Rumen Of Animals Research Articles

Effect of sugarcane genotype and maturity stage at harvest on feed intake and ruminal parameters of growing steers

This experiment was conducted to evaluate the effect of altering fibre digestibility by genotype and maturity stage of sugarcane silage on intake, ruminal fermentation, ruminal kinetics, and rumen bacteria populations. Two genotypes with high or low NDF digestibility (NDFD) harvested for silage at early or late maturity were used in a 2 × 2 factorial arrangement of treatments: two genotypes and two maturity stages. Eight ruminally cannulated Nellore steers were used in a duplicated 4 × 4 Latin square design. Experimental diets were formulated with 40% sugarcane silage on DM basis. The DMI was greater when the animals were fed early-maturity sugarcane silage, but only with low-NDFD genotype. Intake of aNDFom was greater for early-maturity sugarcane diets than late-maturity sugarcane diets. Rumen pool of DM, aNDFom and iNDF were greater when diets with the low-NDFD genotype were fed. Turnover of aNDFom and daNDFom (digestible aNDFom), and aNDFom passage rate were greater when animals were fed high-NDFD sugarcane silage. Passage rate of aNDFom was greater when early-maturity sugarcane silage was provided. Ruminal pH was greater when early-maturity silages were fed, but only with high-NDFD genotype. Total SCFA concentration in the rumen was greater when early-maturity silages were fed, but only with low-NDFD genotype. Proportion of propionate was greater in the rumen of animals fed high-NDFD sugarcane genotype compared to animals fed low-NDFD sugarcane genotype. Megasphaera elsdenii population was greater when diets with late-maturity sugarcane silages were fed. There was a tendency for greater relative populations of Fibrobacter succinogenes and Ruminococcus albus when animals were fed low-NDFD sugarcane silage. In conclusion, feeding growing steers with high-NDFD sugarcane silage can positively affect rumen pool through faster passage rate and turnover of fibre that might benefit intake when metabolic pathways are not driving satiety.

Community dynamics of Neocallimastigomycetes in the rumen of yak feeding on wheat straw revealed by different primer sets

Abstract Anaerobic fungi (Neocallimastigomycetes) play an important role in fermenting lignin-rich plant biomass into sugars in the rumen of animals, representing a very promising enzyme resource to contribute to the conversion of plant biomass into biofuels. However, current studies about their functions mainly focus on limited species, and little is known about the coordination of different members of the anaerobic fungi in the digestion process of plant fibres. In this study, the community composition of anaerobic fungi in the rumens of yaks at five different time points (1, 3, 5, 7.5 and 24 h after feeding wheat straw) was investigated employing a cultivation-independent method using ITS clone libraries. Comparison of five pairs of primers showed that PCR primer sets could have clear amplification bias and therefore potentially affect the interpretation of the resulting fungal community structure; then two primer sets GM1/MNGM2 and ITS1/ITS4 were selected. Among the 398 sequences from 10 clone libraries, 18 operational taxonomic units (OTUs) of Neocallimastigomycetes were obtained, covering five known genera and one yet uncultured lineage. OTUs belonging to the bulbous-type morphotype (Caecomyces- or Cyllamyces-related) and the rhizoidal genus Neocallimastix were abundant and predominantly present, representing 62.7% and 19.3% OTUs respectively. In all the later samples taken from 3 h to 24 Neocallimastigomycetes h after feeding, a relatively stable community composition was revealed: members of Neocallimastix increased to represent 43.4–49.4% and the bulbous-type morphotype declined to represent 39.5–42.7%. This implies a substantial turnover and synergy between bulbous and rhizoidal morphotypes of anaerobic fungi during the process of fibre digestion. Our study provided the first insight into the in vivo temporal change in the anaerobic fungal community, and the role of Neocallimastigomycetes with a bulbous morphotype in the degradation of plant cell wall in the yak rumen.

