The objective of this study was to evaluate the influence of sources of nitrogen on the intake and digestibility of nutrients and production and chemical composition of goat milk. Soybean meal (SBM), soybean meal + urea (SBM+U), cottonseed meal + urea (CM+U), cottonseed cake + urea (CC+U) and whole cottonseed + urea (WC+U) were used, representing the different sources of nitrogen in the diet. Ten crossbred goats were used (Alpine + Saanen), weighing on average 47.90±1.94 kg of body weight at 30 days of lactation, distributed in a double Latin square (5 × 5) with five treatments and five periods. There was influence of the different sources of nitrogen on the intakes of dry matter (DM), organic matter (OM), crude protein (CP), ether extract (EE), neutral detergent fiber (NDF) and non-fiber carbohydrates (NFC) of animals, with the lowest values found in most of the variables studied for animals that received CC+U and WC+U. There was an effect of diets on the DM, OM, CP and NFC digestibility coefficients. The diet with sole addition of SBM presented the best result regarding the amount of milk produced, followed by animals fed SBM+U and CM+U and values of 2.05 kg/day; 1.92 kg/day; 1.73 kg/day; 1.47 kg/day; and 1.24 kg/day of milk for diets with SBM, SBM+U, CM+U, CC+U and WC+U, respectively. Milk composition was also changed, and the diet with WC+U showed higher percentages: 0.1208 and 0.0041 percent, for total solids and fat, respectively. There was no difference in nitrogen balance between treatments. The use of SBM+U and CM+U did not compromise the milk performance and characteristics, but the use of CC+U and WC+U is indicated in periods of low milk production.

Castrated male goats (n = 40) of the Moxotó (n = 20) and Canindé (n = 20) breeds with an average weight of 15.3 kg were studied to determine intake, nutrient digestibility and weight gain for two diets with different energy levels. The experiment utilized a 2 × 2 factorial arrangement (two breeds and two diets), in which goats were randomly allocated. A diet of low energy density and a forage:concentrate ratio of 70:30 was utilized along with a diet of high energy density and a forage:concentrate ratio of 35:64. To determine the nutrient intake and digestibility, at the end of the experiment, goats were kept in metabolism cages for a period of 15 days. Weighing of the goats was conducted weekly over a period of 90 days. The goats that were fed a diet of high energy density displayed significantly increased consumption of metabolic fractions, with the exception of dry matter and neutral detergent fiber, when compared with those fed a diet of low energy density. The lack of difference in dry matter and neutral detergent fiber intake indicated that goats have a high digestive capacity for the diet containing a greater quantity of Maniçoba hay. Weight gain was significantly greater for those on the diet of greater energy density. Among the breeds, Canindé goats recorded the highest average consumption and weight gain. Coefficients of digestibility were significantly greater for the more energy dense diet, with no difference between breeds. Regardless of diet, the Canindé breed shows greater weight gain than the Moxotó breed.