Forestomach pH in hunted roe deer (Capreolus capreolus) in relation to forestomach region, time of measurement and supplemental feeding and comparison among wild ruminant species

There is a debate whether supplemental feeding of deer bears the risk of inducing health problems, in particular acidosis. Here, the pH values of forestomach contents of free-ranging roe deer (Capreolus capreolus) shot in areas with and without supplemental winter feeding were compared. pH was similar in the dorsal and ventral rumen, but lower at these sites than in the Atrium ruminis, where it was again lower than in the reticulum; this pattern corresponds to expectations based on differences in the presence of saliva at the different sites of the forestomach. pH was lower with increasing time that elapsed between death of the animal and measuring pH in unsupplemented animals and was lower in unsupplemented animals in May/June than later in the year. Animals with supplemental winter feeding had significantly lower rumen pH (5.5) than animals without food supplementation (5.7). These data suggest that supplemental feeding of roe deer has the potential to lower forestomach pH. Although pH values measured in supplemented animals in this study would be considered indicative of rumen acidosis in domestic cattle, they are within the range previously measured in various free-ranging Odocoilid species, including roe deer; were of a similar magnitude as the May/June values of unsupplemented roe deer in this study; and must be considered with respect to potentially rapid declines in pH between death of the animal and pH measurement. Given methodological problems, analyses of literature data from free-ranging wild ruminants provide little evidence for a systematic variation of rumen pH with feeding type and body mass, but lead to the hypothesis that some New World cervids, including the roe deer, might either naturally have lower pH values than other ruminants or rumen contents whose pH drops rapidly after death.     

A typical browser, the roe deer, may consume substantial quantities of grasses in open landscapes

In open landscapes, grass leaves provide an abundant resource for ruminants, with potentially high nutritional value. However, their extensive digestion requires a long fermentation time, achieved through large rumen and the stratification of the rumen content. Due to anatomical and physiological differences, ruminants differ in their ability to process grass leaves. Particularly, the small roe deer, with its viscous saliva and unstratified rumen content, is generally classified as a strict browser. We hypothesised that roe deer may be able to use grass leaves in some circumstances, notably when the availability of other resources declines and when the quality of grass leaves is high. We expected that (1) grass leave consumption should be higher in open landscapes than in forest habitat because grasses are more widely available and more nutritious in open landscapes and (2) grass leave consumption should increase in winter when the availability of other resources declines. We assessed grass consumption by microscopic analysis of roe deer faecal pellets collected monthly both in forest habitat and in the surrounding open landscape. We found that both the occurrence and the proportion of grass leaves in the faeces were higher in the open landscape (predicted mean proportion 0.31) than in the forest (predicted mean proportion 0.05). In addition, the proportion of grass leaves in the faeces was higher in winter and lower in spring in both forest and open landscape. We suggest that roe deer are able to use grass leaves with unusually high nutritional quality in winter in this mild climate area. This involves a certain level of digestive plasticity to efficiently digest high quality grasses and may confer nutritional benefit to individuals feeding in an open landscape.     

Physical characteristics of rumen contents in two small ruminants of different feeding type,the mouflon (Ovis ammon musimon) and the roe deer (Capreolus capreolus)

In domestic ruminants, the stratification of forestomach contents – the results of flotation and sedimentation processes – is an important prerequisite for the selective particle retention in this organ. A series of anatomical and physiological measurements suggests that the degree of this stratification varies between browsing and grazing wild ruminants. We investigated the forestomach contents of free-ranging mouflon and roe deer shot during regular hunting procedures. There was no difference between the species in the degree by which forestomach ingesta separated according to size due to buoyancy characteristics in vitro. However, forestomach fluid of roe deer was more viscous than that of mouflon, and no difference in moisture content was evident between the dorsal and the ventral rumen in roe deer, in contrast to mouflon. Hence, the forestomach milieu in roe deer appears less favourable for gas or particle separation due to buoyancy characteristics. These findings are in accord with notable differences in forestomach papillation between the two species. In roe deer, particle separation is most likely restricted to the reticulum, whereas in mouflon, the whole rumen may pre-sort particles to a higher degree. The results suggest that differences in forestomach physiology may occur across ruminant species.     

