Tropical legume grass forage (Stylosanthes hamata L.) reduces enteric methane yield and intensity and improves milk yield in Fulani zebu suckler cows.

In sub-Saharan Africa, enteric methane (eCH4) emissions represent the principal source of greenhouse gases from ruminant livestock. Most milk in this region is produced by suckler cows of local breeds, yet very few references with in vivo eCH4 measurements are available. This study assessed the impact of protein supplementation with Stylosanthes hamata L. on eCH4 emissions in Sudanese Fulani zebu suckler cows. The experiment was conducted under stable conditions with 10 animals: five steers (38 months old, 179 ± 20.3 kg body weight - BW) and five suckler cows (75 months old, 204 ± 13.3 kg BW). Two dietary treatments were offered: a control diet of Brachiaria ruziziensis (100%; hereafter Brach), and an experimental diet combining B. ruziziensis with S. hamata in a 75:25 ratio (hereafter Brach+Stylo). Each diet was provided at 2.5% BW (dry matter [DM] basis) per animal for 4 weeks (2 weeks of adaptation and 2 weeks of data collection). Intake, milk production and gas emissions (GreenFeed® system) were measured (mean ± SD) in cows, while apparent digestibility was measured in steers. Daily DM intake was 17.2 ± 1.66 g/kg BW for Brach and 20.0 ± 3.76 g/kg BW for Brach+Stylo. DM digestibility was 0.46 ± 0.05 for Brach and 0.50 ± 0.06 for Brach+Stylo, while daily milk yield was 1.4 ± 0.08 kg and 2.0 ± 0.08 kg, respectively. The eCH4 yields were 28.4 ± 4.50 (g/kg DMI) for Brach and 24.4 ± 3.90 (g/kg DMI) for Brach+Stylo corresponding to 72.2 ± 9.51 (g/kg milk) and 50.4 ± 4.83 (g/kg milk), respectively (p < 0.05). Our results indicate that protein supplementation with S. hamata increases DM intake, DM digestibility, and milk yield, while reducing eCH4 yield and intensity. These findings highlight the potential of targeted protein supplementation to improve productivity and mitigate eCH4 emissions in suckler cow-based dairy systems.