目的是评估瘤胃后吸收尿素在补充季节性牧场饲养的生长Nellore牛中的作用。对于这项研究,进行了两个实验。在实验1中,使用八只瘤胃插管的Nellore公牛评估了瘤胃和血液参数,其初始体重(BW)为763±44kg,分布在4×4的双拉丁正方形中。在实验2中,使用120辆初始BW为380±35kg的Nellore舵机进行性能评估,分布在随机区组设计(阻断因子或初始BW)中。评估的处理方法为1:(TP-U)(对照)=补充24%含尿素的粗蛋白(CP)作为非蛋白氮(NPN;3%)和豆粕的来源,2:(TP-PRU)=24%CP补充剂含有瘤胃后尿素(PRU;3.6%)和豆粕;3:(NPN-U-PRU)=24%CP补充剂含有尿素+瘤胃后尿素(U=3%,PRU=3.9%),不含豆粕;4:(NPN-PRU)=补充24%CP,含有瘤胃后尿素(7.5%),没有豆粕。补充剂以每只动物3克/千克体重提供,daily,一天一次.所有动物都饲养在Urochloabrizanthacv上。Marandu牧场.使用SASPROCMIXED进行统计分析,并通过以下对比评估数据:C1=TP-U/TP-PRUvs.NPN-U-PRU/NPN-PRU(NPN替代豆粕);C2=TP-Uvs.TP-PRU(常规尿素与免疫后尿素);C3=NPN-U-PRUvs.NPN-PRU(瘤胃后尿素-PRU水平低和高)。干物质的消化率,有机物,当豆粕被非蛋白氮替代时,NDF较低,补品中使用的瘤胃后尿素水平也不同。当大豆粉被NPN替代时,瘤胃pH是不同的(p=0.003)。短链脂肪酸的总浓度,异丁酸的浓度(p=0.003),戊酸(p=0.001),和异戊酸(p=0.001)是不同的,当豆粕被NPN替代时,血液尿素有所不同(p=0.006)。在补充TP-U的动物瘤胃中,辛普森的多样性指数高于补充TP-PRU的动物(p=0.05)。共27门,234个家庭,并鉴定了488属。仅在补充有TP-PRU的牛的瘤胃中就检测到了Nitrosirota和Gemmaatimonadota。性能(最终BW,动物的体重增加和每面积的增加)是不同的,在补充大豆粉的动物中更高(p=0.04),与NPN相比。从补充剂中去除豆粕并用常规尿素加瘤胃后尿素或仅瘤胃后尿素代替豆粕会损害动物的性能。瘤胃后尿素包合水平越低,干物质的表观消化率越低,有机物,NDF,与补充较高水平的动物相比。
The objective was to evaluate the effects of urea with post-ruminal absorption in the supplementation of growing Nellore cattle reared on pasture during a seasonal period. For the study, two experiments were conducted. In experiment 1, rumen and blood parameters were evaluated using eight rumen-cannulated Nellore bulls with initial body weight (BW) of 763 ± 44 kg, distributed in a double Latin square 4 × 4. In experiment 2, 120 Nellore steers with initial BW of 380 ± 35 kg were used for performance evaluation, distributed in a randomized block design (blocking factor or initial BW). The evaluated treatments were 1: (TP-U) (control) = supplement with 24% crude protein (CP) containing urea as a source of non-protein nitrogen (NPN; 3%) and soybean meal, 2: (TP-PRU) = 24% CP supplement containing post-ruminal urea (PRU; 3.6%) and soybean meal; 3: (NPN-U-PRU) = 24% CP supplement containing urea + post-ruminal urea (U = 3% and PRU = 3.9%), without soybean meal; 4: (NPN-PRU) = supplement with 24% CP containing post-ruminal urea (7.5%), without soybean meal. The supplement was offered at 3 g/kg BW per animal, daily, once a day. All animals were kept on Urochloa brizantha cv. Marandu pasture. Statistical analyses were performed using the SAS PROC MIXED, and the data were evaluated by the following contrasts: C1 = TP-U/TP-PRU vs. NPN-U-PRU/NPN-PRU (Soybean meal replacement by NPN); C2 = TP-U vs. TP-PRU (conventional urea vs. post-immune urea); C3 = NPN-U-PRU vs. NPN-PRU (low and high post-ruminal urea-PRU level). The digestibility of dry matter, organic matter, and NDF was lower when soybean meal was replaced by non-protein nitrogen, also being different between the levels of post-ruminal urea used in the supplement. Ruminal pH was different when soybean meal was replaced by NPN (p = 0.003). Total concentration of short-chain fatty acids, concentrations of isobutyrate (p = 0.003), valerate (p = 0.001), and isovalerate (p = 0.001) were different, and blood urea was different when soybean meal was replaced by NPN (p = 0.006). Simpson\'s diversity index was higher in the rumen of animals supplemented with TP-U than in those supplemented with TP-PRU (p = 0.05). A total of 27 phyla, 234 families, and 488 genera were identified. Nitrospirota and Gemmatimonadota phyla were detected just in the rumen of steers supplemented with TP-PRU. The performance (final BW, weight gain and gain per area) of the animals was different, being higher (p = 0.04) in animals supplemented with soybean meal, compared to NPN. The removal of soybean meal from the supplement and its replacement with either conventional urea plus post-ruminal urea or only post-ruminal urea compromises the performance of the animals. The lower the post-ruminal urea inclusion level, the lower the apparent digestibility of dry matter, organic matter, and NDF, when compared to animals supplemented with higher levels.