Management-driven strategies to mitigate environmental impacts and improve productivity of beef systems using precision technologies and nutritional interventions

Abstract

Beef production systems face pressure to improve environmental efficiency while maintaining animal performance and welfare. Nutritional management and environmental monitoring represent two complementary strategies to enhance sustainability in both confined and grazing systems. The objectives of the thesis were to evaluate (1) precision monitoring technologies for assessing feedlot pen-surface nutrient heterogeneity and (2) nutritional interventions aimed at reducing enteric methane (CH₄) emissions in grazing cattle, with emphasis on practical implementation under commercial conditions. Objective 1 was evaluated using UAV-mounted thermal cameras to characterize and predict nutrient distribution within feedlot pens managed under limit-fed (LOW) or ad libitum (HIGH) feeding programs. Six outdoor pens housing crossbred steers were subdivided into 15 quadrants for sample collection and measurement of moisture, organic matter, fiber fractions, and nitrogen content of the pen surface material. Thermal orthomosaics were generated and color metrics were extracted to evaluate associations with measured nutrient components. On a single day evaluation, moisture differed by feeding program (P = 0.01), averaging 44.0% in HIGH pens and 34.0% in LOW pens. Moisture to organic matter ratio was similarly greater in HIGH compared to LOW pens (98.0 vs 71.0; P = 0.02, respectively). Nitrogen concentration (dry matter bais) was greater in LOW pens (21.5%) compared to HIGH pens (18.5%; P < 0.01). Quadrant significantly influenced moisture and nutrient distribution (P < 0.01), confirming structured spatial heterogeneity within pens. When evaluated across multiple days, moisture remained greater in HIGH pens compared to LOW (52.1 vs 42.1%; P < 0.01, respectively), demonstrating consistent feeding program effects despite precipitation variability. Several thermal derived color metrics (R, B, mean RGB, Lab*L; P ≤ 0.04) differed by quadrant over time, and pen-level thermal color metrics demonstrated predictive capability for moisture and organic matter. These findings support UAV-derived thermal imaging as a promising precision management tool for pen-level environmental assessment, though refinement in time of sampling and sensor calibration may enhance sub-pen resolution. Objective 2 examined a nutrient management strategy for grazing cattle systems by evaluating supplementation of an essential oil blend (Agolin; Alltech Inc., Nicholasville, KY) in 63 grazing beef heifers (BW = 274 ± 42 kg) over a 70-day triticale pasture trial beginning mid-winter. Supplement intake averaged approximately 0.30 kg/head/day, resulting in an actual Agolin exposure of 484.6 mg/head/day. Average daily gain (ADG) did not differ between treatments (P = 0.18), with Agolin heifers gaining 0.69 kg/day compared to 0.62 kg/day in control heifers. Despite variable supplement intake, heifers supplemented with Agolin resulted in measured enteric CH₄ emissions of 162.6 g/d compared to 178.6 g/day in control heifers (P = 0.05), corresponding to a 16 g/d absolute reduction and approximately 8.96% mitigation. A decrease in emission intensity (g CH₄/kg ADG) was found for heifers supplemented with Agolin compared to heifers without Agolin supplementation (242.81 and 293.50; P = 0.03, respectively). Carbon dioxide emissions remained unchanged, potentially supporting the interpretation that CH4 reduction occurred through altered hydrogen disposal rather than suppressed overall fermentation. Collectively, observed findings demonstrate that both environmental monitoring technologies and nutritional interventions can improve sustainability outcomes in beef production systems. Integration of precision technologies with targeted nutritional management represents a scalable pathway to improve nutrient efficiency, reduce emission intensity, and maintain productivity across diverse beef production environments.