The Effect of Ensiling Alfalfa with Acacia (Robinia pseudoacacia) Tree Leaves and Sugar Beet Molasses on Silage Fermentation Quality, In-vitro Ruminal Fermentation and Methane Production

Abstract Agroforestry plant leaves notably woody perennials, are widely used to feed animals in many regions of the world, particularly in the tropics. This study also demonstrated a socio-economic and climate viable impact of enislling alfalfa with agroforestry leaves. Acacia is a fast-growing leguminous tree that produces a huge mass of leaves rich in protein (30.43%) and condensed tannins (12.5%), as a waste which can be utilized as a ruminant feed source. In fact, alfalfa is difficult to ensile because it contains a low level of water-soluble carbohydrates, high buffering capacity, prone to extensive proteolysis and nutrient losses. In this study, supplementation of alfalfa silage (AAS) with acacia leaves and molasses significantly decreased NH₃-N production and butyric acid content while increasing the acetic acid and dry matter contents of the silage. In the Hohenheim technique, 5% molasses (M5) increased the net gas production, improved the in vitro dry matter degradability and true NDF degradability; meanwhile, reduced the organic matter degradability during daisy incubation of alfalfa silage compared to the control. Moreover, the addition of acacia leaves with three different levels significantly lowered CH₄ production, total VFAs, and ruminal NH₃-N (an indicator for N excretion) concentrations in a dose-dependent way. The results illustrated that lower level of acacia leaves (3%) in combination with molasses (5%) applied prior to ensiling alfalfa were more useful in reducing silage pH and ruminal NH₃-N (p < 0.001), improving the relative feed value and quality (p < 0.001), metabolizable and net energy lactation of AAS (p < 0.001) without any adverse effect on degradability parameters compared to control.