Densification for block making and evaluation of calcium hypochlorite and alkali treated wheat straw based feed blocks in comparison to urea treated straw feed

摘要

Feeds based on wheat straw, untreated or treated with alkali and NaOH + calcium hypochlorite (CHC) (75%), containing concentrate (12%) and molasses (10%) were compressed with a hydraulic press in a closed cylindrical die (10.5 cm radius) to form feed blocks. A minimum pressure of 2 M pa/kg feed was essential along with 16-18.3% and 18-23% moisture level in untreated and treated straw for block making. Higher moisture resulted in fragile blocks while >10% molasses resulted in sticky blocks. The bulkdensity of blocks varied from 340 to 470 kg/m3. The use of bentonite as a binder was not essential for block-making. Two isonitrogenous mixed feeds based on 4% urea-treated (T1) and CHC + NaOH (2+1%)-treated wheat straw (T2) consisting of straw (73%) and concentrate mixture (20.3%) and cane molasses (6.7%) respectively, were fed to 2 groups of 4 male Murrah buffaloes. Compressed feed blocks (350 kg/m3 bulk density) of mash feed T2 was fed to a similar group of 4 buffaloes (T3). DM intake (DMI) was comparable in T1 and T2 but higher (P<0.01) than in T3. Organic matter intake (OMI) was highest (P<0.01) in T1 followed by T2 and T3. DM digestibility was higher (P<0.01) in T1 than in the other groups while OM digestibility did not differ between the groups. Despite N intake and excretion through urine being similar in all groups, faecal N was highest in T1 and lowest in T3, resulting in improved (P<0.01) balance of N due to block feeding. Digestible DMI and OMI/100 kg body weight were 26% more in T1 thanin T2. Rumen-degradable N (RDN) per se was comparable in the 3 diets but RDN/kg digestible OM was lower (P<0.05) in T1. ME intake appeared to be sufficient to support marginal liveweight gain in T1 whereas only maintenance requirement was met in T2 and T3. It is concluded that urea treatment is more effective than calcium hypochlorite + alkali treatment and block-making resulted in better N retention.