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