Selection for Silage Quality in the Wisconsin Quality Synthetic and Related Maize Populations

Maize (Zea mays L.) silage is a high‐quality forage for ruminants, but there have been few significant breeding efforts specifically dedicated to improving maize forage yield or quality by breeders in the USA. The objective of this study was to evaluate the forage yield and quality of the Wisconsin Quality Synthetic (WQS) and related populations developed by the University of Wisconsin Maize Breeding Program for agronomic and nutritional attributes. Three cycles of divergent S1 recurrent selection have been completed for stover fiber, silica, and lignin concentration for populations WFISIHI (Wisconsin‐fiber‐silica‐high) and WFISILO (Wisconsin‐fiber‐silica‐low). The third cycle (C3) of WFISILO was crossed to two high‐quality inbred lines, Mo17 and H99, to create WQS C0, which then underwent two cycles of S2–topcross selection for improved forage yield and quality. All cycles of selection for WFISIHI, WFISILO, and WQS were evaluated for forage yield and quality at two field locations in Wisconsin in 2000 and 2001. Results for WFISIHI and WFISILO demonstrated that S1 selection for stover composition altered both stover and whole‐plant composition in the anticipated directions. Selection for whole‐plant yield and composition of S2–topcrosses was also effective for WQS, especially when using selection indices incorporating whole‐plant yield, neutral detergent fiber (NDF), neutral detergent fiber digestibility (NDFD), crude protein (CP), and starch. WQS C2 whole‐plant and stover in vitro true digestibility (IVTD), whole‐plant and stover acid detergent lignin, and milk yield per megagram dry matter (DM) were similar to the brown‐midrib check hybrid, F657. WQS C2 whole‐plant and stover NDFD were lower than F657 but higher than other commercial check hybrids. In addition, WQS population testcrosses improved over cycles of selection for whole‐plant yield and most quality attributes. Our results indicate that it is feasible to develop silage maize germplasm with both high whole‐plant yield and excellent nutritional quality.