Rumen bacterial diversity with and without mulga (Acacia aneura) tannins

Feral goats are able to survive in many semi-arid areas of Australia. Under drought conditions, the only form of available feed is often mulga, which has a very high content of condensed tannins (5-24% dry weight). While feral goats apparently thrive on this diet, sheep do very poorly and lose liveweight rapidly. It has been shown that the transfer of rumen contents from feral goats to sheep can significantly improve mulga digestion, suggesting that the ruminal microflora of feral goats may contain tannin tolerant or degrading bacteria. To identify likely communities or associations of bacteria that may undertake this task, a comparative study of the bacterial ecology of the rumens of feral goats fed mulga and sheep fed either mulga or grass was undertaken. This study used the culture independent techniques of generation of 16S rDNA clone libraries and fluorescence in situ hybridisation (FISH) probing. From the clone libraries, bacteria were mainly (>90%) within the divisions Cytophaga-Flexibacter-Bacteroides (CFB) and low mol% G+C Gram positive bacteria (LGCGPB). In animals fed mulga, the CFB predominated (goat - 82% CFB and 11% LGCGPB; sheep - 78% CFB and 21% LGCGPB) whereas in sheep fed grass, the LGCGPB predominated (25% CFB vs 74% LGCGPB). In all clone libraries, few bacterial species were closely related to previously cultured bacteria, making it difficult to assign phenotypic traits. FISH probing of mulga fed -rumen (feral goats and sheep) or -fermentor samples demonstrated a predominance of CFB and gamma proteobacteria. This first molecular ecological study of tannin associated microbial communities suggested that bacteria from these two groups may be either more tolerant to tannins or able to degrade tannins. Further work will be required to elucidate the important members of these groups and to obtain them in culture

Bacteriophages in the rumen: types present, population size and implications for the efficiency of feed utilisation

One cause of a reduction in the efficiency of feed utilisation in the rumen is the non-specific lysis of bacteria within the rumen and subsequent fermentation of the bacterial protoplasm. Bacteriophages are implicated in this lysis, are obligate pathogens of bacteria and occur in dense populations in the rumen. Large numbers are present (up to lo*’ per millilitre of fluid) in the rumen. These viruses are morphologically diverse with 26 distinct types from three viral families (Myoviridae, Siphoviridae and Podoviridae) being represented. The use of the DNA-based methodology, Pulsed Field Gel Electrophoresis, has allowed an estimate of phage numbers in the rumen at a point in time. This procedure will enable investigations of changes in the phage population in relation to changing dietary regimes. Preliminary evidence suggests that diet may influence viral activity and therefore dietary manipulation could, in the future, be used to reduce viral activity and improve the flow of microbial protein to the intestines

Ammonia-hyperproducing bacteria from New Zealand ruminants

Pasture-grazed dairy cows, deer, and sheep were tested for the presence of ammonia-hyperproducing (HAP) bacteria in roll tubes containing a medium in which tryptone and Casamino Acids were the sole nitrogen and energy sources. Colonies able to grow on this medium represented 5.2, 1.3, and 11.6% of the total bacterial counts of dairy cows, deer, and sheep, respectively. A total of 14 morphologically distinct colonies were purified and studied further. Restriction fragment length polymorphisms of 16S rRNA genes indicated that all isolates differed from the previously described HAP bacteria,Clostridium aminophilum, Clostridium sticklandii, and Peptostreptococcus anaerobius. Carbon source utilization experiments showed that five isolates (C2, D1, D4, D5, and S1) were unable to use any, or very few, of the carbon sources tested. Biochemical tests and phylogenetic analyses of 16S ribosomal DNA sequences indicated that all isolates were monensin sensitive; that D1 and S1 belonged to the genusPeptostreptococcus, that D4 and D5 belonged to the familyBacteroidaceae, where D4 was similar to Fusobacterium necrophorum; and that C2 was most similar to an unidentified species from the genus Eubacterium. Growth on liquid medium containing tryptone and Casamino Acids as the sole nitrogen and energy source showed that D1, D4, and S1 grew rapidly (specific growth rates of 0.40, 0.35, and 0.29 h−1, respectively), while C2 and D5 were slow growers (0.25 and 0.10 h−1, respectively). Ammonia production rates were highest in D1 and D4, which produced 945.5 and 748.3 nmol/min per mg of protein, respectively. Tests of individual nitrogen sources indicated that D1 and D4 grew best on tryptone, S1 grew equally well on Casamino Acids or tryptone, and C2 and D5 grew poorly on all nitrogen sources. The intact proteins casein and gelatin did not support significant growth of any of the isolates. These isolates extend the diversity of known HAP rumen bacteria and indicate the presence of significant HAP bacterial populations in pasture-grazed New Zealand ruminants

