补充膳食蛋氨酸来源对肉鸡排泄物中挥发性化合物浓度的影响。

Chavez C, Coufal C D, Carey J B, Lacey R E, Beier R C, Zahn J A

Department of Poultry Science, Texas A&M University, College Station, Texas 77845-2472, USA.

Poult Sci. 2004 Jun;83(6):901-10. doi: 10.1093/ps/83.6.901.

The impact of different Met sources on broiler fecal odor volatiles was determined by evaluating the types of sulfur compounds produced in broiler excreta. Two experiments were conducted using straight-run broiler chicks randomly distributed in battery cages, with 3 replicate pens of 16 birds each. The treatment groups were 1) dry Met hydroxy analogue (dry MetHA), 2) sodium methioninate aqueous solution (NaMet), 3) liquid Met hydroxy analogue (Liq MetHA), 4) D,L- Met, and 5) no supplemental Met (control group). The Met activities of each Met source were 52, 45.9, 88, and 98%, respectively. All diets were formulated to contain either 0.8% (experiment 1) total Met activity or 0.5% Met activity in the starter and 0.38% Met activity in the grower (experiment 2) (except the control group, 0.35% Met activity), but otherwise met NRC nutrient requirements (NRC, 1994). Diets were fed ad libitum from d 1 to 6 wk of age. There were no significant differences in BW among the treatments. All excreta were collected in litter pans lined with aluminum foil. In experiment 1, at wk 6, broiler excreta were collected for a 24-h period, and 4.5 g of broiler excreta from each treatment group was collected into 15-mL headspace vials. Samples were analyzed by gas chromatography/mass spectrometry (GC/MS). The volatile sulfur compounds that were identified and quantified in the broiler excreta were H2S, carbonyl sulfide (COS), methyl mercaptan (CH3SH), dimethyl disulfide (CH3SSCH3), and dimethyl trisulfide (CH3SSSCH3). The NaMet treatment group had significantly higher concentrations of H2S, COS, and CH3SSCH3 compared with all other treatment groups. The Liq MetHA group had significantly lower concentrations of H2S, COS, CH3SH, and CH3SSCH3 compared with the other treatment groups. The dry MetHA group significantly had the highest concentration of CH4SH. The D,L-Met treatment group had the significantly highest concentration of CH3SSSCH3 and the lowest concentration of H2S. The control group had the significantly lowest concentrations of CH3SH, CH3SSCH3, and CH3SSSCH3 compared with the other treatment groups. In experiment 2, at wk 6, an electronic nose was used to evaluate 15 air samples per treatment group. In addition, 15 air samples (containing 6 to 8 L of air in a Tedlar bag, 3 samples per treatment group) were collected for odor evaluation by a sensory panel. Electronic nose sensor data revealed that volatile compounds in broiler excreta from the control group were significantly different from the other 4 treatment groups. Evaluation of the air samples by a sensory panel determined that there was a statistically significant difference in odor threshold detection between the control group and the other treatment groups. The dilutions to threshold of control group, NaMet, dry MetHA, Liq MetHA, and D,L-Met were 350, 492, 568, 496, and 526 odor units, respectively. These findings demonstrate that dietary Met sources significantly influenced odorous volatile concentrations in broiler excreta.

通过评估肉鸡排泄物中产生的硫化合物类型，确定了不同蛋氨酸来源对肉鸡粪便气味挥发物的影响。使用直投式肉鸡雏鸡进行了两项实验，将其随机分布在层叠式笼中，每个处理组有3个重复栏，每个栏16只鸡。处理组分别为：1）干蛋氨酸羟基类似物（干蛋氨酸羟基类似物），2）蛋氨酸钠水溶液（蛋氨酸钠），3）液体蛋氨酸羟基类似物（液体蛋氨酸羟基类似物），4）D，L-蛋氨酸，5）不添加蛋氨酸（对照组）。每种蛋氨酸来源的蛋氨酸活性分别为52%、45.9%、88%和98%。所有日粮的配方均使起始料中总蛋氨酸活性为0.8%（实验1）或0.5%蛋氨酸活性，生长料中为0.38%蛋氨酸活性（实验2）（对照组除外，蛋氨酸活性为0.35%），但其他方面满足NRC营养需求（NRC，1994）。从第1天到6周龄自由采食日粮。各处理组之间的体重无显著差异。所有排泄物均收集在衬有铝箔的垫料盘中。在实验1中，第6周时，收集肉鸡排泄物24小时，每个处理组取4.5克肉鸡排泄物收集到15毫升顶空瓶中。样品通过气相色谱/质谱联用仪（GC/MS）进行分析。在肉鸡排泄物中鉴定并定量的挥发性硫化合物有硫化氢（H₂S）、羰基硫（COS）、甲硫醇（CH₃SH）、二甲基二硫（CH₃SSCH₃）和二甲基三硫（CH₃SSSCH₃）。与所有其他处理组相比，蛋氨酸钠处理组的硫化氢、羰基硫和二甲基二硫浓度显著更高。与其他处理组相比，液体蛋氨酸羟基类似物组的硫化氢、羰基硫、甲硫醇和二甲基二硫浓度显著更低。干蛋氨酸羟基类似物组的甲硫醇浓度显著最高。D，L-蛋氨酸处理组的二甲基三硫浓度显著最高，硫化氢浓度最低。与其他处理组相比，对照组的甲硫醇、二甲基二硫和二甲基三硫浓度显著最低。在实验2中，第6周时，使用电子鼻对每个处理组的15个空气样本进行评估。此外，收集15个空气样本（每个处理组3个样本，在泰德拉袋中含有6至8升空气）由感官小组进行气味评估。电子鼻传感器数据显示，对照组肉鸡排泄物中的挥发性化合物与其他4个处理组有显著差异。感官小组对空气样本的评估确定，对照组与其他处理组之间在气味阈值检测方面存在统计学显著差异。对照组、蛋氨酸钠、干蛋氨酸羟基类似物、液体蛋氨酸羟基类似物和D，L-蛋氨酸的气味阈值稀释倍数分别为350、492、568、496和526气味单位。这些结果表明，日粮中的蛋氨酸来源显著影响了肉鸡排泄物中气味挥发性物质的浓度。