Effect of flow parameters of rumen digesta on effective degradability and microbial yield in sheep

The aim of this experiment was to examine the effect of rumen digesta flow parameters on effective degradability (EDG) and microbial nitrogen (MBN) yield in sheep fed diets of identical provision of both metabolizable energy and rumen degradable nitrogen (RDN). Ruminal degradation parameters of early‐harvested perennial ryegrass hay (EH), late‐harvested perennial ryegrasses hay (LH) and winter sown barley straw (BS) were determined by a nylon bag technique. Subsequently, three experimental diets (EHD, LHD and BSD) were formulated using the tested forages, sucrose and urea as supplements. An in vivo feeding study was conducted using four rumen cannulated sheep in a partial Latin square design. Digestibility, rate constants of rumen particle breakdown and passage, ruminal fermentation parameters and MBN supply to the small intestine were determined. Animals thoroughly consumed the forages fed at a restricted level. Digestion coefficients were greater for EHD than for LHD and were lowest for BSD (P < 0.05). The rate constant of large particle breakdown was 4.3, 5.9 and 6.7 %/h, respectively, and small particle passage was 5.3, 4.7 and 6.3 %/h for EHD, LHD and BSD, respectively. The estimates differed (P < 0.05) between the diets. The overall passage rate constant of total rumen particles was estimated to be higher for BSD than that for EHD or LHD (P < 0.05). Ruminal fermentation parameters were unaffected by dietary treatments (P > 0.05). Intake levels of rumen degradable organic matter (RDOM) and RDN were estimated to be greater for LHD than that for EHD or BSD (P < 0.05). Although dietary arrangements were made to give identical microbial efficiency, the estimated value was higher for EHD than that for LHD or BSD (P < 0.05); and the MBN yield for BSD was estimated to be lower than that for EHD or LHD (P < 0.05). Rumen kinetic parameters of degradation and particle flow of forage affected EDG values and MBN yield from forage‐related RDN intake, although those had little effect on the efficiency of MBN yield from forage‐related RDOM intake.     

Quantitative studies of the in vitro production of pipecolic acid by rumen protozoa and its degradation by rumen bacteria

An in vitro study was conducted to quantitatively investigate the metabolism of pipecolic acid (Pip), a neuromodulator, by mixed rumen bacteria (B), mixed rumen protozoa (P), a combination of B and P (BP), species‐enriched rumen protozoal suspension (Polyplastron sp., Diploplastron sp., entodinia and Entodinium caudatum) and pure cultures of several isolates of rumen bacteria (Prevetolla bryantii, Prevetolla albensis, Streptococcus bovis, Veillonella parvula, Megasphaera elsdenii and Ruminococcus albus). Only P produced Pip from L‐lysine (1.0 mmol/L L‐Lys) at a rate of 83.5 ± 1.6 µmol/L/h and even in BP, Pip was produced from L‐Lys by P and increased at a rate of 31.2 ± 3.8 µmol/L/h. Pip production by P was highest when the substrate (L‐Lys) concentration was 6 mmol/L and then the rate was 580 ± 36 µmol/L/h. Pipecolic acid production by P suspension enriched with different species of protozoa showed that Polyplastron sp. had the highest Pip production rate of 0.907 ± 0.092 µmol/L/mg protozoal protein per h, and Diploplastron sp. had the lowest rate of 0.55 ± 0.13 µmol/L/mg protozoal protein per h. The addition of D‐Lys (1.0 mmol/L) as a substrate to the P suspension revealed that P were also able to produce Pip from D‐Lys, though at a lower rate (1/3) compared with L‐Lys (1.0 mmol/L), suggesting the presence of epimerases in P. It was confirmed that B were unable to produce Pip from L‐ or D‐Lys. Only B degraded Pip (1.0 mmol/L) after a lag phase at a rate of 56.0 ± 1.5 µmol/L/h. The B suspension was able to degrade D‐Lys, though the products were not identified. Pip degradation by pure culture of some species of rumen bacteria showed that P. bryantii and R. albus had the highest rate followed by P. albensis, S. bovis and M. elsdenii with a low rate of Pip degradation. Veillonella parvula showed no ability to degrade Pip. The results suggest that a fairly large proportion of rumen‐produced Pip is likely to be absorbed by the host animal before degradation by rumen bacteria.     

