B was 17.5-fold more abundant in the culture medium of xylan-grown cells, which suggests it plays an important role in hemicellulose degradation. The secretion of three nonxylanolytic enzymes and two CBPs implies they augment hemicellulose degradation by hydrolysis or disruption of associated structural polysaccharides. Sixteen ATP-binding cassette (ABC) transporter substrate-binding proteins were identified, several of which had altered relative abundance levels between growth conditions, which suggests they are important for oligosaccharide uptake. This study demonstrates that B. proteoclasticus modulates the secretion of hemicellulose-degrading enzymes and ATP-dependent sugar uptake systems in response to growth substrate and supports the notion that this organism makes an important contribution to polysaccharide degradation in the rumen.

The large episomes of Butyrivibrio proteoclasticus B316T have arisen through intragenomic gene shuttling from the chromosome to smaller Butyrivibrio-specific plasmids

The genome of Butyrivibrio proteoclasticus B316(T) contains three large episomes including a 302 kb chromid (BPc2) and two large plasmids of 361 (pCY360) and 186 kb (pCY186). The two plasmids are largely cryptic and it is therefore difficult to gauge their contributions or importance to the biology of B. proteoclasticus. Here, we provide evidence that at least BPc2 and pCY360 are essential as neither could be cured using several previously described curing techniques. We show that BPc2 exists at a copy number of 1, while pCY360 and pCY186 exist at copy numbers of 4 and 0.9, respectively. Yet the transcriptional activities of each episome are much less than that of the 3.5 Mb chromosome. Codon usage analyses did not support the hypothesis that the genes of all three episomes were acquired horizontally. Instead our analyses suggest that the vast majority of genes on each episome were transferred from the 3.5 Mb B. proteoclasticus chromosome. Analysis of their replication origins, however, suggests the plasmid backbones share an evolutionary lineage with the smaller Butyrivibrio specific plasmids, pRJF1 and pRJF2. A survey of 13 species of the Butyrivibrio/Pseudobutyrivibrio assemblage identified similar large episomes in nine strains. DNA hybridization experiments revealed none contained an rRNA operon and only a 145 kb episome from Pseudobutyrivibrioruminis possessed an ortholog of the pCY360 plasmid replication initiation protein. The size and distribution of episomes within the nine strains of Butyrivibrio/Pseudobutyrivibrio showed no correlation with 16S rRNA based phylogeny, leading to a hypothesis that the large episomes of Butyrivibrio spp., have arisen through intragenomic gene transfer events from the chromosome to small horizontally acquired elements.

The effect of lipid supplements on ruminal bacteria in continuous culture fermenters varies with the fatty acid composition

A single flow continuous culture fermenter system was used in this study to investigate the influence of dietary lipid supplements varying in their fatty acid content on the DNA concentration of selected rumen bacteria. Four continuous culture fermenters were used in a 4 × 4 Latin square design with four periods of 10 d each. Treatment diets were fed at 45 g/d (DM basis) in three equal portions during the day. The diets were: 1) control (CON), 2) control with animal fat source (SAT), 3) control with soybean oil (SBO), and 4) control with fish oil (FO). Lipid supplements were added at 3% of diet DM. The concentrations of total volatile fatty acids and acetate were not affected (P>0.05) by lipid supplements. Concentrations of propionate, iso-butyrate, valerate and iso-valerate were highest (P<0.05) with the FO diet compared with the other treatment diets. The concentration of til C18:l (vaccenic acid, VA) in effluents increased (P<0.05) with SBO and FO diets and was highest with the SBO diet. The concentrations of C18:0 in effluents were lowest (P<0.05) for the FO diet compared with the other treatment diets. Concentrations of DNA for Anaerovibrio lipolytica, and Butyrivibrio proteoclasticus in fermenters were similar (P>0.05) for all diets. The DNA concentrations of Butyrivibrio fibrisolvens and Ruminococcus albus in fermenters were lowest (P<0.05) with the FO diet but were similar (P>0.05) among the other treatment diets. Selenomonas ruminantium DNA concentration in fermenters was highest (P<0.05) with the FO diet. In conclusion, SBO had no effect on bacterial DNA concentrations tested in this study and the VA accumulation in the rumen observed on the FO diet may be due in part to FO influence on B. fibrisolvens, R. albus, and S. ruminantium.

The glycobiome of the rumen bacterium Butyrivibrio proteoclasticus B316(T) highlights adaptation to a polysaccharide-rich environment

Determining the role of rumen microbes and their enzymes in plant polysaccharide breakdown is fundamental to understanding digestion and maximising productivity in ruminant animals. Butyrivibrio proteoclasticus B316^T is a Gram-positive, butyrate-forming rumen bacterium with a key role in plant polysaccharide degradation. The 4.4Mb genome consists of 4 replicons; a chromosome, a chromid and two megaplasmids. The chromid is the smallest reported for all bacteria, and the first identified from the phylum Firmicutes. B316 devotes a large proportion of its genome to the breakdown and reassembly of complex polysaccharides and has a highly developed glycobiome when compared to other sequenced bacteria. The secretion of a range of polysaccharide-degrading enzymes which initiate the breakdown of pectin, starch and xylan, a subtilisin family protease active against plant proteins, and diverse intracellular enzymes to break down oligosaccharides constitute the degradative capability of this organism. A prominent feature of the genome is the presence of multiple gene clusters predicted to be involved in polysaccharide biosynthesis. Metabolic reconstruction reveals the absence of an identifiable gene for enolase, a conserved enzyme of the glycolytic pathway. To our knowledge this is the first report of an organism lacking an enolase. Our analysis of the B316 genome shows how one organism can contribute to the multi-organism complex that rapidly breaks down plant material in the rumen. It can be concluded that B316, and similar organisms with broad polysaccharide-degrading capability, are well suited to being early colonizers and degraders of plant polysaccharides in the rumen environment.

