This research was carried out to determine the effects of different additions (urea and molasses) used with Italian ryegrass (Lolium multiflorum L.) silage  on fermentation, in vitro gas production, microbiological properties, in vitro digestibility parameters, and relative fodder quality (RFQ) in silages made  under laboratory conditions. The Italian grass (Lolium multiflorum L.) used in the study was chopped to an approximate size of 2–3.0 cm. Amounts of 0, 2,  and 4% molasses and 0, 0.5, and 1% urea were added to the fresh material as a percentage of dry matter. Because of the urea, crude protein (CP) of  Italian ryegrass silage increased, but the content of neutral detergent fibre (NDF), acid detergent fibre (ADF), and acid detergent lignin (ADL) decreased.  While the addition of urea decreased the acetic acid and butyric acid concentrations of the silage, it increased the pH, lactic acid, and ammonia (NH3)  content. Molasses addition increased in vitro gas production and organic matter digestibility (OMD); urea increased metabolic energy (ME) and the net  energy lactation (NEL) values of silages. Urea and molasses both increased in vitro digestibility parameters, microbial protein production and synthesis,  and relative fodder quality of the silage. As a result of the research, it was determined that urea and molasses could be used at contents of 1.5% and 4%,  respectively, in Italian ryegrass silage.