Non chemical control of helminths in ruminants: Adapting solutions for changing worms in a changing world

Infections with gastrointestinal nematodes (GIN) remain a major threat for ruminant production, health and welfare associated with outdoor breeding. The control of these helminth parasites has relied on the strategic or tactical use of chemical anthelmintic (AH) drugs. However, the expanding development and diffusion of anthelmintic resistance in nematode populations imposes the need to explore and validate novel solutions (or to re-discover old knowledge) for a more sustainable control of GIN. The different solutions refer to three main principles of action. The first one is to limit the contact between the hosts and the infective larvae in the field through grazing management methods. The latter were described since the 1970s and, at present, they benefit from innovations based on computer models. Several biological control agents have also been studied in the last three decades as potential tools to reduce the infective larvae in the field. The second principle aims at improving the host response against GIN infections relying on the genetic selection between or within breeds of sheep or goats, crossbreeding of resistant and susceptible breeds and/or the manipulation of nutrition. These approaches may benefit from a better understanding of the potential underlying mechanisms, in particular in regard of the host immune response against the worms. The third principle is the control of GIN based on non-conventional AH materials (plant or mineral compounds). Worldwide studies show that non conventional AH materials can eliminate worms and/or negatively affect the parasite’s biology. The recent developments and pros and cons concerning these various options are discussed. Last, some results are presented which illustrate how the integration of these different solutions can be efficient and applicable in different systems of production and/or epidemiological conditions. The integration of different control tools seems to be a pre-requisite for the sustainable management of GIN infections. This new era of GIN management requires a new paradigm: to achieve enough control to reduce the negative impact of GIN infections enabling an optimum level of production, health and welfare

In vitro AND in vivo ANTHELMINTIC EFFECT OF Coffea arabica RESIDUES AGAINTS AN Haemonchus contortus ISOLATE WITH LOW SUSCEPTIBILITY TO TANNINS

The present study evaluated in vitro and in vivo anthelmintic (AH) effect of the percolated by-product of Coffea arabica against a Haemonchus contortus isolate with low susceptibility to tannins. Firstly, the susceptibility to tannins of Paraíso H. contortus isolate was evaluated with the in vitro larval exsheathment inhibition assay (LEIA) using an acetone:water (70:30) extract of Acacia pennatula. Afterwards, the in vitro AH effect of acetone:water extracts of percolated C. arabica by-products (Clean and Smooth (CS) and Shade Grown (SG) Starbucks®) were evaluated. Then, the in vivo AH effect was determined in growing sheep (4 months old and 15.2 kg bodyweight), infected with H. contortus (Paraiso isolate) and fed with a diet containing the percolated by-product of C. arabica. Three experimental groups were formed (n = 6 lambs): GC Group (control diet without C. arabica), GCA Group (feed containing 10% C. arabica) and, GCA+PEG (polyethilenglycol) Group (feed with 10% C. arabica + PEG as a tannin inhibitor). Fecal samples were obtained daily from the rectum of lambs (days 1 to 20 of the study). The H. contortus isolate tolerated the A. pennatula extract at concentrations of 150 and 300 μg extract/ml PBS (P > 0.05), which confirmed its low susceptibility to tannins. The C. arabica CS extract reduced the exsheatment from 150 μg of extract/ml PBS and the SG variety from 1200 μg of extract/ml PBS (P0.05). In conclusion, the C. arabica percolated by-product extracts showed in vitro AH effect against exsheathment. However, the consumption of feed containing 10% of the percolated by-product did not show an in vivo AH effect in sheep infected with the Paraiso H. contortus isolate. The latter could be due to the low susceptibility towards the secondary compounds of tannin rich plants of the H. contortus isolate used in this study