Mixed ensiling with by-products and silage additives significantly valorizes drought-impaired whole-crop corn

Corn silages constitute an important roughage in diets for high-yielding dairy cows. Due to summer droughts, quantity and quality of corn silages diminish, which both can have drastic consequences on the energy and nutrient provision to dairy cows. Mixed ensiling of drought-impaired whole-crop corn with by-products may represent a promising option to valorize the nutritive value and available biomass, which has not yet received much attention. Our study analyzed the potential of mixed ensiling of drought-impaired corn with either sugar beet pulp (SBP) or wheat gluten feed (WGF), without or with the application of different silage additives, i.e., either anaerobic fungi (AF) culture supernatant, mixed ruminal fluid or lactic acid bacteria. The aim was to study the effects on the chemical composition, fermentation patterns, in vitro gas production (GP), as an indicator of digestibility, and aerobic stability of the silages. We observed an overall sufficient preservation in all silages as evidenced by low dry matter (DM) losses of <= 3.37%, homolactic fermentation as well as lasting aerobic stability (>336 h), while the silage pH was significantly lower with by-product inclusion. The co-ensiling with WGF predominantly increased the crude protein content to similar to 200 g/kg DM with still low ammonia-N levels, i.e., 17 g/kg crude protein, whereas co-ensiling with SBP increased the energy level as evidenced by the in vitro GP kinetics. The application of fresh AF culture supernatant further improved the preservation success, including less ammonia-N and lower silage pH, and considerably increased the energy content of pure corn silages. Remarkably, addition of fresh AF culture supernatant also improved in vitro GP kinetics of WGF-based silages that performed less than other silages when no additives were applied. Using fresh mixed ruminal fluid showed beneficial effects on silage quality, such as lower ammonia-N concentrations in all silages, whereas heat-inactivated mixed ruminal fluid decreased silage pH. For the application of lactic acid bacteria, our results showed their support in facilitating roughage preservation, but without influence on chemical composition or in vitro rumen fermentation. In conclusion, mixed ensiling with by-products is yet an overlooked option for valorizing drought-impaired corn and our data confirmed the effectiveness of this approach. Without increasing the feed-food competition, mixed ensiling represents a promising adaptation strategy to summer droughts, especially in combined use with AF culture supernatant. Future research may now investigate the impact of feeding mixed silages on performance, behavior, and health of dairy cows.

Institute of Animal Physiology and Genetics CAS
Czech Academy of Sciences
Höhere Bundeslehr- und Forschungsanstalt Raumberg-Gumpenstein