Abstract :
This work aimed to evaluate the effects of tannin-containing heather (Calluna vulgaris, Erica
spp.) and energy (oats, Avena sativa) supplementation, combined or not, on feed intake, gastrointestinal
nematode infections and performance of goats grazing mountain grasslands.
Two successive experiments were established across one grazing season on four paddocks.
The first (late April to early August, Period 1) involved two treatments, i.e., supplementation
with heather (+H) vs. non-supplementation (−H), each randomly allocated to two
paddocks. The second (mid-August to mid-November, Period 2) consisted on four treatments
in a 2×2 factorial design, i.e., supplementation with heather and oats (+H+O), only
heather (+H−O), only oats (−H+O), and no supplementation (−H−O). Results from Period
1 indicated that faecal nematode egg counts (FEC) were lower in +H goats (50% less in
August), achieving more favourable live weight (LW) and body condition changes than −H
goats. Total dry matter intake (DMI) in June was similar between treatments, with heather
accounting for 0.21 of +H goat diets. Kids FEC and LW gains were not affected by heather
supplementation. In Period 2, both heather and oat supplementation reduced FEC (45 and
61%, respectively) and improved goat performance, without an interaction between both
factors. Total DMI in October was higher in +H+O compared to other treatments (48 vs.
30g DMkgLW−0.75 d−1; P < 0.01). Rumen ammonia concentration was lower (P < 0.001) in
+H than in −H goats, and in +O than in −O goats, whereas that of volatile fatty acids (VFA)
was not affected by treatments, though the molar proportions of some VFA were modified.
It is concluded that the combination of both supplements (tannins and energy) contributes
to reduce gastrointestinal nematode parasitism and increases goat performance, allowing
a lower dependence on conventional chemotherapy.
