55 Beef steers acceptance of increasing doses of thymol to a basal forage diet

• Published in: Journal of animal science Vol. 103; no. Supplement_2; pp. 151 - 152
• Main Authors: Suter, Jordan, Fruge, Greyson, Fukuda, Emma, Jessup, Russell, Drewery, Merritt L
• Format: Journal Article
• Language: English
• Published: Champaign Oxford University Press 17.06.2025
• Subjects: Alfalfa; Animal health; Beef; Cattle; Cottonseed meal; Cubes; Diet; Dietary supplements; Feed conversion; Feed efficiency; Forage; Hay; Latin square design; Livestock; Livestock industry; Plants; Thymol; Trace minerals
• ISSN: 0021-8812; 1525-3163
• DOI: 10.1093/jas/skaf170.171

The global population is estimated to reach 9.1 billion by 2050, requiring the livestock industry to increase output while also being mindful to animal health and sustainability of production. The use of antimicrobial plant-derived compounds, such as thymol, has been studied to improve feed efficiency, ensure herd health, and reduce methane production in cattle. However, much of the existing research has been conducted in-vitro, creating a gap in the literature regarding the acceptance of cattle for dietary thymol. The objective of this study was to evaluate the acceptance of beef steers to increasing doses of thymol provided as a supplement to a basal forage diet. Procedures involving animals were approved by the Institutional Animal Care Use Committee at Texas State University (#8693). The experiment was a 4×4 Latin Square design with four 3-d experimental periods, each followed with a 3-d washout period. Prior to initiation of the experiment, steers were adapted to individual housing for 10-d. Steers received ad libitum access to forage, a trace mineral block, and water. During the experimental periods, one of four treatments was provided: thymol at 0, 110, 220, and 330 mg/kg forage intake from the previous 3-d. Thymol was stabilized on nanocellulose and soaked on alfalfa cubes that were supplemented at 0.20% BW. Treatments were offered for 30 mins and subsequent refusals were collected. During washout periods, steers were provided 1 kg of cottonseed meal in addition to their basal hay diet. Forage and supplement intake were analyzed using the MIXED procedure in SAS v9.4. Terms in the model were treatment, period, day, and treatment × day, with steer and treatment × period × steer as the random terms. The repeated term was day with treatment × steer as the subject. Hay intake was not affected by treatment × day (P=0.71) or treatment (P=0.18) but was affected by day (P=0.01) with a significant difference between days 2 and 3 (P≤0.01) such that hay intake averaged 10.4 kg on day 2 and 9.2 kg on day 3 of the experimental periods. There was not an effect of treatment × day (P=0.51), treatment (P=0.17), or day (P=0.40) on supplement intake. Supplement intake was 1.14 kg/d for CON, 1.10 kg/d for 110 and 220 mg thymol/kg forage, and 1.06 kg/d for 330 mg thymol/kg forage. While the differences across treatments were not significant, there were numerical differences in the consumption of alfalfa and thymol such that intake was greater when concentrations were lower (110 mg/kg and 220 mg/kg), indicating that cattle may not tolerate thymol provided at 330 mg/kg forage intake. Future studies should determine the upper threshold beyond which cattle would not accept dietary thymol to inform the development of a commercial dietary thymol supplement.