Rumen escape of methionine and lysine administered intraruminally to growing double-muscled Belgian Blue bulls

In many dietary conditions, methionine (Met) and lysine (Lys) are the most limiting amino acids (AA) for ruminants. The AA protected from ruminal fermentation are not commercially available, with the exception of Met which is not always economical, especially for meat production. This study measured ruminal escape of free Met and Lys supplemented intraruminally to fast growing bulls. Six double-muscled Belgian Blue bulls, fed a high concentrate diet and fitted with a rumen cannula, received free Met (40 g x d(-1)) and free Lys (60 g x d(-1)), individually or simultaneously, in a duplicated Latin square design. The mean ruminal escape of Met and Lys reached 37 and 45% respectively, and did not differ if administered separately or together. Plasma Lys and Met concentrations were increased by 504 and 126%, respectively. Substantial proportions of free AA escaped ruminal fermentation and were available for absorption from the small intestine when they were administered at physiologically high levels.     

Seasonal dynamics of digestion in relation to diet quality and intake in European roe deer (Capreolus capreolus)

Three tame, hand-reared adult roe deer (Capreolus capreolus) were fed a low-quality diet (blueberry stems) or high-quality concentrate either restricted or ad libitum in summer and winter. Total mean retention time (TMRT) and rumen retention time (RRT) were significantly longer, indigestible fill was significantly higher and apparent digestibility and intake were significantly lower when fed blueberry stems compared to concentrate. The feeding regimes of concentrate did not affect the digesta kinetic estimates, except that total fill and apprent digestibility were significantly higher when deer were fed ad libitum than when they were fed a restricted ration. TMRT was significantly longer when they were fed a restricted ration of blueberry stems than for ad libitum intake, whereas all other estimates were equal. Intake was significantly higher and TMRT and RRT were significantly shorter in summer compared to winter when they were fed concentrate. These findings support the theory that roe deer, as small-bodied concentrate selectors, are adapted to high intake, rapid turnover, and rapid digestion when fed high-quality concentrate. When fed a low-quality diet the roe deer may be limited by rumen bulk. A strategy based on increased rumen retention accompanied by increased cell-wall digestion has therefore severe limitations in roe deer. This indicates that roe deer are dependent on a selective feeding strategy to enhance winter survival.     

A simulation model “CTR Dairy” to predict the supply of nutrients in dairy cows managed under discontinuous feeding patterns

A simulation rumen model has been developed to function under non-steady state conditions in order to allow prediction of nutrient availability in dairy cows managed under discontinuous feeding systems. The model simulates availability of glycogenic, aminogenic and lipogenic nutrients to lactating dairy cows fed discontinuously. The model structure considers input of up to three different feeds fed independently at any time during the day. Feeds are described by their nitrogen (N), carbohydrate and fatty acid fractions. The N containing feed fractions include ruminally undegraded crude protein (CP), ruminally insoluble but potentially degradable CP, ruminally soluble CP and ammonia N. The feed carbohydrate fractions include ruminally undegradable neutral detergent fibre (NDF), ruminally degradable NDF, ruminally insoluble starch, ruminally soluble starch and sugars. The fatty acids in the feeds are divided between long chain fatty acids and volatile fatty acids (VFA). Additionally four pools were defined representing absorption of amino acids, glucose, long chain fatty acids and volatile fatty acids. The rumen microbial population is represented as a single pool. Besides a flexible structure, new features to the extant model include adoption of the concept of chewing efficiency (or chewing effectiveness) during eating, variable fractional ruminal absorption rates of VFA and variable fractional ruminal degradation rates of NDF as a function of rumen liquid pH, as well as a variable rumen volume which directly affects rumen concentrations of metabolites. The model continuously (i.e., by minute) predicts release of soluble components from the feeds in the rumen, concentration and absorption of fermentation end products in the rumen, rumen pools of nutrients and microbial biomass dynamics, as well as passage of microbial biomass and non-fermented nutrients from the rumen, in response to various feeding strategies. Model evaluation covered a wide range of feeding strategies that included pasture and housed feeding systems. Overall, the mean square prediction error (MSPE) as a percentage of the observed mean was relatively low (<10%) with a high amount of the total variation explained by random variation (>65%). Deviation from unity varied between 23% (rumen dry matter content) and 25% (NDF), indicating some consistent over and/or under prediction. A more detailed evaluation was done based on studies available that reported diurnal behaviour of key model outputs such as rumen pools, rumen pH, and rumen VFA. The predictions broadly simulated the observed values quantitatively, relative to general diurnal patterns, and relative to differences between treatments in the predicted diurnal patterns. Results show that the model provides a tool to assess potential outcomes of changing feeding strategies which may be particularly valuable in assessing selection of feeds, amounts and times of the day to offer the feeds. The continuous nature of the simulated output also allows determination of the time(s) of the day that ruminal (and/or post-ruminal) delivery of nutrients may limit ruminal output of nutrients (and/or availability of nutrients) to support milk nutrient synthesis.     

