In vitro evaluation of forages and feedstuffs from Kenya's semi-intensive zero-grazing dairy system

This study evaluated 9 alternative forages at a realistic 12% of dietary DM within semi-intensive zero-grazing Kenyan dairy cow on in vitro gas production and rumen fermentation parameters. Incubation substrates contained a common basal feed mixture plus either Lolium multiflorum (control treatment) or Medicago sativa, Vicia sativa, Desmodium intortum, Calliandra calothyrsus, Leucaena leucocephala, Sesbania sesban, Tradescantia zebrina, Cichorium intybus, or Ipomoea batatas. Methane production was analyzed with mixed models and its marginal relationships with tannins fractions and nutritional composition with generalized additive models. Results showed that Calliandra calothyrsus and Leucaena leucocephala decreased methane production by 10% to 13% without impairing total gas, digestibility, major VFA profiles, or estimated metabolizable energy. Desmodium uncinatum and Tradescantia zebrina slightly shifted fermentation toward higher propionate, branched-chain VFA, and ammonia, as well as lower pH, whereas Vicia sativa reduced total VFA concentration. Condensed tannins and starch were negatively, and organic matter digestibility positively, associated with methane production. The inclusion level of Calliandra calothyrsus and Leucaena leucocephala legumes tested here demonstrates promising potential for practical incorporation into semi-intensive zero-grazing dairy cattle diets to mitigate enteric methane in Kenyan dairy systems.