Probiotic Bacillus amyloliquefaciens Strain H57 Improves the Performance of Pregnant and Lactating Ewes Fed a Diet Based on Palm Kernel Meal

Probiotic supplements are single or mixed strain cultures of live microorganisms that benefit the host by improving the properties of the indigenous microflora (Seo et al 2010). In a pilot study at the University of Queensland, Norton et al (2008) found that Bacillus amyloliquefaciens Strain H57 (H57), primarily investigated as an inoculum to make high-quality hay, improved feed intake and nitrogen utilisation over several weeks in pregnant ewes. The purpose of the following study was to further challenge the potential of H57 -to show it survives the steam-pelleting process, and that it improves the performance of ewes fed pellets based on an agro-industrial by-product with a reputation for poor palatability, palm kernel meal (PKM), (McNeill 2013). Thirty-two first-parity White Dorper ewes (day 37 of pregnancy, mean liveweight = 47.3 kg, mean age = 15 months) were inducted into individual pens in the animal house at the University of Queensland, Gatton. They were adjusted onto PKM-based pellets (g/kg drymatter (DM): PKM, 408; sorghum, 430; chick pea hulls, 103; minerals and vitamins; Crude protein, 128; ME: 11.1MJ/kg DM) until day 89 of pregnancy and thereafter fed a predominately pelleted diet incorporating with or without H57 spores (10 9 colony forming units (cfu)/kg pellet, as fed), plus 100g/ewe/day oaten chaff, until day 7 of lactation. From day 7 to 20 of lactation the pelleted component of the diet was steadily reduced to be replaced by a 50:50 mix of lucerne: oaten chaff, fed ad libitum, plus 100g/ewe/day of ground sorghum grain with or without H57 (10 9 cfu/ewe/day). The period of adjustment in pregnancy (day 37-89) extended beyond expectations due to some evidence of mild ruminal acidosis after some initially high intakes that were followed by low intakes. During that time the diet was modified, in an attempt to improve palatability, by the addition of oaten chaff and the removal of an acidifying agent (NH4Cl) that was added initially to reduce the risk of urinary calculi. Eight ewes were removed due to inappetence, leaving 24 ewes to start the trial at day 90 of pregnancy. From day 90 of pregnancy until day 63 of lactation, liveweights of the ewes and their lambs were determined weekly and at parturition. Feed intakes of the ewes were determined weekly. Once lambing began, 1 ewe was removed as it gave birth to twin lambs (whereas the rest gave birth to a single lamb), 4 due to the loss of their lambs (2 to dystocia), and 1 due to copper toxicity. The PKM pellets were suspected to be the cause of the copper toxicity and so were removed in early lactation. Hence, the final statistical analysis using STATISTICA 8 (Repeated measures ANOVA for feed intake, One-way ANOVA for liveweight change and birth weight) was completed on 23 ewes for the pregnancy period (n = 11 fed H57; n = 12 control), and 18 ewes or lambs for the lactation period (n = 8 fed H57; n = 10 control). From day 90 of pregnancy until parturition the H57 supplemented ewes ate 17 more DM (g/day: 1041 vs 889, sed = 42.4, P = 0.04) and gained more liveweight (g/day: 193 vs 24.0, sed = 25.4, P = 0.0002), but produced lambs with a similar birthweight (kg: 4.18 vs 3.99, sed = 0.19, P = 0.54). Over the 63 days of lactation the H57 ewes ate similar amounts of DM but grew slower than the control ewes (g/day: 1.5 vs 97.0, sed = 21.7, P = 0.012). The lambs of the H57 ewes grew faster than those of the control ewes for the first 21 days of lactation (g/day: 356 vs 265, sed = 16.5, P = 0.006). These data support the findings of Norton et al (2008) and Kritas et al (2006) that certain Bacillus spp. supplements can improve the performance of pregnant and lactating ewes. In the current study we particularly highlighted the capacity of H57 to stimulate immature ewes to continue to grow maternal tissue through pregnancy, possibly through an enhanced appetite, which appeared then to stimulate a greater capacity to partition nutrients to their lambs through milk, at least for the first few weeks of lactation, a critical time for optimising lamb survival. To conclude, H57 can survive the steam pelleting process to improve feed intake and maternal liveweight gain in late pregnancy, and performance in early lactation, of first-parity ewes fed a diet based on PKM