Biohydrogenation of erucic acid (22:1 n-9 cis) in artificial rumen. I). Effect of octadecapolyenoic fatty acids and the incubation period

Normally dietary octadecapolyenoic fatty acids are anaerobically hydrogenated in ruminants, both "in vivo" in the rumen and "in vitro" with ruminal content. Here it has been investigated in artificial rumen the process concerning the erucic acid (22:1 n-9 cis) compared with and in presence of C 18 polyunsaturated acids at various incubation times. The results have shown that C 18 polyunsaturated acids hydrogenation with conversion into hydrogenation intermediates and stearic acid does always occur in contrast with erucic acid where it is never revealable, unrelated to the incubations conditions applied.     

Effects of the acid–base treatment of corn on rumen fermentation and microbiota,inflammatory response and growth performance in beef cattle fed high-concentrate diet

Beef cattle are often fed high-concentrate diet (HCD) to achieve high growth rate. However, HCD feeding is strongly associated with metabolic disorders. Mild acid treatment of grains in HCD with 1% hydrochloric acid (HA) followed by neutralization with sodium bicarbonate (SB) might modify rumen fermentation patterns and microbiota, thereby decreasing the negative effects of HCD. This study was thus aimed to investigate the effects of treatment of corn with 1% HA and subsequent neutralization with SB on rumen fermentation and microbiota, inflammatory response and growth performance in beef cattle fed HCD. Eighteen beef cattle were randomly allocated to three groups and each group was fed different diets: low-concentrate diet (LCD) (concentrate : forage = 40 : 60), HCD (concentrate : forage = 60 : 40) or HCD based on treated corn (HCDT) with the same concentrate to forage ratio as the HCD. The corn in the HCDT was steeped in 1% HA (wt/wt) for 48 h and neutralized with SB after HA treatment. The animal trial lasted for 42 days with an adaptation period of 7 days. At the end of the trial, rumen fluid samples were collected for measuring ruminal pH values, short-chain fatty acids, endotoxin (or lipopolysaccharide, LPS) and bacterial microbiota. Plasma samples were collected at the end of the trial to determine the concentrations of plasma LPS, proinflammatory cytokines and acute phase proteins (APPs). The results showed that compared with the LCD, feeding the HCD had better growth performance due to a shift in the ruminal fermentation pattern from acetate towards propionate, butyrate and valerate. However, the HCD decreased ruminal pH and increased ruminal LPS release and the concentrations of plasma proinflammatory cytokines and APPs. Furthermore, feeding the HCD reduced bacterial richness and diversity in the rumen. Treatment of corn increased resistant starch (RS) content. Compared with the HCD, feeding the HCDT reduced ruminal LPS and improved ruminal bacterial microbiota, resulting in decreased inflammation and improved growth performance. In conclusion, although the HCD had better growth performance than the LCD, feeding the HCD promoted the pH reduction and the LPS release in the rumen, disturbed the ruminal bacterial stability and increased inflammatory response. Treatment of corn with HA in combination with subsequent SB neutralization increased the RS content and helped counter the negative effects of feeding HCD to beef steers.     

