Metabolic indicators for early pregnancy in zebu and crossbreddairy cows reared in a subtropical climate

Abstract

To identify metabolic indicators in blood and urine for early pregnancy in dairy cows (32 crossbred and 12 purebred zebu cows), blood and urine samples were collected on days 0, 15, 20, 24, and 30 postbreeding. The plasma progesterone (P4) concentration was significantly (P < 0.05) higher in pregnant cows than in nonpregnant cows after day 15. The plasma blood urea nitrogen (BUN) concentration remained significantly (P < 0.05) higher in pregnant cows on day 15. The plasma concentrations of cholesterol, glucose, protein, and nonesterified fatty acid (NEFA) did not differ between pregnant and nonpregnant cows. The urine protein concentration was significantly higher (P < 0.05) in pregnant zebu cows compared to nonpregnant zebu cows. Plasma P4 was significantly (P < 0.001) and positively associated with urine glucose levels in nonpregnant crossbred cows. In nonpregnant zebu cows, the correlation between P4 was positive (P < 0.05) with plasma cholesterol, glucose, urine glucose, and protein. In pregnant zebu cows, P4 was negatively associated with plasma BUN and positively (P < 0.05) associated with both plasma and urine glucose levels. Thus, urinary proteins can be used as a noninvasive tool for early nonpregnancy confirmation in cows with very high accuracy at around 24 days after artificial insemination.