Kusmartono
Four sheep and four crossbred Ongole steers, fitted with rumen cannulas, were used in a 4*4 Latin square arrangement to study the effects of N sources (urea or Gliricidia sepium leaves) on intake, digestibility and rumen parameters. For the sheep the diets were: JF, free access to rice straw and Jackfruit waste; JF-U, same as JF but with 3% urea (DM basis) added to the jack fruit waste; JF-GS, same as JF but with fresh leaves of Gliricidia sepium at 3% of live weight; JF-U-GS, same as JF-U but with fresh gliricidia leaves at 3% of live weight. For the steers the diets were: JF; JF-A same as JF but with ammoniated rice straw (3% of straw DM); JF-U; and JF-MUC, same as JF but with free access to a soft molasses-urea cake (10% urea). Total intakes of dry matter by the sheep and by the steers were not affected by N supplementation. Sheep ate a much greater proportion of the diet in the form of jackfruit waste (92%) than did the cattle (47%). Also, while addition of urea appeared to depress intake of jackfruit waste by sheep, with a compensatory increase in the intake of rice straw, it had no effect on the cattle. For the cattle, treatment of the rice straw with urea did not increase DM intake of the straw. The main treatment effect with the steers was associated with feeding of the molasses-urea cake which led to increases in intake of total DM and crude protein (CP). Rumen ammonia levels in sheep fed un-supplemented rice straw and jackfruit waste were low (50 mg N/litre) but increased to 101 mg N/litre in the diet with added urea and gliricidia leaves. Higher digestibility values (DM, OM and CP) in sheep receiving N supplementation were directly related to their rumen ammonia concentrations. Molar proportions of rumen propionate increased linearly from 18 to 36% as rumen ammonia levels increased in the sheep. It is concluded that jackfruit waste, consisting of aerial, skin, seed and heart parts, has a high potential as a ruminant feed, especially for sheep. Supplementary N is needed to optimise digestibility and, in cattle, it appears this is best given as a molasses-urea cake rather than by mixing urea in the jackfruit waste.
Department of Animal Nutrition, Faculty of Animal Husbandry, Brawijaya University, Malang, Indonesia
