Effect of Dietary Guanidinoacetic Acid Levels on the Mitigation of Greenhouse Gas Production and the Rumen Fermentation Profile of Alfalfa-Based Diets

The objective of this study was to evaluate the effect different percentages alfalfa (Medicago sativa L.) hay (AH) and doses guanidinoacetic acid (GAA) in diet on mitigation greenhouse gas production, vitro rumen fermentation profile methane (CH4) conversion efficiency. AH were defined for diets beef dairy cattle, as well under grazing conditions (10 (AH10), 25 (AH25) 100% (AH100)), while GAA 0 (control), 0.0005, 0.0010, 0.0015, 0.0020, 0.0025 0.0030 g g−1 DM diet. With an increased dose GAA, total production (GP) (p = 0.0439) AH10 diet, AH25 no observed 0.1311), AH100, GP CH4 levels decreased 0.0113). In addition, increase 0.0042) proportion with influence 0.1050) AH100 groups. Carbon monoxide 0.0227) most doses, other did not show 0.0617) carbon monoxide, hydrogen sulfide 0.0441) addition association 0.3162). pH level < 0.0001) dry matter degradation (DMD) when from 10 25%, contents had opposite effect. dose, only 0.0142 p 0.0023) DMD group. Similarly, influenced 0.0002) SCFA, ME efficiency but group, it that SCFA 0.0002), per unit OM 0.0015 0.0020 g, 0.1790 0.1343). conclusion, positive effects depend percentage AH, showed very little improvement 10% presented best results.