Correlations of Dietary Crude Protein and Gross Energy on Blood Glucose and Urea, Milk Urea and Lactose Concentrations in Lactating Ewes

Concentrations of scrum glucose (SG) and urea (SU) milk lactose (ML) and urea (MU) and their relationships to dietary gross energy (GE) and crude protein (CP) were studied in 16 lactating ewes in Urmia Iran Ewes were aged 3 to 5 years and were bred in a closed pen They were fed alfalfa hay pasture grass concentrate and corn silage Each lactating ewe was nursing a single lamb Five ml of blood from v jugularis 50 ml milk and 200 g feed mixture were collected at 15 day intervals up to 135 days (9 samples) Serum glucose and urea concentrations were evaluated using a spectrophotometer milk lactose m Polarimeter gross energy by calculation method and crude protein by Kjeldahl methods The mean values for dietary GE CP SG SU MU and ML were 2 39 Mcal/kg/DM 14 1% food/DM, 2 69 465 3 67 mmol/1 and 4 8 mg/dl milk respectively Significant differences (P < 0 01) were found for scrum and milk indicators during the milking periods among the sampling times Scrum urea and milk urea irregularly increased while serum glucose and milk lactose irregularly decreased Positive correlations were found (P < 0 05) between SU/MU (r = 0 45) MU/GE (r = 0 75) MU/CP (r = 0 70) and SU/CP (r = 0 97) Negative correlations (P < 0 05) were found between MU/SG (r = -0 17) SU/ML (r = 0 20) and MU/ML (r = 0 24) Based on results It is concluded that urea glucose and lactose would be appropriate variables in the prediction of crude protein and gross energy concentration of diet in lactating ewes