High-grain diets supplemented with phytogenic compounds or autolyzed yeast modulate ruminal bacterial community and fermentation in dry cows

Abstract

The feeding of concentrate-rich diets may lead to microbial imbalances and dysfermentation in the rumen. The main objective of this study was to determine the effects of supplementing phytogenic compounds (PHY) or autolyzed yeast (AY) on rumen fermentation and microbial abundance in cows intermittently fed concentrate-rich diets. The experiment was carried out as an incomplete 3 × 4 Latin square design, with 8 nonlactating rumen-fistulated Holstein-Friesian cows. The cows were randomly assigned to a concentrate diet that was either not supplemented (CON), or supplemented with PHY or AY. Each of the 4 consecutive experimental periods was composed of a 1-wk roughage-only diet (RD), 6-d gradual concentrate increase, followed by 1 wk of 65% concentrate (dry matter basis; Conc I), and 1 wk of RD and a final 2-wk 65% concentrate (dry matter basis; Conc II) phase. Digesta samples were collected from the rumen mat for bacterial 16S rRNA gene Illumina MiSeq (Illumina, Balgach, Switzerland) sequencing, and samples of particle-associated rumen liquid were obtained for measuring short-chain fatty acids, lactate, ammonia, and pH during RD (d 6), Conc I (d 19), and Conc II (d 39). The concentrate feeding caused a decrease of overall bacterial diversity indices, especially during Conc I. The genera Ruminococcus, Butyrivibrio, and Coprococcus were decreased, whereas Prevotella, Megasphaera, Lachnospira, and Bacteroides were increased in abundance. Supplementation of both feed additives increased the abundance of gram-positive and decreased that of gram-negative bacteria. Supplementation of AY enhanced cellulolytic bacteria such as Ruminococcus spp., whereas PHY decreased starch and sugar fermenters including Bacteroides spp., Shuttleworthia spp., and Syntrophococcus spp. Moreover, PHY supplementation increased butyrate percentage in the rumen in both concentrate phases. In conclusion, intermittent high-concentrate feeding altered the digesta-associated rumen bacterial community and rumen fermentation with more significant alterations found in Conc I than in Conc II. The data also showed that both feed additives had the most significant modulatory effects on the bacterial community, and their subsequent fermentation, during periods of low pH.

Supplementing phytogenic compounds or autolyzed yeast modulates ruminal biogenic amines and plasma metabolome in dry cows experiencing subacute ruminal acidosis

“…Recent research of our team has shown that intermittent SARA affects pH and causes important bacterial shifts in the rumen. These effects were stronger during the first versus the second SARA bout, despite feeding the same diet (Neubauer et al, 2018). Most interestingly, this research showed that supplementation of phytogenic compounds (PHY) or autolyzed yeast (AY) alleviated the dysbiosis mainly by reducing the drop of ruminal pH, promoting chewing activity, and beneficially affecting microbial community structure.…”

“…Moreover, a decrease in plasma lysoPC has been previously reported in cows receiving LPS from E. coli (O26:B6) intramammarily or experiencing diseases (Hailemariam et al, 2014b;. However, as PC are generally associated with cholesterol to surround triacylglycerols (Gruffat et al, 1996), their decrease might be a common observation in cows receiving high-concentrate diets, as feeding high levels of fermentable carbohydrates is generally associated with a decreased production of acetate (Neubauer et al, 2018), the main precursor of cholesterol synthesis in ruminants (Liepa et al, 1978). Moreover, SM are part of bovine phospholipids of very low-density lipoproteins (Nilsson and Duan, 2006).…”

“…The experiment was part of a larger study and detailed information about cows, feeding, and experimental setup as well as results according to reticuloruminal pH, chewing activity, and ruminal microbiome have been reported in our companion papers (Kröger et al, 2017;Neubauer et al, 2018). In brief, 8 rumencannulated (100 mm i.d.…”

“…This is supported by the strongest decrease in reticuloruminal pH in SARA1 (Kröger et al, 2017), as well as the enhanced abundance of Lactobacillus sp. in the respective feeding phase (Neubauer et al, 2018). Figure 5.…”

“…Most interestingly, this research showed that supplementation of phytogenic compounds (PHY) or autolyzed yeast (AY) alleviated the dysbiosis mainly by reducing the drop of ruminal pH, promoting chewing activity, and beneficially affecting microbial community structure. These effects were observed particularly when severest pH drops occurred (Kröger et al, 2017;Neubauer et al, 2018). However, the extent to which repeated SARA bouts affect the indicators of ruminal dysbiosis such as the release and accumulation of BA and LPS and whether PHY or AY supplementation is also able to modulate these indicators have not yet been evaluated.…”