Four Holstein male calves were used to study the effect of whey protein concentrate (WPC) on postprandial changes in plasma retinol and triglyceride concentrations. Suckling tests were conducted on the calves using Holstein cow whole milk mixed with Vitamin A acetate, with or without WPC, at weekly intervals from immediately after birth to 6 weeks of age. A catheter was inserted into a jugular vein and blood samples were taken from just until 8h after the feeding of the whole milk at 0800h. Plasma retinol and triglyceride concentrations were determined by HPLC and enzymatic methods, respectively.The concentrations of plasma retinol increased gradually following the feeding of both milk. However, no significant effect of WPC on plasma retinol was found. On the other hand, the plasma concentration of triglyceride in the calves fed the milk with WPC were significantly higher than that of the calves fed the milk without WPC 8 h after the feeding. This suggests that WPC participates in milk fatty acid metabolism and not in retinol transport in preruminant calves.

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