The experiment was carried out to evaluate addition effects of five urea levels with four ammonization periods on Agave sisalana residue chemical composition in the different storage times. It was used 300 kg of this co-product, equally distributed in 60 black polyethylene bags, which urea was added in the following concentrations: 0, 2, 4, 6 and, 8% over 0, 2, 4 and, 6 weeks storage periods. It was made determinations of dry matter (DM), crude protein (PB), neutral detergent fiber (NDF), acid detergent fiber (ADF) and, non fibrous carbohydrates (NFC). A completely randomized design was adopted, following factorial arrangement 5 <FONT FACE=Symbol>´</FONT> 4 (urea levels, ammonization periods), with three replications. The variance analyses showed significant effect of urea level on variables CP and DM. For ADF and NFC there were significant effects for the interaction level versus period of fermentation; for NDF variable it was not possible to adjust a statistical model. The CP rates grew linearly with the urea addition. Ammonization did not affect NDF rates. Crude protein level had a linear increase by urea addition. Besides, it was noticed that ADF rate increased in function of NFC decreasing. NFC rate reduced as a consequence of urea level increase, showing that it was likely used for microbial synthesis or carried with the effluent. It was concluded that the addition up to 8 % of urea increased the CP content and reduced the NFC and DMD contents with the increase in the storage time.
agro-industrial residue; ammonization; treatment of roughages; urea
