Effect of postextraction algal residue supplementation on the ruminal microbiome of steers consuming low-quality forage1

Abstract

Cattle consuming low-quality forages (LQF) require protein supplementation to increase forage utilization via ruminal fermentation. Biofuel production from algal biomass results in large quantities of postextraction algal residue (PEAR), which has the potential to elicit LQF utilization responses similar to cottonseed meal (CSM); however, its effect on ruminal bacterial communities is unknown. Five ruminally and duodenally cannulated Angus steers in a 5 × 5 Latin square had ad libitum access to oat straw diets. Treatments were infused ruminally and consisted of an unsupplemented control; PEAR at 50, 100, and 150 mg N/kg BW; and CSM at 100 mg N/kg BW. Ruminal samples were collected 4 h after supplementation on d 14 of each period and separated into solid and liquid fractions. Each sample was extracted for genomic DNA, PCR amplified for the V4 to V6 region of the 16S rRNA, sequenced on the 454 Roche pyrosequencing platform, and analyzed using the QIIME pipeline. Weighted UniFrac analysis and Morisita-Horn index demonstrated different community composition between liquid and solid fractions. Measures of richness including observed operational taxonomic units (OTU) and abundance coverage estimator metric decreased with greater PEAR provision (P ≤ 0.09). There were 42 core microbiome OTU observed in all solid fraction samples while the liquid fraction samples contained 30 core OTU. Bacteroidetes was the predominant phylum followed by Firmicutes in both fractions, which together characterized more than 90% of sequences. Relative abundance of Firmicutes increased with PEAR supplementation in the liquid fraction (linear, P = 0.02). Among Firmicutes, Lachnospiraceae, Ruminococcaceae, and Clostridiaceae families increased in the liquid fraction with greater PEAR supplementation (linear, P ≤ 0.03). Prevotella represented over 25% of sequences in all treatments, and relative abundance decreased in the solid fraction with increasing PEAR provision (linear, P = 0.01). Fibrobacter and Treponema decreased in the liquid fraction with increasing PEAR (linear, P < 0.10). Results suggest PEAR supplementation increased forage utilization by increasing members of Firmicutes within the liquid fraction of the rumen microbiome.

Rumen bacterial communities can be acclimated faster to high concentrate diets than currently implemented feedlot programs

“…Family S24‐7 has been detected in dairy and beef cattle (McCann et al . ; Lima et al . ), however, the role of S24‐7 in the rumen is poorly understood.…”

“…We also noted a decrease in family S24-7 as the adaptation steps progressed. Family S24-7 has been detected in dairy and beef cattle (McCann et al 2014;Lima et al 2015), however, the role of S24-7 in the rumen is poorly understood. Bacteria belonging to family S24-7 have been identified in mice fed high fat diets and gluco-oligosaccharides (Serino et al 2012).…”

Starter Feeding Supplementation Alters Colonic Mucosal Bacterial Communities and Modulates Mucosal Immune Homeostasis in Newborn Lambs

“…On the one hand, the enrichment of starch degraders, like unclassified S24-7, Prevotella, Bifidobacterium , and Ruminobacter , may be due to greater starch availability in the colon during starter feeding. Other studies have demonstrated the presence of family S24-7 in dairy and beef cattle (McCann et al, 2014; Lima et al, 2015; Anderson et al, 2016); however, the role of S24-7 in the colon of ruminants remains poorly understood. Bacteria belonging to family S24-7 have also been identified in the colons of mice fed high-fat diets and gluco-oligosaccharides (Serino et al, 2012).…”

In vitro digestion of microalgal biomass from freshwater species isolated in Alberta, Canada for monogastric and ruminant animal feed applications

“…These results could be related to impacts on rumen microflora. McCann et al [36] examined the effects of Chlorella spp. LEB on the ruminal microbiome.…”