Determinants of degradability among sugarcane clones in bovine rumen / Determinantes da degradabilidade entre clones de cana-de-aÃÃcar no rÃmen de bovinos

AUTOR(ES)
DATA DE PUBLICAÇÃO

2004

RESUMO

The objective of this work was to evaluate the variability of nutritive value among sugarcane clones, to estimate the correlation between plant digestibility and productivity, and to define which agronomical and chemical traits would be most important as determinants of nutritive value. Twenty sugarcane industrial clones were evaluated in a completely randomized block design with four replicates. Clones cultivated in Campos, RJ state, originated from the Plant Breeding Program for Sugar and Alcohol Production of the Federal Rural University of Rio de Janeiro. Plants were harvested when the Brix was superior to 18%, at an age between 370 and 374 days after the second ratoon cut. Nine agronomical traits, ten chemical traits and the ruminal NDF and dry matter (DM) in situ degradability were evaluated. Productivity was 21.2  5.67 t DM/hectare and ruminal DM degradability was 57.1  2.64 % of DM (mean  standard deviation). The percentage of ADF (negative r2), stalk length (negative r2) and stalk percentage (positive r2) were the only variables included in the multivariate regression model correlating ruminal DM degradability to chemical and agronomical traits. Obtaining clones that conciliate high stalk yield to high digestibility was feasible, since the phenotypic as well as the genetic correlation between these traits were of low magnitude. The estimated h2 for the ruminal DM degradability trait was superior to 85%. Improving digestibility by indirect selection did not seem justifiable, since traits indirectly correlated to the digestibility had smaller estimated h2 values than the value obtained for the ruminal DM degradability trait.

ASSUNTO(S)

cana-de-aÃÃcar rumen rÃmen caracterÃsticas quÃmicas caracterÃsticas agronÃmicas zootecnia sugarcane chemical traits agronomical traits

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