Forage type and fish oil cause shifts in rumen bacterial diversity

Despite evidence supporting improved incorporation of beneficial polyunsaturated fatty acids (PUFA) into ruminant products, such as meat and milk, following red clover and fish oil (FO) inclusion in the ruminant diet, little is known regarding the concomitant bacterial diversity. We evaluated the effects of feeding grass vs. red clover silage with incremental FO inclusion on known lipolytic, biohydrogenating, cellulolytic and proteolytic rumen bacterial communities of steers. Following 14 days of dietary adaptation, liquid-associated (LAB) and solid-associated (SAB) bacterial communities were harvested, DNA extracted and bacterial denaturing gradient gel electrophoresis (DGGE) and specific-bacterial quantitative PCR (QPCR) were undertaken. DGGE-derived dendrograms showed that diet caused the greatest change in LAB and SAB bacterial diversity, with FO inclusion at the 2% and 3% dry matter intake also causing some changes. QPCR revealed that diet resulted in changes in the DNA concentration of Anaerovibrio lipolytica, the Butyrivibrio proteoclasticus group, Fibrobacter succinogenes, Ruminococcus albus and Ruminococcus flavefaciens. FO inclusion caused changes in A. lipolytica, F. succinogenes and R. flavefaciens DNA concentration only. In the B. proteoclasticus group, which are the only known bacteria with the capacity to biohydrogenate PUFA to 18:0, DNA concentration did not correlate to 18:0 flow to the duodenum, however, suggesting that other bacteria may play a role in biohydrogenation. A greater understanding of microbial changes that accompany beneficial dietary changes will lead to novel strategies to improve ruminant product quality.

Bacterial and protozoal communities and fatty acid profile in the rumen of sheep fed a diet containing added tannins

This study evaluated the effects of tannins on ruminal biohydrogenation (BH) due to shifts in the ruminal microbial environment in sheep. Thirteen lambs (45 days of age) were assigned to two dietary treatments: seven lambs were fed a barley-based concentrate (control group) while the other six lambs received the same concentrate with supplemental quebracho tannins (9.57% of dry matter). At 122 days of age, the lambs were slaughtered, and the ruminal contents were subjected to fatty acid analysis and sampled to quantify populations of Butyrivibrio fibrisolvens, which converts C(18:2) c9-c12 (linoleic acid [LA]) to C(18:2) c9-t11 (rumenic acid [RA]) and then RA to C(18:1) t11 (vaccenic acid [VA]); we also sampled for Butyrivibrio proteoclasticus, which converts VA to C(18:0) (stearic acid [SA]). Tannins increased (P < 0.005) VA in the rumen compared to the tannin-free diet. The concentration of SA was not affected by tannins. The SA/VA ratio was lower (P < 0.005) for the tannin-fed lambs than for the controls, suggesting that the last step of the BH process was inhibited by tannins. The B. proteoclasticus population was lower (-30.6%; P < 0.1), and B. fibrisolvens and protozoan populations were higher (+107% and +56.1%, respectively; P < 0.05) in the rumen of lambs fed the tannin-supplemented diet than in controls. These results suggest that quebracho tannins altered BH by changing ruminal microbial populations.

Short communication: Genome-wide scan for bovine milk-fat composition. II. Quantitative trait loci for long-chain fatty acids

We present the results of a genome-wide scan to identify quantitative trait loci (QTL) that contribute to genetic variation in long-chain milk fatty acids. Milk-fat composition phenotypes were available on 1,905 Dutch Holstein-Friesian cows. A total of 849 cows and their 7 sires were genotyped for 1,341 single nucleotide polymorphisms across all Bos taurus autosomes (BTA). We detected significant QTL on BTA14, BTA15, and BTA16: for C18:1 cis-9, C18:1 cis-12, C18:2 cis-9,12, CLA cis-9,trans-11, C18:3 cis-9,12,15, the C18 index, the total index, total saturated fatty acids, total unsaturated fatty acids (UFA), and the ratio of saturated fatty acids:unsaturated fatty acids on BTA14; for C18:1 trans fatty acids on BTA15; and for the C18 and CLA indices on BTA16. The QTL explained 3 to 19% of the phenotypic variance. Suggestive QTL were found on 16 other chromosomes. The diacylglycerol acyltransferase 1 (DGAT1) K232A polymorphism on BTA14, which is known to influence fatty acid composition, most likely explains the QTL that was detected on BTA14.