RELATIONSHIP BETWEEN MILK UREA NITROGEN AND LACTATION STAGE OF DAIRY COWS

The experiment was conducted to investigate milk urea nitrogen (MUN) in relation to lactation stage of dairy cows. Milk samples, feed samples and necessary data were collected from 30 lactating dairy cows of different lactation stage from Sirajganj district. All cows were crossbreed in which 10 were at early (1^st 45 DIM), 10 were at mid (46-150 DIM) and rest 10 were at late (>150 DIM) lactation stage. Milk urea nitrogen concentration were 37.0 mg/dl, 38.6 mg/dl and 37.64 mg/dl at 1^st 45 DIM, at 46 to 150 DIM and at > 150 DIM of dairy cows respectively. Days in milk (DIM) did not affect the live weight, BCS, daily feed intake, milk yield also percentage of milk protein, fat, lactose, SNF and minerals but affected the level of MUN. MUN was used to evaluate the plane of nutrition of a group of crossbred dairy cows and was significantly correlated with DIM. MUN level is the highest at mid (46 to 150 DIM) lactation stage.