Abstract
Proper nutritional management during the dry period is required to prevent cow from metabolic disorders during the transition period and to increase milk yield during early lactation, especially in summer. We investigated the effects of nutrient balance on plasma metabolites of dry pregnant cows 9 days prepartum under high ambient temperature. Eleven cows were used in this experiment. Plasma NEFA concentration was negatively correlated with energy balance of dry, pregnant cows (P<0.01) . Energy balance did not have the apparent effect on plasma glucose and insulin concentrations. Nitrogen balance was not correlated with plasma total protein, albumin, and urea nitrogen concentration. Nitrogen balance was not correlated with plasma 3-methylhistidine concentration as a marker of myofibrillar protein degradation. Nitrogen balance was positively correlated with plasma essential amino acid (P<0.01), non-essential amino acid (P<0.05) and total amino acid (P<0.01) concentration. Plasma Ca concentration was positively correlated with Ca balance and P balance. Plasma osteocalcin as bone formation marker was correlated positively with Ca balance. Calcium and phosphorus balance did not affect the urinary deoxypyridinoline excretion as bone resorption marker. These results suggested that decreased nutrient intake negatively affects plasma metabolites in dry, pregnant cows under high ambient temperature.
