Abstract:
Proc. Aust. Soc. Anim. Prod. (1972) 9: 262 HIGH MOISTURE GRAIN SORGHUM IN A FEEDLOT RATION A. W. PLASTO* and M. J. GELLERT Summary The feeding of high moisture grain sorghum for 113 days in a feedlot ration, when compared with dry grain, resulted in a slightly higher daily liveweight gain, but a lower feed intake; this gave a higher conversion efficiency. These differences were not significant, but the liveweight gains made during the period of high grain feeding (day 14 to day 113) by the steers on the high moisture grain ration were significantly better (P < 0.01) than the animals receiving dry grain. The addition of 5 per cent molasses significantly increased liveweight gains but also increased feed intake and lowered feed conversion. Mild diarrhoea occurred in steers receiving high moisture grain/molasses between day 1 and day 13. I. INTRODUCTION Previous experiments have shown that grain sorghum is suitable for the intensive finishing of steers (Morris, Pepper, and Gartner 1969). In the U.S.A. improved performance has been obtained by feeding processed grain. High moisture (HM) grain sorghum has been found to result in superior weight gains and feed efficiency when compared with dry grain (Hale et al. 1969; Riggs and McGinty 1970). In Australia, feedlot finishing of cattle is increasing and grain sorghum is a common grain used in feedlot rations. With the development of permanent feedlots, feedlot operators are seeking methods of increasing feed efficiency. HM grain sorghum appears to be one method of achieving this. Generally cattle in American feedlots receive a hormone implant and are fattened for a longer period than are Australian cattle. *Consequently, this experiment was designed to evaluate, under Queensland conditions, reconstituted HM grain sorghum and molasses in a feedlot ration in a commercial feedlot on the Darling Downs. II. MATERIALS AND METHODS 188 Hereford steers, approximately 18 months old, with a mean initial full Iiveweight of 270 t- 26 kg were randomly allocated to four yards so that each contained 47 steers. The yards measured 40 m x 30 m and provided 0.85 m feed trough space per animal. The cattle were treated for lice and worms and vaccinated with a polyvalent vaccine prior to the commencement of the experiment. The cattle were gradually introduced to their diets over a period of 14 days. On day 1 they received 2.3 kg of grain plus additive mixture per head and ad lib. * Department of Primary Industries, Toowoomba, Queensland, 4350. t Logan Downs Pty. Ltd., Jimbour, Queensland, 4405. roughage. The proportion of this grain plus additive mixture was increased over the next 13 days until the diets shown in table 1 were reached. These diets were then offered ad Lib. for a further 100 days. Hybrid grain sorghum of mixed varieties (87 per cent dry matter and 2.18 per cent nitrogen) and panicum (Setaria italica) stubble (92 per cent dry matter and 0.85 per cent nitrogen) were the main components of the diet. The HM sorghum was prepared by the following method. The flow rate of dry grain along a 9 m horizontal auger was set at 204 kg/min. By calculation, 39 1 of water/min. were required to increase the moisture level of the dry grain to approximately 27 per cent. A spray line was positioned above the horizontal auger for this purpose. The wet grain was then augured into an airtight steel silo and stored for 39 days before use. The average moisture content of the HM grain used in the experiment was 26 per cent. Both the dry and HM grain were prepared by coarse rolling in a mill set to just fracture the grain. Restricted randomization, on the basis of full liveweight, was used to allocate the cattle into four groups. Following the initial weighing, all cattle were weighed on day 14 with subsequent weighings at approximately 30 day intervals until day 113. Daily feed intakes for each group were recorded. The design was a 2 x 2 factorial of the two grain types with and without molasses. Growth rates for each animal were calculated (as the slope of a linear regression of weight on time) over the two periods l-l 13 days, 14-113 days and analysed by analysis of variance. Feed conversion for each weighing interval was calculated as the ratio of group feed intake to total weight gain for the group. An analysis of variance of group feed intake and of feed conversion over the three weighing intervals making up the period on high grain ration (days 14-113) was performed. An analysis including the adjustment period (days l-l 3) was not done, as mild scouring in the HM grain/molasses group during this period resulted in negligible weight gains, thus rendering an analysis over the four intervals invalid. However, overall figures for the period l-l 13 days were calculated directly. III. RESULTS The average final liveweight for all steers in the experiment was 422 -t- 60 kg resulting in an average gain of 152 kg in 113 days. There was no significant 263 difference between the liveweight performance of steers receiving dry or HM grain over the total feeding period of 113 days. However, for the period on the high grain ration, (day 14 - day 113), steers fed HM grain had a superior