Plasma biochemical profile of dairy cows, with respect to diet and breed

The aim of this study was to determine if total replacement of soybean meal (SBM) with a rapeseed by-product (RS-by) in the diets of Romanian Black Spotted (RBS) and Montbéliarde (MB) breeds will cause changes of the biochemical profile in lactating cows. Thirty-two healthy multiparous dairy cows, mid-lactation stage, were randomly assigned to four homogeneous groups (2 RBS and 2 MB) of 8 cows each for 42 days of experiment. Groups received the same basal diet (maize silage and alfalfa hay) and two types of compound feed: control (with 12.5% SBM) and experimental (with 12.5% RS-by). Individual blood samples were collected at the end of the trial from the mammary vein and plasma biochemical parameters were determined. The main effects of feed, breed and their interaction were statistically analyzed with SPSS software. Plasma energy parameters were not affected by the dietary treatments, but glucose was higher in MB breed. Total protein and urea were significantly higher (7.99 vs. 6.93 g/dL; 18.50 vs. 15.31 mg/dL) in control compared to the experimental group; urea was also influenced by the feed x breed interaction. Magnesium was significantly higher (1.98 vs.1.59 mg/dL) in the experimental group. Alanine aminotransferase and alkaline phosphatase were significantly higher (35.75 vs. 29.00 U/L; 43.62 vs. 36.40 U/L) in the control group. The mineral or enzimatic analytes were not affected by animal breed. The majority of the parameters ranged between the normal limits.