Development of, and natural fluctuations in, rumen microbial populations

Dehority, Burk A.; Orpin, C. G.

doi:10.1007/978-94-009-1453-7_5

Cited by 139 publications

(118 citation statements)

References 182 publications

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“…The greater rates of starch degradation for BBD compared with CBD led to greater propionate concentrations in the former and greater acetate concentrations for the latter consistent with the findings of previous studies (McCarthy et al, 1989;Casper et al, 1990;Yang et al, 1997;Khorasani et al, 2001). Greater concentrations of acetate for rolling than for grinding and greater concentrations of propionate for grinding than for rolling could be attributed to the inverse relationship between acetate and propionate, which reflect the relative proportions of cellulolytic and amylolytic bacteria in the rumen (Knowlton et al, 1996;Dehority and Orpin, 2003). A reduction in the grain particle size with grinding increases starch fermentability in the rumen resulting in an increase in propionate and a decrease in acetate.…”

Section: Rumen Fermentationsupporting

confidence: 85%

Effect of grain type and processing method on rumen fermentation and milk rumenic acid production

Mohammed

Kennelly

Kramer

et al. 2010

Animal

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It was hypothesized that differences in starch degradability account for observed differences in rumen vaccenic acid (t11-18:1) and milk rumenic acid (RA) concentrations. To test this hypothesis, starch degradability was varied through grain source and by processing. Eight Holstein cows in mid-lactation were assigned to two 4 3 4 Latin squares with four 21-day periods and four diets: dry rolled barley, ground barley, dry rolled corn and ground corn. Diets contained similar starch content and were supplemented with whole sunflower seed to provide similar total polyunsaturated fatty acid (PUFA) (18:2n-6 1 18:3n-3) contents. Forage/ concentrate ratios of all diets were 42 : 58. Rumen, plasma and milk samples were collected in the third week of each period. In situ degradation rates (%/h) for rolled corn, ground corn, rolled barley and ground barley were 5.4, 8.9, 17.0 and 19.4, respectively, for dry matter (DM) and 6.3, 10.8, 25.3 and 43.8, respectively, for starch. DM intakes were greater for corn-based diets (CBD) than for barley-based diets (BBD) with no difference between rolled and ground diets. Daily minimum rumen pH was less (5.2 v. 5.5) and pH duration ,5.8 (h/d) was greater (7.4 v. 4.3) for BBD than for CBD. Milk fat content and yield were less for BBD than for CBD with greater values observed for rolling compared with grinding. Variability in milk fat yield was strongly related (R 2 5 0.55; P , 0.01) to total starch intake (45%) and milk c9t11-CLA (10%) and none of the t-18:1 isomers or CLA isomers that are typically associated with milk fat depression entered the model. The concentrations (%) of t10-18:1 and t11-18:1 were greater for BBD than for CBD in rumen contents (t10-18:1, 3.5 v. 1.3; t11-18:1, 3.2 v. 1.9), plasma (t10-18:1, 1.2 v. 0.2; t11-18:1, 0.97 v. 0.58) and milk (t10-18:1, 3.8 v. 1.0; t11-18:1, 2.6 v. 1.7) despite greater total PUFA intakes for CBD. Milk RA concentration was greater for BBD than for CBD (1.46 v. 0.89) but was not influenced by the method of grain processing. This study clearly demonstrated that the milk content and profile of t-18:1 and CLA isomers were more strongly influenced by the source of grain starch (barley . corn) than by the method of grain processing indicating that factors inherent in the source of starch were responsible for the observed differences and these factors could not be modified by the processing methods used in this study.Keywords: grain processing, vaccenic acid, conjugated linoleic acid, corn, barley ImplicationsConjugated linoleic acid (CLA) is a component of milk fat with demonstrated health benefits. It was hypothesized that a difference in rate of starch digestion, varied through source of grain and processing method (rolling v. grinding), would influence rumen PUFA digestion and thus milk CLA. Concentrations of ruminal CLA precursors and milk CLA were greater for barley-based diets than corn-based diets but were not different between rolling and grinding indicating that factors inherent in the source of starch were responsible for the observed ...

