Feeding value of whole and extracted Moringa oleifera leaves for ruminants and their effects on ruminal fermentation in vitro

Chemical composition and energetic value of whole (unextracted) and ethanol/acetone-extracted Moringa (Moringa oleifera Lamarck) leaves, and their effect on ruminal N turnover and other ruminal fermentation traits were investigated in comparison with soybean meal and rapeseed meal, using the Hohenheim gas test (HGT) and the Rumen Simulation Technique (RUSITEC). Crude protein (CP) content was 321, 486, 584 and 391 g/kg dry matter (DM) in unextracted Moringa leaves (ML), extracted Moringa leaves (EML), soybean meal and rapeseed meal, respectively. The corresponding concentrations of net energy for lactation, as predicted from HGT gas production, were 6.6, 7.5, 8.1 and 6.8 MJ/kg DM, and the enzymatically determined CP degradabilities were 0.629, 0.594, 0.751 and 0.677, respectively. The ML were characterised by a high total fatty acid content (35 g/kg DM), mainly consisting of α-linolenic acid (667 g/kg total fatty acids). RUSITEC fermenter fluid ammonia concentration was particularly low in complete ML diets. In both, complete ML and EML diets CP degraded and not recovered in ammonia was at least as high as with the soybean meal or rapeseed meal diets suggesting a substantial synthesis of microbial protein. Apparent in vitro degradabilities of organic matter (OM) and fibre of the complete ML and EML diets were similar or even higher as compared with those containing soybean meal or rapeseed meal. Daily methane emission was 17% lower (P < 0.05) with the complete EML diet as compared with the diets containing soybean meal or rapeseed meal. Overall, the results indicate that in ruminants ML and EML have a high potential as alternatives to soybean meal and rapeseed meal as protein sources. Although ML and EML are not suggested as a source of rumen-protected protein, these feedstuffs might enhance the metabolic protein supply of ruminants by supporting the synthesis of microbial protein in the rumen due to their substantial contents of readily fermentable N and energy.