Mammary Uptake, Portal-Drained Visceral Flux, and Hepatic Metabolism of Free and Peptide-Bound Amino Acids in Cows Fed Steam-Flaked or Dry-Rolled Sorghum Grain Diets
| Autor: | Flávio Augusto Portela Santos, H. Tagari, Kenneth E. Webb, J.M. Simas, Carla Maris Machado Bittar, M. Sadik, D. DeYoung, A. Delgado-Elorduy, José E. P. Santos, T. Huber, Brent Theurer, A. Alio, Luiz Gustavo Nussio, P. Cuneo, O. Lozano |
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| Rok vydání: | 2008 |
| Předmět: |
medicine.medical_specialty
Animal feed Total mixed ration Hepatic Veins Intestinal absorption Random Allocation Mammary Glands Animal fluids and secretions Animal science Lactation Internal medicine Genetics medicine Animals Dry matter Amino Acids Sorghum Dairy cattle Cross-Over Studies Portal Vein Chemistry food and beverages Metabolism Milk Proteins Animal Feed Milk medicine.anatomical_structure Endocrinology Intestinal Absorption Liver Cattle Female Animal Science and Zoology Splanchnic Food Science |
| Zdroj: | Journal of Dairy Science. 91:679-697 |
| ISSN: | 0022-0302 |
| DOI: | 10.3168/jds.2007-0629 |
| Popis: | Our objectives were to measure net fluxes of free AA (FAA) and peptide-bound AA (PBAA) across portal-drained viscera, liver, splanchnic tissues, and mammary tissues, and milk AA output of lactating Holstein cows (n = 8, 86 +/- 8 d in milk). Cows were fed an alfalfa-based total mixed ration containing 40% steam-flaked (SFS) or dry-rolled (DRS) sorghum grain. The total mixed rations were offered at 12-h intervals in a crossover design. Blood samples were obtained from indwelling catheters in portal, hepatic, and mammary veins and from mesenteric or costoabdominal arteries every 2 h from each cow and diet. Intake of dry matter was 17.9 and 18.6 kg/d of the SFS and DRS diets, respectively, but dropped to 16.3 kg/d for cows fed the SFS diet in the last 3 experimental days, sampling day included. Milk and milk crude protein yields (kg/12-h sampling) were 13.85 vs. 13.25 and 0.425 vs. 0.396 for cows fed SFS or DRS, respectively, and were not affected by the considerable drop in dry matter intake of cows fed the SFS diet during the last 3 experimental days. The portal-drained visceral flux of total essential FAA was 417 and 442 g/12 h (SEM 63) in cows fed SFS and DRS, respectively. However, the portal-drained visceral flux of 7 essential PBAA out of the 9 determined was numerically greater in cows fed the SFS diet, and total essential PBAA in that treatment was 77.4 +/- 22.2 compared with 35.4 +/- 50.2 g/12 h for cows fed the DRS diet. This phenomenon was again observed in a greater total splanchnic flux (FAA + PBAA) of 462 and 371 g/12 h in SFS- and DRS-fed cows, respectively. Mammary uptake of essential AA from both pools (free and peptide bound), and recovery of essential AA in milk, was again numerically higher in SFS-fed cows. In addition to FAA, quantifying the contribution of PBAA may improve our understanding of tissue use of AA substrates, and this may ultimately lead to improved diet formulations with respect to intestinal absorption and mammary uptake of AA. |
| Databáze: | OpenAIRE |
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