Can tropical legume grass forage reduce enteric methane yield from suckler cows in the Sahel?
Abstract
Enteric methane emissions (eCH4) from ruminants are the main source of greenhouse gas from the livestock sector in sub-Saharan Africa. In this region, very few references with in vivo measurements are available on local breeds, particularly on suckler cows. With the development of the dairy sector in Africa, it is important to integrate the evaluation of enteric methane emissions into the various feeding strategies. The aim of this study was to evaluate the impact of protein supplementation with a legume grass fodder (Stylosanthes hamata) on enteric methane emissions
in Sudanese Zebu suckler cows. The study was conducted with Greenfeed in stall at CIRDES (Burkina Faso). The experiment was carried out on 10 animals: 5 steers (38 months old with liveweight (LW) of 179±20.3 kg, i.e. 0.72 Tropical Livestock Unit (TLU), and 5 suckler cows (75 months old with LW of 204±13.3 kg, i.e. 0.82 TLU). Animals were kept in individual boxes. The measurements of eCH4 and milk production were made on the cows, and in vivo digestibility test was made simultaneously on the steers. Two trials of 4 week including 2 rounds of one-week data collection were successively conducted. The animals were fed respectively with Bracharia ruziziensis (100) (R1) and Bracharia ruziziensis + S. hamata (75:25) (R2). The results showed that the daily dry matter intake (DMI) is 15.67±2.70 g/kg LW for R1 and 20.33±4.28 g/kg LW for R2. In vivo DM digestibility (%) was 52.72±1.4 for R1 and 58.25±1.43 for R2 when milk production was 3.0±1.2 kg/d for R1 and 3.46±0.98 kg/d for R2. Amounts of eCH4 (g/
kg DMI) emitted were 25.05±8.27 for R1 and 20.99±7.30 for R2. Our results show that protein supplementation with S. hamata L. increases the DM intake (g/kg LW) for 30%, the digestibility (%) for 11%, and reduces eCH4 yield (g/ kg DMI) for 16%.