Abstract :
Gastrointestinal nematode (GIN) resistance to synthetic anthelmintics in small ruminants
has led to the evaluation of feed sources containing naturally occurring bioactive secondary
metabolites that lessen parasite activity. Plants rich in condensed tannins (CT) can have
beneficial anthelmintic properties. Peanut (Arachis hypogea L.) skins (testa), an agricultural
by-product, are a rich source of CT, have low fiber and high levels of oil and crude protein,
and have been incorporated into feed products for the cattle industry. Anthelmintic
activity of pellets formulated with peanut skins was compared to that of commercial alfalfa
(Medicago sativa L.) pellets (control diet) fed to lambs in two separate experiments, one
with initially low (220 eggs g−1 feces; 2008) and the other high (4260 eggs g−1 feces; 2009)
burden of GIN. In both experiments lambs were maintained on bermudagrass (Cynodon
dactyon (L.) Pers.) pastures except when pellets were fed (six lambs per treatment) at 2.3%
BW every other day three times a week. Overall, average daily intake of CT as quebracho
(Schinopsis sp.) equivalents of peanut skin pellets formulated with 5% molasses was 0.38%
BW (low GIN lambs), and that of peanut skin pellets formulated with 48% alfalfa and 7%
molasses was 0.53% BW (high GIN lambs). Regardless of the initial level of GIN burden
and the formulation of the peanut skin pellets, average daily weight gain of all lambs was
about 94±7.2 g per day. Increases in fecal egg count and decreases in blood packed cell
volumes that occurred during the trials were not significantly different (P > 0.05) between
lambs fed the control alfalfa pellets and lambs fed peanut skin containing pellets. In these
trials, intake of peanut skin may have been insufficient to decrease GIN parasite activity,
or perhaps the low prodelphinidin subunit composition of CT in peanut skin prevented a
beneficial response.
