Composi o química e perdas totais de matéria seca na silagem de planta de soja = Chemical composition and dry matter total losses of soybean plant silage

Objetivou-se avaliar a composi o química e as perdas totais de MS na silagem de soja colhida em diferentes estádios reprodutivos. O trabalho foi dividido em dois períodos experimentais, safras de 2005 e de 2006. Foram determinados quatro estádios reprodutivos (R3, R4, R5 e R6) como tratamento no Experimento I (2005) e três estádios reprodutivos (R5, R6 e R7) no Experimento II (2006). O material foi acondicionado em silos experimentais de PVC, sendo as amostragens efetuadas na abertura do silo (60 dias após a ensilagem) para avaliar a composi o química. No Experimento I, houve diferen as (p < 0,05) nos quatro estádios reprodutivos para os teores de MS, CZ, MO, PB, LIG, EE e CT. N o se verificou diferen a (p > 0,05) para os valores de FDN, FDA, NIDN, NIDA, CEL, CHO e pH. No Experimento II, as silagens n o apresentaram diferen as (p > 0,05) para o teor de MS, CZ, MO, PB, FDN, FDA, EE e CHO em fun o do estádio de desenvolvimento da cultura de soja. Os valores de pH, CE e CT das silagens apresentaram diferen as (p < 0,05) entre os estádios reprodutivos. O avan o do estádio reprodutivo altera o valor nutricional da silagem da planta inteira de soja. O déficit hídrico influencia negativamente o desenvolvimento adequado dos gr os de soja,ocasionando prejuízo especialmente em rela o ao valor proteico da silagem. This trial was carried out to study the chemical composition and total DM losses of soybean silage at different reproductive stages. The work was divided in two evaluation periods: the 2005 and 2006 harvests. Four reproductive stages were determined (R3, R4, R5 and R6) as treatments in trial I (2005) and three reproductive stages (R5, R6 and R7) in trial II (2006). The material was conditioned in PVC experimental silos, and the samples were taken at the time thesilo was opened (60 days after ensilage) to evaluate the chemical composition. In trial I, there were differences (p < 0.05) in the four reproductive stages for DM, ash, OM, CP, LIG, EE and BC. No differences were observed (p > 0.05) for NDF, ADF, NDIN, ADIN, CELL, total carbohydrate and pH. In trial II, the silages did not present differences (p > 0.05) for DM, ash, OM, CP, NDF, ADF, EE and total carbohydrate in function of the soybean harvest stage. The pH values, electric conductivity and buffering capacity of the silages were different (p < 0.05) among the reproductive stages. The advance of reproductive stage changes the nutritional value of whole-plant soybean silage. The water deficit adversely affects the suitable development of soybeans, where the protein value of silage is penalized.