Evaluation of the effects of dietary particle fractions on fermentation profile and concentration of microbiota in the rumen of dairy cows fed grass silage-based diets

The study evaluated the effects of three different theoretical particle lengths (TPL) of grass silage on the distribution of particle fractions of the diet and the resulting effects on fermentation profile and concentrations of protozoa and mixed bacterial mass in the rumen of three lactating Holstein cows fed total mixed rations (45% grass silage, 5% grass hay and 50% concentrate) ad libitum. Decreasing TPL of grass silage (long, medium, short) reduced particles retained on the 19-mm sieve of the Penn State Particle Separator, while particle fractions from 8 mm to 19 mm and smaller than 8 mm were increased. Different TPL did not affect pH and the concentration of volatile fatty acids in the rumen. However, lowering the TPL from long to medium increased significantly the bicarbonate concentration, acetate proportion and protozoal number in the rumen, whereas the proportion of bacterial protein in ruminal digesta and its amino acid concentration were significantly increased by the short TPL. For the current feeding conditions, it can be concluded that increasing the fraction of particles between 8 and 19 mm and probably even the fraction below 8 mm by decreasing TPL of grass silage do not adversely affect rumen conditions and can be beneficial in terms of optimising concentration and activity of ruminal microbiota in high-yielding dairy cows.     

Rumen chemical and bacterial changes during stepwise adaptation to a high-concentrate diet in goats

The correlation between rumen chemical and bacterial changes was investigated during a four periodical stepwise adaptation to a high-concentrate diet (concentrate level at 0%, 30%, 50% and 70% for diet I to IV, respectively) in goats. The results showed that ruminal pH decreased from 6.7 to 5.5 after switching from diet I to II, and was maintained at about 5.5 on diet III. Denaturing gradient gel electrophoresis results showed that the rumen bacterial community was relatively stable during the initial three feeding periods, except for the appearance of three bands when diet changed from I to II, suggesting that an appropriate concentrate level can promote the proliferation of some bacteria. After 12 days of feeding diet III, total volatile fatty acid (VFA) concentration and butyrate proportion decreased. At days 2 and 3 of feeding diet IV, ruminal pH declined sharply to 5.3 and 4.7, respectively, and total VFA concentration decreased further while lactic acid concentration increased markedly, suggesting a relation between lactic acid accumulation and ruminal pH decline. At the same time, many bacteria disappeared, including most fibrolytic-related bacteria while Streptococcus bovis and Prevotella-like species dominated. Interestingly, Succinivibrio dextrinosolvens-like species maintained throughout the experiment, suggesting its tolerance to low pH. In conclusion, rumen bacterial community was relatively stable feeding 0% to 50% concentrate diets, and it was observed that appropriate concentrate levels in the diet could increase the diversity of rumen bacteria. However, concentrate-rich diets caused lactic acid accumulation and low ruminal pH that caused the disappearance of most fibrolytic-related bacteria sensitive to low pH while S. bovis and genus Prevotella persisted.     

The influence of an increased cobalt supply on ruminal parameters and microbial vitamin B12 synthesis in the rumen of dairy cows

The aim of the study was to examine the effects of an elevated dietary cobalt supply to dairy cows on rumen fermentation parameters and microbial vitamin B12 synthesis in the rumen. Five lactating dairy cows fitted with a ruminal and a duodenal cannula were subsequently fed either a ration containing only the native cobalt content (0.17 mg Co/ kg DM) or a ration supplemented with cobalt sulphate (0.29 mg Co/kg DM). The pH-value, the ammonia concentration as well as the concentration and the molar proportions of short chain fatty acids in the rumen were not significantly influenced by feeding the ration with the higher cobalt content. While there was no difference in microbial protein flow, the cobalamin flow at the duodenum was significantly elevated in supplemented animals (3.67 +/- 0.69 vs. 8.63 +/- 2.22 mg B12/d). The efficiency of cobalt utilisation for ruminal vitamin B12 synthesis was calculated to be 7.1 +/- 1.3% for the unsupplemented and 9.5 +/- 2.4% for the supplemented ration. Further investigation has to prove if there are any benefits for cows resulting from the elevated cobalamin synthesis measured, caused by feeding higher amounts of dietary cobalt.     

