Prepartum nutrient intake alters glucogenic capacity of liver slices from peripartal dairy cows.

Abstract

Ruminants rely on hepatic gluconeogenesis to support whole-body glucose metabolism and to supply glucose for lactose synthesis. Understanding the effect of plane of nutrition before parturition on the capacity for hepatic gluconeogenesis in dairy cows may provide a basis for improved cow health and productivity in the subsequent lactation. Our objectives were to determine the effects of far-off (FO) dry period diet, close-up (CU) period diet, and their interaction on adaptations in metabolism of gluconeogenic substrates (Ala and propionate) in liver slices. Multiparous Holstein cows (n = 71) were fed different amounts of nutrients during the FO and CU dry periods in a 3 (FO diet) × 2 (CU diet) factorial arrangement. During the FO period (d -60 to -25 before calving) cows received a control diet fed for ad libitum intake to meet NRC recommendations (100NRC), a moderate energy diet fed ad libitum to exceed NRC recommendation for NEL by at least 50% (150NRC), or the moderate energy diet fed at restricted intake to meet 80% of NEL requirements (80NRC). During the CU period (d -24 until parturition), cows were fed a diet either for ad libitum intake (CUA) to meet or exceed NRC recommendations or in restricted (CUR) amounts to provide 80% of calculated NEL requirements. All cows received the same lactation diet postpartum. Liver slices from biopsies at d -30, -14, 1, 14, and 28 relative to parturition were used to determine in vitro conversion of [1-¹⁴C] Ala and [1-¹⁴C] propionate to glucose and CO₂. Gluconeogenic rates from propionate were 71%, 37%, and 73% greater than from Ala on d 1 for cows fed 100NRC, 150NRC, and 80NRC, respectively. Gluconeogenesis from propionate was significantly greater on d -14 and d 28 for cows fed 80NRC compared with 100NRC and 150NRC. Oxidation of propionate to CO₂ increased from d -14 to d 1 postpartum for all far-off treatments. On d -14, oxidation of propionate to CO₂ tended to be lower for 100NRC versus 150NRC and 80NRC. Gluconeogenesis from Ala on d -30 tended to be less for 150NRC compared with 80NRC. Gluconeogenesis from Ala tended to be greater for CUR on d 14. Oxidation of Ala to CO₂ was not significantly different among treatments tended to be higher on d 1 postpartum for 100NRC. Close-up diets had minimal effects on gluconeogenesis and substrate oxidation. Cows fed restricted amounts of energy in the FO dry period had greater hepatic gluconeogenic capacity both prepartum and postpartum compared with those fed excess amounts of energy relative to requirements. Controlling energy intake during the far-off dry period can alter hepatic capacity for gluconeogenesis from propionate and Ala, which may confer an advantage to the cow by adapting metabolic processes before parturition and resulting in improved health and productivity.