Effect of bromochloromethane and fumarate on phylogenetic diversity of the formyltetrahydrofolate synthetase gene in bovine rumen

Effect of the methane inhibitor, bromochloromethane (BCM) and dietary substrate, fumarate, on microbial community structure of acetogen bacteria in the bovine rumen was investigated through analysis of the formyltetrahydrofolate synthetase gene (fhs). The fhs sequences obtained from BCM‐untreated, BCM‐treated, fumarate‐untreated and fumarate‐treated bovine rumen were categorized into homoacetogens and nonhomoacetogenic bacteria by homoacetogen similarity scores. Phylogenetic tree analysis indicated that most of the fhs sequences categorized into homoacetogens were divided into nine clusters, which were in close agreement with a result shown in a self‐organizing map. The diversity of the fhs sequences from the BCM‐treated rumen was significantly different from those from BCM‐non‐treated rumen. Principal component analysis also showed that addition of BCM to the rumen altered the population structure of acetogenic bacteria significantly but the effect of fumarate was comparatively minor. These results indicate that BCM affects diversity of actogens in the bovine rumen, and changes in acetogenic community structure in response to methane inhibitors may be caused by different mechanisms.     

ORIGINAL ARTICLE: Description of development of rumen ecosystem by PCR assay in milk‐fed,weaned and finished lambs in an intensive fattening system

This study examined the reticulo‐rumen characteristics of the microbial community and its fermentative characteristics in milk‐fed, at weaning and finished lambs in a conventional fattening system. Five lambs were assigned to each of three groups: milk‐fed lambs slaughtered at 30 days (T30), weaned lambs slaughtered at 45 days (T45) and ‘finished lambs’ slaughtered at 90 days (T90). At slaughter, rumen size, fermentation parameters (pH, volatile fatty acids and microbial enzyme activity) and protozoal counts were recorded. Quantitative PCR was used to quantify the genes encoding 16S and 18S ribosomal DNA of the rumen bacterial and protozoal populations, respectively, and the sequential colonization of the rumen by cellulolytic (Ruminococcus albus, Ruminococcus flavefaciens) and amylolytic (Prevotella ruminicola, Streptococcus bovis) bacteria, and protozoa (Entodinium sp.). Denaturing gradient gel electrophoresis was used to study the development of rumen microbiota biodiversity. Intake of solid food before weaning caused a significant increase in rumen weight (p < 0.0001) and bacterial DNA (p < 0.05) and volatile fatty acid analysis concentration (p < 0.01), whereas pH declined. In milk‐fed lambs, cellulolytic bacteria were evident after 30 days. Thereafter, in the 45‐day and 90‐day groups, the proportions of R. flavefaciens decreased and R. albus increased. Amylolytic bacteria were present in milk‐fed lambs; the proportion of P. ruminicola increased in fattening lambs and S. bovis was the least abundant species. Protozoal concentrations were irregular; milk‐fed lambs had a significant number of protozoa species from Entodinium and subfamily Isotrichiidae, but they disappeared at weaning. Lamb rumen were refaunated in some individuals at 90 days (Entodinium and subfamily Diplodiniinae spp.), although individual concentrations were variable.     