Variables de la digesta en rumen de novillos y toros de lidia con diferencias en la procedencia y estación del año en las corridas taurinas del estado de Tlaxcala, México

El objetivo del estudio fue evaluar el peso corporal (PC), la edad y las variables digestivas en el rumen de los animales lidiados en eventos taurinos del estado de Tlaxcala durante un año. En veinte eventos taurinos se registró la procedencia (ganadería de Tlaxcala [GL]; ganadería fuera del estado de Tlaxcala [GF]) y la época de estudio (sequía y lluvia), registrándose las variables: PC, edad (dentición), peso de la digesta del rumen, contenido de la fibra detergente neutro (FDN), pH, ácidos grasos volátiles (AGV), conteo de protozoarios en rumen y la presencia de abscesos hepáticos. Los toros tuvieron mayor PC que los novillos (456 vs 361, p ≤ 0.05). En la estación de sequía se registró mayor PC (432 vs 405, p ≤ 0.05) que durante la estación de lluvia; presentando interacción estadística entre la clasificación (novillo o toro) y la estación (p ≤ 0.05). Los animales del GF tuvieron mayor contenido de la digesta que el GL (8.1 vs 7.25%, p ≤ 0.05). El pH ruminal fue menor en los novillos que en los toros (5.86 vs 6.54, p ≤ 0.05), al igual que el contenido de FDN (61.2 vs 64.7, p < 0.05). En conclusión, los novillos presentaron mayores problemas de acidosis ruminal que los toros. El reglamento taurino, con base al peso y edad de los animales, no es aplicado correctamente por las autoridades.

Paenibacillus 79R4, a potential rumen probiotic to enhance nitrite detoxification and methane mitigation in nitrate-treated ruminants

The effects of supplemental nitrate administered alone or with a denitrifying ruminal bacterium, designated Paenibacillus 79R4 (79R4) intentionally selected for enhanced nitrate- and nitrite-metabolizing ability, on select rumen fermentation characteristics was examined in vivo. Rumen and blood samples were collected from cannulated Holstein steers one day prior to and one day after initiation of treatments applied as three consecutive intra-ruminal administrations of nitrate, to achieve the equivalent of 83 mg sodium nitrate/kg body weight day, given alone or with the nitrite-selected 79R4 (provided to achieve 106 cells/mL rumen fluid). Results revealed a day effect on methane-producing activity, with rates of methane production by ruminal microbes being more rapid when collected one day before than one day after initiation of treatments. Nitrate-metabolizing activity of the rumen microbes was unaffected by day, treatment or their interaction. A day by treatment interaction was observed on nitrite-metabolizing activity, with rates of nitrite metabolism by rumen microbes being most rapid in populations collected one day after initiation of treatment from steers treated with nitrate plus 79R4. A day by treatment interaction was also observed on plasma methemoglobin concentrations, with concentrations being lower from steers one day after initiation of treatments than from collected one day prior to treatment initiation and concentrations being lowest in steers treated with nitrate plus 79R4. A major effect of treatment was observed on accumulations of most prominent and branched chain volatile fatty acids produced and amounts of hexose fermented in the rumen of animals administered nitrate, with concentrations being decreased in steers administered nitrate alone when compared to steers treated with nitrate plus the 79R4. These results demonstrate that the nitrite-selected Paenibacillus 79R4 may help prevent nitrite toxicity in nitrate-treated ruminants while maintaining benefits of reduced methane emissions and preventing inhibition of fermentation efficiency by the microbial ecosystem.

Signal level performance variation of radio frequency identification tags used in cow body

Ruminant diseases are strictly connected to pH and temperature values of the rumen. Therefore, the attenuation to dynamic measurement and tracking of both pH and temperature values through animal rumen has grown rapidly for decades. Reading performance of RFID tags depends on signal quality and signal level, and this can be understood by means of wave attenuation through tissue. In this article, attenuation through cow body is investigated for improving reading performance and battery life. Number of receiving antennas will be used in the system, their location and heights are critical for this aim. Signals from different points of animals' body are measured and compared with the signals spread just out of RFID tags. Equivalent dielectric constants of tissue between RFID tag and receiving antenna is modeled by using literature data, and finally simulation and analytical results are verified by measurement results. Measured value of attenuation through the cow body is varying between 25 dB and 87 dB for RFID tags operating at 434 MHz. Within the 30 m radius, the strongest signal is obtained at 50 cm height and taken from the left side of the animal body, which is offered as optimum communication position.

