Ruminal fermentation and passage of nutrients to the duodenum of lactating cows fed mixtures of corn and barley

• Published in: Journal of dairy science Vol. 78; no. 9; pp. 1981 - 1998
• Main Authors: OVERTON, T. R, CAMERON, M. R, ELLIOTT, J. P, CLARK, J. H, NELSON, D. R
• Format: Journal Article
• Language: English
• Published: Savoy, IL American Dairy Science Association 01.09.1995
• Subjects: acide amine; almidon; amidon; amino acids; Amino Acids - administration & dosage; Amino Acids - metabolism; aminoacidos; Animal Feed; Animal Nutritional Physiological Phenomena; Animal productions; Animals; barley; Biological and medical sciences; Cattle - metabolism; cebada; contenido de materia seca; dairy cows; dietary fibres; digestibilidad; digestibilite; digestibility; Digestion; digestion du rumen; digestion ruminal; dry matter content; Duodenum - metabolism; Eating; Fatty Acids, Volatile - metabolism; feed intake; Female; Fermentation; fibra de la dieta; fibre alimentaire; Fundamental and applied biological sciences. Psychology; Hordeum; ingestion de piensos; intestin; intestines; intestinos; Lactation; mais; maiz; maize; materia organica; matiere organique; Nitrogen - administration & dosage; Nitrogen - metabolism; organic matter; orge; prise alimentaire animaux; Rumen - metabolism; rumen digestion; soybean meal; starch; Starch - metabolism; teneur en matiere seche; Terrestrial animal productions; tortas de soja; tourteau de soja; vacas lecheras; vache laitiere; Vertebrates; Zea mays; Performance evaluation; Barley; Lactation; Starch; Dairy cattle; Ox; Rumen; Cow; Fermentation; Corn starch; Vertebrata; Mammalia; Diet; Cow milk; Artiodactyla; Ungulata; Digestibility
• ISSN: 0022-0302; 1525-3198
• DOI: 10.3168/jds.S0022-0302(95)76824-2

Five Holstein cows were used in a 5 X 5 Latin square design and fed dies containing five different ratios of starch from ground shelled corn and steam-rolled barley. The DMI decreased and both the proportions of OM and starch digested in the rumen increased as barley starch increased in the diet. Corn and barley starches fed in a ratio of 75:25 maximized the proportions of ADF and NDF digested in the rumen. Replacement of 25% of the corn starch with barley starch resulted in the largest increase in the molar percentage of propionate and the largest decrease in the molar percentage of acetate in ruminal fluid. Passage of NAN to the duodenum was not affected by treatment; however, the percentage of nonammonia nonmicrobial N in NAN decreased as barley starch increased. Passage of AA to the duodenum was largest when corn and barley starches were fed in ratios of 100:0 and 0:100 because of the influence of DMI and microbial protein synthesis. Production of milk, CP, and SNF was similar when cows were fed diets containing corn and barley starches in ratios of 100:0, 75:25, and 50:50 but was decreased when the ratios were 25:75 and 0:100. Increased production responses of cows when diets contained larger amounts of starch from ground shelled corn were probably due to increased DMI.