PS12-25. Effects of a Phytogenic Additive and Sodium Monensin on Performance and Health of Weaned Beef Cattle.

Abstract

The objective was to evaluate the use of sodium monensin and a phytogenic additive (Digestarom Prime®) mixed with protein-energy supplements on supplement intake (SI), average daily gain (ADG), final body weight (fBW), serum protein and energy metabolites, acute-phase proteins (APP), and immunoglobulin G (IgG) of post-weaned Nellore cattle under tropical conditions. The experiment was carried out in ∼43 hectares tropical pastures with electronic feed bunks and BW platforms. For 100 days (may-sep 2025), 120 Nellore young bulls (227±12 kg, ∼7 months of age) received supplement ad libitum, with additive dosage adjusted weekly according to SI. Treatments were: CON, protein-energy supplement (PES, 25% CP); PHY, PES+600 mg.animal-1.day-1 phytogenic additive; or MON, PES+0.3 mg.kg-1 BW sodium monensin. Animals were weighed at the beginning and at the end of the experimental period after ∼14 h fasting to determine shrunk ADG and fBW. Blood samples were collected on days 37 and 44 for APP (ceruloplasmin, haptoglobin) and IgG, and at the end for APP, IgG, metabolites (urea nitrogen, total proteins, glucose), and insulin-like growth factor 1 (IGF-1). Data were analyzed considering treatment, day, and their interaction as fixed effects, with initial BW as a covariate for fBW. Significance was declared at p < 0.05 and trends at 0.05 ≤ p < 0.10. The SI was affected by treatment (p < 0.001), being lower for MON. ADG and fBW were also affected by treatment (p < 0.001), being higher for PHY compared to CON. The phytogenic additive increased ADG by 26.7% compared with the control treatment, whereas the monensin treatment did not differ from the control treatment. Serum urea nitrogen was affected by treatment (p < 0.001), with higher concentration for CON, lower for MON, and intermediate for PHY. Ceruloplasmin concentration was affected by treatment (p = 0.009), being higher for PHY compared to CON, and tending to be higher for PHY compared to MON, while IgG concentration trends to be affected by treatments, being higher for PHY compared to CON, but both were similar to MON. Treatment did not affect IGF-1, glucose, or total protein concentrations (p > 0.10), and treatment, day of collection, and their interaction did not affect haptoglobin levels (p > 0.10). In conclusion, the phytogenic additive improved the performance of post-weaned Nellore young bulls managed on tropical pastures during the dry season, increasing growth performance and promoting favorable immune responses. Under the evaluated conditions, the phytogenic additive delivered superior productive responses comparable to sodium monensin, highlighting its potential as a natural and effective alternative to ionophores in tropical beef production systems.

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