Lactobacilli as Probiotics and their Isolation from Different Sources

Probiotics play a pivotal role in health maintenance and prevention of many disorders. They are microbial feed supplements that confer the health effect on the host. Probiotics protects the body itself from infection, especially gastrointestinal tract. Acidophilus is a probiotic microorganisms that have a beneficial effect on the host. Lactobacilli acidophilus are friendly bacteria that normally live in our digestive, urinary and genital systems without causing disease. The therapeutic benefits have been investigated in women having vaginal and urinary tract infections. In this review, we studied about previous 15 years articles in which the isolation of Lactobacilli bacteria from different sources was mentioned. It has been found that they may be isolated from fruits and vegetables, human stool culture, natural antimicrobial agent, cheese, kefir grains, dairy and non-dairy products, fermented and raw milk, feces of breast fed infants, lactating milk, sheep, buffalo and cow milk, yogurt, beverages, poultry sources, animal rumen contents, pengging duck’s caecum, chicken intestine and fecal samples, chicken feed, enzymes, fermented rice, curd, meat and yeast extracts, glucose and sucrose, human gut, human colonial epithelial cells, human and animal vagina and mouth extraction, diapers of human babies, pineapples wastes, industrial sausages, ice-cream, small intestines of piglets, corn slurry, crop and intestinal ducks. Hence the paper reviews the current scenario of isolation of Lactobacilli from different sources, their proposed mechanisms and health benefits for human beings along with their future perspectives.

Nutritive evaluation and milk quality of including of tomato or olive by-products silages with sunflower oil in the diet of dairy goats

There are worldwide a number of by-products with a strong potential for use in animal feeding to cover purposes as farm economic profitability enhancement or searching of functional food ingredients. Probably fruit and vegetable industry (i.e. olive milling wastes) are amongst the most representative sectors. Two experiments were performed with lactating Murciano-Granadina goats. In Experiment 1 the objective was to assess the effect of the partial replacement of the forage in the diet with olive by-products or tomato silages supplemented with sunflower oil (SFO, 20g/kg DM) on the nutrient utilization, rumen fermentation parameters and microbial abundances, methane production and milk yield and composition. Eighteen goats were distributed in three experimental groups and fed control diet (CD) against diets containing olive by-products silage (OBSD) or tomato surplus silage (TSD). Both OBSD and TSD resulted in higher fat intake and apparent digestibility, higher digestible and metabolizable energy and total purine derivatives excretion. The rest of measured parameters remained unaffected. Diets OBSD and TSD promoted higher milk content in C18:1 trans-11, C20:2 and CLA. Milk fat of goats consuming TSD had the lowest content in C4:0, C6:0 and C8:0, while OBSD produced more total saturated FA (SFA) and less C18:1 n-9 cis and both total mono- and polyunsaturated FA. The acetate concentration was lower in the rumen of animals fed silages, while the butyrate and protozoa concentrations were higher in OBSD. The CH4 production (L/kg DMI) tended to be lower in goats consuming TSD. Experiment 2 was conducted to test the persistence (over 90 days) and in a larger number of animals (n=24) of the effects observed with TSD diet in experiment 1. The TS diet promoted higher DM intake and body weight and lower acetate:propionate ratio than CD, whereas milk yield and composition were not affected. The FA profile was modified by increases in SFA and reducing monounsaturated FA and CLA. It may be concluded that the strategy of partial replacement of conventional forage by local by-products silage combined with SFO supplementation is valuable nutritional strategy in dairy goats since it may improve the animal energy balance while ruminal fermentation, nutrients utilization and milk yield are not compromised.

Effects of fibre digestibility and level of roughage on performance and rumen fermentation of finishing beef cattle.

The objective was to evaluate effects of neutral detergent fibre (NDF) digestibility and level of fresh sugarcane on intake, body fatness, carcass characteristics, and rumen kinetics and fermentation of beef cattle. Forty-eight Nellore young bulls were used in a complete randomized block design with a 2×2 factorial arrangement of treatments. Eight rumen-cannulated Nellore steers were used in a replicated 4×4 Latin square design. Two sugarcane genotypes divergent for stalk NDF digestibility (NDFD) were used. Experimental diets were formulated with 20 or 40% of sugarcane on a dry matter (DM) basis. High-NDFD genotype associated with the lower level of roughage in the diet promoted greater DM intake, resulting in greater body gain. Sugarcane with high-NDFD increased final body weight, hot carcass weight, and back-fat thickness. Animals receiving the genotype with high NDFD had greater rump-fat thickness only with 40% sugarcane in the diet. Animals receiving the low-NDFD genotype at 20% of the diet had lower NDF passage rate. Rumen pH was greater for diets with greater NDF content. There was greater proportion of butyrate in the rumen of animals receiving diets with greater NDF content. In conclusion, high-NDFD sugarcane increased final body and carcass weight, HCW, and fat thickness. When associated with lower inclusion of roughage in the diet, it can also increase DM intake and body weight gain of beef cattle.

