PRACTICES AFFECTING QUALITY AND PRESERVATION OF WHOLE-PLANT CORN SILAGE

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Abstract
Low seasonal heat-unit accumulation is the major climatic restraint for the production of whole-plant corn (Zea mays L.) silage in Canada. As the crop is produced under increasingly cool seasonal conditions, reductions in dry matter (DM) yield can be expected because of environment and because whole-plant DM yield will maximize earlier in relation to grain development. Dry matter yields should remain competitive, however, with those of alternate forage crops grown under similar low corn heat unit (CHU) conditions. More serious are the feeding and storage problems which occur when corn is ensiled at increasingly immature stages of development. Attendant reductions in percent grain and DM content of the forage should have minimal effects on DM digestibility, but decreases in voluntary DM intake of ensiled corn forage occur at DM percentages below 30. Seepage and over-winter freezing are also major hazards with low-DM silages, particularly in tower silos. In higher-CHU regions of Canada, production techniques which augment forage DM production but which permit the crop to attain 30% DM by harvest or first fall frost should have limited effects on feeding quality. In marginal areas, desirable cultural practices should encourage rapid development, to permit the corn crop to achieve the highest possible DM percentage before frost. In many regions, attainment of 30% whole-plant DM before frost is usually impossible and some reduction in animal intake, or increase in the level of grain supplement needed to obtain equivalent animal performance will occur, relative to 30–35% DM silage. Recent research suggests that possibilities exist to increase DM intake of low-DM silages through the addition of chemical or feed-stuff additives at ensiling. Investigations on this subject should receive major attention from research dedicated to expanded utilization of forage corn in Canada.