Near complete genome sequence of the animal feed probiotic, Bacillus amyloliquefaciens H57

Bacillus amyloliquefaciens H57 is a bacterium isolated from lucerne for its ability to prevent feed spoilage. Further interest developed when ruminants fed with H57-inoculated hay showed increased weight gain and nitrogen retention relative to controls, suggesting a probiotic effect. The near complete genome of H57 is ~3.96 Mb comprising 16 contigs. Within the genome there are 3,836 protein coding genes, an estimated sixteen rRNA genes and 69 tRNA genes. H57 has the potential to synthesise four different lipopeptides and four polyketide compounds, which are known antimicrobials. This antimicrobial capacity may facilitate the observed probiotic effect

Near complete genome sequence of the animal feed probiotic, Bacillus amyloliquefaciens H57

Bacillus amyloliquefaciens H57 is a bacterium isolated from lucerne for its ability to prevent feed spoilage. Further interest developed when ruminants fed with H57-inoculated hay showed increased weight gain and nitrogen retention relative to controls, suggesting a probiotic effect. The near complete genome of H57 is ~3.96 Mb comprising 16 contigs. Within the genome there are 3,836 protein coding genes, an estimated sixteen rRNA genes and 69 tRNA genes. H57 has the potential to synthesise four different lipopeptides and four polyketide compounds, which are known antimicrobials. This antimicrobial capacity may facilitate the observed probiotic effect

Naturally occurring DNA transfer system associated with membrane vesicles in cellulolytic Ruminococcus spp. of ruminal origin

A genetic transformation system with similarities to those reported for gram-negative bacteria was found to be associated with membrane vesicles of the ruminal cellulolytic genus Ruminococcus. Double-stranded DNA was recovered from the subcellular particulate fraction of all the cellulolytic ruminococci examined. Electron microscopy revealed that the only particles present resembled membrane vesicles. The likelihood that the DNA was associated with membrane vesicles (also known to contain cellulosomes) was further supported by the adherence of the particles associated with the subcellular DNA to cellulose powder added to culture filtrates. The particle-associated DNA comprised a population of linear molecules ranging in size from <20 kb to 49 kb (Ruminococcus sp. strain YE73) and from 23 kb to 90 kb (Ruminococcus albus AR67). Particle-associated DNA from R. albus AR67 represented DNA derived from genomic DNA of the host bacterium having an almost identical HindIII digestion pattern and an identical 16S rRNA gene. Paradoxically, particle-associated DNA was refractory to digestion with EcoRI, while the genomic DNA was susceptible to extensive digestion, suggesting that there is differential restriction modification of genomic DNA and DNA exported from the cell. Transformation using the vesicle-containing fraction of culture supernatant of Ruminococcus sp. strain YE71 was able to restore the ability to degrade crystalline cellulose to two mutants that were otherwise unable to do so. The ability was heritable and transferred to subsequent generations. It appears that membrane-associated transformation plays a role in lateral gene transfer in complex microbial ecosystems, such as the rumen

Effects of Two Intake Levels of \u3cem\u3eLeucaena leucocephala\u3c/em\u3e on Rumen Function of Sheep

Ruminant production systems based on grass pastures often produce poor animal performance as expressed by growth or reproductive rates. The nutrient imbalance affecting rumen function is due to their low energy and protein intake. The incorporation of leguminous forages such as Leucaena leucocephala, in the diet of ruminants, can stimulate rumen function by providing protein-rich forage (Barros-Rodriguez et al. 2012). This increases the availability of compounds such as ammonia, amino acids and peptides as well as branched short-chain fatty acids, which are produced as a result of degradation of proteins. These substances promote fibre breakdown by acting as ruminal growth activators for rumen bacteria, especially cellulolytic bacteria (Hoover and Stokes 1991). This study aimed to evaluate the effects of 2 intake levels of L. leucocephala on rumen function of sheep fed Pennisetum purpureum