VALOR NUTRITIVO DE SILAGEM DE CAPIM-PIATÃ EM MONOCULTIVO E EM CONSÓRCIO COM SORGO DE CORTE E PASTEJO

Resumo Objetivou-se avaliar a influência da idade de corte no valor nutritivo de silagem de capim-piatã em monocultivo e em consórcio com sorgo. Utilizou-se o delineamento em blocos casualizados com quatro repetições. Os tratamentos foram dispostos em esquema de parcelas subdivididas, como parcelas sistemas (capim-piatã; sorgo de corte e pastejo e consórcio) e como subparcelas as idades de corte (70, 90 e 110 dias após a semeadura). Os minissilos foram abertos aos 46 dias, avaliando-se na silagem os teores de proteína bruta (PB), fibra em detergente ácido (FDA), fibra em detergente neutro (FDN), nutrientes digestíveis totais (NDT), nitrogênio amoniacal, lignina e pH. Com o avanço da idade, ocorreu redução linear no teor de PB de 0,12; 0,08 e 0,16 unidades percentuais a cada dia após a semeadura nas silagens de sorgo, sorgo+capim e capim-piatã, respectivamente. Verificou-se aumento linear no valor de pH da silagem de sorgo + capim, em função do avanço na idade de 0,03 unidade a cada dia após a semeadura. Nas silagens de sorgo e de capim em monocultivo, o pH apresentou valores médios de 4,63 e de 5,20, respectivamente. Os sistemas com sorgo apresentam potencial para produção de silagem de boa qualidade aos 70 dias de idade. Palavras-chave: gramíneas tropicais; idade de corte; minissilo; silagem

NUTRITIVE VALUE OF SILAGE OF PIATÃ GRASS MONOCROP AND INTERCROPING WITH SORGHUM FOR FORAGE AND GRAZING

Abstract The objective of this study was to evaluate the influence of the time of cutting on the nutritive value of Piatã silage grass in monocrop and intercropping with sorghum for cutting and grazing. We used a randomized block design with four replications. Treatments were arranged in a split plot design, with systems as plots (Piata grass, sorghum for cutting and grazing, and intercropping), cutting ages as sublots (70, 90, and 110 days after sowing). The minisilos were opened at 46 days to evaluate silage crude protein (CP), acid detergent fiber (ADF), neutral detergent fiber (NDF), total digestible nutrients (TDN), ammonia nitrogen, lignin, and pH. We observed significant interaction between system and age on the variables CP, ADF, NDF, lignin and pH. With the advancement of age, there was a linear reduction in crude protein content of 0.12, 0.08, and 0.16 percentage units for each day after sowing in sorghum silage, sorghum grass and grass + Piata, respectively. There was a linear increase in the pH value of sorghum silage + grass due to the advancement of age of 0.03 units for each day after sowing. In sorghum silage and monocrop grass, the pH did not vary with the cutting age, with values of 4.63 and 5.20, respectively. Sorghum systems showed potential for the production of good quality silage at 70 days of age. Keywords: cutting age; minisilo; silage; tropical grass

Production and nutrition rates of piatã grass and hybrid sorghum at different cutting ages - doi: 10.4025/actascianimsci.v35i3.18016

The influence of cutting age on yield and nutrition rates of piatã grass (Brachiaria brizantha cv. BRS Piatã) and hybrid sorghum (Sorghum spp. cv. BRS 801) under an integrated crop-livestock system was evaluated. The trial was carried out at the Embrapa Beef Cattle (20°27¢ S; 54°37¢ W) in Campo Grande, Mato Grosso do Sul State, Brazil, between April and October 2009. Experimental design consisted of randomized blocks with four replicates. Treatments were distributed across a split-plot design, which included three production systems (single piatã grass; single hybrid sorghum; mixed cultivation of sorghum and piatã grass). Half-plots consisted of three forage ages at harvest (with 70, 90 and 110 days after seeding). Variables included agronomical characteristics, productivity and nutrition value. Regardless of the evaluated systems, cutting age affected agronomical characteristics and in vitro digestibility of organic matter (IVDOM). Production was highest (4,048 kg ha-1) within the integrated system. Regardless of cutting age, monoculture sorghum had the highest crude protein level. Results showed that integrated sorghum and piatã grasses were an asset for forage productivity. Forages had higher rates in crude protein and in in vitro digestibility of organic matter on the 70th day after seeding.   The influence of cutting age on production and nutritive value of piatã grass (Brachiariabrizantha cv. BRS Piatã) and hybrid sorghum (Sorghum spp. cv. BRS 801) under an integrated croplivestocksystem was evaluated. The trial was carried out at the Embrapa Beef Cattle (2027 S; 5437 W) inCampo Grande, Mato Grosso do Sul State, Brazil, between April and October 2009. Experimental designconsisted of randomized blocks with four replicates. Treatments were distributed across a split-plot design,which included three production systems (single piatã grass; single hybrid sorghum; mixed cultivation ofsorghum and piatã grass). Half-plots consisted of three forage ages at harvest (with 70, 90 and 110 days afterseeding). Variables included agronomical characteristics, productivity and nutrition value. Regardless of theevaluated systems, cutting age affected agronomical characteristics and in vitro digestibility of organic matter(IVDOM). Production was highest (4,048 kg ha-1) within the integrated system. Regardless of cutting age,monoculture sorghum had the highest crude protein level. Results showed that integrated sorghum andpiatã grasses were an asset for forage productivity. Forages had higher values in crude protein and in in vitrodigestibility of organic matter on the 70th day after seeding