Effects of chop length and ensiling period of forage maize on in vitro rumen fermentation characteristics

The effect of chop length and ensiling period on in vitro rumen fermentation characteristics of forage maize was studied in two experiments. In the first experiment, maize plants of eight cultivars representing different combinations of Dry Down, Stay Green, early ripening, late ripening, starch and cell wall types were chopped at harvest into pieces of 6 or 15 mm and ensiled in small laboratory silos. After 8 weeks, silage samples were taken and freeze-dried (not ground] before in vitro rumen fermentation characteristics were determined using the gas production technique. Chop length appeared not to affect the in vitro fermentation characteristics. In the second experiment, plants of two of these maize cultivars were chopped into 6-mm pieces and ensiled for different periods in small laboratory silos and in large bunker silos as used in practice. After 0, 14, 42 and 180 days of ensiling, chemical composition and in vitro rumen fermentation characteristics were determined using the gas production technique. The in vitro fermentation characteristics were not influenced by the ensiling period up to 180 days. During the first two weeks of the ensiling period sugar content decreased and so did the gas production caused by fermentation of the soluble components.