Post-absorptive metabolism of energy-yielding nutrients and starch digestibility by steers fed sorghum grain flaked at different densities

Persistent Link:
http://hdl.handle.net/10150/282356
Title:
Post-absorptive metabolism of energy-yielding nutrients and starch digestibility by steers fed sorghum grain flaked at different densities
Author:
Lozano-Ascencio, Oscar German, 1956-
Issue Date:
1997
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Objectives were to determine the effects of feeding dry-rolled (DR) vs steam-flaked (SF) sorghum grain and degree of processing (flake density, FD) of corn and sorghum grain on site and extent of starch digestion and post-absorptive metabolism of energy-yielding nutrients in steers fed 77% grain. The design for each trial was a randomized block. Seven steers (400 kg) with duodenal and ileal cannulas were used to determine corn and sorghum starch digestibilities (Cr ratio, 3-d collection). Steers fed SF versus DR sorghum increased starch digestibility in the rumen (23%; P < .01), total tract (2.3%; P < .01), and in the small intestine (6%; P < .01, as percentage of starch entering duodenum). Decreasing flake density of SF sorghum grain increased linearly (P < .05) starch digestion (percentage of intake) in the rumen and total tract, and diminished linearly (P < .05) starch digestibilities post-ruminally and in the small intestine. Similar responses in starch digestibilities occurred by lowering FD of SF corn. Percent dietary corn or sorghum starch digestibility in the large intestine was less than 2% of intake. Feeding SF compared to DR sorghum did not alter net absorption and uptake or release of energy-yielding nutrient across SPL tissues. As expected, net absorption of glucose across portal-drained viscera (PDV) was negative (-.60 mol/d). Incrementally decreasing FD of SF sorghum linearly increased net PDV absorption of lactate (P =.04), glucose synthesis by the liver (P =.03), and SPL output of glucose (P < .01) and L-lactate (P =.03). Net propionate PDV absorption (P =.18), hepatic uptake (P =.21), and SPL output (P =.15) tended to be increased with lower FD. Increasing degree of grain processing, by incrementally decreasing FD, linearly increased ruminal and total tract starch digestibilities and net absorption of glucose precursors (propionate and L-lactate), resulting in increased hepatic synthesis and greater output of glucose from the gut and liver to the rest of the body. Based on these changes, the optimum FD for SF sorghum grain was 283 g/L (SF22).
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Biology, Animal Physiology.; Agriculture, Animal Culture and Nutrition.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Animal Science
Degree Grantor:
University of Arizona
Advisor:
Theurer, C. Brent

Full metadata record

DC FieldValue Language
dc.language.isoen_USen_US
dc.titlePost-absorptive metabolism of energy-yielding nutrients and starch digestibility by steers fed sorghum grain flaked at different densitiesen_US
dc.creatorLozano-Ascencio, Oscar German, 1956-en_US
dc.contributor.authorLozano-Ascencio, Oscar German, 1956-en_US
dc.date.issued1997en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractObjectives were to determine the effects of feeding dry-rolled (DR) vs steam-flaked (SF) sorghum grain and degree of processing (flake density, FD) of corn and sorghum grain on site and extent of starch digestion and post-absorptive metabolism of energy-yielding nutrients in steers fed 77% grain. The design for each trial was a randomized block. Seven steers (400 kg) with duodenal and ileal cannulas were used to determine corn and sorghum starch digestibilities (Cr ratio, 3-d collection). Steers fed SF versus DR sorghum increased starch digestibility in the rumen (23%; P < .01), total tract (2.3%; P < .01), and in the small intestine (6%; P < .01, as percentage of starch entering duodenum). Decreasing flake density of SF sorghum grain increased linearly (P < .05) starch digestion (percentage of intake) in the rumen and total tract, and diminished linearly (P < .05) starch digestibilities post-ruminally and in the small intestine. Similar responses in starch digestibilities occurred by lowering FD of SF corn. Percent dietary corn or sorghum starch digestibility in the large intestine was less than 2% of intake. Feeding SF compared to DR sorghum did not alter net absorption and uptake or release of energy-yielding nutrient across SPL tissues. As expected, net absorption of glucose across portal-drained viscera (PDV) was negative (-.60 mol/d). Incrementally decreasing FD of SF sorghum linearly increased net PDV absorption of lactate (P =.04), glucose synthesis by the liver (P =.03), and SPL output of glucose (P < .01) and L-lactate (P =.03). Net propionate PDV absorption (P =.18), hepatic uptake (P =.21), and SPL output (P =.15) tended to be increased with lower FD. Increasing degree of grain processing, by incrementally decreasing FD, linearly increased ruminal and total tract starch digestibilities and net absorption of glucose precursors (propionate and L-lactate), resulting in increased hepatic synthesis and greater output of glucose from the gut and liver to the rest of the body. Based on these changes, the optimum FD for SF sorghum grain was 283 g/L (SF22).en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectBiology, Animal Physiology.en_US
dc.subjectAgriculture, Animal Culture and Nutrition.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineAnimal Scienceen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorTheurer, C. Brenten_US
dc.identifier.proquest9738921en_US
dc.identifier.bibrecord.b37456696en_US
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