Corn Forage Yield and Quality for Silage in Short Growing Season Areas of the Canadian Prairies

The development of short-season hybrids has made corn (Zea mays L.) silage (CS) production possible in cooler areas. This work aimed at determining biomass yield and nutritive quality of short-season corn CS hybrids. Six corn hybrids were grown in three years at four locations within the Canadian prairies with four field replications. Hybrids were harvested before occurrence of frost at a target dry matter (DM) content of 300 to 400 g kg(-1). Corn heat units (CHU) from seeding to harvesting (CHUseed-harv) and water supply were recorded. Samples were analysed for nutrient content; i.e., DM, neutral detergent fiber (NDF), crude protein (CP), starch, and in vitro DM and NDF digestibilities (48 h incubation). Then, CHUseed-harv, water supply, whole plant DM, CHU rating of the hybrid, and cob percentage were assessed as predictors of nutrient content. Location, hybrid, and year affected nutrient composition and yield. Overall, CP and NDF were positively correlated (r = 0.48, p < 0.01), but both were negatively correlated with DM yield (r = -0.63, -0.28, p < 0.01) and starch (both r = 0.71, p < 0.01). Within and among locations, CHUseed-harv differently affected nutrient composition and DM yield. However, DM yield was the most predictable factor (R-2 = 0.86) with CHUseed-harv being the strongest contributor (48%) to the overall variability, followed by water supply (23%). Whole plant DM and CHUseed-harv were also good predictors of starch (R-2 = 0.54). This work showed the high variability of biomass yield and nutritive quality of short-season CS hybrids grown in Northern areas.