Impact of hybrid and growing location on yield and composition of corn plants harvested for silage

Abstract Text: Relative effects of hybrid, growing location, and DM at harvest on corn silage yield and composition have not been clearly defined.  Their impacts on yield, plant and grain composition at silage harvest, and potential milk yields were examined using corn plants and grain from 5 Pioneer hybrids grown in each of 15 environmentally diverse Michigan locations in 2013 all harvested at silage maturity.  Nutrient compositions were determined at a commercial laboratory; milk yields were predicted from Milk 2006 equations.  Relationships were evaluated using regression and GLM procedures of SAS. Whole plant DM, grain DM, starch, and NDF ranged from 24.2 to 47.8, 49 to 76, 17.2 to 39.6, and 37.1 to 49; 24 hour NDF disappearance ranged from 36.3 to 55.6 percent of NDF; DM yield ranged from 8 to 23 metric ton (MT) per hectare while milk ranged from 1444 to 1873 kg per MT.  Growing location altered (P < 0.01) every measurement.  Harvest DM had quadratic effects on milk per hectare and on yields of DM, starch and NDF, each peaking at 41% DM; hence relative nutritional values can be biased if hybrids differ in DM content even when harvested on the same date.  Among environmental measures, growing degree days prior to harvest (range 1916 to 2367) was related (P < 0.05) negatively to sugar but positively to starch content of plants.  Precipitation (36 to 65 cm during the season) was related (P < 0.02) positively to yield and milk per hectare but negatively to crude protein content and NDF digestibility.  Locations that received less than 41 cm of rain had lower (P< 0.05) plant yields and milk per hectare but greater (P < 0.05) NDF digestibility (48.3 versus 45.8 percent of NDF) and CP, fat, and prolamin content of grain.  Greater plant weight was associated with increased kernel density and yield of milk and DM per hectare.  Hybrids with greater drought tolerance had greater (P < 0.04) starch content of plants and grain and greater starch availability from grain but lower NDF digestibility.  The growing environment and harvest DM generally had greater impact on silage yield and nutritive value than hybrid choice among the corn silage hybrids tested. 

Keywords: Corn silage, location, harvest