Quinn M J, May M L, Hales K E, DiLorenzo N, Leibovich J, Smith D R, Galyean M L
Department of Animal and Food Sciences, Texas Tech University, Lubbock 79409-2141, USA.
J Anim Sci. 2009 May;87(5):1705-13. doi: 10.2527/jas.2008-1549. Epub 2009 Feb 11.
Effects of 3 ionophores and 2 antibiotics on in vitro H(2)S production, IVDMD, total gas production, and VFA profile with or without added S were examined. In Exp. 1, ruminal fluid from 2 ruminally cannulated steers fed a steam-flaked corn-based diet (75% concentrate) without ionophore and antibiotics for 28 d before collection was used to inoculate in vitro cultures. Treatments were control (no ionophore or antibiotic), 3 ionophores (lasalocid sodium and monensin sodium at 5 mg/L or laidlomycin propionate at 1.65 mg/L), and 2 antibiotics (chlortetracycline hydrochloride at 5 mg/L and tylosin tartarate at 1.25 mg/L). Cultures also had 0 or 1.75 mg of S/L (from sodium sulfate). No S x ionophore-antibiotic treatment interactions were noted (P > 0.53) for IVDMD, total gas production, and H(2)S production. Hydrogen sulfide (mumol/g of fermentable DM) was increased (P < 0.001), and total gas production tended (P = 0.09) to be increased with additional S; however, IVDMD was not affected by added S (P = 0.90). Production of H(2)S was not affected by ionophores or antibiotics (P > 0.18). On average, IVDMD (P = 0.05) was greater for ionophores than for antibiotics, whereas total gas production was less for ionophores than for control (P < 0.001) and antibiotics (P < 0.001). Molar proportions of acetate (P < 0.01) and acetate:propionate (P < 0.01) were decreased and propionate was increased (P < 0.001) in ionophore treatments when no S was added, but when S was added there were no differences (P > 0.20) in acetate, propionate, or acetate:propionate between ionophores and control (S x treatment interaction, P = 0.03). In Exp. 2, the effects of ionophore-antibiotic combinations with added S were examined using the same procedures as in Exp. 1. Treatments were control, monensin plus tylosin (MT), and lasalocid plus chlortetracycline (LCTC), with concentrations of the ionophores and antibiotics as in Exp. 1. No differences were observed among treatments for H(2)S production (P > 0.55). Treatments MT and LCTC tended (P = 0.06) to increase IVDMD and decreased (P = 0.02) gas production vs. control. Proportion of acetate (P = 0.01) and acetate:propionate (P < 0.01) were decreased and propionate increased (P = 0.01) for both MT and LCTC compared with control. These data suggest that when S is approximately 0.42% of substrate DM, the 3 ionophores and 2 antibiotics we evaluated did not affect production of H(2)S gas in an in vitro rumen culture system.
研究了3种离子载体和2种抗生素对体外硫化氢生成、体外干物质消化率（IVDMD）、总产气量以及添加或不添加硫时挥发性脂肪酸（VFA）谱的影响。在实验1中，使用来自2头安装了瘤胃瘘管的阉牛的瘤胃液接种体外培养物，这2头阉牛在收集瘤胃液前28天饲喂以蒸汽压片玉米为基础的日粮（75%精料），且未添加离子载体和抗生素。处理组包括对照组（不添加离子载体或抗生素）、3种离子载体（5 mg/L的拉沙洛西钠和莫能菌素钠或1.65 mg/L的丙酸拉沙里菌素）以及2种抗生素（5 mg/L的盐酸金霉素和1.25 mg/L的酒石酸泰乐菌素）。培养物中还添加了0或1.75 mg/L的硫（来自硫酸钠）。对于IVDMD、总产气量和硫化氢生成，未观察到硫×离子载体 - 抗生素处理的交互作用（P>0.53）。添加硫后，硫化氢（μmol/g可发酵干物质）增加（P<0.001），总产气量有增加趋势（P = 0.09）；然而，添加硫对IVDMD没有影响（P = 0.90）。离子载体或抗生素对硫化氢生成没有影响（P>0.18）。平均而言，离子载体组的IVDMD高于抗生素组（P = 0.05），而离子载体组的总产气量低于对照组（P<0.001）和抗生素组（P<0.001）。不添加硫时，离子载体处理组中乙酸的摩尔比例（P<0.01）和乙酸:丙酸比例（P<0.01）降低，丙酸增加（P<0.001），但添加硫后，离子载体组与对照组在乙酸、丙酸或乙酸:丙酸方面没有差异（硫×处理交互作用，P = 0.03）。在实验2中，采用与实验1相同的程序研究了添加硫时离子载体 - 抗生素组合的影响。处理组包括对照组、莫能菌素加泰乐菌素（MT）以及拉沙洛西加金霉素（LCTC），离子载体和抗生素的浓度与实验1相同。各处理组之间硫化氢生成没有差异（P>0.55）。与对照组相比，MT和LCTC处理组有增加IVDMD的趋势（P = 0.06），且产气量降低（P = 0.02）。与对照组相比，MT和LCTC处理组的乙酸比例（P = 0.01）和乙酸:丙酸比例（P<0.01）降低，丙酸增加（P = 0.01）。这些数据表明，当硫约占底物干物质的0.42%时，我们评估的3种离子载体和2种抗生素在体外瘤胃培养系统中不影响硫化氢气体的生成。
