Forage peanut legume as a strategy for improving beef production without increasing livestock greenhouse gas emissions
Bruno Grossi Costa Homem, Lucas Peralta Carneiro Borges, Ítalo Braz Gonçalves de Lima, Bianca Costa Guimarães, Paola Palauro Spasiani, Igor Machado Ferreira, Paulo Méo-Filho, A. Berndt, Bruno José Rodrígues Alves, S. Urquiaga, Robert M. Boddey, Daniel Rume Casagrande
Abstract
The transformation of pastures from a degraded state to sustainable productivity is a major challenge in tropical livestock production. Stoloniferous forage legumes such as Arachis pintoi (forage peanut) are one of the most promising alternatives for intensifying pasture-based beef livestock operations with reduced greenhouse gas (GHG) emissions. This 2-year study assessed beef cattle performance, nutrient intake and digestibility, and balance of GHG emissions in three pasture types (PT): (1) mixed Palisade grass - Urochloa brizantha (Hochst. ex A. Rich.) R.D. Webster (syn. Brachiaria brizantha Stapf cv. Marandu) and forage peanut (A. pintoi Krapov. & W.C. Greg. cv. BRS Mandobi) pastures (Mixed), (2) monoculture Palisade grass pastures with 150 kg of N/ha per year (Fertilized), and (3) monoculture Palisade grass without N fertilizer (Control). Continuous stocking with a variable stocking rate was used in a randomized complete block design, with four replicates per treatment. The average daily gain and carcass gain were not influenced by the PT (P = 0.439 and P = 0.100, respectively) and were, on average, 0.433 kg/animal/day and 83.4 kg/animal, respectively. Fertilized and Mixed pastures increased by 102 and 31.5%, respectively, the liveweight gain per area (kg/ha/yr) compared to the Control pasture (P < 0.001). The heifers In the Mixed pasture had lower CH4 emissions (g/animal/day; P = 0.009), achieving a reduction of 12.6% and 10.1% when compared to the Fertilized and Control pastures, respectively. Annual (N2O) emissions (g/animal) and per kg carcass weight gain were 59.8 and 63.1% lower, respectively, in the Mixed pasture compared to the Fertilized pasture (P < 0.001). Mixed pasture mitigated approximately 23% of kg CO2eq/kg of carcass when substituting 150 kg of N/ha per year via fertilizer. Mixed pastures with forage peanut are a promising solution to recover degraded tropical pastures by providing increased animal production with lower GHG emissions.