Milk production in goats fed with increasing levels of urea

Abstract

This experiment was carried out to study the use of urea for goats to fit the nitrogen level of the diet to animal requirements for milk production and the effect on the milk production and milk physical and chemical characteristics. Twenty anglonubian goats individualy stall-fed during experimental period which lasted eight weeks were utilized. Four isonitrogenous and isoenergetic complet rations (sugar cane + concentrate) with increasing levels of urea replacing the protein nitrogen (PN) sources were fed to the animals. The substitution of the PN for NPN resulted in significant (P < 0.01) decrease in milk production. The total dry-matter intake based on the unity of metabolic weight was not altered by the levels of urea but a increasing tendency of roughage dry matter intake and a significant (P < 0.01) decrease of concentrate dry-matter intake were observed. The level of total dry-matter intake (75 to 79 g DM/kg body weight^{0, 75}) was considered low in all the treatments. The metabolic weight gain decreased significantly (P < 0.01) with the increases of urea level. As to milk characteristic, a linear and significant (P < 0.01) increase in the fat content related to the increase of the urea level was observed. Total solids and acidity did not show variations. The milk density increased significantly (P < 0.01) with the increase of the urea level. It was concluded that the utilization of urea in milk goats diet decreased significantly the milk performance in all of the levels utilized but did not affect significantly the body weight variation in the lowest level of replacing of PN for NPN.