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Browsing by Author "Ritten, John P., committee member"

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    Effects of origin on enteric greenhouse gas emissions and growth performance
    (Colorado State University. Libraries, 2024) Mesa Gandolfo, María Inés, author; Carvalho, Pedro H. V., advisor; Stackhouse-Lawson, Kim R., committee member; Place, Sara E., committee member; Ritten, John P., committee member
    Methane (CH4) emissions from cattle across various origins remain inadequately understood, representing a significant knowledge gap for sustainable beef production. This study investigates enteric CH4 emissions from yearling steers of different origins and under different management practices. The experiment was divided into two phases. In Phase 1, steers were managed according to local practices: grazing in Colorado and confined background feeding in Nebraska and Wyoming. In Phase 2, all steers were moved to a common grazing environment in Colorado. Methane emissions were measured using the Automated Head Chamber System (AHCS). During Phase 1, CH4 emissions and growth performance varied significantly among the groups, influenced by diet and management. Nebraska steers had the greatest CH4 production (MP), while Colorado steers had the least, reflecting differences in diet composition and feed intake. However, CH4 intensity (MI) was similar across all groups due to compensatory differences in average daily gain (ADG). In Phase 2, when all steers grazed under the same conditions, Colorado steers exhibited the greatest ADG and MP, indicating better adaptation and suitability to the grazing system than Nebraska and Wyoming steers. Results suggest that enteric CH4 emissions are influenced by cattle's origin and previous management. This highlights the need for context-specific studies to accurately assess the sustainability and greenhouse gas (GHG) mitigation strategies for grazing beef cattle. Further research should address these variations to improve the accuracy of CH4 emissions estimates in different rangeland ecosystems. This study also evaluated different CH4 prediction equations using various statistical approaches (RMSE, R2, Mean and Slope bias, correlation coefficients, and least square differences). Three equations showed potential for predicting CH4 emissions for the steers of the current study: the one by Ellis et al. (2009), the one by Escobar-Bahamondes et al. (2016), and Moraes et al. (2014). Even though the CH4 estimated by these equations was similar to the observed, there is room for improvement in the development of accurate equations to predict cattle enteric CH4 emissions in grazing systems. Lastly, the animals were ranked in both Phases by their MI and MP, and it was evaluated if the animals changed their ranking in Phase 1 when moved to Phase 2. Animals from all origins experienced shifts in their classification categories, indicating the dynamic nature of CH4 across different contexts. However, it was observed that steers from the Wyoming group exhibited the most significant changes in MP classification categories when transitioning from a confinement system with grain-based diets to a grazing system. Based on the current results, the background of the steers may need to be considered when evaluating sustainability goals in beef cattle production systems.