Effects of Levels of Protein, Sources of Protein and an Antibiotic on Performance, Carcass Characteristics, Rumen Environment and Liver Abscesses of Steers Fed All-Concentrate Rations

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Abstract
Eighty steers were used to study the effects of urea versus soybean meal, 11% protein vs. 14% protein and Bacitracin supplementation on performance, carcass characteristics, rumen environment and liver abscesses of cattle fed all-concentrate rations based on ground shelled corn. Increasing the level of protein from 11% to 14% significantly increased gains. An apparent but nonsignificant increase in growth response was obtained from Bacitracin supplementation. Performance of steers fed rations containing urea was comparable to steers fed soybean meal. A significantly greater percent of butyric acid was observed in rumen fluid of steers consuming rations containing 14% protein. Differences in pH and buffering capacity of rumen fluid could not be related to levels of protein, sources of protein or Bacitracin supplementation. Significant interactions between protein treatments and Bacitracin treatments for pH and buffering capacity were observed. Rumen parakeratosis was present in all steers at slaughter. Dark-colored papillae as well as extensive sloughing and clumping were found in a large proportion of rumen wall samples. Seventy-two percent of the livers were condemned at slaughter due to liver abscesses. Degree of severity of rumen parakeratosis and incidence of liver abscesses could not be related to levels or sources of protein, or to presence of Bacitracin in the rations. Copyright © 1967. American Society of Animal Science . Copyright 1967 by American Society of Animal Science