Effect of Sodium Bicarbonate and Limestone Additions to High Grain Diets on Feedlot Performance and Ruminal and Fecal Parameters in Finishing Steers

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Abstract
A feedlot trial was conducted to determine the effects of supplementing a high corn .diet (control) with .9% NaHC03, 1.8% limestone or a combination of .9% NaHC03 and 1.8% limestone on gain, feed efficiency, rumianl pH, volatile fatty acid concentration and fecal pH and starch concentration. One-hundred and twenty-eight yearling, crossbred steers (average weight 325 kg) were grouped according to weight and randomly allotted to the diets. Steers were fed in pens of eight head each and each treatment was replicated four times. Rumen samples were taken via stomach tube and fecal samples were taken as rectal grab samples on days 56 and 112 of the 140-day trial. Although the differences were not significant (P>.05), steers fed the NaHC03-supplemented diet and those fed the limestone diet tended to have poorer gains and feed efficiencies than those fed the control diet. Animals fed the NaHC03 plus limestone-supplemented diet gained 11 and 12% slower than those fed control or NaHC03-supplemented diets, respectively (P<.05). This reduction in gain by steers fed the buffer combination appeared to be due to a 3.7% (nonsignificant) lower dry matter intake than by steers fed the control diet. Carcasses from steers fed the 1.8% limestone diet had higher (P<.05) marbling scores than did carcasses from the other groups. However, carcass weights, ribeye areas and grade were not affected (P>.05) by the diets fed. Carcass fat thickness was less (P<.05) for the limestone and the buffer combination groups and contributed to a lower (P<.05) yield grade for these groups. Supplementation of the high corn diet with the buffer combination decreased ruminal pH and increased butyric acid (moles/100 g) at 56 days. However, at 112 days, there were no differences in ruminal VFA patterns, but addition of 1.8% limestone to the diet increased ruminal pH (P<.05). Buffer additions increased fecal pH but had little effect on fecal starch concentration. Fecal pH and fecal starch concentrations were negatively correlated (r = −.35). Copyright © 1980. American Society of Animal Science . Copyright 1980 by American Society of Animal Science.