Effects of Dietary Linseed Oil and Propionate Precursors on Ruminal Microbial Community,Composition, and Diversity in Yanbian Yellow Cattle

The rumen microbial ecosystem is a complex system where rumen fermentation processes involve interactions among microorganisms. There are important relationships between diet and the ruminal bacterial composition. Thus, we investigated the ruminal fermentation characteristics and compared ruminal bacterial communities using tag amplicon pyrosequencing analysis in Yanbian yellow steers, which were fed linseed oil (LO) and propionate precursors. We used eight ruminally cannulated Yanbian yellow steers (510 ± 5.8 kg) in a replicated 4 × 4 Latin square design with four dietary treatments. Steers were fed a basal diet that comprised 80% concentrate and 20% rice straw (DM basis, CON). The CON diet was supplemented with LO at 4%. The LO diet was also supplemented with 2% dl-malate or 2% fumarate as ruminal precursors of propionate. Dietary supplementation with LO and propionate precursors increased ruminal pH, total volatile fatty acid concentrations, and the molar proportion of propionate. The most abundant bacterial operational taxonomic units in the rumen were related to dietary treatments. Bacteroidetes dominated the ruminal bacterial community and the genus Prevotella was highly represented when steers were fed LO plus propionate precursors. However, with the CON and LO diet plus malate or fumarate, Firmicutes was the most abundant phylum and the genus Ruminococcus was predominant. In summary, supplementing the diets of ruminants with a moderate level of LO plus propionate precursors modified the ruminal fermentation pattern. The most positive responses to LO and propionate precursors supplementation were in the phyla Bacteriodetes and Firmicutes, and in the genus Ruminococcus and Prevotella. Thus, diets containing LO plus malate or fumarate have significant effects on the composition of the rumen microbial community.     

Activity of cellulolytic enzymes in the contents of reticulorumen and caecocolon of roe deer (Capreolus capreolus)

Selective ruminants, which prefer easily digestible plants, cannot digest fibrous forage as well as grass eaters. Low enzyme activity or short retention time of ingesta particles in fermentation chambers appeared to be responsible for reduced cellulose breakdown. Seasonal activity of cellulolytic enzymes, cellulose concentration and protozoa population in reticulorumen (RR) and caecocolon (CC) of roe deer as a typical concentrate selector were investigated. Cellulase activities were lowest in winter when cellulose concentration in RR contents were highest. Highest enzyme activities and lowest cellulose concentration were measured in early spring. Cellulolytic activities were significantly correlated with the number of protozoa in RR. Only one entodinomorphic genus was identified in the RR. The enzyme activities in CC were far lower compared with those in RR. Low cellulose digestion in the RR cannot be compensated for by cellulose breakdown in the CC. The reduced cellulose digestion of roe deer may be attributed to the short retention time of food particles in spring and summer, whereas decreased colonisation of microorganisms in the rumen may be the main reason for low cellulose breakdown in winter.     

Rubber seed oil and flaxseed oil supplementation alter digestion,ruminal fermentation and rumen fatty acid profile of dairy cows

Rubber seed oil (RO) that is rich in polyunsaturated fatty acids (FA) can improve milk production and milk FA profiles of dairy cows; however, the responses of digestion and ruminal fermentation to RO supplementation in vivo are still unknown. This experiment was conducted to investigate the effect of RO and flaxseed oil (FO) supplementation on nutrients digestibility, rumen fermentation parameters and rumen FA profile of dairy cows. Forty-eight mid-lactation Holstein dairy cows were randomly assigned to one of four treatments for 8 weeks, including basal diet (CON) or the basal dietary supplemented with 4% RO, 4% FO or 2% RO plus 2% FO on a DM basis. Compared with CON, dietary oil supplementation improved the total tract apparent digestibility of DM, neutral detergent fibre and ether extracts ( P < 0.05). Oil treatment groups had no effects on ruminal digesta pH value, ammonia N and microbial crude protein ( P > 0.05), whereas oil groups significantly changed the volatile fatty acid (VFA) profile by increasing the proportion of propionate whilst decreasing total VFA concentration, the proportion of acetate and the ratio of acetate to propionate ( P < 0.05). However, there were no differences in VFA proportions between the three oil groups (P > 0.05). In addition, dietary oil supplementation increased the total unsaturated FA proportion in the rumen by enhancing the proportion of trans-11 C18:1 vaccenic acid (VA), cis-9, trans-11 conjugated linoleic acid (CLA) and α-linolenic acid (ALA) ( P < 0.05). These results indicate that dietary supplementation with RO and FO could improve nutrients digestibility, ruminal fermentation and ruminal FA profile by enhancing the VA, cis-9, trans-11 CLA and ALA composition of lactating dairy cows. These findings provide a theoretical basis for the application of RO in livestock production.     