<i>In situ </i>ruminal degradability of protein feeds with distinct physical forms: a meta-analysis

In ruminant livestock, rumen undegradable protein (RUP) derived from the diet and microbial protein synthesized in the rumen are essential for animal survival, maintenance, growth, production, and reproduction. RUP is influenced by diet composition, physical form, and ruminal metabolism. Here, we aimed to evaluate the ruminal degradability of protein feeds with different physical forms (meal versus grain) through a meta-analysis study. A database, composed of 45 treatments from 12 studies carried out in Brazil, was evaluated to compare the degradability of soybean, sunflower, canola, and flaxseed grains with the meal forms of soybean, peanut, sunflower, cottonseed, and corn gluten. The degradation parameters of dry matter did not differ significantly between meals and grains. However, the effective degradability of crude protein at a passage rate of 2% per hour was higher in meals than in grains. Overall, it was concluded that meal protein might be more degradable in the rumen of animals on an energy intake lower than the maintenance. Keywords : Concentrated feed, metabolism, passage rate, processing, ruminants

Effects of defaunation on rumen fermentation features, feed intake, digestibility and animal performance

The objective of the review was to provide compiled information on the effects of defaunation on rumen fermentation features, feed intake, digestibility and animal performance for development workers, academic user’s, researchers and other interested readers. Defaunation is the selective removal of protozoa from the rumen of animals. Based on the most of information reviewed defaunation decreases rumen pH, ruminal ammonia concentration, methane emissions, fibre carbohydrate digestibility and organic matter digestibility, and it increases total volatile fatty acids concentration, numbers of bacteria, feed conversion efficiency and weight gain but it did not affect dry matter intake.

Isolation and Characterization of Tannic Acid Hydrolysing Bacteria from Soil

Soil around slaughter house is continuously inoculated with aerobic bacteria from rumen of animals. Ruminant microflora, is able to degrade phenolic compounds such as tannins. Soil containing ruminant micro flora near slaughter house is cultured on Bushnell and Hans's medium containing tannic acid. Three bacterial colonies were isolated, cultivated for identification which are then analysed for biochemical characterization and physiological characterization. Furthermore tannase activity and tannin protein degrading activity of each isolate were determined qualitatively.

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.

Differences in transcript abundance of genes on BTA15 located within a region associated with gain in beef steers

Using results from a previous GWAS, we chose to evaluate seven genes located within a 229Kb region on BTA15 for variation in RNA transcript abundance in a library of tissue samples that included adipose, liver, rumen papillae, spleen, muscle, and small intestine epithelial layers from the duodenum, ileum and jejunum collected from steers (n=14) with positive and negative residual GN near mean dry matter intake (DMI). The genes evaluated were two olfactory receptor-like genes (LOC525033 and LOC618173), RRM1, STIM1, RHOG, PGAP2, and NUP98. The rumen papillae transcript abundance of RHOG was positively correlated with residual GN (P=0.02) and ruminal STIM1 exhibited a trend towards an association with residual GN (P=0.08). The transcript abundance of one olfactory receptor (LOC618173) in the ileum was also positively associated with residual GN (P=0.02) and PGAP2 and LOC525033 in the ileum displayed trends for association with GN (P≤0.1). To further evaluate the differential expression detected in the ileum and rumen of these animals, the transcript abundance of STIM1 and RHOG in the rumen and of PGAP2 and the olfactory receptors in the ileum were assessed in an additional group of 32 animals with divergent average daily gain (ADG) and average daily feed intake (ADFI) collected over two groups. The olfactory receptor, LOC525033, was not expressed in the ileum for the majority of these animals. Only RHOG showed a slight, but non-significant trend towards greater expression in animals with greater gain. We have detected differences in the transcript abundance of genes within this region in the rumen and ileum of animals selected for greater and less residual gain; however, we were unable to validate the expression of these genes in the larger group of cattle possibly due to the differences in phenotype or contemporary group.

