DIFFERENT METABOLIZABLE PROTEIN LEVELS IN SUGAR CANE DIETS TO LACTATING DAIRY COWS

Abstract

The objective of this trial was to evaluate the effect of different metabolizable protein (MP) levels on lactating dairy cows fed sugarcane diets. Eighteen lactating cows, divided in two groups of milk production (10 or 18 kg/d), were used, being data analyzed separately. Three treatments with varying levels of MP and rumen degradable protein (RDP), by different urea and soybean meal inclusions, were evaluated: 1) 1% of the mixture urea and ammonium sulfate on sugarcane in natura (control); 2) adequate levels of RDP and MP; and 3) adequate levels of RDP and MP in excess. A 3 x 3 Latin Square design was utilized with three replicates for each production group. There were not statistical difference between treatments (P>0.05) for dry matter intake, milk production, fat and protein milk levels, milk urea nitrogen (MUN) and plasma urea nitrogen (PUN), independently of the milk production level. Recommendation of sugarcane diet in nature correction by adding 1% of urea-ammonium sulfate was adequate for cows producing 10 or 18 kg milk/d. There were no advantages of increasing MP levels for those cows.

KEY WORDS: Milk production, protein sources, rumen degradable protein, urea.