Vargas Juan de J, Tarnonsky Federico, Podversich Federico, Maderal Araceli, Fernández-Marenchino Ignacio, Cuervo Wilmer, Schulmeister Tessa M, Ruiz-Ascacibar Isabel, Ipharraguerre Ignacio R, DiLorenzo Nicolás
Department of Animal Sciences, North Florida Research and Education Center, University of Florida, Marianna, FL 32446, USA.
Yara Industrial Solutions, Madrid, Spain.
Transl Anim Sci. 2024 Apr 23;8:txae065. doi: 10.1093/tas/txae065. eCollection 2024.
Non-protein nitrogen () supplements improve animal performance in backgrounding diets. However, there is scarce information regarding the effect of different NPN sources and combinations on ruminal fermentation profile. The current study aimed to evaluate the effect of different NPN sources and their combinations on in vitro fermentation, microbial N synthesis, and methane (CH) production in a backgrounding diet. Incubations were conducted on three separate days for 24 h using corn silage and cotton gin byproduct (70% and 30% of DM, respectively) as substrate. Treatments were control (without NPN), urea, and five different proportions of urea-biuret and nitrate (100:0, 75:25, 50:50, 25:75, and 0:100). Each treatment, except control, was formulated to be isonitrogenous and equivalent to 1% urea inclusion. Ruminal fluid was collected from two ruminally cannulated Angus crossbred steers fed ad libitum corn silage and cotton gin byproduct plus 100 g of a urea-biuret-nitrate mixture. The concentration of volatile fatty acids () and ammonia nitrogen () were determined at 12 and 24 h of incubation. Final pH, in vitro dry and organic matter digestibility, total gas production, and concentration of CH were determined at 24 h. The supplementation of NPN increased ( < 0.05) the concentration of NH-N at 12 and 24 h. Although NPN supplementation increased ( < 0.05) the concentration of total VFA and acetate at 12 h, treatments did not differ ( > 0.05) at 24 h. Supplementation of NPN increased ( < 0.05) the proportion of acetate at 12 and 24 h but tended to reduce ( = 0.054) the proportion of propionate only at 12 h. Digestibility and pH were not different ( > 0.05) among treatments. Increasing nitrates in the NPN supplement increased ( < 0.05) the proportion of acetate and reduced ( < 0.05) the proportion of butyrate at 12 and 24 h. The supplementation of NPN increased ( < 0.05) microbial N synthesis. Furthermore, increasing nitrate proportion in the NPN supplement increased ( < 0.05) the microbial N synthesis and efficiency of N use. Supplementation of NPN did not modify ( > 0.05) total gas or CH production. However, increasing nitrate proportion in the NPN supplement linearly reduced ( < 0.05) CH production. Supplementation of NPN increased NH-N concentration and microbial N while increasing the inclusion of nitrate decreased the production of CH and increased the microbial N synthesis in a corn silage-based substrate under in vitro conditions.
非蛋白氮（NPN）补充剂可提高育成期日粮中动物的生产性能。然而，关于不同NPN来源及其组合对瘤胃发酵特征影响的信息却很少。本研究旨在评估不同NPN来源及其组合对育成期日粮体外发酵、微生物氮合成和甲烷（CH₄）产生的影响。使用玉米青贮和轧棉副产品（分别占干物质的70%和30%）作为底物，在三个不同的日子进行24小时的培养。处理组包括对照组（不添加NPN）、尿素，以及五种不同比例的尿素-缩二脲和硝酸盐（100:0、75:25、50:50、25:75和0:100）。除对照组外，每个处理组的配方均为等氮，且相当于添加1%的尿素。从两只自由采食玉米青贮、轧棉副产品加100克尿素-缩二脲-硝酸盐混合物的瘤胃插管安格斯杂交阉牛采集瘤胃液。在培养12小时和24小时时测定挥发性脂肪酸（VFA）和氨氮（NH₃-N）的浓度。在24小时时测定最终pH值、体外干物质和有机物消化率、总产气量以及CH₄浓度。添加NPN可提高（P<0.05）12小时和24小时时NH₃-N的浓度。虽然添加NPN在12小时时提高了（P<0.05）总VFA和乙酸盐的浓度，但在24小时时各处理组之间没有差异（P>0.05）。添加NPN在12小时和24小时时提高了（P<0.05）乙酸盐的比例，但仅在12小时时倾向于降低（P=0.054）丙酸盐的比例。各处理组之间的消化率和pH值没有差异（P>0.05）。在NPN补充剂中增加硝酸盐含量，在12小时和24小时时提高了（P<0.05）乙酸盐的比例并降低了（P<0.05）丁酸盐的比例。添加NPN提高了（P<0.05）微生物氮合成。此外，在NPN补充剂中增加硝酸盐比例提高了（P<0.05）微生物氮合成和氮利用效率。添加NPN对总产气量或CH₄产量没有影响（P>0.05）。然而，在NPN补充剂中增加硝酸盐比例可线性降低（P<0.05）CH₄产量。在体外条件下，以玉米青贮为底物时，添加NPN可提高NH₃-N浓度和微生物氮，而增加硝酸盐的添加量可降低CH₄产量并提高微生物氮合成。
