Impact of condensed tannins from tropical forages on Haemonchus contortus burdens in Mongolian gerbils (Meriones unguiculatus) and Pelibuey lambs

Two experiments were conducted to assess effects of condensed tannins (CT) from tropical forage crops on Haemonchus contortus burdens, feed intakes and body weights of experimentally infected Mongolian gerbils (Meriones unguiculatus) and Pelibuey lambs. Forty weaned gerbils were assigned to 10 treatments with four replicates. Gerbils of treatments 2–10 were orally fed 1000 exsheathed larvae and two levels (7.5 and 15 mg/kg body weight, BW) of purified CT from Arachis pintoi, Leucaena leucocephala, Manihot esculenta or Albendazol. Nine days after oral infection, gerbils were killed and the number of larvae in the stomach was determined. There were effects on stomach larvae counts (P<0.05) with the highest average count (135 larvae) occurring in the untreated control (P<0.05) and the L4 larvae (i.e., developing in intestinal submucosa phase) was lowest (18, 17 and 16 larvae) for gerbils receiving extracts from L. leucocephala, A. pintoi and M. esculenta, respectively. The uninfected control, and the Albendazol-treated groups, had practically no larvae. In the second experiment, fifty-two 45-day old Pelibuey lambs were randomly assigned to nine treatments: an uninfected control, or fed either Medicago sativa and/or three tannin containing forages (i.e., A. pintoi, Gliricidia sepium, M. esculenta), and an Albendazol-treated group. Treatments 2–9 were artificially infected with 5000 exsheathed L3 larvae (i.e., infective phase). Lambs were killed 36 days after infection and the number of parasites in the abomasum was quantified. In lambs on the test diets, the number of larvae were decreased (P<0.05) by up to 70% compared to the untreated control (3801 larvae). Lambs consumed from 0.5 to 4.9 g/kg BW/day of CT. In neither of the experiment was feed intake or BW adversely affected by administration of CT.