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Effect of Energy Concentration in the Feed and Milking Frequency on Liver LCFA Metabolism in Early Lactating Dairy Cows
© The Author(s); licensee BioMed Central Ltd. 2003
Published: 31 March 2003
Hepatic lipidosis has been a problem for decades and it seems to cause problems for more than 50% of dairy cows in the periparturient period . High milk production and large losses of body condition score in early lactation have been concluded to be risk factors for hepatic lipidosis . Two key factors may be assumed important for preventing hepatic lipidosis: 1) avoiding excessive mobilization of LCFA from adipose tissue, 2) a stimulation of the hepatic capacity for LCFA oxidation. Different energy concentration in feed affects energy intake and mobilization in early lactation. Further, milk yield may be increased at a high level by milking 3 × daily instead of 2 × daily. The purpose of the present study was to test the combined effects of TMR energy concentration and increased milk yield, obtained by increased milking frequencies, on hepatic LCFA metabolism in early lactation.
Material and methods
Forty multiparous Danish Holstein cows, fed the same TMR during the dry period, were included in a 2 × 2 factorial design. One factor was feeding a high energy density TMR (H: 75% concentrate) or a low (L: 25% concentrate) from calving to eight weeks postpartum. The other factor was milking two (2) or three (3) times daily. The four treatments were designated L2, L3, H2, and H3. Liver biopsies were sampled week -2, 2, and 7 postpartum, and analyzed for triacylglycerol (TAG), glycogen, and in vitro capacity of palmitate oxidation.
Results and discussion
There were no differences between any of the analyzed parameters in hepatic tissue prior to calving (week -2). Liver TAG content was lowest for cows fed diet H compared with cows feed diet L in early lactation (10.6 vs. 15.7 mmol/g tissue, P = 0.04). Liver glycogen content was not affected by diet or milking frequencies in the present experiment. Cows allocated diet H had the highest in vitro capacity for oxidation of LCFA in early lactation (23.5 vs. 17.7 nmol/g tissue/h, P < 0.03). However, a significant interaction between energy density in the diet and milking frequencies (P < 0.05) showed that particularly cows on treatment L3 had less hepatic activity than cows on treatment H2 and H3. The present experiment shows that high compared to low TMR energy density has a positive effect on risk of hepatic lipidosis in early lactation. Further, increased milk yield, due to increasing milking frequencies, increases the risk of hepatic lipidosis, unless the cows are fed a high TMR energy concentration.
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