Potential in vitro methane mitigation on Mulato II brachiariagrass pastures as affected by stocking method and supplementation source

• Grant number: 19/12724-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: August 01, 2019
• End date: July 31, 2020
• Field of knowledge: Agronomical Sciences - Animal Husbandry - Pastures and Forage Crops
• Principal Investigator: Carlos Guilherme Silveira Pedreira
• Grantee: Vinícius Grillo
• Host Institution: Escola Superior de Agricultura Luiz de Queiroz (ESALQ). Universidade de São Paulo (USP). Piracicaba , SP, Brazil

Abstract

Studies comparing rotational with continuous stocking and using mean canopy height as a comparative reference are scarce, but necessary for fine-tuning of management techniques. Grazing management can be a tool to manipulate forage digestibility and to reduce methane emissions by ruminants. The manipulation of the dietary substrate via supplementation of grazing animals has been reported as an efficient strategy to modulate rumen fermentation and reduce CH4 production. The objective of this study is to compare and contrast the effects of grazing method and supplement use on CH4 emissions and in vitro fiber degradability profile. The treatments will correspond to all combinations, among six grazing methods of experiment 1 (to the field): 1) Continuous 20 cm (± 10%); 2) Continuous 30 cm (± 10%); 3) Rotational lenient 30 (36 to 24 cm, or ±20% around mean height of 30 cm); 4) Rotational lenient 20 (24 to 16 cm, or ± 20% around mean height of 20 cm); 5) Rotational moderate 30 (39 to 21 cm, or ± 30% around mean height of 30 cm); and 6) Rotational moderate 20 (26 to 14 cm, or ± 30% around mean height of 20 cm) - and five supplementation strategies: a) No supplementation; b) 2% NO3- + 0,24% S (elemental) in the dry matter intake (DMI); c) 60 g soybean oil per kg of DMI; d) 5% concentrate in the DMI; and e) 60 g soybean oil per kg of DMI + 5% concentrate in the DMI. It is expected that the combined effects of stocking method and supplementation will help rationalize on the pasture responses and assess their flexibility under grazing, adding to the strategies for mitigating methane emissions and identifying opportunities for enhancing the sustainability of forage-livestock systems.