A note on suitable laboratory stover quality traits for multidimensional maize improvement

A total of 10 maize stovers from two open pollinated varieties (OPV's), four hybrids (one grown in two different seasons, Kharif and summer) and at two different locations and two parental lines were tested for a range of laboratory fodder quality traits and for in vivo digestibility and voluntary feed intake in sheep. Laboratory stover fodder quality traits measured were nitrogen (N), neutral (NDF) and acid detergent (ADF) fiber, acid detergent lignin (ADL), in vitro organic matter digestibility (IVOMD) and metabolisable energy (ME) content. Highly significant (P < 0.0001) differences among the stovers were observed for all laboratory fodder quality traits and for dry matter digestibility (DMD), dry matter intake (DMI) and digestible dry matter intake (DDMI) with DMD (%) DMI (g/d) and DDMI (g/d) ranging from 53 to 65, 325 to 635 and 194 to 382, respectively. The total amount of stover refused (DMR) by the sheep did not differ significantly (P = 0.67) among the stovers, however when DMR was expressed relative to DMI significant differences (P = 0.0007) were observed. Laboratory fodder quality traits most closely correlated to the in vivo measurements were ADF with r = −0.83, r = −0.92 and r = −0.93 for DMD, DMI and DDMI, respectively, and ME with r = 0.77, r = 0.94 and r = 0.94 for DMD, DMI and DDMI, respectively. Applying statistical cross-validation procedures where the predicted values were not used for the development of the regression equations (“blind-predictions”), DMD, DMI and DDMI could be predicted by ADF with resulting R2 for good-of-fitness between observed and predicted values of 0.46, 0.76 and 0.79, respectively. Similarly DMD, DMI and DDMI could be predicted by ME with resulting R2 for good-of-fitness between observed and predicted values of 0.40, 0.83 and 0.83, respectively.