Forage quality of sorghum, sudan-grass sorghum x sudan-grass and pearl millet cultivars in Manawatu

Sorghum, sudan-grass and pearl millet are summer forages typically fed to lactating cows and beef animals as a supplementary feed. Forage quality has a major influence on the intake and performance of animals in dairy and beef systems. A trial planted at Massey University, Palmerston North on 8 December 2009 compared agronomic traits, crop morphology and forage quality of four sorghum x sudan-grass hybrids (Pac 8421, Pac 8423, Pacific BMR and Bettagraze), two sudangrass (Superdan 2 and Sprint), one sweet sorghum (Sugargraze) and one pearl millet (Nutrifeed) cultivar. There were significant cultivar differences in leaf: stem ratio, tiller density and crop height at the time of yield measurement. Sugargraze (153.9 cm) was taller than all other cultivars while Nutrifeed (76.9 cm) was shorter than all other cultivars apart from Pacific BMR (89.1 cm). Metabolisable energy (P=0.0001) ranged from 10.1 to 11.0 MJ kg(-1) DM with Pacific BMR having higher levels than other cultivars apart from Nutrifeed and Pac 8421. Sugargraze had the lowest metabolisable energy. Sugargraze also had significantly (P<0.0001) lower crude protein content (10.3%) than all other cultivars; highest crude protein occurred in Nutrifeed (18.0%), Pacific BMR (16.8%) and Bettagraze (16.1%). Both metabolisable energy and crude protein were strongly, negatively associated with plant height.