Correlation between Milk Urea Nitrogen (MUN) Levels with Metabolizable Energy (ME) and Crude Protein (CP) Provided with Ratio of Roughage Concentrate by Supplied Feed of Dairy Cattle and its Effect on Milk Yield and Milk Composition

Background: Proportion of roughage and concentrate supply to dairy animal is a major challenge in commercial dairying of Bangladesh that directly correlated with quality and quantity of milk. Several studies revealed that, level of milk urea nitrogen (MUN) is an indication of proper feed supply of the animals. Therefore, the study was the attempt to find, the relationship between the level of MUN with metabolic energy (ME) and crude protein (CP) by supplied ratio of roughage, concentrate and effect of altered level MUN with milk quality and quantity in commercial dairy farms of Chittagong, Bangladesh. Methods: For the study, feed and milk samples were taken from randomly selected three different farm categories for the period of July 2014 to June 2015 monthly. The herd average milk production was taken from the recorded data. The feed and milk composition were analyzed in the dairy lab of Chittagong Veterinary and Animal Sciences University (CVASU). MUN was determined by spectrophotometric method in the Poultry Research and Tanning Laboratory (PRTC) of CVASU, Chittagong, Bangladesh. Observed data was analyzed by using Pearson’s correlation methods to find out the correlation among MUN level, supplied source of ME and CP and milk production and composition. Result: The results suggested that there was significant level difference of MUN (P less than 0.05) irrespective of seasons and farm categories with the sources of ME and CP of supplied feed. Milk yield relate significantly (P less than 0.05) with MUN level when there was lowest supply of roughage and maximum M.E comes from concentrate feed irrespective of farm categories. So, determination of MUN level will be helpful to commercial dairy farmers when the issues related to milk quality and quantity.