Energy Values of Registered Corn Forage Hybrids in France over the Last 20 Years Rose in a Context of Maintained Yield Increase

The cultivation of corn silage has developed in France since the 1970s to reach 1.5 million of hectares nowadays. Since 1998, a feeding value criterion (namely UFL for “Unite Fourrage Laitiere”) has been taken into account to register forage varieties in the French forage maize hybrids catalog in addition to other criteria related to plant agronomical performances such as yield, earliness and lodging resistance. It is frequently stated that the improvement of plant’s agronomic performances would led to a decline in forage energy value. Decline of “Unite Fourrage Laitiere” values has been repeatedly reported and the expected increase was not yet visible in 2002. In the present study, a set 47 early and mid-early hybrids commercialized in France between 1958 and 2015 has been cultivated in 3 locations in France. “Unite Fourrage Laitiere” values and yield have been estimated in order to shed light on the evolution of feeding value criteria during this period and to conclude on the evolution of “Unite Fourrage Laitiere” values since the introduction of this criterion for registration. Results obtained in our study demonstrated a recent rise in “Unite Fourrage Laitiere” value in a context of strong yield increase. This increase was not necessarily attributable to high cob proportion in the harvested silage. Breeder’s work since the 2000’s has succeeded to offer hybrids that recover “Unite Fourrage Laitiere” values similar to the ones of hybrids from the 1960’s (Royal, 1960, 91 UFL/100 kg DM). We propose to accentuate this effort targeting the enhancement of lignocellulosic cell wall digestibility to breed for future forage maize hybrids.