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Abstract
Accurate estimates of microbial synthesis in the rumen are vital to optimize ruminant nutrition. Liquid- (LAB) and solid-associated bacterial fractions (SAB) harvested from the rumen are generally considered as microbial references when microbial yield is calculated; however, factors that determine their composition are not completely understood. The aim of this study was to evaluate the effect of diet and absence or presence of rumen protozoa on the rumen microbial community. It was hypothesized that these treatments could modify the composition and representativeness of LAB and SAB. Twenty twin lambs (Ovis aries) were used; one-half of the twins were kept protozoa-free, and each respective twin sibling was faunated. At 6 mo of age, 5 animals from each group were randomly allocated to the experimental diets consisting of either alfalfa hay as the sole diet, or 50:50 mixed with ground barley grain. After 15 d of adaptation to the diet, animals were euthanized, rumen and abomasum contents were sampled, and LAB and SAB isolated. The presence of protozoa buffered the effect of diet on the rumen bacterial population. Faunated animals fed alfalfa hay had a greater abundance of F. succinogenes, anaerobic fungi and methanogens, as well as an enhanced rumen bacterial diversity. Cellulolytic bacteria were more abundant in SAB, whereas the abomasal abundance of most of the microorganisms studied was closer to those values observed in LAB. Rumen and abomasal samples showed similar bacterial DNA concentrations, but the fungal and protozoal DNA concentration in the abomasum was only 69% and 13% of that observed in the rumen, respectively, suggesting fungal and protozoal sequestration in the rumen or possible preferential degradation of fungal and protozoal DNA in the abomasum, or both. In conclusion, absence of protozoa and type of diet extensively modified the chemical composition of LAB and SAB as a consequence of changes in the microbial composition of these fractions.
Original language | English |
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Pages (from-to) | 3924-3936 |
Number of pages | 13 |
Journal | Journal of Animal Science |
Volume | 90 |
Issue number | 11 |
Early online date | 04 Jun 2012 |
DOIs | |
Publication status | Published - Nov 2012 |
Keywords
- bacterial structure
- denaturing gradient gel electrophoresis
- microbial synthesis
- quantitative polymerase chain reaction
- rumen protozoa
- terminal restriction fragment length polymorphism
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- 1 Finished
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RSB : Rumen Systems Biology
Kingston-Smith, A. (PI)
Biotechnology and Biological Sciences Research Council
01 Apr 2012 → 31 Mar 2017
Project: Externally funded research