The Effects of Commercial Processing Method of Cottonseed Meal on Site and Extent of Digestion in Cattle

Abstract

The effects of commercial oil extraction (direct solvent extraction, DS; prepress solvent extraction, PP; screw press, SP) of cottonseed meal (CSM) on ruminal protein escape was measured using solubility measurements, in situ methods, ruminal and duodenal-cannulated dairy steers and duodenal-cannulated cows. Steers were fed an 80% concentrate diet at 1.8% of body weight (dry matter) and the dairy cows received 60% concentrate diets at a dry matter (DM) intake level of 3.1% of body weight. Amount of nitrogen (N) soluble in .15 N NaCl from SP CSM (14.7% of N) was about one-half that of DS and PP (28.8 and 27.4%, P<.01). Rate of N disappearance from 4 to 12 h and from 12 to 20 h tended to be greater for DS than for PP and SP CSM. In the cow trial, ruminal escape of supplemental N was highest (P<.05) for SP (SP 57.0% vs DS 34.7%, PP 35.3% and SBM 35.0%). Rumen escape of CSM N did not differ significantly with processing method (SP 42.9%, DS 33.9%, PP 38.3%) in the trial with steers, though trends were similar to those found in the cow trial. In both trials, organic matter (OM) and starch digestion were decreased in the rumen and increased postruminally with SP as compared with DS and PP. These data indicate that processing method of CSM alters site of protein and OM digestion and that protein escape will vary with experimental conditions.