This study aimed to evaluate the intake and digestibility of nutrients, nitrogen use, performance and blood metabolic profile of lambs in finishing fed with urea supplemented alternative feeds. Forty Santa Ines lambs, uncastrated males, with an average body weight of 22.8 ± 2.1 kg, were used in a completely randomized design. Four diets were tested, with Tifton-85 hay as forage (580 g/kg of dry matter) and corn + soybean meal (CSM), corn + urea (CU), cassava scraping + urea (CSU), and spineless cactus + urea (SCU). The lambs fed with SCU diet had lower (P < 0.05) intake of dry matter (DM), organic matter (OM), lignin, total carbohydrates (TCH), non-fibrous carbohydrates, and energy; lower (P < 0.05) apparent digestibility of DM, OM, and TCH, as well as lower (P < 0.05) final body weight and mean daily gain (g day⁻¹). However, they presented a higher (P < 0.05) serum concentration of magnesium, higher urinary volume, and higher microbial efficiency (relationship between microbial N flux (g day⁻¹) and digestible organic matter fermented in the rumen in kg day⁻¹; DOMR). Plasma concentrations of glucose were higher (P < 0.05) in lambs fed CSM concerning to CSU and SCU lambs. Diets containing corn resulted in higher (P < 0.05) serum concentrations of cholesterol, triglycerides, and phosphorus. Serum albumin concentration was affected (P < 0.05) by soybean meal replacement. The carbohydrate sources corn, cassava scraping, or spineless cactus, in association with urea, in diets for finishing lambs did not allow the same performance compared to that of animals feed CSM. The SCU diet use can reduce freshwater intake and allow reasonable body weight gain. So, this diet may be more sustainable option in Arid and Semiarid livestock production. Diets containing spineless cactus allow a better efficiency (g N kg⁻¹ DOMR) of the use of non-protein nitrogen in the rumen.

这项研究旨在评估补充尿素替代饲料的肥育羔羊的营养摄入和消化率，氮的使用，生产性能和血液代谢状况。在完全随机设计中使用了四十只平均体重为22.8±2.1千克的未cast割雄性圣伊内斯羔羊。测试了四种饮食，以Tifton-85干草作为草料（580克/千克干物质）和玉米+豆粕（CSM），玉米+尿素（CU），木薯刮scrap +尿素（CSU）和无脊椎仙人掌+尿素（SCU）。用SCU饲喂的羔羊的 干物质（DM），有机物质（OM），木质素，总碳水化合物（TCH），非纤维性碳水化合物和能量的摄入量较低（P <0.05）；较低的（P  <0.05）DM，OM和TCH的表观消化率，以及较低的（P <0.05）最终体重和平均日增重（g day ^-1）。然而，他们表现出较高的（P  <0.05）血清镁浓度，较高的尿量和较高的微生物效率（微生物氮通量（g day ^-1）与瘤胃中发酵的可消化有机物的千克天^-1关系； DOMR）。 与CSU和SCU羔羊相比，饲喂CSM的羔羊的血浆葡萄糖浓度更高（P <0.05）。含玉米的饮食导致较高的（P  <0.05）血清胆固醇，甘油三酸酯和磷浓度。血清白蛋白浓度受到影响（P <0.05）通过豆粕替代。与精制羔羊的饲料相比，精制羔羊日粮中的碳水化合物来源包括玉米，木薯刮片或无脊椎仙人掌以及尿素。使用SCU饮食可以减少淡水摄入量，并可以使体重合理增加。因此，在干旱和半干旱牲畜生产中，这种饮食可能是更可持续的选择。含无脊柱仙人掌的日粮在瘤胃中使用非蛋白质氮的效率更高（g N kg ^-1 DOMR）。