In 2006, GQS604S testcrosses were evaluated at two locations, Madison and Arlington. There were two replications at each location. The 78 entries consisted of 73 S2 families from the GEM Quality Composite (GQS) crossed to W604S and five hybrid checks. The GQS604S trial represents the first cycle of selection in the GQS breeding population. The 20 best S2 families will be recombined to create GQS C1.

The planting date at Madison was 5/21/2006. The Arlington trial was planted on 6/2/2006. The average planting densities were 30,400 plants/acre at Madison and 28,600 plants/acre at Arlington. There were extreme winds during July at both locations causing extensive lodging.

Based on forage yield, 41 GQS604S testcrosses were chosen for nutritional evaluation (GQS604S – Forage yield evaluation). Nutritional evaluations included assessment of neutral detergent fiber (NDF), in vitro true digestibility (IVD), in vitro NDF digestibility (IVNDFD), crude protein (CP), and starch concentration. Based on these values, milk/ton of forage and milk/acre were estimated based on MILK2006, which uses forage composition (NDF, IVD, IVNDFD, CP, and starch) to estimate potential milk production per ton of forage. Forage yield is then used to estimate potential milk per acre (GQS604S – Forage quality evaluation).