Application of hops (Humulus lupulus L.) and Beta-acid extract to improve aerobic stability and in vitro ruminal fermentation of maralfalfa grass silage

Authors: ROMERO-VILORIO, LIANNE - Universidad Autonoma De Chihuahua; GONZALEZ-MORA, BEXY - Universidad Autonoma De Chihuahua; CASTILLO-CASTILLO, YAMICELA - Universidad Autonoma De Chihuahua; CASTILLO-RANGEL, FRANCISCO - Universidad Autonoma De Chihuahua; VARGAS-BELLO-PEREZ, EINAR - Universidad Autonoma De Chihuahua; DOMINGUEZ-VIVEROS, JOEL - Universidad Autonoma De Chihuahua; FELIX-PORTILLO, MONSERRATH - Universidad Autonoma De Chihuahua; Anderson, Robin; Hume, Michael; Flythe, Michael; NÁJERA-PEDRAZA, OMAR - University Of Tamaulipas; SALINAS-CHAVIRA, JAIME - University Of Tamaulipas; RUIZ-BARRERA, OSCAR - Universidad Autonoma De Chihuahua

Submitted to: Fermentation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/29/2025
Publication Date: 9/10/2025
Citation: Romero-Vilorio, L., Gonzalez-Mora, B., Castillo-Castillo, Y., Castillo-Range, F., Corral-Luna, A., Dominguez-Viveros, J., Ordoñez-Baquera, P.L., Anderson, R.C., Hume, M.E., Flythe, M.D., Nájera-Pedraza, O.G., Salinas-Chavira, J., Ruiz-Barrera, O. 2025. Application of hops (Humulus lupulus L.) and Beta-acids extract to improve aerobic stability and in vitro ruminal fermentation of maralfalfa grass silage. Fermentation. 11(9):529. https://doi.org/10.3390/fermentation11090529.
DOI: https://doi.org/10.3390/fermentation11090529

Interpretive Summary: One of the most common methods for preserving forages as a feedstuff for cattle and sheep is a process called ensiling. This method is an oxygen-free fermentation process that is facilitated by the growth of lactic acid producing bacteria (LAB), in which lactic acid accumulation leads to a pH decrease, creating an inhospitable environment for pathogens and other unwanted microorganisms during the ensiling process. However, the exposure of the silage to oxygen during the feeding phase can allow the growth of spoilage and pathogenic microbes and thus new technologies are needed to help restrict the growth of the unwanted microbes during feeding. In the present study, we evaluated the potential of hops (a plant component often used in beer making) and certain chemicals contained in the hops (called beta-acids) as a treatment to prevent spoilage of ensiled forage. We found that the beta-acid treatment controlled yeast populations and had no negative effect on the pH of the ensiled forage. Moreover, the beta-acid treatment helped prevent oxygen-caused deterioration of nutritious fermentation acids that normally occur upon exposure to air. These results demonstrate that beta-acids from hops can help preserve the microbial safety and nutritional quality of ensiled feedstuffs thereby helping livestock producers continue to produce safe and wholesome meat and milk at less cost for the American consumer.

Technical Abstract: The potential of hops (Humulus lupulus L) and beta-acids extract were evaluated for improving the quality of maralfalfa grass (Cenchrus purpureus) silage during aerobic exposure and their residual effects on in vitro ruminal fermentation characteristics. Silage samples of ground hops pellets (varieties Galena and Chinook) as well as beta-acids mixtures were incubated at 37C for 24 hours then maintained under aerobic exposure for 12 hours. Sample pH, counts of filamentous fungi, yeasts, total coliforms, and volatile fatty acid (VFA) concentrations were determined. Subsequently, in vitro ruminal fermentation was conducted to determine total gas production and concentrations of hydrogen, methane, carbon dioxide, and volatile fatty acids (VFAs). The beta-acids treatment controlled yeast populations, but an increase (p < 0.05) in pH values was observed for the Galena and Chinook treatments compared to the Control. However, pH did not differ significantly (p > 0.05) between the Control and the beta-acids treatment. Butyric acid concentrations in the silage were lower (p < 0.05) compared to the Control, except in the silage treatment with Galena. In the in vitro ruminal fermentation, the beta-acids treatment showed higher butyric acid levels than the Chinook and Galena, but these differences were not significant (p > 0.05). There were no differences (p > 0.05) in methane between the treatments. An increase (p < 0.05) in propionic acid concentration was observed in the in vitro ruminal fermentation with beta-acids. It was concluded that beta-acids could help reduce silage deterioration during the aerobic phase, and their residual effect could improve ruminal fermentation.