In vitro metabolism of tyrosine by rumen bacteria, protozoa and their mixture

An anaerobic in vitro study of tyrosine (Tyr) metabolism by rumen bacteria (B), protozoa (P) and their mixture (BP) was conducted using an HPLC analytical method to obtain some basic and systematic information on aromatic amino acid metabolism in the rumen. Most of the Tyr (> 96%) disappeared after 12 h incubation in B and BP, but only 58% in P. Tyr was converted mainly to p‐hydroxyphenylacetic acid (HPA) in all microbial suspensions. About 45% of disappeared Tyr in B and P, and about 35% in BP were converted to HPA. An appreciable amount of phenylalanine (Phe), 13 and 3% of disappeared Tyr, and a small amount of tryptophan (Trp), 8 and 1% of disappeared Tyr, were also produced from Tyr by rumen bacteria and protozoa, respectively. Small amounts of p‐hydroxyphenylpyruvic acid (about 4 and 6% of disappeared Tyr) were produced from Tyr in B and P, respectively. A moderately large amount of phenylacetic acid (14% of disappeared Tyr) was produced from Tyr in P which was 1.9 times higher than that in B. Phenylpropionic acid and p‐hydroxybenzoic acid were produced only in B and BP. It was concluded that the Tyr degradation ability of rumen bacteria was about 1.5 times higher than that of rumen protozoa. Degraded Tyr mainly produces HPA and then two other aromatic amino acids, Phe and Trp, which are considered essential amino acids for ruminants. Therefore, it is speculated that the requirement for Phe and Trp in ruminants may be partially fulfilled if Tyr is sufficiently supplied in rations.     

The impact of rumen cannulation on the microbial community of goat rumens as measured using 16S rRNA high‐throughput sequencing

The main objective of this study was to determine the impact of rumen cannulation on the microbial community of goat rumens using 16S rRNA high‐throughput sequencing. Twelve Boer crossbred goats were used in the experiment: six goats were surgically fitted with rumen cannula, and the other six were used as controls. All goats were fed the same diet for 20 days, after which their rumen digesta were sampled once per week for three consecutive weeks. Total microbial DNA was extracted from the collected rumen fluid and was used as a template to amplify the V4 hypervariable region of the 16S rRNA gene. High‐throughput sequencing was performed using an Illumina MiSeq platform, and the sequences were analyzed primarily using the Quantitative Insights into Microbial Ecology pipeline software. The results showed that the Chao 1 index, the observed species index and the Shannon‐Wiener index were not significantly different (p > 0.05) between the two groups. Bacteroidetes, Firmicutes, Tenericutes were the predominant phylum in both groups, and their relative abundance was 60.63%, 29.48%, 2.24% (n = 6, CT group) and 61.17%, 26.92%, 1.66% (n = 6, RC group) respectively. At the phylum level, the relative abundance of Proteobacteria was significantly higher (p < 0.001) in the microbial communities of RC goats, and Planctomycetes and Chloroflexi were significantly lower (p = 0.02). The abundances of other phyla were not significantly different between treatments. A total of 19 lower‐level taxa also exhibited significant differences (p < 0.05) in relative abundance between the groups. In addition, there were 18 genera shared within the control group, 26 shared within the rumen‐cannulated group, and 16 shared by both groups. Prevotella was the most abundant shared genus, although its abundance was not significantly different (p > 0.05) between the groups. In conclusion, although the most abundant microbes kept stable, rumen cannulation had the potential to significantly change rumen microbial communities in goats.     

A quantitative study on arginine catabolism by mixed ruminal bacteria,protozoa and their mixture in vitro

The catabolism of arginine (Arg) by mixed rumen bacteria (B), mixed rumen protozoa (P), and their mixture (BP) was quantitatively investigated in an in vitro system in order to confirm the metabolic pathway of Arg and provide basic information for enzymatic and molecular studies as well as an understanding of the quantitative distribution of metabolites. Rumen microbial suspensions (B, P, and BP) collected from fistulated goats were anaerobically incubated with or without 1 mmol/L Arg at 39°C for 12 h. Arg and other related compounds such as citrulline (Cit), ornithine (Orn), proline (Pro) and 5‐aminovaleric acid (5AV) in both supernatant and hydrolyzates of B, P, and BP suspensions were analyzed by HPLC. The metabolic pathways of Arg in mixed rumen bacteria and mixed rumen protozoa were considered to be as follows: rumen bacteria, Arg → Cit → Orn → Pro → 5AV → VFAs + NH₃; rumen protozoa, Arg → Cit → Orn → Pro → 5AV. The disappearance of Arg (1 mmol/L) was approximately 52.9 and 88.2% in B, 33.9 and 55.6% in P, and 52.8 and 85.2% in BP during 6 and 12 h incubations, respectively. When expressed in units of ‘per gram (g) of microbial nitrogen (MN)’, the net degradation rate of Arg in BP (50.3 µmol/g MN/h) was approximately 46% lower than that of B during a 12 h incubation period. The presence of protozoa tended to inhibit the production of Orn from Cit and the production of 5AV from Pro which were thought to be rate‐limiting steps of Arg metabolism in rumen microorganisms. As a result, protozoa appeared to have a saving effect on Arg metabolism, that is, protozoa protected Arg from wasteful exhaustion in the rumen.     

