Effect of cutting height and genetics on composition, intake, and digestibility of corn silage by beef heifers1

Abstract

This research was conducted to determine the effect of corn genetics and cutting height on the composition and nutritive characteristics of corn silage. An in situ study involving eight commercially available corn hybrids indicated main effects and interactions (P < 0.01) of hybrid and cutting height on NDF, ADF, and starch content and on in situ DM and NDF degradablility. Four ruminally cannulated Angus heifers (initial BW = 378 +/- 3 kg) were used in a 4 x 4 Latin square digestion experiment with a 2 x 2 factorial treatment arrangement. Main effects and interactions of hybrid (Pioneer Hi-Bred Int., Inc., hybrids 3335 and 3223) and cutting height (LO = 20.3 cm, and HI = 61 cm) were evaluated. Dietary treatment consisted of 40% chopped alfalfa hay and 60% corn silage. Although corn silage hybrids used were of equivalent maturity at harvest (60% milkline), 3335 treatments had 37.8% starch and 34.8% NDF, whereas 3223 treatments had 33.7% starch and 38.6% NDF. The LO treatments averaged 3.1 percentage units greater in NDF and 3.45 percentage units less in starch content than the HI treatments. Intake of DM was greater for heifers fed 3335-HI than 3335-LO; however, DMI was greater by heifers fed 3223-LO than 3223-HI (hybrid x cutting height interaction, P < 0.05). Starch intake was greater (P < 0.05) and NDF intake was less (P < 0.05) by heifers fed HI vs. LO and fed 3335 vs. 3223 dietary treatments. Digestibility of DM, starch, and NDF was greater (P < 0.05) by heifers fed 3223 than 3335 dietary treatments, but digestibility differences were not observed (P > 0.10) between cutting heights. Rate of in situ DM and starch degradability was not affected (P > 0.10) by hybrid or cutting height; however DM degradability was greater (P < 0.05) for HI than LO corn silage substrates at 8, 16, and 24 h of incubation. Rate of NDF degradability tended (P = 0.08) to be greater for 3223 than for 3335, and for LO compared with HI corn silage. Degradability of NDF was greater (P < 0.05) for 3223 compared with 3335 substrates at 24, 36, and 48 h of incubation. These data suggest fiber may not be an accurate measure of corn silage quality. Whereas cutting height affected chemical composition, we observed genetics to have a greater effect on corn silage quality.

Altura De Corte E Adição De Inoculante Enzimo-Bacteriano Na Composição Químico-Bromatológica E Digestibilidade De Silagens De Milho Avaliada Em Ovinos

“…Mesmo comportamento foi observado em outros trabalhos (1,2,15,25) , uma vez que cortes mais baixos apresentam maiores contribuição de colmo na massa ensilada. Assis et al (26) , avaliando as características de híbridos para ensilagem, observaram que os materiais que apresentaram maiores teores de lignina também apresentaram maiores proporções de colmo.…”

Produtividade e valor nutricional da silagem de híbridos de milho em diferentes alturas de colheita

“…A ocorrência de interações entre híbridos e altura de colheita pode ser por diferenças na composição em lignina entre os híbridos (Jung & Deetz, 1993;Jung & Allen, 1995), já que não houve alterações da relação LDA/FDN. Kennington et al (2005), estudando os efeitos da altura de corte e híbridos sobre a composição, ingestão e digestibilidade da silagem de milho em novilhas, encontraram diferença entre os híbridos para a digestibilidade e concluem que a composição genética do milho tem papel mais importante na digestibilidade da silagem do que a elevação da altura de corte na colheita.…”

“…Com a elevação da altura de colheita de 15 cm para 35 e 55 cm houve aumento (P<0,01) no teor de MS (Tabela 3). Esse aumento é bem documentado (Neylon & Kung Junior, 2003;Kennington et al, 2005;Kung Junior et al, 2008) e ocorre porque a espiga é normalmente mais seca que folhas e colmo. modelo matemático inclui os efeitos de tratamento, bloco, altura de colheita, além do erro experimental:…”

Caracterización fenotípica de híbridos y variedades de maíz forrajero en Valles Altos del Estado de México, México

“…Ambos fueron más tardíos (FM), tuvieron más hojas por planta (NH), mayor diámetro de tallo (DT), y produjeron más biomasa (MVTH, MVE, MVT) y materia seca (MSTH, MSE, MST) que los materiales de G1, G2 y G3. Kennington et al (2005) sugirieron que la eficiencia en la producción y calidad de forraje en maíz dependen principalmente del cultivar. Ambos cultivares tuvieron un DT inferior al registrado por Bosch et al (1992) en los materiales más sobresalientes, que fue de 2.33 cm.…”

“…Both were late (FM), had more leaves per plant (NH), increased stem diameter (DT), and produced more biomass (MVTH, MVE, MVT) and dry matter (MSTH, MSE, MST) that materials G1, G2 and G3. Kennington et al (2005) González et al (2008).…”