Effect of urea supplemented and urea treated straw based diet on milk urea concentration in crossbred Karan-Fries cows

Abstract

The study was undertaken to evaluate the effect of urea supplemented and urea treated straw based diet on milk urea concentration. Six multiparous crossbred Karan-Fries (Holstein Friesian × Tharparkar) cows were blocked into three groups of nearly equal body weight, DIM, milk yield and milk fat content and were randomized into a 3 × 3 Latin square design with 3-week period. Three experimental diets were fed to the animals. Composition of these diets were: Diet 1) green maize, wheat straw and concentrate mixture; Diet 2) green maize, wheat straw, concentrate mixture (urea supplemented) and molasses; Diet 3) green maize (4 % of total DM), 4 % urea treated wheat straw and concentrate mixture. Intake of DM and CP did not vary across the diets. Intake of digestible crude protein (DCP) was found significantly higher in diet 2, while ME and NEl intakes were found significantly lower in diet 3 but did not differ between diets 1 and 2. Average milk and plasma urea concentrations (mg dl-1) were found 29.2 ± 2.6, 45.3 ± 0.9, 34.5 ± 2.3 and 28.9 ± 2.4, 36.6 ± 1.4, 33.9 ± 2.2, respectively in diet 1, diet 2 and diet 3. Urea concentrations in morning milk samples were found significantly lower than noon or evening samples in all the three diets. Concentrations of urea in milk and plasma were found closely correlated (r = 0.94) and the regression equation developed was, plasma urea = 8.90 (.89) + .79 (.02) milk urea. Intake (g) of DCP than CP, per unit (MCal) of ME was found more closely associated with milk urea concentration. The study revealed that urea supplementation and urea treated straw based diet increased urea concentration significantly in milk and plasma. Morning milk urea values that estimated at a time gap of 15 hr since last major feeding may be considered as the lowest level and can be used for interpretation to monitor feeding adequacy or reproductive performances in dairy cows.