Abstract:
Animal Production in Australia Vol. 15 INTENSIVE BEEF PRODUCTION FROM DRIED CASSAVA TUBERS G.D. TUDOR* The starch rich tuberous roots of the perennial plant cassava (Manihot esculenta Crantz.) are a traditional staple food for many people in the wet tropics. Although the tubers are very low in protein, diets based on dried cassava tubers with supplemental nitrogen (N) are highly digested by cattle (Tudor and N orton 1982) and although intake and daily gain may be lower than grain based diets, feed conversion is comparable (Tudor and McGuigan 1982). The performance of 48 Hereford steers fed to appetite on high concentrate diets based on either dried cassava tubers or rolled sorghum grain was measured over a period ( + S.D.) of 85 t, 13 days. The diets comprised 90% concentrate (including minerals, N and 3% molasses) and 10% Rhodes grass chaff. Sixty cattle were stratified on liveweight (LW) into blocks of five and then randomly allocated into five treatments each with three replicates of four animals. Cattle were slaughtered in blocks when the mean block L37 exceeded 420 kg. Individual daily gains were calculated from the regression relating individual liveweights to time. Initial carcass weights were estimated using the equation which was derived from 12 cattle slaughtered at the start 'of the experiment: RSD 2 7.1 r 0.87 Y = 0.378~ + 43.296 w'nere y = hot carcass weight (HCW) and x = fasted liveweight (FLW). The data were analysed by analysis of variance with missing values estimated by covariance, + Meat and bone meal Cattle fed the grain diet ate more (P<O.Ol) organic matter (OM) and gained LW faster (P<O.Ol) than cattle fed cassava, but, the conversion of OM to LW was similar, with the cassava + MBM (C) being 8% better than the grain diet. The differences between treatments in estimated daily carcass gain were not significant resulting in better (P<O.Ol) conversions of OM to HCW for the cassava fed cattle. There were no differences in fat depth over the 12th rib. Cattle fed cassava were observed to eat many small feeds rather than 2 to 4 large feeds and had more butyric acid to total acids in rumen fluid than cattle fed grain. The 23 to 27% better feed conversion per unit carcass gain in cattle fed cassava is probably due to the simultaneous release of dietary N and energy resulting from the small feeds. This would allow for optimal microbial growth and maximal utilization of N and starch. TUDOR, G.D. and NORTON, B.W. (1982). TUDOR, G.D. and McGUIGAN, K-R. (1982). Proc. Aust. Soc. Anim. Prod. 14: Z 599. 14: Proc. Aust. Soc. Anim. Prod. C 600. * Dept. of Primary Industries, Animal Research Institute, Yeerongpilly, Qld, 4105. 763