Ruminal fermentation and microbial ecology of buffaloes and cattle fed the same diet

Although buffaloes and cattle are ruminants, their digestive capabilities and rumen microbial compositions are considered to be different. The purpose of this study was to compare the rumen microbial ecology of crossbred water buffaloes and cattle that were fed the same diet. Cattle exhibited a higher fermentation rate than buffaloes. Methane production and methanogen density were lower in buffaloes. Phylogenetic analysis of Fibrobacter succinogenes‐specific 16S ribosomal RNA gene clone library showed that the diversity of groups within a species was significantly different (P < 0.05) between buffalo and cattle and most of the clones were affiliated with group 2 of the species. Population densities of F. succinogenes, Ruminococcus albus and R. flavefaciens were higher until 6 h post‐feeding in cattle; however, buffaloes exhibited different traits. The population of anaerobic fungi decreased at 3 h in cattle compared to buffaloes and was similar at 0 h and 6 h. The diversity profiles of bacteria and fungi were similar in the two species. The present study showed that the profiles of the fermentation process, microbial population and diversity were similar in crossbred water buffaloes and crossbred cattle.     

Induction of a transient acidosis in the rumen simulation technique

Feeding high concentrate diets to cattle results in an enhanced production of short‐chain fatty acids by the micro‐organisms in the rumen. Excessive fermentation might result in subclinical or clinical rumen acidosis, characterized by low pH, alterations in the microbial community and lactate production. Here, we provide an in vitro model of a severe rumen acidosis. A transient acidosis was induced in the rumen simulation technique by lowering bicarbonate, dihydrogen phosphate and hydrogen phosphate concentrations in the artificial saliva while providing a concentrate‐to‐forage ratio of 70:30. The experiment consisted of an equilibration period of 7 days, a first control period of 5 days, the acidosis period of 5 days and a second control period of 5 days. During acidosis induction, pH decreased stepwise until it ranged below 5.0 at the last day of acidosis (day 17). This was accompanied by an increase in lactate production reaching 11.3 mm at day 17. The daily production of acetate, propionate and butyrate was reduced at the end of the acidosis period. Gas production (methane and carbon dioxide) and NH₃‐N concentration reached a minimum 2 days after terminating the acidosis challenge. While the initial pH was already restored 1 day after acidosis, alterations in the mentioned fermentation parameters lasted longer. However, by the end of the experiment, all parameters had recovered. An acidosis‐induced alteration in the microbial community of bacteria and archaea was revealed by single‐strand conformation polymorphism. For bacteria, the pre‐acidotic community could be re‐established within 5 days, however, not for archaea. This study provides an in vitro model for a transient rumen acidosis including biochemical and microbial changes, which might be used for testing feeding strategies or feed additives influencing rumen acidosis.     

Effect of donor animals and their diet on in vitro nutrient degradation and microbial protein synthesis using grass and corn silages

