Inclusion of Yerba Mate (Ilex paraguariensis) Extract in the Diet of Growing Lambs: Effects on Blood Parameters, Animal Performance, and Carcass Traits

SIMPLE SUMMARY: Yerba mate (Ilex paraguariensis) is a plant widely used for human consumption in Latin America, with important health benefits for people. However, limited knowledge on its effects on animal health and nutrition are available. In this study, we evaluated the inclusion of yerba mate extract at levels up to 4% of the dry matter in the diets of growing lambs and its effects on blood parameters, animal performance, body metrics and carcass traits. Yerba mate extract up to 2% of inclusion had positive effects on feed intake and animal performance; however, greater inclusion rates had negative effects on feed intake and animal performance. Supplementation of yerba mate extract up to 2% also increased white blood cells and globulins, which have been closely related to a better immune response in animals. ABSTRACT: This study aimed to evaluate levels of yerba mate (Ilex paraguariensis) extract (YME), as a feed additive in the diets of growing lambs on serum biochemical parameters and hematological indices, animal performance, body metrics and carcass traits. Thirty-six entire (nine per treatment), male growing lambs, weighing 23.8 ± 3.7 kg, were fed the experimental diets which were treatments consisting of increasing levels of YME (0, 1, 2, and 4% inclusion on a dry matter [DM] basis) during an experimental period of 53 days. The experiment was carried out in a randomized block design, which initial body weight was used as blocking factor and the results were analyzed by orthogonal contrasts (linear, quadratic, and cubic). Yerba mate extract did not change the general health status of the animals; however, inclusions of up to 2% of the extract increased globulins (p = 0.05) and white blood cell count, as segmented neutrophils (p = 0.02) and lymphocytes (p = 0.04). Additionally, inclusion of up to 2% YME increased dry matter intake, final weight gain, total and daily gain (p < 0.05), also tended to increase ribeye area and reduce fat thickness (p < 0.10); however, YME above 2% of inclusion reduced animal productive parameters (p < 0.05). In conclusion, levels up to 2% of YME were beneficial to the health and productive parameters of growing lambs.