This study aimed to evaluate the effectiveness of different additives in preventing urolithiasis in lambs fed a diet rich in concentrate and their impact on performance and blood and urinary parameters. Thirty-two noncastrated male lambs, crossbred Dorper × Santa Inês, with initial body weights (BWs) of 23 ± 0.1 kg and ages of 50 ± 5 days, were kept in individual pens and fed a diet composed of 6% Cynodon ssp. hay and 94% concentrate and subjected to four treatments: CON without inclusion of additives, addition of ACL 5 g/kg of dry matter (DM), addition of CCL 6.3 g/kg of DM, and addition of BZA 5 g/kg of DM. There was no effect of treatment or interaction with time on blood parameters (p > 0.050), and performance characteristics, morphometry of ruminal papillae, and scores of cecum and rumen lesions were not affected by the addition of additives to the diet (p > 0.050). Greater urinary acidification was observed in animals from CCL and ACL treatments (p = 0.033). Calcium chloride acidified the urinary pH and can be used instead of ammonium chloride at a concentration of 0.63% based on DM, when this is the objective.

Background: Phytogenic feed additives are being explored as alternatives to conventional rumen modulators, yet their effects on the ruminal ecosystem remain insufficiently characterized when assessed only through conventional fermentation parameters. This study evaluated the effects of ethanolic and hydroethanolic extracts of Urochloa brizantha on ruminal fermentation, methanogenic archaeal diversity, and the ruminal metabolome of sheep. Methods: Eight rumen-cannulated wethers were assigned to a replicated 4 × 4 Latin square design with four 28-day periods. Treatments consisted of no additive (CTL), ethanolic extract of U. brizantha (EE; 50 mL/day), hydroethanolic extract (HE; 80 mL/day), and monensin (MON; 25 mg/kg of DMI). Ruminal fluid was evaluated for fermentation traits, archaeal 16S rRNA gene diversity, and untargeted metabolomic profiles. Results: Dry matter intake and fermentation parameters were unaffected by treatment. Archaeal alpha diversity showed a contrast-dependent response, with lower Shannon diversity in sheep receiving plant extracts than in those receiving monensin (p = 0.034), and Methanimicrococcus was selectively enriched in the EE group (p = 0.012). Untargeted metabolomics revealed the clearest response: despite substantial overlap in global PCA profiles, PLS-DA indicated treatment-specific temporal separation between day 0 and day 21 only in EE-treated sheep, supported by permutation testing based on classification error rate (p = 0.027), although predictive performance should be interpreted cautiously. This EE-specific response was characterized by a significant shift in the carboxylic acid subclass (FDR = 0.022). Top VIP-ranked discriminants (aspartate, succinate, glutamate, phenylalanine, leucine, and choline) decreased nominally but failed multiple-testing correction (FDR = 0.0602–0.2580). CTL, HE, or MON showed no temporal separation. Conclusions: Urochloa brizantha extracts produced limited effects on conventional ruminal fermentation parameters but were associated with selective archaeal responses. In particular, the ethanolic extract was associated with a treatment-specific temporal metabolomic pattern, including a significant shift in the carboxylic acid subclass, while individual metabolite changes remained exploratory and warrant further investigation.

Background: Phytogenic feed additives are being explored as alternatives to conventional rumen modulators, yet their effects on the ruminal ecosystem remain insufficiently characterized when assessed only through conventional fermentation parameters. This study evaluated the effects of ethanolic and hydroalcoholic extracts of Urochloa brizantha on ruminal fermentation, methanogenic archaeal diversity, and the ruminal metabolome of sheep. Methods: Eight rumen-cannulated wethers were assigned to a replicated 4 × 4 Latin square design with four 28-day periods. Treatments consisted of no additive (CTL), ethanolic extract of U. brizantha (EE; 50 mL/day), hydroalcoholic extract (HE; 80 mL/day), and monensin (MON; 25 mg/day). Ruminal fluid was evaluated for fermentation traits, archaeal 16S rRNA gene diversity, and untargeted metabolomic profiles. Results: Conventional fermentation parameters and dry matter intake were largely unaffected by treatment, with only marginal shifts detected by orthogonal contrasts. Archaeal alpha diversity remained stable, although Methanimicrococcus was selectively enriched in the EE group (P = 0.012). Untargeted metabolomics revealed the clearest response: despite substantial overlap in global PCA profiles, PLS-DA showed significant temporal separation between day 0 and day 21 only in EE-treated sheep (P = 0.027). This EE-specific response was characterized by lower levels of aspartate, succinate, glutamate, phenylalanine, leucine, and choline, with an increased relative contribution of carboxylic acids. No comparable temporal discrimination was observed in CTL, HE, or MON. Conclusions: Urochloa brizantha extracts produced limited effects on conventional ruminal fermentation and methanogenic archaeal diversity. However, the ethanolic extract induced a distinct temporal metabolomic shift, suggesting a selective metabolic response that warrants further investigation.