The traditional accepted range for bulk tanks samples is 10 to 14 milligrams per deci litre. MUN values are representative of urea levels of blood and other body fluids. Because MUN is a breakdown product of protein, it can be used to monitor protein status of Goat. MUN values can be used to improve the efficiency of microbial protein synthesis, which may reduce N excretion into the environment. Some researchers recommend a range of 10 to 14 milligrams per deciliter (mg/dl) while others recommend at range of 8 to 12 mg/dl. MUN above 12-14 mg/dl would have increased urinary N excretion and there would be opportunities for improvements. There are many factors affecting MUN values. The feeding system, i.e. total mixed rations (TMR) versus component-fed herds, and Goat eating patterns can affect MUNs. The time of feeding relative to milking time; MUN values usually peak 3-5 hours after feeding. In addition, herds milked 3x tend to have higher MUN values than herds milked 2x. The AM MUN value is usually lower than PM samples taken from the same herd. When comparing MUN values in a herd between months, account for differences in sampling times.

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Metwalli, A. A. M., & van Boekel, M. A. J. S. (1996). Effect of urea on heat coagulation of milk. Netherlands Milk and Dairy Journal, 50, 459-476.