Two nonlactating cows and two wether sheep, all fitted with a permanent cannula into the rumen, were fed either hay plus concentrate, grass silage or corn silage to study the effect of the donor animal and its diet on in vitro fermentation and microbial protein synthesis. Rumen inoculum was obtained before the morning feeding. Grass silage or corn silage was incubated in a semi‐continuous rumen simulation system for 14 days. Four replicated vessels were used per treatment. Degradation of crude nutrients and detergent fibre fractions as well as microbial protein synthesis and the production of volatile fatty acids were studied. Additionally, total gas and methane production was measured with a standard in vitro gas test. Gas production and methane concentration was higher when the inoculum used was from sheep than that from cows. The donor animal also affected the degradation of organic matter and ether extract as well as the amount of propionate and butyrate, and the acetate‐to‐propionate ratio. The effect of the diet fed to the donor animal on fermentation was much greater than the effect of the donor animal itself. Feeding hay plus concentrate resulted in higher gas production and degradation of acid detergent fibre, but in lower degradation of ether extract and reduced microbial protein synthesis. Additionally, the pattern of volatile fatty acids changed significantly when the diet of the donor animals was hay plus concentrate or one of the silages. These results show that in vitro fermentation and microbial protein synthesis is different when based on inoculum from either cattle or sheep. The diet fed to the donor animal is more important than the animal species and is probably mediated by an adjusted microbial activity. With regard to standardized feed evaluations, these results further support the need to harmonize in vitro approaches used in different laboratories.     

Provision of beta‐glucan prebiotics (cellooligosaccharides and kraft pulp) to calves from pre‐ to post‐weaning period on pasture

We conducted two feeding experiments to evaluate the effects of supplementation with either cellooligosaccharide or kraft pulp on growth performance in grazing beef calves (Japanese Black) from 4 weeks pre‐weaning to 12 to 16 weeks post‐weaning. In Experiment 1 (20‐week duration), nine calves (2.9‐month‐old females) were assigned to either a control group (CON) or an experimental group (CEL) fed cellooligosaccharide at a rate of 10 g/day mixed with concentrate. Average daily weight gain tended to be greater in CEL than in CON, especially after 1 month of weaning. In Experiment 2 (16‐week duration), 10 calves (2.0‐month‐old females) were assigned to either a control group or an experimental group (KRA) fed kraft pulp at a rate of 10% replacement of total digestible nutrients with concentrate. The proportion of fibrolytic bacteria increased and that of methanogenic Archaea decreased in the rumen microbial community composition of KRA calves in Experiment 2, whereas the decrease in Fibrobacter and Archaea was observed in CEL calves at first 4 weeks in Experiment 1. We conclude that beta‐glucan prebiotic supplementation to grazing calves at pre‐weaning would affect rumen microbial composition and modified rumen fermentation characteristics, leading to a better rumen environment via different means.     

Microbial population in the rumen of swamp buffalo (Bubalus bubalis) as influenced by coconut oil and mangosteen peel supplementation

Four, rumen fistulated swamp buffalo bulls were used to study microbial populations in the rumen when supplemented with coconut oil and mangosteen peel. Animals were randomly assigned to a 4 × 4 Latin square design. Four treatments were un‐supplemented (Control), supplementation with coconut oil at 50 g/kg (CO5), supplementation with mangosteen peel at 30 g/kg (MP3) and supplementation with CO5 and MP3 (COM), of total DM intake. Animals received concentrate at 10 g/kg of BW, and rice straw was given ad libitum. Abundance of total bacteria was increased by CO5 supplementation, whereas populations of protozoa and Fibrobacter succinogenes were reduced by CO5 and COM supplementation. Dietary supplementation did not affect methanogen, Ruminococcus flavefaciens or Ruminococcus albus abundances. Dietary treatments changed denaturing gradient gel electrophoresis (DGGE) band patterns of methanogens and protozoa when compared with the control group, especially when supplemented with MP3. Supplementation of COM resulted in the greatest difference in pattern of DGGE bands for total bacteria compared with the control. Coconut oil and mangosteen peel supplementation resulted in changing of rumen microbial abundances and communities; however, combination of them could be more benefit to improve rumen fermentation of swamp buffalo fed on rice straw.     

