Department of Animal Science, Universidade Federal de Viçosa, Viçosa, MG, Brazil.
Muscle Biology, and Nutrigenomics Laboratory, Universidade Federal de Viçosa, Viçosa, MG, Brazil.
PLoS One. 2023 Oct 19;18(10):e0293216. doi: 10.1371/journal.pone.0293216. eCollection 2023.
We aimed to evaluate the effects of post-ruminal supply of urea (PRU) on nutritional status, and liver metabolism of pregnant beef cows during late gestation. Twenty-four Brahman dams, pregnant from a single sire, and weighing 545 kg ± 23 kg were confined into individual pens at 174 ± 23 d of gestation, and randomly assigned into one of two dietary treatments up to 270 d of gestation: Control (CON, n = 12), consisting of a basal diet supplemented with conventional urea, where the cows were fed with diets containing 13.5 g conventional urea per kg dry matter; and PRU (PRU, n = 12), consisting of a basal diet supplemented with a urea coated to extensively prevent ruminal degradation while being intestinally digestible, where the cows were fed with diets containing 14,8 g urea protected from ruminal degradation per kg dry matter. Post-ruminal supply of urea reduced the urine levels of 3-methylhistidine (P = 0.02). There were no differences between treatments for dry matter intake (DMI; P = 0.76), total digestible nutrient (TDN) intake (P = 0.30), and in the body composition variables, such as, subcutaneous fat thickness (SFT; P = 0.72), and rib eye area (REA; P = 0.85). In addition, there were no differences between treatments for serum levels of glucose (P = 0.87), and serum levels of glucogenic (P = 0.28), ketogenic (P = 0.72), glucogenic, and ketogenic (P = 0.45) amino acids, neither for urea in urine (P = 0.51) as well as urea serum (P = 0.30). One the other hand, enriched pathways were differentiated related to carbohydrate digestion, and absorption, glycolysis, pyruvate metabolism, oxidative phosphorylation, pentose phosphate pathway, and biosynthesis of amino acids of the exclusively expressed proteins in PRU cows. Shifting urea supply from the rumen to post-ruminal compartments decreases muscle catabolism in cows during late gestation. Our findings indicate that post-ruminal urea supplementation for beef cows at late gestation may improve the energy metabolism to support maternal demands. In addition, the post-ruminal urea release seems to be able to trigger pathways to counterbalance the oxidative stress associated to the increase liver metabolic rate.
我们旨在评估瘤胃后供应尿素（PRU）对妊娠后期肉牛的营养状况和肝脏代谢的影响。24 头婆罗门母牛，由单一公牛配种，体重 545 公斤±23 公斤，妊娠 174±23 天被限制在单个围栏中，并随机分配到妊娠 270 天的两种饮食处理之一：对照（CON，n=12），包括补充常规尿素的基础日粮，其中奶牛以含有 13.5 克常规尿素的日粮喂养；PRU（PRU，n=12），由补充了一种尿素的基础日粮组成，这种尿素被涂覆以广泛防止瘤胃降解，同时在肠道中可消化，其中奶牛以含有 14.8 克尿素的日粮喂养，这种尿素可以防止瘤胃降解。瘤胃后供应尿素降低了 3-甲基组氨酸的尿水平（P=0.02）。两种处理之间的干物质采食量（DMI；P=0.76）、总可消化养分（TDN）采食量（P=0.30）以及体成分变量，如皮下脂肪厚度（SFT；P=0.72）和肋眼面积（REA；P=0.85）没有差异。此外，两种处理之间的血清葡萄糖水平（P=0.87）和血清生糖（P=0.28）、生酮（P=0.72）、生糖和生酮（P=0.45）氨基酸以及尿中尿素（P=0.51）和血清中尿素（P=0.30）均无差异。另一方面，在 PRU 奶牛中，与碳水化合物消化和吸收、糖酵解、丙酮酸代谢、氧化磷酸化、磷酸戊糖途径以及氨基酸生物合成有关的途径被区分出来。将尿素从瘤胃转移到瘤胃后室会减少妊娠后期奶牛的肌肉分解代谢。我们的研究结果表明，妊娠后期给肉牛补充瘤胃后尿素可能会改善能量代谢，以满足母体的需求。此外，瘤胃后尿素的释放似乎能够触发途径来平衡与肝脏代谢率增加相关的氧化应激。
