Effect of dietary carbohydrate and monensin on expression of gluconeogenic enzymes in liver of transition dairy cows

• Published in: Journal of animal science Vol. 85; no. 3; pp. 690 - 699
• Main Authors: Karcher, E.L, Pickett, M.M, Varga, G.A, Donkin, S.S
• Format: Journal Article
• Language: English
• Published: Savoy, IL American Society of Animal Science 01-03-2007; Am Soc Animal Sci
• Subjects: Animal Feed - analysis; Animal Nutritional Physiological Phenomena; Animal productions; Animals; Antiprotozoal Agents - pharmacology; Biological and medical sciences; calving; carboxy-lyases; Cattle; cottonseed hulls; cow feeding; dairy cows; Dairying; Diet - veterinary; dietary carbohydrate; Dietary Carbohydrates - pharmacology; dietary fiber; dosage; dry matter intake; enzymes; Female; fermentation end products; Fundamental and applied biological sciences. Psychology; gene expression; Gene Expression Regulation, Enzymologic - drug effects; gluconeogenesis; Gluconeogenesis - drug effects; lactation; Lactation - drug effects; Lactation - metabolism; liver; Liver - drug effects; Liver - enzymology; messenger RNA; monensin; Monensin - pharmacology; parturition; phosphoenolpyruvate carboxykinase; Pregnancy; protein synthesis; pyruvate carboxylase; rumen fermentation; Ruminantia; soybean hulls; Terrestrial animal productions; transition to lactation; Vertebrates; transition dairy cow; Farming animal; Enzyme; Monensin; Liver; Dairy cattle; Gene expression; Vertebrata; Antifungal agent; Mammalia; Carbohydrate; Artiodactyla; Ungulata
• ISSN: 0021-8812; 1525-3163
• DOI: 10.2527/jas.2006-369

Thirty-four multiparous Holstein cows were used in a randomized block design to evaluate the effects of feeding nonforage fiber sources (NFFS), monensin, or their combination on expression of gluconeogenic enzymes in the liver during the transition to lactation. The addition of 0 or 300 mg/d of monensin to a conventional (CONV) or NFFS prepartum diet was evaluated in a 2 x 2 factorial arrangement of treatments. The NFFS diet was formulated by replacing 30% of the forage component of the CONV diet with cottonseed hulls and soyhulls. The CONV and NFFS basal diets were fed at dry-off and continued through parturition. Monensin was fed from -28 d relative to calving (DRTC) through parturition. At calving, all cows were placed on the same diet. Liver biopsy samples obtained at -28, -14, +1, +14, and +28 DRTC were used to determine pyruvate carboxylase (PC) and cytosolic phosphoenolpyruvate carboxykinase (PEPCK-C) mRNA expression. Feeding NFFS resulted in greater (P < 0.05) prepartum DMI compared with the CONV diet. There was no effect of prepartum diets on postpartum DMI or average milk production to 56 d of lactation. Expression of PC mRNA was elevated (P < 0.05) at 1 d postpartum, but there was no effect of NFFS or monensin on PC mRNA abundance. Expression of PEPCK-C mRNA at calving was increased (P < 0.05) with prepartum monensin feeding. The data indicate that feeding monensin to transition cows induces hepatic PEPCK-C mRNA expression before calving. The increased expression of hepatic PEPCK-C mRNA with monensin feeding suggests a feed-forward mechanism of metabolic control in ruminants that links molecular control of gluconeogenesis with the profile of rumen fermentation end products.