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

Samples of peritoneal fluid and jugular venous blood were taken simultaneously from 95 clinically healthy Holstein-Friesian cows. The concentrations of total protein, albumin, glucose, cholesterol, fibrinogen, L-lactate and D-dimer, the activities of lactate dehydrogenase (LDH), alkaline phosphatase and creatine kinase, and the white blood cell count were determined in the samples. Light's criteria, the serum-ascites albumin gradient (SAAG) and the ratios of the concentration of each parameter in peritoneal fluid to its concentration in blood were calculated. The mean concentrations of total protein, albumin and D-dimer, the activity of LDH and the SAAG were different from the reference values for monogastric animals and human beings.

Amelioration of abomasal hypomotility after laparoscopy-guided abomasopexy rather than omentopexy via right flank laparotomy may result in faster clinical improvement in the immediate postoperative period in cows undergoing correction of an LDA.