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Investigation of the biotransformation of undesirable substances and contaminants in silages and during the ruminal fermentation (RUSITEC)
Project
Project code: BfR-SiN-08-1322-729
Contract period: 01.01.2019
- 31.12.2019
Purpose of research: Experimental development
Keywords: dairy cows, ensiling, biotransformation,food health security
In Germany dairy cows produce the largest share of food of animal origin. Forages form the basis of the cows' diets, with silages being a major component in intensive dairy production systems. Ensiling forages is a highly complex microbial process, ideally resulting in high-quality feedstuffs. However, contaminants like plant derived toxins (e.g. pyrrolizidine alkaloids (PA)) present in the original plant material can substantially compromise feed quality (Driehus et al., 2018). In this respect a big unknown component is the possible biotransformation of the toxins, which might occur during the process of ensiling. Dairy cows as ruminants possess a forestomach system comprising the rumen, reticulum, and omasum, followed by the abomasum. The rumen as anaerobic fermentation chamber with its complex symbiotic microbiota plays the major role in nutrient degradation. Because of this microbial ecosystem, containing bacteria, archaea, protozoa and fungi, ruminants can digest fibrous plant material, which offers little nutritive value to monograstic animals (VAN SOEST, 1994; ERTL et al., 2014; PITTA et al., 2018). However, comparable to the ensiling process, biotransformation of contaminants can occur during the rumen microbial fermentation. Depending on the contaminant little is known about the metabolites resulting from biotransformation and their possible carry-over into the animal derived products. Thus, in order to answer the question, if undesirable substances in feedstuffs for dairy cows pose a threat for the consumers’ health, investigation of the microbial biotransformation processes of contaminants in silage and in the rumen is needed. Therefore it is one aim of unit 84 to conduct ensiling experiments under diverse conditions (PA contamination with Senecio-species, differing DM contents and silage inoculants) by using laboratory scale 1.5 liter glasses. In addition it is the aim of the proposed project to establish the RUSITEC system at the BfR in order to investigate the biotransformation of undesirable substances and contaminants in the rumen. The RUSITEC system permits investigating the rumen microbial degradation of undesirable substances without conducting intensive feeding trials. The RUSITEC-system was developed in the 1970s (CZERKAWSKI und BRECKENRIDGE, 1977) and is an established and among ruminant nutrition scientist accepted in vitro method to simulate the rumen microbial fermentation (BOGUHN et al., 2006; EGER et al., 2018). So far the RUSITEC system was mainly used to investigate the degradation extents of the crude nutrients (especially crude protein and the fiber fractions, e.g. HINDRICHSEN et al., 2004; ERTL et al., 2014; TERRY et al., 2018), while the microbial biotransformation of undesirable and toxic compounds in the rumen was mostly neglected. To inoculate the fermentation vessels of the RUSITEC system with a representative spectrum of the ruminal microbes, freshly collected ruminal fluid of the ventral rumen sac and solid ruminal content from the fiber mat of donor animals are used. In addition a ruminant diet is added to each fermentation vessel daily to support microbial growth for several weeks. In order to evaluate the biotransformation of undesirable substances and contaminants like e.g. PA in ruminants, processes occuring in the rumen of dairy cows are to be compared with processes occuring in the rumen of sheep. In conclusion it is the aim of this project to investigate the biotransformation of undesirable substances and contaminants during the production of silage and during the microbial fermentation in the rumen.
Literature:
BOGUHN J et al. (2006), J Dairy Sci, 89:1580–1591. CZERKAWSKI JW, BRECKENRIDGE G (1977), Br J Nutr, 38:371–384. DRIEHUIS et al. (2018), J Dairy Sci, 101:4093-4110. EGER M et al. (2018),J Anim Physiol Anim Nutr, 102: 94–102. ERTL P et al.(2014), J Dairy Sci, 98:4762–4771. HINDRICHSEN I et al. (2004), Can J Anim Sci, 84(2):265–276. PITTA DW et al. (2018), J Dairy Sci, 101:1–19. TERRY SA et al. (2018), Front Microbiol, 9:1410. VAN SOEST PJ (1994), Nutr Ecol Rumin. Cornell University Press, N.Y., USA.
Section overview
Subjects
- Food microbiology
- Toxicology
