Silage review: Interpretation of chemical, microbial, and organoleptic components of silages

Abstract

The goal of making silage is to produce a stable feed with a high recovery of dry matter, energy, and highly digestible nutrients compared with the fresh crop. Microbial fermentation in the silo produces an array of end products and can change many nutritive aspects of a forage. High-quality silage should be void of undesirable compounds that could negatively affect animal performance, the environment, or net farm income. This review discusses the interpretation of the common fermentation end products, microbial populations, organoleptic properties, and changes in nutritive aspects of silages during storage of silages with emphasis on a North American perspective.

Effect of maturity stage at harvest on the ensilability of maize hybrids in the early and late FAO classes, grown in areas differing in yield potential

“…In this study, all the hybrids showed an FQI value higher than 48.2, which, according to Andrighetto et al (), represents the cut‐off between excellent and not excellent maize silage from a fermentative point of view, confirming the goodness of the ensiling method used. In this regard, the early hybrids have generally shown a slightly lower production of ammonia, acetic and propionic acid, as also reported by Gerlach et al (), although both compounds have a concentration well below the suggested critical limit (Kung et al, ). Better fermentations were also found in plants grown in the area characterized by the highest fertility, and in those harvested earlier.…”

“…To obtain high performance of healthy animals, it is therefore necessary to feed them with high‐quality maize silage, characterized by adequate nutrient content (Krämer‐Schmid, Lund, & Weisbjerg, ) and a lack of harmful compounds, such as mycotoxins (Cavallarin, Tabacco, Antoniazzi, & Borreani, ; Driehuis, ). Furthermore, maize silage should have an optimal fermentation profile (Gallo et al, ; Kung, Shaver, Grant, & Schmidt, ) and aerobic stability (Borreani, Piano, & Tabacco, ; Elferink, Driehuis, Gottschal, & Spoelstra, ). This is especially important when highly productive animals are fed, because they have very high metabolic needs and are easily affected by any alterations to the ration, which could lead to reduced DM intake (DMI), low performance (Gerlach, Weiss, Ross, Buscher, & Sudekum, ; Grant & Ferraretto, ) and poor health (Borreani, Bernades, & Tabacco, ).…”

“…profile (Gallo et al, 2016;Kung, Shaver, Grant, & Schmidt, 2018) and aerobic stability (Borreani, Piano, & Tabacco, 2014;Elferink, Driehuis, Gottschal, & Spoelstra, 2000). This is especially important when highly productive animals are fed, because they have very high metabolic needs and are easily affected by any alterations to the ration, which could lead to reduced DM intake (DMI), low performance (Gerlach, Weiss, Ross, Buscher, & Sudekum, 2013;Grant & Ferraretto, 2018) and poor health (Borreani, Bernades, & Tabacco, 2008).…”

“…Ideally, to lower the pH of a substrate and minimize energy and DM loss during the anaerobic fermentation, all water-soluble carbohydrates (WSC) should be metabolized by homofermentative bacteria to lactic acid (Pahlow, Muck, Driehuis, Elferink, & Spoelstra, 2003). However, a large number of factors, including DM content, the amount of WSC and the buffering capacity of the substrate, alter many nutritive characteristics of forage (Kung et al, 2018), leading to the production of a complex array of compounds, such as volatile acids, alcohols and esters. Among these compounds, acetic acid, at moderate concentrations, seems to be beneficial, as it improves silage aerobic stability owing to its antifungal activity (Nishino, Wada, Yoshida, & Shiota, 2004).…”

“…Among these compounds, acetic acid, at moderate concentrations, seems to be beneficial, as it improves silage aerobic stability owing to its antifungal activity (Nishino, Wada, Yoshida, & Shiota, 2004). The analysis of these compounds, along with the measure of pH, still represents the main way of assessing the fermentation quality of maize silage (Andrighetto et al, 2018;Kung et al, 2018).…”