Effects of Propionibacterium strains on ruminal fermentation,nutrient digestibility and methane emissions in beef cattle fed a corn grain finishing diet

Twenty ruminally cannulated beef heifers were fed a high corn grain diet in a randomized block design to determine the effect of three direct fed microbial (DFM) strains of Propionibacterium on ruminal fermentation, nutrient digestibility and methane (CH₄) emissions. The heifers were blocked in five groups on the basis of BW and used in five 28-day periods. Dietary treatments included (1) Control and three strains of Propionibacterium (2) P169, (3) P5, and (4) P54. Strains were administered directly into the rumen at 5×10⁹ CFU with 10 g of a maltodextrin carrier in a gel capsule; Control heifers received carrier only. All heifers were fed the basal diet (10 : 90 forage to concentrate, dry matter basis). Rumen contents were collected on days 15 and 18, ruminal pH was measured continuously between days 15 and 22, enteric CH₄ emissions were measured between days 19 and 22 and diet digestibility was measured from days 25 to 28. Mean ruminal pH was 5.91 and was not affected by treatments. Similarly, duration of time that pH<5.8 and 5.6 was not affected by treatment. Likewise, total and major volatile fatty acid profiles were similar among all treatments. No effects were observed on dry matter intake and total tract digestibility of nutrients. Total enteric CH₄ production (g/day) was not affected by Propionibacterium strains and averaged 139 g/day. Similarly, mean CH₄ yield (g CH₄/kg of dry matter intake) was similar for all the treatments. The relative abundance of total Propionibacteria in the rumen increased with administration of DFM and were greater 3 h post-dosing relative to Control, but returned to baseline levels before feeding. Populations of Propionibacterium P169 were higher at 3 and 9 h as compared with the levels at 0 h. In conclusion, moderate persistency of the inoculated strains within the ruminal microbiome and pre-existing high propionate production due to elevated levels of starch fermentation might have reduced the efficacy of Propionibacterium strains to increase molar proportion of propionate and subsequently reduce CH₄ emissions.     

Effects of sampling location and time,and host animal on assessment of bacterial diversity and fermentation parameters in the bovine rumen

Aims: To investigate, using culture‐independent methods, whether the ruminal bacterial structure, population and fermentation parameters differed between sampling locations and time. Methods and Results: The detectable bacteria and fermentation parameters in the digesta from five locations in the rumen of three cows at three time points were analysed. The PCR‐denaturing gradient gel electrophoresis (PCR‐DGGE) profiles were similar among digesta samples from five locations (95·4%) and three time points (93·4%) within cows; however, a lower similarity was observed for samples collected from different host animals (85·5%). Rumen pH and concentration of volatile fatty acids (VFA) were affected by time points of sampling relative to feeding. Conclusions: The detectable bacterial structure in the rumen is highly conserved among different locations and over time, while the quantity of individual bacterial species may change diurnally in response to the feeding. Significance and impact of the study: This study supplies the fundamental understanding of the microbial ecology in the rumen, which is essential for manipulation of ruminal microflora and subsequent improvement in animal production.     

Bacteria and Methanogens Differ along the Gastrointestinal Tract of Chinese Roe Deer (Capreolus pygargus)

