【作者】 李斌；

【导师】 孟庆翔；

【作者基本信息】 中国农业大学 ， 动物营养与饲料科学， 2004， 硕士

【摘要】 本论文通过三个动物试验研究奶牛干奶期应用阴离子盐对瘤胃发酵、离子平衡和泌乳性能的影响。 试验一 研究在低产奶水平下干奶期奶牛饲喂阴离子盐对体内酸碱平衡、离子平衡和生产性能的影响。试验选用10头荷斯坦干奶牛，按照配对原则分组，在分娩前21天分别饲喂阴离子盐和对照组日粮。结果表明，阴离子盐日粮略微降低了产前干物质采食量，但对产后奶牛采食量的恢复具有积极作用。从采食阴离子盐日粮第3天开始，处理组奶牛尿液pH值降低，但降低程度（7.31 vs 8.09；P=0.08）还远未达到预期的要求。随阴离子盐的饲喂，动物粪便pH值与尿液pH值没有呈现一致性规律变化，表明动物粪便pH值不能替代尿液pH值作为监控动物体内酸碱环境变化的指标。与对照组相比，饲喂阴离子盐显著提高了尿钙排泄量（P＜0.031），并具有降低血磷和提高血镁的趋势，但对血钙和其他离子浓度没有显著影响（P＞0.1）。在较低产奶水平下，饲喂阴离子盐不能体现出预防产后疾病的优势。 试验二 研究在高产奶水平下饲喂阴离子盐对干奶期奶牛酸碱平衡、离子平衡和生产性能的影响。选择28头荷斯坦干奶牛作为试验动物，按照配对原则分组，产前21天饲喂阴离子盐和对照组日粮，以羊草替代苜蓿干草。结果表明，饲喂阴离子盐降低了干奶牛尿液pH值，饲喂5天后尿液pH值显著下降（6.24 vs 7.36；P＜0.001）；在高产奶水平下，饲喂阴离子盐使产后胎衣不下的发病率从43.7％下降至12.5％（P＜0.05）。饲喂阴离子盐提高了产后前1个月、2个月以及第4个月的标准乳产奶量（38.9 vs 32.4，44.8 vs 36.5，38.8 vs 33.2；P＜0.06），并有提高乳脂率的趋势，但对其他乳成分没有明显影响（P＞0.1）。饲喂阴离子盐不能有效提高产后血中总钙浓度，但趋于提高血镁、降低血磷浓度，而对血浆其他离子浓度没有影响（P＞0.1）。 试验三 研究阴离子盐对瘤胃内环境、血气指标及饲料中淀粉、纤维素消化率的影响。选用4头3岁荷斯坦阉公牛进行交叉试验。结果表明，与对照组相比，在饲喂后第5和第7天，瘤胃液pH值出现降低变化（6.71 vs 7.15，P=0.05；6.67 vs 7.03，P=0.02），但这种差异很快消失，说明瘤胃微生物对阴离子盐有某种适应作用。饲喂阴离子盐能够显著改变动物血液的酸碱平衡状况，表现为降低血液pH值（P＜0.1）、血中Pco₂（P＜0.05）浓度、血中碱储值（P=0.01）和血中HCO₃^-离子浓度（P＜0.01）。饲喂阴离子盐对血液平均pH值、氨态氮浓度、总挥发性脂肪酸浓度、总挥发酸中各种酸的摩尔比例均没有显著影响（P＞0.1）。阴离子盐对血浆尿素N和血糖浓度、对淀粉、ADF和NDF24小时瘤胃消失率也没有明显影响（P＞0.1）。更多还原

【Abstract】 Three experiments were conducted using prepartum cows having ligh or low milk yield to examine the effect of anionic salts on acid-base balance, ion-balance, umen fermentation or lactation performance.In Exp. 1, ten prepartum Holstein cows with low milk yield background were used to study the effect of feeding anionic salts on acid-base balance, ion-balance, and lactation performance. The result showed that feeding the anionic salt slightly decreased the dry matter intake (DMI) prior to parturition, but had a higher DMI postpartum. From the 3rd day after feeding urine pH values in anionic salt treatment decreased significant (7.31 vs 8.09; P = 0.08), but much higher than those expected. Fecal pH values did not exhibit a change consistent with urine pH occurring with feeding anionic salts, suggesting that fecal pH could not be used as an indicator of acid-base status of dry cows. Feeding anionic salts resulted in an increase in urine Ca concentrations (P<0.031), a tendency in decreased blood P concentrations and increased blood Mg concentrations, but had no effect on calcium and other ion concentrations in plasma (P>0.1). When cows were at low milk yield level, feeding anionic salts would not have any advantages for preventing the postpartum diseases.Exp. 2 was conducted to study the effect of anionic salts fed to dry cows with a high producing background on acid-base balance, ion-balance, and lactation performance. In this experiment, alfalfa hay in the diet was replaced by Chinese wildrye grass hay and twenty eight non-lactating Holstein cows in their last 3 wk of gestation were random assigned a control diet of a diet included anionic salts. The urine pH values were dropped to 6.24 (P<0.01) after feeding anionic salts for 5 days, and incidence of retained placenta decreased from 43.7% to 12.5% (P<0.05). In the first 1, 2 and 4 month after parturition, feeding anionic salts had a significant promotion on fat corrected milk yielding (38.9 vs 32.4; 44.8 vs 36.5; 38.8 vs 33.2; P < 0.05), and tended to yield more milk fat, but had no effect on other milk compositions (P>0.1). When the anionic salts were fed, total Ca concentrations in plasma did not effectively increased, whereas there was a tendency of increased Mg concentrations, decreased P concentrations and unchanged other ions in plasma.In Exp. 3, four 3-year old Holstein steers installed with permanent rumen cannulae were used in a crossover design to investigate the effect of aionic salts on rumen fermentation, blood parameters and ruminal digestions of starch and fibers. When anionic salts were fed, rumen pH values were dropped on day 5 (6.71 vs 7.15, P = 0.05) and day 7 (6.67 vs 7.03, P = 0.02), and this drop did not exist afterwards, indicating adaptation of rumen microorganisms to anionc salts. The anionic salt did significantly change whole blood parameters reflected by decreased pH values (P<0.1), pCO2 (P<0.05), base excess (P=0.01) and the concentration of HCO3- in plasma (P<0.01). As steers fed anionic salt diets, ruminal fermentation parameters including concentrations of ammonia nitrogen and total VFA, and individual VFA molar percentages was unaffected (P>0.1). No differences were also found in urine-N and glucose concentration in plasma, and in rumen digestion of starch, NDF and A OF between treatment and control更多还原