Comparison of Microbiological and Probiotic Characteristics of Lactobacilli Isolates from Dairy Food Products and Animal Rumen Contents.

Lactobacilli are employed in probiotic food preparations and as feed additives in poultry and livestock, due to health benefits associated with their consumption. The objective of this study was to evaluate and compare the probiotic potential of ten lactobacilli strains isolated from commercial dairy food products and animal rumen contents in New Zealand. Genetic identification of the isolates revealed that all belonged to the genus Lactobacillus, specifically the species L. reuteri, L. rhamnosus and L. plantarum. All isolates did not show any haemolytic behaviour. Isolates of dairy origin showed better tolerance to low pH stress. On the other hand, rumen isolates exhibited a higher tolerance to presence of bile salts. All isolates exhibited resistance to aminoglycoside antibiotics, however most were sensitive to ampicillin. Isolates of rumen origin demonstrated a higher inhibitory effect on Listeria monocytogenes, Enterobacter aerogenes and Salmonella menston. Bacterial adherence of all isolates increased with a decrease in pH. This screening study on lactobacilli isolates has assessed and identified potential probiotic candidates for further evaluation.

Feeding Oil Palm (Elaeis Guineensis, Jacq.) Fronds Alters Rumen Protozoal Population and Ruminal Fermentation Pattern in Goats

Oil palm fronds (OPF), normally available all the year round, may provide a sustainable ruminant feed for livestock industry in tropical regions. A feeding trial was conducted to study the effects of feeding OPF on the rumen protozoal population, rumen fermentation and fatty acid profiles of rumen fluid in goats. Twenty-four five-month-old Kacang crossbred male goats were individually housed and fed for 100 d with concentrate diets supplemented with oil palm (Elaeis guineensis Jacq.) frond pellets. The treatments were: CON (100% concentrate), MOPF (75% concentrate + 25% OPF, w/w) and HOPF (50% concentrate + 50% OPF, w/w). The diets were adjusted to be isocaloric. The pH of rumen fluid was in the order of HOPF (5.90)>MOPF (5.74)>CON (5.62). Both HOPF (17.75x104/mL) and MOPF (17.13x104/mL) had significantly (P<0.05) higher population of Entodinium sp. than CON (14.88x104/mL). Although populations of Holotrichs and total protozoa among the three groups did not show any significant difference (P>0.05), populations were in the numerical order of HOPF>MOPF>CON. The molar proportions of acetate were significantly higher (P<0.05) in HOPF animals compared to MOPF and CON. The altered status in the rumen environment due to supplementation of OPF in the diets resulted in the highest (P<0.05) amount of unsaturated fatty acids (UFA) in the rumen of animals receiving HOPF and MOPF diet. These results were suggestive of a decreased biohydrogenation in the rumen, resulting in higher levels of UFA available for hindgut absorption, and hence their increased incorporation in the plasma and edible tissues of the HOPF animals.

Impact of rumen emptying on rumen fermentation and animal welfare in cannulated sheep

Emptying the rumen of animals fitted with rumen cannulas is a regularly used experimental technique. This study in sheep aimed to evaluate whether total rumen emptying (TRE) results in disturbances in digestive parameters such as rumen pH, fermentation and microbial ecosystem, and whether it affects animal welfare. Eight adult wethers from two breeds offered hay and water ad libitum were rumen-emptied manually. Ruminal parameters were assessed 2 days before and 7 days after TRE. Welfare was assessed by measuring behavioural and cardiac responses to TRE involving human handling. Behavioural and cardiac measurements were performed (i) 2 h before, (ii) during and (iii) 2 h after the rumen emptying–filling session on wethers exposed to the same TRE operator. Results showed that TRE did not affect most of the digestive parameters analysed (ruminal pH, bacteria, methanogens) but did modify Dasytricha population and volatile fatty acid concentrations. Likewise, rumen emptying did not alter most behavioural and cardiac parameters, and we found no TRE-related change in fear reactions to the operator.

