Using Tannin-Containing Legumes to Control GI Parasites:
To Pellet or Not?
Dr. Herve Hosté
INRA Senior Researcher
Université de Toulouse
The use of heat and pressure in the pelleting process can affect the
condensed tannins and therefore, the bioactivity of the pellets.
After twenty years of research, the exploitation of different species of bioactive legumes containing condensed tannins (CT) (e.g. = sericea lespedeza (Lespedeza cuneata) in the USA or sainfoin (Onobrychis viciifoliae) in the EU) as nutraceuticals has nowadays been validated.
The term “nutraceuticals” means that these plants are combining high nutritional values and beneficial effects on animal health and welfare, including anthelmintic (AH) effects. Therefore these tanniniferous legumes represent a key option to consider in the control of parasitic gastro-intestinal nematodes (GINs) in sheep and goats.
A wide range of results have now been conducted, indicating that the consumption of these two legumes (Sericea lespedeza and Sainfoin) can contribute to disturb the biology of worms, the dynamics of infection, and improve the sheep and goat health when infected (their resilience).
These two models of bioactive legumes have been exploited either in grazing conditions, or as conserved forms and used as hay or silages. Moreover, for these two bioactive legume species, technological processes have been developed to produce dehydrated pellets. However, the use of heat and
pressure in the pelleting process can affect the condensed tannins and therefore, the bioactivity of the pellets.
The advantages of such pelleting technology are multiple. Pellets can facilitate 1) storing; 2) exporting; 3) distribution at the farm level as a concentrate to achieve a defined threshold of CTs in total diet; and 4 ) measuring of the concentrations of bioactive compounds (namely CTs) before use to make differences between legume pellets with only high nutritional values and legume pellets with nutraceutical values (nutritional + AH properties).
The pelleting process also provides solutions to increase the CT content either by selecting legume cultivars or better conditions of culture. Alternatively, to rely exclusively on leaves (rich in CT) to produce the pellets has also been examined with sericea lespdeza
On the other hand, it is worth mentioning that this technological option also includes some cons, namely 1) a lower autonomy at the farm level; 2) a higher cost compared to hay produced directly on farm; and 3) higher environmental impact (C0² cost)