29º Congresso Brasileiro de Zootecnia

Urea nitrogen in milk is an indicator of protein nutrition for dairy cattle and its supervision is indicated as accessible, quick and simple. Excess protein in the diet, besides increasing the costs of the diet, causes problems in the female reproductive system, reducing the fertility of the cows. In contrast, lack of protein in the diet may limit milk production. Therefore, the objective of this work was to evaluate the composition of urea nitrogen in the milk with the substitution of extruded urea at increasing levels in the concentrate (0, 125, 250, 375 and 500 g/kg) of 20 Jersey cows in the medium period of lactation. According to the data obtained it is possible to consider the substitution of soybean meal with extruded urea of up to 500 mg/kg without causing metabolic damage to the animal.