Características agronômicas, bromatológicas e nutricionais de silagens de genótipos de sorgo forrageiro

Abstract

Sorghum is a forage with good production rates and nutritional quality, and its silage is an important alternative for feeding livestock. Genetic enhancement seeks to produce and improve cultivars that are adapted to the different regions of the country, and because of this, their evaluation as to productivity and nutritional value precede further planting instructions. The first objective of this study was to evaluate the productivity, the silage quality and the chemical composition of 21 experimental and 4 commercial sorghum genotypes. The experiment was carried out in a randomized block design, with 25 treatments and 3 repetitions each. The silages were made in experimental plastic bag silos when the forage reached the developmental stage of doughy grain. Data were subjected to analysis of variance and means were grouped by Scott-Knott test (5%). DM productivity level ranged from 9.22t/ha to 13.83t/ha with good participation of panicle for most materials and crude protein levels ranged from 4.69% to 7.10%. All materials presented good quality of fermentation, with TDN ranging from 60.37% to 69.89%, and the average levels of NDF and ADF were 50.28% and 32.59%, respectively. According to the results, the earlier cycle genotypes 12F40014 and BRS 610, and the later cycle genotypes 12F39014, 12F40006 and 12F40007, stood out due to their good DM production, with greater participation of panicles, low levels of NDF and ADF and good levels of protein and TDN. The second objective was to evaluate the ruminal in situ degradability of the dry matter of the five genotypes of sorghum (Sorghum bicolor, L. Moench) that stood out as the productivity and nutritional quality in the first study. The experimental design was completely randomized in a factorial fashion, consisting of five cultivars and seven incubation times. To compare the means of each treatment in different periods the SNK test (5%) was used. The effective degradability for all passage rates was better for genotype 12F40006, with 52.12%, 56.50%, 66.35%, followed by genotype 12F40007, with 51.73%, 55.69%, 64.63%. Overall, it is concluded that the genotypes 12F40006 and 12F40007, under the conditions of this study, gather the largest number of production characteristics, nutrition and digestibility and can be recommended for planting and production of silage.