Greenhouse Gas Emissions and Crossbred Cow Milk Production in a Silvopastoral System in Tropical Mexico

Lucero Sarabia-Salgado; Bruno J R Alves; Robert Boddey; Segundo Urquiaga; Francisco Galindo; Gustavo Flores-Coello; Camila Almeida Dos Santos; Rafael Jiménez-Ocampo; Juan Ku-Vera; Francisco Solorio-Sánchez

doi:10.3390/ani13121941

Greenhouse Gas Emissions and Crossbred Cow Milk Production in a Silvopastoral System in Tropical Mexico

Animals (Basel). 2023 Jun 9;13(12):1941. doi: 10.3390/ani13121941.

Affiliations

¹ Department of Ethology, Wildlife and Laboratory Animals, Faculty of Veterinary Medicine and Animal Science, National Autonomous University of Mexico (UNAM), Ciudad Universitaria, Mexico City C.P. 04510, Mexico.
² EMBRAPA/Agrobiologia, Brazilian Corporation for Agricultural Research-National Centre for Agrobiology Research, Seropédica 23891-000, RJ, Brazil.
³ Department of Soil Sciences, Federal Rural University of Rio de Janeiro (UFRRJ), Seropédica 23890-000, RJ, Brazil.
⁴ National Institute for Forestry, Agriculture and Livestock Research-INIFAP, Experimental Field Valle del Guadiana, Durango C.P. 34170, Mexico.
⁵ Animal Nutrition Department, Campus of Animal Production and Biological Sciences, Autonomous University of Yucatán, Merida C.P. 97000, Mexico.

Abstract

In Mexico, pasture degradation is associated with extensive pastures; additionally, under these conditions, livestock activities contribute considerably to greenhouse gas (GHG) emissions. Among the options to improve grazing systems and reduce GHG emissions, silvopastoral systems (SPS) have been recommended. The objectives of this work were to quantify the N outflow in a soil-plant-animal interface, as well as the CH₄ emissions and milk production in an SPS with woody legumes (Leucaena leucocephala) that is associated with stargrass (Cynodon nlemfuensis). This was then compared with stargrass in a monoculture system (MS) in the seasons (dry and rainy period) over a two-year period. Dung was collected from the animals of each of the grazing systems and applied fresh to the land plots. Fresh dung and urine were collected from the cows of each grazing system and were applied to the experimental plots. In addition, the soil CH₄ and N₂O contents were measured to quantify the emissions. Average milk yield by seasons was similar: MS (7.1 kg per animal unit (AU)/day^-1) and SPS (6.31 kg per AU/day^-1). Cows in the MS had a mean N intake of 171.9 g/UA day^-1 without seasonal variation, while the SPS animals' mean N intake was 215.7 g/UA day^-1 for both seasons. For the urine applied to soil, the N₂O outflow was higher in the MS (peak value = 1623.9 μg N-N₂O m^-2 h^-1). The peak value for the SPS was 755.9 μg of N-N₂O m^-2 h^-1. The N₂O emissions were higher in the rainy season (which promotes denitrification). The values for the feces treatment were 0.05% (MS) and 0.01% (SPS). The urine treatment values were 0.52% (MS) and 0.17% (SPS). The emissions of CH₄ showed that the feces of the SPS systems resulted in a higher accumulation of gas in the rainy season (29.8 g C ha^-1), followed by the feces of the MS system in the dry season (26.0 g C ha^-1). Legumes in the SPS helped to maintain milk production, and the N₂O emissions were lower than those produced by the MS (where the pastures were fertilized with N).

Keywords: N balance; milk production; nutrient cycling; tropical grassland; urine.

Grants and funding

This research was partially funded by the Coordination for the Improvement of Higher Education Personnel (CAPES), the Foundation for Research Support of the State of Rio de Janeiro (FAPERJ), the National Council for Scientific and Technological Development (CNPq), and the PAPIIT-UNAM Project IG201621. This study was also supported by the post-doctoral scholarship program of UNAM_DGAPA at the Faculty of Veterinary Medicine, National Autonomous University of Mexico (UNAM). We wish to thank all the donors that supported this work. The views expressed in this document cannot be taken to reflect the official opinions of these organizations.