Faculty of Technical Sciences

As the use of antibiotics is being restricted in animal husbandry, certain bacteria that used to be well controlled seem to thrive and create problems. Economically important diseases like gas gangrene and necrotic enteritis, where C. perfringens may play an important role, and which may cause sudden death in pigs are in many case not diagnosed in advance of the fatal course of the disease. In herds with this type of problems, a feed component that inhibits C. perfringens should therefore be used in a constant supply to all pigs at all times. Plant extracts with high content of tannins are well known modifiers of the microbiota and experience from many farms has shown that tannins may protect farm animals against pathogenic Clostridia as well as protect protein from microbial degradation. While hydrolysable and condensed tannins are defined by their common ability to precipitate protein, high antioxidant capacity and astringent ability, they differ in many chemical and biological characteristics.

The aim of this study was to evaluate the Non-Inhibitory and Minimum Inhibitory Concentrations (NIC and MIC) of hydrolysable and condensed tannin extracts against 9 strains of Clostridium perfringens. We applied standard photometric procedures for evaluation of MIC of extract from Sweet Chestnut (Castanea sativa, Mill.) (CE), Mimosa (Acacia sp.) (ME) and Quebracho (Schinopsis balansae Engl.) (QE). The extracts were tested in a dilution series of 8 concentrations from 10 to 0.08 mg/ml (10,000 – 80 ppm). The NIC and MIC values are calculated via fitted Gompertz curves.

Of the 9 types tested it was possible to obtain full dataset of 6. The preliminary results show that extract from Sweet Chestnut consistently were more efficient in its inhibition of C. perfringens than the 2 other extracts. The average MIC of Sweet Chestnut, Mimosa and Quebracho extracts were 290 ppm (90-760 ppm), 1,140 ppm (400-1,620 ppm) and 2,300 ppm (650-6,310 ppm) respectively. The Castanea extract therefore on average needed 4 to 8 times lower dosage compared to Mimosa and Quebracho extracts.

Selected plant metabolites may have a new and more deliberate role to play in the future of antibiotic restricted production of pigs.