daily weight gain (P < 0.01) to those fed dry grain (Table 2). The addition of molasses to the diet resulted in an increase in liveweight gain during the 113 days of feeding (P < 0.05) and during the period on the high grain ration (P < 0.01). TABLE 2 Eflect of diet gain, and The daily feed intake of HM fed steers was slightly, but not significantly lower than those receiving dry grain during the period on the high grain ration. There was a similar result, obtained by direct calculation (i.e., total feed intake divided by 113 days) for the total feeding period (Table 2). Molasses, however, resulted in a significant increase in daily feed consumption in the former period (P < 0.05). The better liveweight gain of the steers fed HM grain, coupled with a slightly lower feed intake, resulted in a better feed conversion compared with those receiving dry grain. For the period on the high grain diet the difference between the two groups approached significance at the 5 per cent level. Animals receiving molasses had a slightly diminished feed conversion due to their higher feed intake. Mild scouring was observed for approximately 5 consecutive days during the first two weeks in animals receiving the HM grain/molasses ration. No other disease problems were encountered during the experiment. IV. DISCUSSION The feeding of reconstituted sorghum grain to steers resulted in an increase in daily liveweight gain of 7.5 per cent, an improvement in feed conversion of 10.9 per cent and a decrease of 5.8 per cent in feed intake over the period of 100 days on the final high grain ration. No improvement in Iiveweight gain was obtained over the total 113 day feeding period; however, feed intake was reduced and feed conversion improved by feeding HM grain. Mild scouring in the HM grain/molasses group for 5 days during the changeover period may have confounded the overall results. The scouring resulted in a low weight gain for this group in this period, thus reducing the overall gain of the HM grain treatment. This may have eliminated 264 any significant difference in liveweight gain between the HM and dry grain treatments. Likewise feed intake and conversion may have been affected. The results during the period when the high grain rations were fed are of a similar order to the findings from North America in which liveweight gains were comparable or superior (up to 18.4 per cent), and less dry matter (lo-20 per cent) was required per unit of gain in rations based on HM grain compared with dry sorghum grain (Penic et aZ. 1968; Hale et al. 1969; Riggs and McGinty 1970). One of these papers (Penic et al. 1968) reported an 11 per cent decrease in daily feed intake on a HM grain sorghum ration. A decrease was also apparent in our experiment, although this result was not significant. For the total feeding period the results are not as good as those reported by the American authors who used hormone implanted animals and generally longer feeding periods. Possibly these two factors could account for some of the variation between the American results and the results of this experiment. The improved digestibility of the dry matter, organic matter, non protein organic matter and crude protein in HM grain sorghum reported by McGinty, Breuer, and Riggs (1967) and Buchanan-Smith, Totusek, and Tillman (1968) could explain the improved performance of cattle fed HM grain sorghum. The addition of molasses to the ration improved Iiveweight gain, but also increased costs due to higher feed intake and lowered feed conversion. It would seem therefore that the increased cost and inconvenience of adding 5 per cent molasses to these experimental rations was not justified. In this experiment, cattle performance for the period on the high grain ration was superior to their overall performance which included the 13 day changeover period. By reducing this period, a better overall performance should result. Subsequent to this experiment, over 400 steers have been fattened in the feedlot, and it has been found that cattle can be changed to a 90 per cent HM grain sorghum ration (DM basis) within 9 days. Shortening the changeover period did not result in any digestive troubles, nor have any been experienced at any stage using HM grain sorghum. V. ACKNOWLEDGMENTS The authors wish to thank Mr. A. Swain for the statistical analyses. The co-operation and facilities provided by Logan Downs Pty. Ltd. Jimbour, Queensland is gratefully acknowledged. VI. REFERENCES Buchanan-Smith, J. G., Totusek, R., and Tillman, 27: 525. A. D. (1968). Journal of Animal Science, Hale W. H., Theurer, B., Loynachan, E., Taylor, B., and Kuhn, J. (1969). 'Cattle Feeders' Day' (Agricultural Experiment Station: University of Arizona). McGinty, D. D., Breuer, J. H., and Riggs, J. K. (1967). Journal of Animal Science, 26: 223. (Abstr.) Morris, J. G., Pepper, Patricia M., and Gartner, R. J. W. (1969). Australian Journal o f Penic, P., Marion, P. T., Riggs, J. K., and McGinty, D. D. (1968). 'Beef Cattle Research In Texas' (Texas A. & M. University: Texas). Riggs, J. K., and McGinty, D. D. (1970). Journal of Animal Science, 31: 991. 265 Experimental Agriculture. Animal Husbandry, 9: 57.