The chemical composition, rumen degradability, in vitro gas production, energy content and digestibility of olive cake ensiled with additives

Document Type : Full paper (Original article)


Department of Animal Science, College of Agriculture, Shiraz University, Shiraz, Iran


The chemical composition, in situ  rumen degradability coefficients of dry matter (DM) and crude protein (CP), in vitro gas production and in vivo  digestibility were evaluated for olive cake (OC) silage treated (DM basis) with different additives as follows: (1) untreated OC; (2) OC, 8% molasses and 0.4% formic acid and (3) OC, 8% molasses, 0.4% formic acid and 0.5% urea. After addition of the additives, materials were ensiled for 60 days in plastic bags. The addition of molasses, formic acid and urea resulted in higher DM, CP, pH and NH3 -N content. There were some reductions in neutral detergent fiber, acid detergent lignin and acid detergent fiber contents of silages especially with treatment 3. The additives increased the nutritive value and preserved well the ensiled OC. Ruminal maximum potential degradability (a+b), and effective degradability (ED) of DM and CP were higher for treatment 3. Total gas production was higher (P<0.05) for treatments 2 and 3 and was associated with increased (P<0.05) in vitro  organic matter digestibility and a non-significant increase in metabolizable energy content. Only CP digestibility was affected by treatments and was highest for treatment 3. In vitro  dry matter and organic matter digestibilities improved with treatments 2 and 3. The results indicated that, treating OC (DM basis) before ensiling with molasses (8%), formic acid (0.4%) and urea (0.5%) resulted in a satisfactory and economical source of a non-conventional feed for ruminants.