Extracts of herbs and spices as feed additives mitigate ruminal methane production and improve fermentation characteristics in West African Dwarf sheep

Abstract

The study aims to evaluate the effect of aqueous and methanolic extracts of three herbs, namely, neem (Azadirachta indica), drumstick (Moringa oleifera) and scent (Ocimum gratissimum), and three spices garlic (Allium sativum), ginger (Zingiber officinale) and onion leaflets (Allium cepa) on ruminal methane production and fermentation characteristics. The feed samples (200 mg substrates plus extracts of the selected herbs and spices) were incubated with rumen liquor taken from three mature West African dwarf ewes at 3, 6, 9, 12, 15, 18, 21 and 24 h. The results show that extracts of the selected herbs and spices increased the gas produced, from the insoluble fraction, degradability rate, volume of gas produced at time and time of most rapid change in gas produced. The organic matter digestibility (OMD), metabolizable energy (ME) and short-chain fatty acid (SCFA) contents of aqueous extracts of the selected herbs and spices (1 ml/200 mg substrates samples) were between 32.82 and 71.34 g/100 g OM, 4.10 and 10.25 MJ/kg DM and 0.28 and 1.31 μmol, respectively. Furthermore, the OMD, ME and SCFA contents of methanolic extracts of the selected herbs and spices (1 ml/200 mg substrates samples) were between 32.82 and 99.50 g/100 g OM, 4.10 and 14.37 MJ/kg DM and 0.28 and 2.07 μmol, respectively. Methane produced from the methanolic extracts of the herbs and spices highly differed (P < 0.05). This study suggests that extracts of the selected herbs and spices have the potential to affect rumen fermentation and also to reduce the methane production in sheep.