Factors Affecting Degradation and Utilization of Protein Sources by Ruminants
Loerch, Steven Christopher
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https://hdl.handle.net/2142/69992
Description
Title
Factors Affecting Degradation and Utilization of Protein Sources by Ruminants
Author(s)
Loerch, Steven Christopher
Issue Date
1982
Department of Study
Animal Science
Discipline
Animal Science
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Agriculture, Animal Culture and Nutrition
Abstract
In vivo, in situ and in vitro studies were conducted to evaluate degradation and utilization of various protein sources by ruminants.
Blood meal (BM), meat and bone meal (MBM), and dehydrated alfalfa (DA) were compared with soybean meal (SBM) as supplemental protein sources in two steer and two lamb feedlot trials. Medium to high energy diets, typical of feedlot conditions were fed. No consistent differences in average daily gain, feed intake, or feed efficiency were noted between treatments.
N solubility of casein (C), SBM, BM, MBM, DA, and corn gluten meal was determined in .867% MaCl, MeDougall's artificial saliva, 10% modified Burroughs' mineral mixture, and .02N NaOH. A solvent X protein source interaction suggested that none of these solvents could adequately predict rumen solubility for all protein sources tested. A solvent pH X protein source interaction also existed when solubility of protein sources was determined in McDougall's artificial saliva adjusted to pHs of 5, 6, or 7. In situ N disappearance of C, SBM, and DA decreased with increasing levels of dietary high-moisture corn. Increasing levels of NaOH-treated corn did not affect in situ N disappearance of these protein sources, suggesting that the decreased ruminal protein degradation observed when ruminants were fed high energy diets was primarily due to depressed rumen pH. In situ N disappearance of four protein sources after 12 hours incubation varied depending upon dietary protein supplement, suggesting a possible adaptation of rumen microorganisms to dietary protein source.
Estimated true digestibility of SBM, BM, MBM, and DA was 100.4, 99.1, 86.4, and 85.2%, respectively. Rumen N bypass of BM, MBM, and DA was greater than N bypass of SBM. A method of estimating digestible N bypass suggested that BM provided the greatest amount of digestible N to the duodenum. N bypass was more highly correlated with in situ residual N at 3, 12, and 24 hours than with in situ residual N at 6 hours, rate of N disappearance from 3-12 hours, or in vitro N insolubility.
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