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Section: Rumen Fermentationsupporting

confidence: 85%

Effect of grain type and processing method on rumen fermentation and milk rumenic acid production

Mohammed

Kennelly

Kramer

et al. 2010

Animal

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“…Previous studies showed that diet may significantly affect the composition of the rumen bacterial community (Dehority and Orpin, 1997;Tajima et al, 2000). Undoubtedly, a unique bacterial community in the rumen was likely to form with Chinese wildrye in our study.…”

Section: Discussionsupporting

confidence: 48%

DGGE and 16S rDNA analysis reveals a highly diverse and rapidly colonising bacterial community on different substrates in the rumen of goats

Sun

Mao

Yao

et al. 2008

Animal

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In the rumen, plant particles are colonised and degraded by the rumen micro-organisms. Although numerous important findings about fibre-associated bacterial community were obtained using traditional or molecular techniques, little information is available on the dynamics of bacteria associated with feed particles during incubation in the rumen. In the present study, ryegrass leaf, ryegrass stem and rice straw, representing different carbohydrate compositions, were used as substrates and placed in the rumen of goats by using nylon bags, and PCR/DGGE (denaturing gradient gel electrophoresis) with subsequent sequence analysis were used to monitor the dynamics of and identify bacteria associated with the substrates during 24 h of incubation. DGGE results showed that substrate samples collected from 10 min to 6 h had similar DGGE patterns, with up to 24 predominant bands to each sample, including 14 common bands to all samples, suggesting a rapid and stable colonisation by a highly diverse bacterial community. Substrate samples collected at 12 and 24 h showed similar DGGE patterns but had great difference in DGGE patterns from those collected at 10 min to 6 h, suggesting an apparent shift in bacterial community. Sequence analysis indicated that most substrate-associated bacteria were closely related to fibrolytic bacteria. In conclusion, a highly diverse and similar rumen bacterial community could immediately colonise to different substrates and remained stable during the initial 6 h of incubation, but experienced a marked change after 12 h of incubation. Italian ryegrass leaf, Italian ryegrass stem and rice straw were colonised with a similar bacterial community.

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“…Oligonucleotide probes can be used to determine the relative abundance of a particular species (Lin et al, 1994;Lin & Stahl, 1995) or groups of organisms at higher levels of hierarchal complexity such as kingdoms or domains (Fry et al, 1997). If a set of probes with increasing levels of hierarchical complexity are used on the same sample, an estimate of undescribed diversity can be obtained (Lin et al, 1994;Lin & Stahl, 1995 Published literature (see reviews by Dehority & Orpin, 1988;Hungate, 1966) indicates that the TCC in the rumen is usually 12-80% of the direct count. These studies demonstrated that a large proportion of ruminal diversity could be cultured, unlike that in many other environments where only 0-1-10 O/ O is culturable (Head et al, 1998;Pace, 1997).…”

Section: Discussionmentioning

confidence: 99%

16S rDNA sequencing of Ruminococcus albus and Ruminococcus flavefaciens: design of a signature probe and its application in adult sheep

et al. 1999

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The ruminococci are an important group of fibrolytic bacteria inhabiting the rumen. Seventeen strains of presumptively identified Ruminococcus were evaluated by a combination of nearly complete and partial 165 rDNA sequence that identified all strains as either Ruminococcus albus or Ruminococcus flavefaciens. All sequences fell into cluster IV of the clostridia, while other species of ruminococci (eg. Ruminococcus obeum, Ruminococcus gnaws, Ruminococcus lactaris) fall into cluster XlVa of the clostridia. Ruminococcus cluster IV sequences were used to design a 165 rRNA oligonucleotide probe to assess the relative abundance of target populations in a stable ruminal environment. A stable population (animals fed eight times per day) was established in sheep so that statistically robust comparisons could be made in the absence of variation due to diurnal rumen fluctuations. The steady state populations were sampled six times over a 24 d period and direct microscopic counts (DC), total culturable counts (TCC), and total cellulolytic counts (CEL) were determined. DC and culturable data (TCC and CEL) were compared with relative abundance estimates of Ruminococcus IV and Fibrobacter succinogenes. A combination of the Ruminococcus and i. succinogenes probes accounted for 4 9 *!o of the bacterial population and cellulolytic bacteria (measured by most-probable numbers) were 5 2 % of the total culturable count. These data suggest that a major portion of the Ruminococcus and Fibmbacter diversity has been cultured and is represented by available sequences. Steady state populations were measured over several days in three sheep and an estimate of variation in DC, TCC, CEL and 16s-based data were obtained. These variance estimates could be used to determine the theoretical sample sizes required to obtain statistically significant differences under different experimental conditions.

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Development of, and natural fluctuations in, rumen microbial populations

Cited by 139 publications

References 182 publications

Effect of grain type and processing method on rumen fermentation and milk rumenic acid production

Effect of grain type and processing method on rumen fermentation and milk rumenic acid production

DGGE and 16S rDNA analysis reveals a highly diverse and rapidly colonising bacterial community on different substrates in the rumen of goats

16S rDNA sequencing of Ruminococcus albus and Ruminococcus flavefaciens: design of a signature probe and its application in adult sheep

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