The effects of incorporating sugar beet pulp with forage maize at ensilingon silage fermentation and effluent output using drum silos

The effects of incorporating sugar beet pulp with forage maize at ensiling on silage fermentation, effluent output and pollution potential of the effl uent was investigated using 200-litre drum silos. A forage maize crop (Zea mais) was harvested on four different dates, generating four different stag es of maturity [dry-matter (DM) content 154-235 g kg(-1) DM], and molassed sugar beet pulp (MSBP) was added at five different rates (0, 2, 7, 13, 18 k g MSBP 100 kg(-1) fresh maize crop). A total of fourteen treatments (each r eplicated three times) were evaluated. The chemical analysis of the maize s ilages and the mixtures produced showed that MSBP addition increased DM, as h, neutral cellulase gaminase digestibility (NCGD) and metabolizable energy (ME) contents of the mixture significantly (P < 0.01) for all harvesting d ates except for harvest date 1. Silage fermentation in terms of final pH wa s unaffected by MSBP addition, although lactic acid concentration of the ef fluent tended to increase with increased MSBP addition. When no MSBP was in cluded, large volumes of effluent were produced, ranging from 200 g kg(-1) to 100 g kg(-1). MSBP addition significantly (P < 0.01) decreased effluent production except for the driest material. A curvilinear equation was fitte d to predict effluent production from DM of the forage maize and pressure a pplied to the sample (adjusted r(2) = 0.95). In addition, a curvilinear equ ation was fitted to predict the MSBP addition rate required to prevent effl uent production (adjusted r(2) = 0.65). For harvest dates 1, 2 and 3, the b iological oxygen demand for 5 days (BOD5) and the chemical oxygen demand (C OD) concentration of the effluent were significantly increased (P < 0.05) w ith increased levels of MSBP addition. However, the pollution potential per kg of material ensiled was significantly reduced (P < 0.05) with increased MSBP addition, since less effluent was produced. The experiment indicates that ensiling low DM silages with appropriate levels of MSBP produces nutri tionally valuable silages with reduced pollution potential.