Exploring the role of seasonal variation in livestock feed composition on diet quality and methane emissions in Kenyan livestock

Abstract

Livestock contribute significantly to greenhouse gas (GHG) emissions, mainly through enteric fermentation and manure management. Feed composition plays a crucial role in both livestock diet quality and emissions. However, feed availability varies seasonally particularly in tropical environments such as Kenya with long dry periods. This study investigated the influence of seasonal feed variations and relative availability of feed types in Kenya on livestock diet quality and enteric methane (CH4) emissions. Geographical information systems and data sources including crop distribution data, land use information, and nutritive value data were employed to generate livestock diet composition maps. Data from field measurements were used to validate these maps. Livestock diets varied across the country, with coarse-stemmed cereals and legume crops dominant in mixed rainfed temperate systems, diverse feed resources including cultivated forages in mixed rainfed humid systems, and pasture in mixed rainfed arid and livestock-only systems. Livestock diet quality measured as dry matter digestibility (DMD), was approximately 581 g/kg DM. This value was greater than the default digestibility value of 550 g/kg DM set by the Intergovernmental Panel on Climate Change (IPCC) for livestock production systems in the region.

Monte carlo simulation revealed a range of possible outcomes of DMD depending on the livestock production system and the composition of livestock diet. Estimated minimum and maximum DMD differed within and between livestock production systems (513.2 - 664.5 g/kg DM), thus exhibiting uncertainty and potential spatial and temporal variability. Methane emissions varied between and within livestock production systems (36.6 – 67.5 kg CH4/head/yr for adult female cows; p < 0.05). Variability in methane emissions can be attributed to factors such as changes in feed availability and management practices.

These results provide evidence that livestock diet quality and methane emissions are influenced by inter- and intra-season variations in feed composition. Consequently, season and location-specific strategies and interventions are necessary to improve livestock feeding practices as part of efforts to reduce methane emissions from livestock.