Effects of supplementing an active dry yeast product on rumen microbial community composition and on subsequent rumen fermentation of lactating cows in the mid‐to‐late lactation period

The effects of supplementing feed of cows in mid‐to‐late lactation with an active yeast product (Actisaf Sc 47) were evaluated using 15 Holstein cows in a replicated 3 × 3 Latin square design. The animals were fed a mixed ration with 33% neutral detergent fiber, consisting of timothy hay (29.8%), a commercial concentrate (70.0%) and commercial calcium triphosphate (0.2%), twice daily to meet 105% of their energy requirement. Yeast supplement was set at 0, 5 and 10 g per day over 21‐day periods, each of which consisted of 14 days for adaptation followed by 7 days of data collection. Milking performance, plasma metabolite parameters, rumen volatile fatty acids, lipopolysaccharide and microbial properties were measured. Although there were no significant differences in feeding and milking performance or blood parameters associated with supplementation, the acetate to propionate ratio in the rumen fluid tended to decrease (P = 0.08). The population of Bacteroidetes tended to be less prominent (P = 0.07) and the fibrolytic bacterium Fibrobacter significantly increased (P < 0.05) in the rumen fluid of the yeast 10 g group compared with that of the control. These data suggest that effects of supplementing live yeast to cows in mid‐to‐late lactation may be limited to microbial composition and fermentation characteristics in the rumen.     

Comparison of feed intake,digestion and rumen function among domestic ruminant species grazing in upland vegetation communities

This study aimed to compare feed intake, digestion, rumen fermentation parameters and bacterial community of 5 beef cows, 12 crossed ewes and 12 goats grazing together in spring–early summer on heather–gorse vegetation communities with an adjacent area of improved pasture. Organic matter intake (OMI) and digestibility (OMD) were estimated using alkane markers. Ruminal fluid samples were collected for measuring fermentation parameters, and studying the bacterial community using terminal restriction fragment length polymorphism (T‐RFLP). Spot samples of urine were taken to determine purine derivative (PD) and creatinine concentrations to estimate microbial protein synthesis in the rumen. Herbaceous species were the main dietary component in all animal species. Cattle had higher (p < 0.05) daily OMI (g/kg LW^0.75) and OMD, whereas sheep and goats showed similar values. The highest ammonia concentration was observed in sheep. Total VFA, acetate and butyrate concentrations were not influenced by animal species, while propionate concentrations in goats were 1.8 times lower (p < 0.05) than in sheep. Acetate:propionate ratio was greater (p < 0.05) in goats, whereas cattle excreted more allantoin (p < 0.05). Estimated supply of microbial N was higher in cows (p < 0.01), whereas the efficiency of microbial protein synthesis was lower (p < 0.01) in this animal species. Hierarchical clustering analysis indicated a clear effect of animal species on rumen bacterial structure. Differences among animal species were also observed in the relative frequency of several T‐RFs. Certain T‐RFs compatible with Lachnospiraceae, Proteobacteria and Clostridiales species were not found in goats, while these animals showed high relative frequencies of some fragments compatible with the Ruminococcaceae family that were not detected in sheep and cattle. Results suggest a close relationship between animals’ grazing behaviour and rumen bacterial structure and its function. Goats seem to show a greater specialization of their microbial populations to deal with the greater fibrous and tannin content of their diet.     

Effects of dietary Greek oregano (Origanum vulgare ssp. hirtum) supplementation on rumen fermentation,enzyme profile and microbial communities in goats

This study was conducted to examine in vivo long‐term effects of dietary dried oregano (Origanum vulgare ssp. hirtum) whole plant on rumen fermentation, enzyme profile and microbial communities. For this purpose, eight healthy, adult, non‐lactating Alpine goats were kept in tie stalls equipped for individual feeding and randomly divided into two homogeneous groups: one fed 0.6 kg of a concentrate mixture and 0.6 kg of wheat straw without any supplementation and served as control group (CON) while the other group (OR) fed the same diet of CON but supplemented with 20 g of dried oregano plants (OPs) to provide daily dosage of 1 ml of essential oil (EO) per animal. The experimental period lasted 69 days and individual rumen fluid samples were obtained every 2 weeks at 0 and 4 hr after feeding. The results showed that dietary supplementation with OPs increased the protease activity (p < .001) and ammonia concentration (p < .05) in the rumen. Among the studied microbial populations, Peptostreptococcus anaerobius (p = .028) and Clostridium sticklandii (p < .001) were found to be the most sensitive to oregano at the current dosage. Furthermore, the total methanogen population significantly decreased (p < .05). It is concluded that a long‐term dietary administration of OPs can suppress specific rumen micro‐organisms and modify rumen fermentation favourably at least by means of suppressing methanogens.     

