Imbalance in protein and carbohydrate consumption, which is the main source of energy, has an important influence on milk quality/quantity, health, and fertility of dairy cattle. This relates to significant economic consequences, especially in high producing cows. Milk Urea Nitrogen (MUN) testing is an indicator of the status of the protein metabolism in cattle and thereby is a tool in the management of milk production, health, and fertility.

The interest in measuring the urea content in milk has been increasing for the past several years and will continue to do so. This interest stems from the fact that urea is the waste product of protein metabolism with the majority of the urea in milk producing cows originating from unused dietary protein. A direct correlation has been shown to exist between urea levels, milk production, and reproductive performance.

Protein ingested by cows is first converted into ammonia that is then used by microbes and converted into other forms of protein that may be utilized by the cows. This leads to five possible scenarios:

1) Optimum: shown by moderate MUN levels, indicates the nutritional management of the cattle is maximized for the greatest milk yield, health, and reproductive performance.

2) Protein deficiency: shown by low MUN level, leads to low milk protein and a rapid
decrease in milk yield.

3) Protein surplus: shown by increased MUN level, does not lead to high milk protein
content. Instead, energy is diverted from other needs of the cow to facilitate the metabolism of this excess protein resulting in lower milk yields, lower reproductive rates, and increased levels of disease.

4) Energy Surplus: shown by reduced MUN level, yielding increased milk protein and lower milk yields.

5) Energy deficiency: shown by increased MUN level, yielding lower milk protein, reduced milk yields, and lower reproduction rates.

Using this MUN level information it is possible to decide if the cow is receiving a balanced fodder ration thereby saving cost, maximizing milk production, increasing reproductive performance, and improving the health of the cow. It should be noted studies are still being conducted by researchers and will likely indicate that the many negative effects associated with a protein surplus (3) are also present in the other scenarios, excluding the optimum.

Currently studies are being conducted investigating MUN as a means of production and pollution management. Investigators have already shown a correlation between MUN level and coagulation time. MUN level is becoming a relevant raw milk testing method for use in cost improvement and control, production management, and pollution control.

Milk Urea Nitrogen testing is going to be an integral part of the future of the dairy industry. By starting this testing as early as possible a head start on the future of the industry will be gained, giving a competitive advantage. This testing will provide results of Milk Urea Nitrogen along with fat, protein, and lactose results, with a large potential economic savings, for little added cost. With consistent MUN testing at the bulk tank level and the individual cow level a clear picture of dietary needs will be established. A qualified individual, such as a veterinarian or nutritionist should interpret the data.

Whenever you are ready to use MUN testing, I & A Lab will be ready for you.