Spiehs M J, Varel V H
USDA-ARS, US Meat Animal Research Center, Clay Center, NE 68933, USA.
J Anim Sci. 2009 Sep;87(9):2977-84. doi: 10.2527/jas.2008-1584. Epub 2009 Jun 5.
Twenty-four cross bred steers (BW 452.5 +/- 15.5 kg) were used to evaluate nutrient excretion and odorous compounds in urine and feces of feedlot steers fed diets containing corn wet distillers grains with solubles (WDGS). Cattle were weighed, blocked by BW, and assigned randomly to 1 of 4 dry-rolled corn-based diets containing 0, 20, 40, or 60% WDGS (DM basis). A 96-h total fecal and urine collection was conducted. Orts, feces, and urine were collected daily. Samples were analyzed for moisture, total N, total P, water soluble P, and total S. Fresh fecal samples were collected at the end of the balance trial for analysis of VFA, phenol, p-cresol, indole, skatole, ammonia-N, and lactate concentration. Total P, N, and S intake increased linearly as the amount of WDGS increased in the diet (P <or= 0.02). Total P excretion increased linearly (P < 0.01), attributed to a significant linear increase in urinary P excretion as the amount of WDGS increased in the diet (P = 0.02). Water-soluble P excretion in feces was similar for cattle fed all 4 diets (P >or= 0.11). Total N excretion increased linearly as dietary WDGS inclusion increased (P < 0.01) and was due to a linear increase in urinary N excretion (P < 0.01). Total S excretion also increased as WDGS concentration increased in the diet (P < 0.01). Dietary treatment did not affect the concentration of odorous compounds in urine (P >or= 0.07). Total VFA concentration in feces decreased as WDGS increased in the diet (P < 0.01), but branched-chained VFA concentrations (isobutyrate and isovalerate) and phenol in feces increased when WDGS replaced corn in the diet (P <or= 0.04). There was no difference in the concentration of the other aromatic compounds (p-cresol, indole, skatole) in feces from cattle fed the 4 dietary treatments (P >or= 0.09). This study indicates that feedlot cattle fed increasing amounts of WDGS had increased P, N, and S intake and excretion, which may contribute to the production of odorous compounds (primarily long- and branched-chain VFA, and phenol) as well as increased ammonia and H(2)S emissions from the feedlot. Increased P concentration in livestock waste will increase the amount of land necessary to utilize manure P. Because of increased urinary P excretion, producers should consider environmental implications of liquid runoff from the feedlot surface as well as solid manure when WDGS are fed to feedlot cattle.
选用24头杂交阉牛（体重452.5±15.5千克）来评估饲养场阉牛采食含玉米酒精糟及可溶物（WDGS）日粮时尿液和粪便中的养分排泄及气味化合物。对牛只进行称重，按体重进行分组，并随机分配到4种以干碾压玉米为基础的日粮中，日粮中WDGS含量分别为0%、20%、40%或60%（干物质基础）。进行了96小时的粪便和尿液总收集。每天收集剩料、粪便和尿液。分析样品中的水分、总氮、总磷、水溶性磷和总硫。在平衡试验结束时收集新鲜粪便样品，分析挥发性脂肪酸、苯酚、对甲酚、吲哚、粪臭素、氨氮和乳酸浓度。日粮中WDGS含量增加时，总磷、氮和硫摄入量呈线性增加（P≤0.02）。总磷排泄量呈线性增加（P＜0.01），这归因于日粮中WDGS含量增加时尿磷排泄量显著线性增加（P = 0.02）。采食所有4种日粮的牛粪便中水溶性磷排泄量相似（P≥0.11）。随着日粮中WDGS添加量增加，总氮排泄量呈线性增加（P＜0.01），这是由于尿氮排泄量线性增加（P＜0.01）。日粮中WDGS浓度增加时，总硫排泄量也增加（P＜0.01）。日粮处理对尿液中气味化合物浓度没有影响（P≥0.07）。随着日粮中WDGS含量增加，粪便中总挥发性脂肪酸浓度降低（P＜0.01），但当WDGS替代日粮中的玉米时，粪便中支链挥发性脂肪酸（异丁酸和异戊酸）浓度和苯酚增加（P≤0.04）。采食4种日粮处理的牛粪便中其他芳香族化合物（对甲酚、吲哚、粪臭素）浓度没有差异（P≥0.09）。本研究表明，饲养场阉牛采食WDGS量增加时，磷、氮和硫的摄入量及排泄量增加，这可能导致气味化合物（主要是长链和支链挥发性脂肪酸以及苯酚）的产生，以及饲养场氨和硫化氢排放量增加。畜禽粪便中磷浓度增加会增加利用粪便磷所需的土地量。由于尿磷排泄量增加，当给饲养场阉牛饲喂WDGS时，生产者应考虑饲养场表面液体径流以及固体粪便对环境的影响。
