Reis Irene Alexandre, Souza Mailza Gonçalves de, Granja-Salcedo Yury Tatiana, Carvalho Isabela Pena Carvalho de, Porcionato Marco Aurélio De Felicio, Prados Laura Franco, Siqueira Gustavo Rezende, De Resende Flávio Dutra
Department of Animal Sciences, São Paulo State University "Júlio de Mesquita Filho" (UNESP), Jaboticabal 14884-900, SP, Brazil.
Corporación Colombiana de Investigación Agropecuaria (AGROSAVIA), Centro de Investigación El Nus, San Roque, Antioquia 053030, Colombia.
Animals (Basel). 2023 Jan 6;13(2):207. doi: 10.3390/ani13020207.
The objective of this study was to evaluate the effect of the use of post-ruminal urea on performance, nitrogen metabolism and the ruminal environment of Nellore cattle reared on pasture during the dry season. In experiment 1 (Exp. 1), nine ruminal-cannulated Nellore steers, 30 ± 2 months old (651 ± 45 kg body weight (BW)), were allotted to a 3 × 3 Latin triple square. In experiment 2 (Exp. 2), 84 Nellore bulls, 18 ± 3 months old (315 ± 84 kg BW), were distributed in complete randomized blocks, by initial BW. Protein supplements were supplied daily, in the amount of 2 g/kg BW, and consisted of either CONT: protein + conventional urea (50% CP), PRU: protein + post ruminal urea (50% CP) and U + PRU: protein + urea conventional + post-ruminal urea (70% CP). The paddocks were composed of Urochloa brizantha cv. Marandu grass. In Exp. 1, there was no treatment effect for DM, OM, NDF, forage intake, and CP, but there was a higher intake for PRU (p < 0.005) and a higher digestibility for U+ PRU (p = 0.001). There was no effect on ruminal pH or NH3-N concentration (p ≥ 0.232), but there was an interaction between treatment and time for them (p < 0.039). Furthermore, there was a treatment effect on the total SCFA concentration, with CONT being higher than the others. A difference in the acetate:propionate ratio was found (p < 0.027), with a greater relationship for PRU and U + PRU. A treatment effect (p = 0.049) was found for the propionate proportion, with a higher proportion in the CONT. Nitrogen intake was consequently lower for the CONT and higher urinary excretion for the U + PRU (p = 0.002). Animals supplemented with CONT showed a tendency to have more Bacteria and fewer Archaea (p = 0.086). In Exp. 2, there was a treatment effect for the disappearance rate of the supplement (p < 0.001). Intake was faster for PRU and CONT, but performance was not affected by PRU (p = 0.311). The use of post-ruminal urea alters the microbial population, but does not affect performance. Therefore, supplementation with post-ruminal urea presented similar results compared to conventional urea. Ruminal and blood parameters and animal performance were not influenced by treatments.
本研究的目的是评估在旱季放牧饲养的内洛尔牛中，瘤胃后注射尿素对其生产性能、氮代谢和瘤胃环境的影响。在实验1（实验1）中，将9头瘤胃插管的内洛尔阉牛（30±2月龄，体重651±45千克）分配到一个3×3拉丁三方格设计中。在实验2（实验2）中，84头内洛尔公牛（18±3月龄，体重315±84千克）按初始体重分配到完全随机区组中。每天按2克/千克体重的量供应蛋白质补充剂，其组成分别为：对照（CONT）：蛋白质+常规尿素（粗蛋白含量50%）、瘤胃后尿素（PRU）：蛋白质+瘤胃后尿素（粗蛋白含量50%）和尿素+瘤胃后尿素（U+PRU）：蛋白质+常规尿素+瘤胃后尿素（粗蛋白含量70%）。牧场由马兰杜臂形草（Urochloa brizantha cv. Marandu）组成。在实验1中，干物质、有机物、中性洗涤纤维、采食量和粗蛋白方面没有处理效应，但PRU的采食量较高（p<0.005），U+PRU的消化率较高（p = 0.001）。对瘤胃pH值或氨氮浓度没有影响（p≥0.232），但处理和时间之间存在交互作用（p<0.039）。此外，总挥发性脂肪酸浓度存在处理效应，CONT组高于其他组。发现乙酸:丙酸比例存在差异（p<0.027），PRU组和U+PRU组的比例关系更大。丙酸比例存在处理效应（p = 0.049），CONT组的比例更高。因此，CONT组的氮摄入量较低，U+PRU组的尿排泄量较高（p = 0.002）。补充CONT的动物倾向于有更多的细菌和更少的古菌（p = 0.086）。在实验2中，补充剂的消失率存在处理效应（p<0.001）。PRU组和CONT组的采食速度更快，但PRU对生产性能没有影响（p = 0.311）。瘤胃后尿素的使用改变了微生物种群，但不影响生产性能。因此，与常规尿素相比，补充瘤胃后尿素呈现出相似的结果。瘤胃和血液参数以及动物生产性能不受处理的影响。