ÁCIDO LINOLEICO CONJUGADO: ESTRUTURA QUÍMICA, EFEITOS SOBRE A SAÚDE HUMANA E ANÁLISE EM LÁCTEOS

Conjugated linoleic acid (CLA) is the group of positional and geometric isomers of linoleic acid, which are naturally synthesized in the rumen of animals. The main dietary sources of CLA are milk, dairy products end meat from ruminant animals. For over two decades, numerous studies both in animals and in humans, have been linking CLA to several beneficial effects such as reduction of carcinogenesis, atherosclerosis,body fat mass and increase muscle mass. This study aimed to present an overview of current studies related to CLA, regarding the synthesis of CLA by lactic acid bacteria and in animals rumen, as well as the beneficial effects and scientifically proved ways to quantify, always emphasizing milk and milk products.

Atypical bacterial rRNA operon structure is prevalent within the Lachnospiraceae, and use of the 16S-23S rRNA internal transcribed spacer region for the rapid identification of ruminal Butyrivibrio and Pseudobutyrivibrio strains

The rumen is the fermentative forestomach of ruminant animals, and is host to a wide range of anaerobic bacteria whose primary function is to facilitate forage degradation. Butyrivibrio and Pseudobutyrivibrio are closely related proteolytic and fibrolytic genera within the family Lachnospiraceae, and are commonly isolated from the rumens of animals fed fibrous diets. The ribosomal RNA (rRNA) operon is an important phylogenetically informative locus that is present in multiple copies in bacterial genomes. Ribosomal RNA genes are typically arranged in the order 16S-23S-5S, with internal transcribed spacer (ITS) regions located between the genes. However, in the rumen bacterium, Butyrivibrio proteoclasticus B316, rRNA operons have a 16S-5S-23S rRNA gene arrangement, and analysis of bacterial genome projects revealed that this configuration was present in all publicly available complete genomes from members of the family Lachnospiraceae. The 16S-23S ITS region is commonly used to identify bacterial strains, thus we sought to determine the utility of this region from rumen Butyrivibrio and Pseudobutyrivibrio isolates for their rapid molecular identification. Polymerase chain reaction was used to amplify 16S-23S ITS regions, which were assessed for length polymorphism (ITS-LP), and restriction fragment length polymorphism (ITS-RFLP) using AluI, HaeIII and HhaI on a panel of 13 Butyrivibrio and Pseudobutyrivibrio reference strains. Cluster analysis of the resulting banding patterns revealed that while the ITS-LP method did not group the strains according to major Butyrivibrio and Pseudobutyrivibrio clades identified via 16S rRNA gene sequences, ITS-RFLP was more discriminative, and able to rapidly delineate the strains into these clades.

Coating of Mixed Commercial β-Mannanase and Phytase through Spraying on Capra Hircus Pelleted Feed

Pelleting ingredients were processed and subsequently coated homogeneously with mixed solution of β-mannanase and phytase. The objective of this study was to evaluate the efficiency of enzyme coated and colour measurement on goat pelleted feed containing mixed commercial enzymes. The coated enzymes efficiency (%) and colour characteristic of feed were investigated. The high percentage of coating efficiency was obtained. After sprayed pellet demonstrated darker colour of brown compared to initial pellet. High coating efficiency and determination colour values are important attributes for initial step towards enzymes delivery in animal rumen and attributes to the value-added characteristic of the pellet, respectively.

Rumen Methanogenic Genotypes Differ in Abundance According to Host Residual Feed Intake Phenotype and Diet Type

Methane is an undesirable end product of rumen fermentative activity because of associated environmental impacts and reduced host feed efficiency. Our study characterized the rumen microbial methanogenic community in beef cattle divergently selected for phenotypic residual feed intake (RFI) while offered a high-forage (HF) diet followed by a low-forage (LF) diet. Rumen fluid was collected from 14 high-RFI (HRFI) and 14 low-RFI (LRFI) animals at the end of both dietary periods. 16S rRNA gene clone libraries were used, and methanogen-specific tag-encoded pyrosequencing was carried out on the samples. We found that Methanobrevibacter spp. are the dominant methanogens in the rumen, with Methanobrevibacter smithii being the most abundant species. Differences in the abundance of Methanobrevibacter smithii and Methanosphaera stadtmanae genotypes were detected in the rumen of animals offered the LF compared to the HF diet while the abundance of Methanobrevibacter smithii genotypes was different between HRFI and LRFI animals irrespective of diet. Our results demonstrate that while a core group of methanogen operational taxonomic units (OTUs) exist across diet and phenotype, significant differences were observed in the distribution of genotypes within those OTUs. These changes in genotype abundance may contribute to the observed differences in methane emissions between efficient and inefficient animals.