AGRE-0041 Development of Biological Silage Additives

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Agricultural Residues : Biological Conversion : Biotechnology : ECLAIR Cluster VII - Proteins : Sugar

AGRE-0041 Development of Biological Silage Additives 1 November 1990 - 30 October 1991

This summary is based on the final report to the European Commission concerning work funded under the ECLAIR programme. The objective was to improve the characteristics of bacteria and enzymes used as inoculants in the preparation of silage from grass, as well as various agricultural residues. There are a number of aims in producing any new product which is to compete in the highly competitive area of silage inoculants (for instance over 110 products are currently registered in the UK under the UKASTA, ADAS-DANI-SAC scheme. Taking this scheme as an example, the requirements cover short term nutrition studies and long term animal performance, as well as the impact on the silage itself. Inoculants are expected to improve fermentation, this means faster reduction in pH through faster sugar utilisation, better spectrum of organic acids (enhanced lactic acid), and nitrogen retention. Environmental aspects are also important with a reduction in effluent production, whilst from the economic viewpoint the use of the additive must significantly reduce the amount of dry matter, energy and nitrogen lost from the silo. Screening of a large number of lactic acid bacteria resulted in selection of , as prototypes: Lactobacillus plantarum DCU101, L plantarum B41 and Pediococcus acidilactici G24. A number of hydrolytic enzymes were also tested as to their ability to release fermentable carbohydrate from the insoluble storage or cell wall carbohydrates. The final choice of Lp DCU101 and Pa G24 were used to produce silage from grass (fed to Charolais crossbred heifers) and alfalfa (fed to sheep for metabolism studies and lactating Fresian cows for milk production). Enzymes were not found to confer any benefit as they increased effluent, but had no significant effect on lactic acid fermentation. The research included the use of genetic probing methods (RFLP, RAPD and riboprobing) and endogenous plasmid probing to study population kinetics. The results of these studies showed that the introduced strains were able to multiply in competition with the natural flora, resulting in an initial faster rate of drop in pH. Attempts were made to enhance the rate of lactic acid production by transformation introducing multiple copies of the enzyme lactic dehydrogenase. However, no significant improvement was observed. No benefit was observed by disrupting the pathway to D-lactic acid. Animal trials showed a slight beneficial effect on milk production and a small positive effect was observed on carcass weight of finishing bulls. The product is being test marketed.

Contacts

Coordinator

• Jean DELCOUR / Universite Catholique de Louvain Laboratoire de Genetique moleculaire / BELGIUM

EC Scientific Officer

• Ciarán MANGAN / European Commission - DG Research Quality of Life Programme - Unit B1.2 / BELGIUM