A By-Product Blended Diet to Reduce Enteric Methane Emissions from Sheep in Argentina

Abstract

While livestock production is a significant source of greenhouse gas emissions, it remainsvital for fulfilling the growing global demand for animal protein. Including by-products inruminant diets can enhance food circularity and reduce competition for human food, whilealso increasing the likelihood of reducing methane (CH4) emissions. This study aimed toevaluate the impact of fully replacing corn grain and urea in the control diet with localby-products, specifically corn distillers’ grains combined with either barley brewed grainsor with wheat middlings, on enteric CH4 emissions and performance of sheep. Diets werebalanced to be isoproteic and isoenergetic with 2.6 Mcal ME/kg of dry matter (DM) and160 g crude protein/kg DM, respectively. Corn silage is the only source of forage in thediet, and the forage-to-concentrate ratio was maintained to 60:40 on a DM basis. TwelveHighlander female sheep of 35.9 ± 3.12 kg initial body weight (BW, mean ± standarddeviation), were used in a Completely Randomized Block design, with four sheep pertreatment and two measurement periods under the same treatment. Experiment lasted 60 d,30 d acclimatization and 30 d measurements. Dry matter intake (DMI) was restricted to 2.5%of BW. Enteric CH4 emissions of individual sheep were quantified in respiration chambersover a 48 h period. Dietary treatments did not have a significant effect either on DMI orBW gain. The diet containing barley brewed grains significantly reduced total daily CH4production by 22.3%, CH4 emissions per kg of DMI by 34% and energy loss as CH4 by 38%compared to the control diet. In conclusion, the agro-industrial by-products combinationsevaluated in this study effectively replaced corn grain and urea without compromisingfeed intake or animal performance. Additionally, the diet containing barley brewed grainssignificantly reduced CH4 yield, and energy loss compared to the control diet.