Abstract
The objective of this study was to evaluate the agronomic characteristics, bromatological-chemical composition and digestibility of 11 corn cultivars (Zea mays) harvested at two cutting heights. Cultivars D 766, D 657, D 1000, P 3021, P 3041, C 805, C 333, AG 5011, FO 01, CO 9621 and BR 205 were evaluated when they were harvested 5 cm above ground (low) and 5 cm below the insertion of the first ear (high). The experiment was designed as random blocks, with three replicates, arranged in an 11 x 2 factorial scheme. Cultivars presented similar productions of forage dry matter and grains. Percentages of stalk, leaf, straw, cob and kernel fractions were different among cultivars, as well as dry matter content of the whole plant at harvest. Considering the whole plant, only the contents of gross energy, nitrogen in neutral detergent fiber, and in vitro neutral and acid detergent fiber digestibility did not differ among cultivars. Increase on the cutting height improved forage quality due to the reduction of stalk and leaf fractions and contents of cell wall constituents.
Highlights
In order to produce high quality whole-plant corn silage, several technical recommendations should be observed, such as the proper of maturity stage and characteristics of plant components at harvest, which result in increased nutritional value and reduced production costs (Ferreira, 1990)
According to Demarquilly (1994), the optimum stage for harvesting the whole-plant corn, described in literature, is at the maximum dry matter (DM) yield per hectare, which occurs when the corn kernel is at the dent stage (33 to 35% dry matter)
According to Hunter et al (1991), the importance of kernels, as the main factor responsible for the whole-plant corn silage quality is questionable, inasmuch as there is genotypic variation in fiber quality of the plant, expressed in terms of DM intake and forage digestibility. These values do not depend on the proportion of grains in the whole corn plant DM, indicating that the forage portion significantly contributes to the overall silage quality
Summary
In order to produce high quality whole-plant corn silage, several technical recommendations should be observed, such as the proper of maturity stage and characteristics of plant components at harvest, which result in increased nutritional value and reduced production costs (Ferreira, 1990).According to Demarquilly (1994), the optimum stage for harvesting the whole-plant corn, described in literature, is at the maximum dry matter (DM) yield per hectare, which occurs when the corn kernel is at the dent stage (33 to 35% dry matter).in order to evaluate the DM production of the corn plant, agronomical conditions, such as planting density, cutting height and DM content of the whole corn plant components, should be considered. According to Hunter et al (1991), the importance of kernels, as the main factor responsible for the whole-plant corn silage quality is questionable, inasmuch as there is genotypic variation in fiber quality of the plant, expressed in terms of DM intake and forage digestibility. These values do not depend on the proportion of grains in the whole corn plant DM, indicating that the forage portion significantly contributes to the overall silage quality. This confirms that the quality of the forage produced may determine several advantages regarding to intake, for efficiency of nutrient use, which is intensified by the higher silage digestibility
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