Feed intake, digestibility, plane of nutrition and live weight gain by crossbred growing bulls fed on grainless diets containing different nitrogen sources

Twenty five growing crossbred bulls (Bos indicus x Bos taurus) were used in a randomised block design experiment for 196 days to determine the effect of grainless concentrate containing different supplemental nitrogen sources along with wheat straw based diet on feed intake, nutrient digestibility, plane of nutrition and daily live weight gain. The animals in control group received barley 30% in the concentrate mixture (Cm-1) as a source of grain , where as other concentrate mixtures contained only wheat bran (Cm-2) or w heat bran supplemented with 2.5% urea (Cm-3), 21.5% groundnut oil cake (Cm- 4) or 27% mustard ail cake (Cm-5) as source of supplemental nitrogen. Fortn ightly live weight gain was recorded and a metabolism trial of 6 days durat ion was conducted after 120 days of feeding trial in order to assess nutrie nt utilisation and retention as well as plane of nutrition; The mean dry matter (DM) intake and digestibility of the nutrients except c rude protein (CP) were similar in all the groups. CP digestibility was sign ificantly higher (P<0.05) in urea fed animals. A positive nitrogen balance was recorded in all the groups. Though gross energy (GE) and digestible energy (DE) intake were not affecte d, the urinary loss of energy (UE) was significantly lower (P<0.05) in anim als fed Cm-2. A positive calcium and phosphorus balance was observed in all the treatments though phosphorus balance in Cm-2 fed animals was significa ntly higher (P<0.05). Average daily live weight gains were 443, 344, 370, 435 and 423 g in Cm-1, Cm-2, Cm-3, Cm-4 and Cm-5 fed animals, respectively. A marginal less daily live weight gain was recorded in Cm-2 fed animals and the results were non- significant among the treatments. Active growth could be obtained in animal s fed grainless concentrates having wheat bran as its main component: at an amount or 1% of the live weight daily without showing significant influenc e on nutritional status and growth of growing bulls. (C) 2000 Elsevier Scie nce B.V. All rights reserved.