Evaluation of Selection for Silage Quality in Wisconsin Quality Synthetic and Connections to Maize Biofeedstock Breeding.

The development of maize cultivars with enhanced forage yield and compositional attributes is of interest not only in ruminant nutrition but more recently in lignocellulosic biofeedstock research as well. The Wisconsin Quality Synthetic (WQS) maize population has undergone four cycles of S2 topcross selection for increased biomass yield and digestibility on the whole plant level. A previous evaluation conducted after the second cycle of selection showed a positive trend in whole plant yield, neutral detergent fiber (NDF), NDF digestibility (NDFD), crude protein, and starch for this population, however some of the differences were not significant. The objective of this research is to test, after four cycles of selection, whether selection for yield and quality on a whole-plant basis has improved stover digestibility or has simply increased the contribution of the highly digestible grain portion. In summer 2007, cycle 0 through 3 of the WQS population per se, along with the hybrids resulting from the cross of each population cycle to two stiff-stalk testers were planted in three replications at two locations in south central Wisconsin. A bm3 hybrid, two commercial grain hybrids, and a high fiber cultivar were also included as checks. Preliminary data analysis indicate continued improvement in silage-stage stover and whole plant NDFD, milk yield per hectare, and milk yield per Mg of dry matter at both the population per se and testcross level. Whole plant yield and stover yield have also increased. Evaluation of stover quality at full maturity suggests that the WQS population may also be a good germplasm source for the development of cultivars with enhanced characteristics for lignocelluosic biofeestock production.