Overcomming the nutritional limitations of rice straw for ruminants 4. Urea ammonia treatment and supplementation with gliricidia maculata for growing Sahiwal bulls
Forty bull calves of Sahiwal crosses were fed either urea treated or untreated rice straw with 4 levels of Gliricidia (0, 1, 2, and 4 kg fresh material). Dry matter intake (DMI) of straw and Gliricidia was measured during 2 periods. Straw intakes in period 1 and 2 were significantly different (P<0.001). Supplementation of Gliricidia depressed the DMI of straw during the second period (P<0.01), but not in the first period. Urea-ammonia treatment increased straw intake and total intake in both periods, but the increase in dry matter digestibility (DMD) of the ration was not significant (P>0.05). Liveweight gain (LWG) was increased significantly, both by urea ammonia treatment (P<0.01) and by supplementation with Gliricidia (P<0.001). Animals on treated straw gained on an average 137 g.d-1 more than those on untreated straw.