瘤胃能氮同步释放对奶牛微生物蛋白合成和瘤胃发酵的影响

本研究通过体外产气试验,研究瘤胃能氮同步释放对微生物蛋白合成和瘤胃发酵的影响。试验选用4头健康、泌乳中期的荷斯坦奶牛作为瘤胃液供体动物,采用单因子试验设计,设置3种不同能氮同步化指数的等能、等氮日粮(日粮A,SI=0.74;日粮B,SI=0.83;日粮C,SI=0.91)。结果表明,随着日粮SI值增加,微生物蛋白合成量显著增加(P<0.05)、氨氮浓度在8和12 h极显著下降(P<0.01);A组与B组相比,在8 h时,产气量、pH达到了显著或极显著差异(P<0.05;P<0.01),12 h时,挥发性脂肪酸含量达到了极显著差异(P<0.01)。结果显示,日粮能氮同步释放可显著影响瘤胃微生物蛋白的合成量和氨氮浓度。     

Analysis of methanogenic archaeal communities of rumen fluid and rumen particles from Korean black goats

Molecular diversity of methanogens in the rumen of Korean black goats was investigated with 16S rRNA gene clone libraries using methanogen‐specific primers. The libraries were composed of rumen fluid‐associated methanogens (FAM) and rumen particle‐associated methanogens (PAM) from rumen‐fistulated Korean black goats. Among the 141 clones of the FAM library, the sequences were mostly related to two phyla, the Methanobacteriaceae family (77.3%) and the Thermoplasmatales family (22.7%); and among the 68 clones of the PAM library, sequences were also mainly clustered in the two phyla, the Thermoplasmatales family (63.24%) and the Methanobacteriaceae family (35.29%). Most of the sequenced clones in the two libraries were closely related to uncultured methanogenic archaeon. Quantitative real‐time PCR revealed that PAM (8.97 log 10) had significantly higher (P < 0.01) density of methanogens by the methanogenic 16S rRNA gene copies than FAM (7.57 log 10). The two clone libraries also showed difference in Shannon index (FAM library 1.70 and PAM library 1.59) and Chao 1 estimator (FAM library 18 and PAM library 17 operational taxonomic units). Apparent differences found in the microbial community from the two 16S rRNA gene libraries could be a result of such factors as the chemical and physical nature of the target material surface, types or component of diets, the interaction between the methanogens and other microbes, and age of the experimental goats.     

Using a novel macro in vitro technique to estimate differences in absorption rates of volatile fatty acids in the rumen

A novel macro in vitro system was used to test the theory that rumen proportions of acetate, propionate and butyrate are not representative of their respective net production rates. Whole rumen content (10–16 kg) from two cows was mixed with a bicarbonate buffer and incubated separately in two 40‐l in vitro vessels for 3 h. A total of six experimental periods were used. In this study, a total of six cows were used and fed 1/8 of the daily ration by hand every 3 h. To obtain differences in rumen volatile fatty acids (VFA) composition, 1 l of acetate (416 mm ), propionate (108 mm ), butyrate (79 mm ), lactic acid (300 mm ) or nothing was infused during 24 h into the rumen before collection of representative samples of rumen contents. Infusions of acids were then continued during the in vitro incubations in exact proportion to the digesta removed from the rumen. In Periods 1 and 2, the cows were alternatively infused with acetate or nothing. In Periods 3 and 4, the infusions consisted of propionate or butyrate and in Periods 5 and 6 of lactate or nothing. Nine liquid samples were obtained between 3 and 180 min after the start of incubation and analysed for concentrations of VFA. Changes in proportions of individual VFA were estimated by linear regression. No differences in VFA proportions were observed in the absence of infusion (p > 0.5) over time, but when individual VFA were infused, their respective proportions increased. This was interpreted as the result of a decreased in vitro fermentation rate of digesta substrates compared with that in the rumen. Lactate infusion increased butyrate proportion in vitro. It is concluded that this study could not provide any evidence that ruminal VFA proportions are unrepresentative of the proportions of net production.     

