Inhibition of Growth and Ammonia Production of Ruminal Hyper Ammonia-Producing Bacteria by Chinook or Galena Hops after Long-Term Storage

Abstract

Surplus hops (Humulus lupulus L.) that are not needed by the brewing industry could be used as a feed supplement for cattle and other ruminants. Previous research indicates that antimicrobial hops plant secondary metabolites (i.e., α-and β-acids) inhibit methane and ammonia production and promote the growth of ruminant animals. The goal was to determine that hop pellets produced for brewing still possessed the requisite antimicrobial activity after 5-year storage. HPLC (high performance liquid chromatography) analysis indicated that the α-and β-acid concentrations in two varieties of hops were relatively stable after 5 years of storage under N 2 . Either hop variety inhibited the growth of the ruminal hyper ammonia-producing bacterium, Clostridium sticklandii SR, in broth culture and Petri plate bioassays. Either hop variety inhibited ammonia production from amino acids or peptides by mixed rumen microorganisms from Holstein steers. These results are similar to those previously obtained with fresh hops, hops extracts, other antimicrobial phytochemicals and typical feed ionophores, such as monensin. The rumen-active antimicrobial phytochemicals in hops can still be present and active after years under certain storage conditions. Further investigation is warranted to determine how surplus and older hops can be used to benefit ruminant nutrition and ruminant industries.

Effects of Hops (<i>Humulus lupulus</i> L.) Beta-Acids on Short Chain Fatty Acid Production from Complex Carbohydrates by Rumen Microbiota

“…Some results have shown that spent brewers' yeast inhibited rumen ammonia and methane production [25] [26]. Another DOI: 10.4236/aim.2019.912063 990 Advances in Microbiology study indicates that older stored hops are adequately antimicrobial for feeding applications even after they are no longer desirable by brewers [27]. The antimicrobial spectrum of activity of hop phytochemicals should be considered when planning diets to test these co-products.…”

Spent Craft Brewer's Yeast Reduces Production of Methane and Ammonia by Bovine Rumen Microbes

“…Hop acids are known inhibitors of bovine hyper ammoniaproducing bacteria (Flythe, 2009;Flythe et al, 2017a). Supporting the role of hop acids in suppressing ammonia formation by rumen microbes, craft yeast was previously found to generate less ammonia than baker's yeast even in the presence of exogenous amino acids by inhibition of hyper ammonia-producing bacteria (Harlow et al, 2016).…”

Effects of Hops Treatment on Nitrogen Retention, Volatile Fatty Acid Accumulations, and Select Microbial Populations of Composting Poultry Litter Intended for Use as a Ruminant Feedstuff

“…The composition of the bluestem hay, as determined by the Texas A&M AgriLife Extension Service Soil, Water and Forage Testing Laboratory (soiltesting.tamu.edu), was 4.8% crude protein, 39.8% acid detergent fiber, 52.5% total digestible nutrients-based acid detergent fiber, and 0.53, 0.56, and 0.23 Mcal/kg net energy for lactation, maintenance, and gain, respectively. The Chinook hops and Galena hops pellets used for both compost simulations were provided by Lupulin Exchange (Charlottesville, VA, USA) and their composition, with α-acid contents of about 12 and 13%, and β-acid contents of about 3 and 9%, respectively, have been described earlier [31]. The α-acids and β-acids from hops exhibit antimicrobial properties [23,31,32], with β-acids more specifically affecting amino acid-degrading, hyper ammonia-producing bacteria [33].…”