This study evaluated the effects of capsaicin (CAP) supplementation on the intake, nutrient digestibility, ruminal fermentation, nitrogen balance, microbial protein synthesis and health traits of bulls managed on pasture. Eight crossbred (Holstein x Zebu) cattle averaging 313 ± 31 kg of body weight (BW) were arranged in a replicated 4 × 4 Latin square design (one square of four bulls, rumen fistulated with 4-inch silicone cannulas and one square of four non-fistulated bulls), which were kept on Pangola grass pasture (Digitaria decumbens). Each experimental period consisted of 21 days, with 7 days for data collection (no washout between periods). Bulls were randomly assigned to the following treatments: CON (control): concentrate supplementation at 0.5% live weight (BW) and no additive (CAPCIN®), or concentrate supplementation at 0.5% BW in association with CAPCIN® (NutriQuest, Campinas, Brazil) fed at the inclusion rates of 150 (CAP150), 300 (CAP300) and 450 (CAP450) mg/animal/day. Digestibilities of dry matter, organic matter and neutral detergent fibre showed quadratic responses to CAP supplementation. Rumen pH linearly increased with CAP supplementation. The numbers of lymphocytes and eosinophils were linearly increased with CAP supplementation. The use of encapsulated pepper in supplements of crossbred (Holstein x Zebu) bulls managed on D. decumbens pasture up to 450 mg/animal/day improves nutrients digestibility and ruminal fermentation and can positively influence the health status of beef cattle managed under tropical conditions.

DNA barcoding approaches have been successfully applied for estimating diet composition. However, an accurate quantification in the diets of herbivores remains to be achieved. In the current study, we present a novel methodology that reveals the relationship between the actual proportions (by mass) of each herbage species in the diets and the relative proportions of the ITS2 gene sequences obtained from faecal samples to evaluate the diet composition of sheep in a meadow steppe. Nine common and 12 rare species of plants were employed for formulating 6 diets, along with the addition of feed supplements for improving the growth performance of sheep. Faecal samples were collected for DNA analysis over the period spanning days 7–12. A significant positive correlation (Spearman’s ρ = 0.389) was obtained between the actual proportions (by mass) of the herbage in the diet provided and the relative abundance of ITS2 sequences obtained from the faecal samples. A significant regression coefficient was found between the relative abundance of all common species and their respective herbage mass proportions. The accuracy of the relation equations, evaluated by utilizing the similarity coefficient, showed 84.69% similarity between the actual diet composition and the correct percentage. Taken together, the current study has provided empirical evidence for the accuracy and applicability of ITS2 as a DNA barcode for obtaining quantitative information about the diet composition of sheep grazing in species-rich grasslands.