Using a complex non-TDN based model (the DVE/OEB system) to predict microbial protein synthesis, endogenous protein, degradation balance, and total truly absorbed protein supply of different varieties of cereal oats for ruminants

Recently a new super‐genotype of oat has been developed in the Crop Development Center called CDC SO‐I (‘SuperOat’: low lignin and high fat). In a previous study, we evaluated total metabolizable protein using a TDN‐based model‐NRC‐2001 which is popular in North America. However, the TDN‐based NRC model is not accepted universally. The objectives of this study were to use a complex non‐TDN based model, the DVE/OEB system, to evaluate potential nutrient supply to ruminants from the SuperOat in comparison with two normal varieties of oats (CDC Dancer and Derby) in western Canada. The quantitative predictions were made in terms of: (i) truly absorbed rumen synthesized microbial proteins in the small intestine; (ii) truly absorbed rumen undegraded feed protein in the small intestine; (iii) endogenous protein in the digestive tract; (iv) total truly absorbed protein in the small intestine; and (v) protein degraded balance. Results showed that using the DVE/OEB system to predict the potential nutrient supply, it was found that the SuperOat had similar truly absorbed rumen synthesized microbial protein levels (61, 63, 59 g/kg DM, P > 0.05, for SuperOat, CDC Dancer and Derby, respectively), higher truly absorbed rumen undegraded feed protein than CDC Dancer (22 vs. 17 g/kg DM P < 0.05, for SuperOat, CDC Dancer, respectively), but similar to Derby (22 vs. 21 g/kg DM; P > 0.05), and similar endogenous protein (16, 16, 18 g/kg DM; P > 0.05). Total truly absorbed protein in the small intestine is only numerically higher in the SuperOat (67 vs. 65, 62 g/kg DM, P > 0.05, for CDC Dancer and Derby, respectively). However, the protein degraded balance was significantly different (P < 0.05) with a positive value for the SuperOat (7.0 g/kg DM) and negative values for two normal varieties (?1.5, ?6.8 g/kg DM for CDC Dancer and Derby, respectively). In conclusion, the model predicted significantly different protein degradation balance. The SuperOat had positive degradation balance but other two normal varieties had negative protein degraded balance However, the SuperOat had similar total absorbed protein value to the two normal varieties of oats.     

Influence of vitamin E on organic matter fermentation,ruminal protein and fatty acid metabolism,protozoa concentrations and transfer of fatty acids

Vitamin E (Vit. E) is discussed to influence ruminal biohydrogenation. The objective of this study was to investigate the influence of a Vit. E supplementation on rumen fermentation characteristics, ruminal microbial protein synthesis as well as ruminal organic matter fermentation. Furthermore, we aimed to investigate the influence of Vit. E supplementation on short‐chain fatty acids (SCFA) and protozoa concentrations in the rumen and, in addition, on transfer rates of middle‐chain and long‐chain fatty acids into the duodenum in lactating dairy cows. Eight rumen and duodenum fistulated German Holstein cows were assigned to either a group receiving 2,327 IU/d Vit. E (138.6 IU/kg DM DL‐α‐tocopherylacetate; n = 4) or a control group (23.1 IU/kg DM; n = 4). Neither ruminal protein synthesis nor organic matter fermentation was influenced by treatment. Vit. E did not act on the concentrations of short‐chain fatty acids and protozoa in rumen fluid. Duodenal flow of C13:0 (1.3 versus 0.2 g/d, p = 0.014) and iso‐C14:0 (1.0 versus 0.5 g/d, p = 0.050) was higher in the Vit. E group. We observed a trend for higher duodenal flows for C12:0 (1.6 versus 0.9 g/d, p = 0.095) and anteiso‐C15:0 (12.2 versus 8.9 g/d, p = 0.084). Transfer rate of C12:0 tended to be higher in the Vit. E group (125.61 versus 73.96, p = 0.082). No other transfer rates were affected by treatment. Further studies are necessary to investigate the influence of Vit. E on rumen microbiota and their fatty acid production as well as on the impact of different doses of Vit. E supplementation on variables of protein synthesis efficiency.