Evaluation of Effective Microorganisms (EM) as an Additive to Improve Feed Value of Maize II Stovers

Abstract

Four studies were conducted to assess the potential of locally available feed additives in enhancing the feeding value of maize stovers. The first study surveyed the constraints to, and status of maize stover use in two target districts, namely; Kiambu and Thika districts. The results showed storage problems including termite attack during storage and low quality of the stovers as the major constraints to utilization of maize stovers. Among the major coping strategies for the low quality were supplementation with spent brewers grain (SBG) (25 and 53%) and fodder grasses (11 and 41%) in Kiambu and Thika districts respectively. Treatment of dry maize stovers with urea was among the least adopted technologies in the two districts (7 and 8% respectively). The second study was designed to investigate the fermentation processes and subsequent nutritional quality of silage made from dry maize stovers, ensiled with selected locally available feed additives. The treatments were: maize stovers stored under shade (control); maize stovers (MS) ensiled with urea; MS + effective micro-organisms (EM); MS + SBG + EM; MS + SBG + molasses; MS + Desmodium intortum (D) + molasses and MS + D + EM. The materials were ensiled in laboratory mini-silos of 4.5 kg capacity for 0, 30 and 60 days and then analysed for indicators of fermentation quality (PH, Lactic acid and NH3-N) and chemical composition (CP and NDF). The results of the study showed that crude protein content of the silages was increased (P<O.OOI)by inclusion ofN-rich additives (urea, SBG and D. intortum), from 43.8 for the control to a high of 109.3 g/kg DM for the SBG/molasses additive. However, the CP contents declined (P<O.OOI) with ensilage period across all the treatments, with significantly higher decrease observed in the treatments with urea and D. intortum. In the treatments with SBG and D. intortum + molasses, there was reduction (P<O.OOI) in NDF contents from 80% (control) to 68 and 67% respectively. The

pH levels were within the range 3.9-5.4 which is acceptable for high DM silages and the NH3-N levels below the critical 110gkg DM, above which would be indicative of extensive proteolysis. The SBG + EM combination with maize stover produced the best silage stability (indicated by low levels of NH3-N) and the highest improvement in CP content. The third study involved isolation, identification and characterization of microbial species in EM, a recently introduced commercial product with reported wide usage in both crops and livestock production. The results revealed that EM contained two groups of microorganisms, namely; yeasts and a Gram positive non-spore forming bacillus bacterial species. In the in vitro studies, mixed cultures of the yeast and the bacterium had marked effect on substrate degradability. However, stronger hydrolytic activity was observed in the yeast isolates than in the bacterial and mixed cultures. In the fourth study, in sacco degradability of four substrates, namely; maize stovers + SBG, maize stover + Desmodium intortum, cellulose and lignin, was assessed in the rumen of a steer inoculated with EM through drinking water. The results of this study confirmed the probiotic properties of EM by enhancing (P<O.05) degradability of all the substrates except lignin. In general, these studies indicated that EM has beneficial effects on nutrient utilization, and thus it can be included in the formulation of ruminant diets.