THE EFFECT OF CALCIUM HYDROXIDE AND UREA TREATMENT OF BARLEY STRAW ONCHEMICAL-COMPOSITION AND DIGESTIBILITY IN-VITRO

An experiment was conducted to investigate the effectiveness of calciu m hydroxide (Ca(OH)(2)) and urea treatment of straw. Chopped barley st raw was treated with mixtures of Ca(OH)(2) (0, 30 and 60 g kg(-1) stra w dry matter, DM) and urea (0, 30 and 60 g kg(-1) straw DM) dissolved in 0.81 water kg(-1) straw DM and 'ensiled' in a polythene bag (1.0 kg per bag) at 15 degrees C or 25 degrees C for 60 days. Control treatme nt at each temperature involved untreated straw and treatment with 30 or 60 g NaOH kg(-1) straw DM dissolved in 0.81 water kg(-1) straw DM. Ensiled straws were examined for mould, chemically analysed and assess ed for organic matter digestibility (OMD) in vitro. Mould occurred in Ca(OH)(2)-alone and water-alone ensiled straw, but other ensiled straw s were apparently mould free. In the presence of Ca(OH)(2) with urea t reatment, the nitrogen content of ensiled straw increased more than ur ea-alone treatment. Analysis of variance of OMD in vitro results showe d that Ca(OH)2, urea and temperature interact significantly (P<0.01). Interactions were found to be non-significant for other parameters (ni trogen, acid detergent fibre and hemicellulose). However, straw ensile d at 15 degrees C with 30 g urea +60 g Ca(OH)(2) kg(-1) straw DM, 60 g urea + 60 g Ca(OH)(2) kg(-1) straw DM or 30 g NaOH kg(-1) straw DM ha d similar OMD in vitro (67%). Untreated straw OMD was 48.5%. It can be concluded that mixtures of Ca(OH)(2) and urea would be the alternativ e chemicals to NaOH or ammonia for improvement of the nutritive value of straw.