Increasing intravenous infusions of glucose improve body condition but not lactation performance in midlactation dairy cows

摘要: Abstract The present study was intended to test whether intravenously applied glucose would elicit dose effects on lactation performance similar those observed after gastrointestinal application. Six midlactation cows received intravenous infusions (GI), increasing by 1.25% of the calculated net energy for (NE L ) requirement per day, whereas control volume-equivalent saline (SI). Measurements and samples were taken at surplus levels 0, 10, 20, 30% NE requirement, respectively. Body weight backfat thickness increased linearly with GI compared SI. No differences in daily feed intake, milk output, energy-corrected yield between treatments. However, protein percentage infused group. Although lactose not affected treatment during infusion period, decreased GI, but SI, once ceased. Based 5 diurnal blood samples, mean maximum concentrations plasma serum insulin showed linear increases their minimum unaffected. At marked hyperglycemia hyperinsulinemia 1600h (i.e., 1h postprandially), coinciding glucosuria. revised quantitative insulin-sensitivity check index indicated development resistance no such change SI cows. Glucose β-hydroxybutyrate nonesterified fatty acid relative urea nitrogen only numerically GI. changes activities γ-glutamyl transferase aspartate transaminase bilirubin macrominerals. phosphorus concentration withdrawal Only did glycogen content increase or tend liver skeletal muscle. In conclusion, dairy an energy-balanced diet directed predominantly body fat reserves rather than performance. This may suggest that metabolic fate is modified signals, hormonal both from portal-drained viscera when absorbed intestine.