ARS | Publication request: Polyphenol oxidase activity in co-ensiled temperate grasses

Submitted to: International Silage Conference
Publication Type: Abstract Only
Publication Acceptance Date: January 2, 2012
Publication Date: N/A

Technical Abstract: Polyphenol oxidase (PPO) and its o-diphenol substrates have been shown to effectively decrease proteolytic activity during the ensiling of forages such as red clover. Orchardgrass and smooth bromegrass both contain high levels of PPO activity, but lack appropriate levels of o-diphenols to adequately inhibit proteolysis. On the other hand, tall fescue and timothy contain high levels of the o-diphenol, chlorogenic acid, but no PPO activity. Investigations were undertaken to determine the feasibility of co-ensiling pairs of these grasses in order to provide a source of PPO and a source of chlorogenic acid in the same ensiled material. Field-grown materials were harvested, macerated, and ensiled in mini-silos, either as a single grass or as a mixture. Levels of PPO activity and concentrations of chlorogenic acid were measured at the time of harvest and after sixty days of ensiling for each of the individual grasses and in the mixtures. Ensiling parameters (pH, VFA production, proteolytic activity) were measured for ensiled forages. All ensiled grasses produced silages with low pH and normal VFA production levels. In addition, proteolytic activity was reduced in the silos that contained both a PPO grass and an o-diphenol grass. This work suggests that PPO and o-dihenols can inhibit excessive proteolysis during ensiling. Co-ensiling grasses containing PPO and o-diphenols, respectively, can also achieve this inhibition.