Evaluation of Grape Pomace Supplementation in Lamb Diets to Mitigate Haemonchus contortus Infection

This study aimed to evaluate the potential benefits and feasibility of adding dried and ground grape pomace to the concentrate fed to lambs experimentally infected with Haemonchus contortus. Eighteen male Santa Inês lambs, recently weaned, were housed in individual pens and were allocated into two groups based on their body weight. The lambs in the supplemented group (n = 9) initially received a diet composed of 50% ground hay and 50% concentrate. Subsequently, these animals were gradually adapted to grape pomace until its final inclusion in the concentrate reached 20%. The lambs in the control group received a concentrate without grape pomace. Both groups of lambs were artificially infected with 4000 infective larvae of H. contortus, and 28 days later, the lambs were euthanized for quantification of the nematodes present in the abomasum. The following variables showed no statistical differences (p > 0.05) between the groups: worm burden, packed cell volume, total plasma protein, blood eosinophil count, and daily weight gain. Regarding anti-Haemonchus IgG plasma levels, there was a significant time * treatment interaction (p = 0.0099) with higher values in the supplemented group. At the two final samplings, the supplemented group showed significantly lower values of eggs per gram of feces than the control group (p < 0.05). The supplemented group showed female worms shorter and with less eggs in utero than those of the control group, with significant difference for these variables (p < 0.05). In conclusion, grape pomace can be included in the diet, as it promotes more sustainable animal production, and, additionally, it can cause a reduction in H. contortus fecundity, benefiting haemonchosis prophylaxis.