The current study provides the insight into the bacteria in the gastrointestinal tract (GIT) and methanogens presented in the rumen and cecum of the Chinese roe deer (Capreolus pygargus). The ruminal, ileal, cecal, and colonic contents, as well as feces, were obtained from each of the three, free-range, roe deer ingesting natural pasture after euthanasia. For the bacterial community, a total of 697,031 high-quality 16S rRNA gene sequences were generated using high-throughput sequencing, and assigned to 2,223 core operational taxonomic units (OTUs) (12 bacterial phyla and 87 genera). The phyla Firmicutes (51.2%) and Bacteroidetes (39.4%) were the dominant bacteria in the GIT of roe deer. However, the bacterial community in the rumen was significantly (P<0.01) different from the other sampled regions along the GIT. Secondly, Prevotella spp., Anaerovibrio spp., and unidentified bacteria within the families Veillonellaceae and Paraprevotellaceae were more abundant in the rumen than in the other regions. Unidentified bacteria within the family Enterobacteriaceae, Succinivibrio spp., and Desulfovibrio spp. were more predominant in the colon than in other regions. Unidentified bacteria within the family Ruminococcaceae, and Bacteroides spp. were more prevalent in the ileum, cecum and fecal pellets. For methanogens in the rumen and cecum, a total of 375,647 high quality 16S rRNA gene sequences were obtained and assigned to 113 core OTUs. Methanobrevibacter millerae was the dominant species accounting for 77.3±7.4 (S.E) % and 68.9±4.4 (S.E) % of total sequences in the rumen and cecum of roe deer, respectively. However, the abundance of Methanobrevibacter smithii was higher in the rumen than in the cecum (P = 0.004). These results revealed that there was intra variation in the bacterial community composition across the GIT of roe deer, and also showed that the methanogen community in the rumen differed from that in the cecum.     

An in vitro evaluation of browser and grazer fermentation efficiency and microbiota using European moose spring and summer foods

Evolutionary morphological and physiological differences between browsers and grazers contribute to species‐specific digestion efficiency of food resources. Rumen microbial community structure of browsers is supposedly adapted to characteristic nutrient composition of the diet source. If this assumption is correct, domesticated ruminants, or grazers, are poor model animals for assessing the nutritional value of food consumed by browsing game species. In this study, typical spring and summer foods of the European moose (Alces alces) were combined with rumen fluid collected from both dairy cows (Bos taurus) and from moose, with the aim of comparing fermentation efficiency and microbial community composition. The nutritional value of the food resources was characterized by chemical analysis and advanced in vitro measurements. The study also addressed whether or not feed evaluation based on in vitro techniques with cattle rumen fluid as inoculum could be a practical alternative when evaluating the nutritional value of plants consumed by wild browsers. Our results suggest that the fermentation characteristics of moose spring and summer food are partly host‐specific and related to the contribution of the bacterial phyla Firmicutes and Bacteriodetes to the rumen microbial community. Host‐specific adaptations of the ruminal microbial community structure could be explained from the evolutionary adaptations related to feeding habitats and morphophysiological differences between browsers and grazers. However, the observed overall differences in microbial community structure could not be related to ruminal digestion parameters measured in vitro. The in vitro evaluation of digestion efficiency reveals that equal amounts of methane were produced across all feed samples regardless of whether the ruminal fluid was from moose or dairy cow. The results of this study suggested that the nutritional value of browsers' spring and summer food can be predicted using rumen fluid from domesticated grazers as inoculum in in vitro assessments of extent of digestion when excluding samples of the white water lily root, but not of fermentation characteristics as indicated by the proportions of individual fermentation fatty acids to the total of volatile fatty acids.     

Evaluation of the effects of dietary particle fractions on fermentation profile and concentration of microbiota in the rumen of dairy cows fed grass silage-based diets

The study evaluated the effects of three different theoretical particle lengths (TPL) of grass silage on the distribution of particle fractions of the diet and the resulting effects on fermentation profile and concentrations of protozoa and mixed bacterial mass in the rumen of three lactating Holstein cows fed total mixed rations (45% grass silage, 5% grass hay and 50% concentrate) ad libitum. Decreasing TPL of grass silage (long, medium, short) reduced particles retained on the 19-mm sieve of the Penn State Particle Separator, while particle fractions from 8 mm to 19 mm and smaller than 8 mm were increased. Different TPL did not affect pH and the concentration of volatile fatty acids in the rumen. However, lowering the TPL from long to medium increased significantly the bicarbonate concentration, acetate proportion and protozoal number in the rumen, whereas the proportion of bacterial protein in ruminal digesta and its amino acid concentration were significantly increased by the short TPL. For the current feeding conditions, it can be concluded that increasing the fraction of particles between 8 and 19 mm and probably even the fraction below 8 mm by decreasing TPL of grass silage do not adversely affect rumen conditions and can be beneficial in terms of optimising concentration and activity of ruminal microbiota in high-yielding dairy cows.