Effects of Adding Low Levels of Roughages or Roughage Substitutes to High Energy Rations for Fattening Steers

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Abstract
Two experiments utilizing 104 Hereford steers were conducted to study the influence of low levels of roughages and roughage substitutes on performance, carcass characteristics, rumen environment, rumen parakeratosis and liver abscesses of steers fed high energy rations. The treatments were: basal all-concentrate ration; basal plus 1.36 kg. hay per head daily; basal containing 5% cottonseed hulls; or 5% ground corn cobs; or 2% oyster shells, or 4% oyster shells; or 2% sand; or 5% ground polyethylene. Eighty steers were group fed in Experiment I and 24 steers were individually fed in Experiment II. The addition of low levels of roughages and roughage substitutes to the basal ration did not significantly increase body weight gains in Experiment I. In Experiment II, the addition of cottonseed hulls to the basal ration significantly increased gains (P<.05) over the basal and basal plus 2% or 4% oyster shell rations. Steers on the basal, basal plus hay and basal plus cob treatments yielded carcasses with larger ribeyes, thinner rinds and improved cutability scores, while carcass grades and marbling scores were not significantly different from the other treatments. The basal plus hay was the only treatment which gave any appreciable protection against rumen parakeratosis and liver abscesses. Total volatile fatty acids was highest and pH lowest on the basal and basal plus 2% oyster shell treatments in Experiment I. These two treatments also elicited severe rumen parakeratosis and a high incidence of liver abscesses. Rumen pH was highest on the basal plus hay treatment in both experiments. Lactic acid concentrations and molar percentages of VFA's could not be related to incidence of rumen parakeratosis and liver lesions in these experiments. Copyright © 1969. American Society of Animal Science . Copyright 1969 by American Society of Animal Science

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