ARS | Publication request: HEAT TREATED SOYBEANS AND WHOLE COTTONSEED FOR LACTATING DAIRY COWS

Submitted to: Proceedings of the Georgia Dairy Herd Management Conference
Publication Type: Proceedings
Publication Acceptance Date: November 8, 1995
Publication Date: N/A

Technical Abstract: Soybeans that have been properly heat treated are a very palatable and effective supplement of by-pass protein and oil for lactating dairy cows. To be properly treated, soybeans need to be heated to approximately 295 deg F, and then held without cooling for approximately 30 minutes. Overheating of soybeans is seldom a problem - underheating often is. A laboratory procedure (PDI test) is commercially available for determining whether or not soybeans have been given an optimum heat treatment. The laboratory and in situ procedures for estimating protein degradation by rumen microbes differ greatly in their estimation of protein degradation, and the estimates are highly `procedure dependent.' Oftentimes the procedure used has more influence on the `by-pass' value obtained than does the protein source itself. Furthermore, the laboratory or in situ procedures (dacron bag) rely on ground samples of the feedstuff tested. Particle size and specific gravity are very important in determining extent of protein degradation in the rumen. In the case of roasted soybeans, we feel that either whole soybeans or soybeans broken into halves and quarters should be fed. Ground roasted soybeans do not have as much by-pass protein as soybeans fed as larger pieces.