THE ENTERIC METHANE EMISSION OF CATTLE GRAZING RANGELAND ECOSYSTEMS OF SOUTHEASTERN KENYA

Abstract

Cattle produced in the rangelands under extensive grazing, characterized by large herds grazing degrades poor pastures to support livelihoods and coping with drought risk. However, this can be associated with enteric methane emissions and contributions to Global Warming Potential, yet these are hardly quantified to inform emerging threats to sustainable use of grassland ecosystems. This study estimated enteric methane emission and the GWP associated with cattle grazing in the rangelands of Southeastern Kenya, specifically Makueni County. Data on cattle population, animal classes and their performance and animal activity for the year 2019 was obtained from the County livestock inventory reports while feed quality data was sourced from recently published literature. Estimation applied the IPCC approaches for Tier I and Tier II. Application of Tier II incorporated seasonal differences in feed quality, dry matter intake and animal performance according to Goopy et al., (2018). The resultant emission factors were 47.1 kg for females>2yrs; 27.2 kg for heifer 1-2 yrs; 46.5 kg for males>2yrs; 32.9 kg for young males 1-2yrs; and 17.2 kg for calves <1yr. Total estimated enteric methane emission or cattle population grazing the

County using Tier I approach was 8,889,997 kg /year with GWP of 248,919,916 Kg CO₂ eq, which was only 4.4% lower than the total enteric methane emission estimates with the Tier

II approach of 9,279,526.80 Kg/year and GWP of 259,826,750.4Kg CO_{2 eq.} The results show that the use of IPCC Tier I and II did not substantially differ in estimated enteric methane emission and GWP for zebu cattle population grazing the Makueni County rangeland ecosystem.