To determine the effect of Dietary Crude Protein (DCP) on milk production and protein metabolism, a two group pre/post experimental design was used

To determine the effect of Dietary Crude Protein (DCP) on milk production and protein metabolism, a two group pre/post experimental design was used. The CP level in the ration fed to the two groups (high, low) of lactating dairy cows was increased by 2% for a period of 21 days. Data from each group was collected regarding manure scores, milk fat, milk protein, Milk Urea Nitrogen (MUN) and overall milk production. It was hypothesized that increasing the dietary crude protein would result in increased milk components, higher MUN and lower manure scores. Analysis of data indicated mean milk production decreased by 8 #/day in the low producing group, but the decrease was not significant (P=0.06). In the high producing group significant differences were observed in a Milk Urea Nitrogen increase (P=0.001), milk fat decrease (P=0.025), and a decrease in manure scores (P=0.042) when DCP was increased. Introduction Lower milk prices and higher operating expenses have dairy producers across the nation searching for ways to increase profits. Protein supplements are said to be the most expensive portion of the dairy cattle ration (Espe and Smith, 1952). Some producers are feeding higher levels of dietary crude protein in order to obtain higher levels of milk solids (protein and fat), since premiums are paid for milk with higher milk solids content. Research suggests that 17% to 19% dietary crude protein should be provided to the lactating cow to meet required nutritional needs. As a cow progresses through lactation a 16% crude protein diet is recommended. However, excess dietary crude protein (EDCP) may result in negative health impacts. Excess Dietary Crude Protein is converted to ammonia in the rumen. Ammonia that is not utilized in the rumen is transferred to the small intestines and absorbed into the blood stream. The blood stream conveys ammonia to the liver where it is converted to urea, a non-toxic form of nitrogen. In this way, the liver is protecting the animal, since ammonia is toxic to the animal. Excess urea is then excreted in urine or reused by the