The objectives were to nutritionally induce or blunt ruminal acidosis in young calves and to compare indicators of rumen and systemic health. Ten bull calves (n = 5/diet) were ruminally cannulated at 3 wk of age and received milk replacer and 1 of 2 calf starter diets that were designed to cause (AC; pelleted, 42.7% starch, 15.1% neutral detergent fiber, 57.8% nonfiber carbohydrates) or blunt (BL; texturized, 35.3% starch, 25.3% neutral detergent fiber, 48.1% nonfiber carbohydrates) ruminal acidosis. Mean birth weight was 38.7 ± 1.3 kg. Body weight and calf starter intake were measured weekly. Rumen contents were sampled at -8, -4, 0, 2, 4, 8, 12, and 24 h relative to starter feeding during wk 6, 8, 10, 12, 14, and 16 of age. Blood was collected from the jugular vein during the same weeks for complete blood cell count, blood pH, and partial pressures of oxygen and carbon dioxide. Rate of starter consumption was assessed during wk 16. Marker systems were used to estimate liquid passage and volatile fatty acid absorption rates. Calves were slaughtered at 17 wk, and rumen tissue was collected and assessed for papillae length, width, and degree of tissue degradation. Mean ruminal pH ± standard error was 5.37 ± 0.24 and 5.63 ± 0.24 for AC and BL calves, respectively. Lowest pH values were observed the week after weaning. Total ruminal volatile fatty acid concentrations were 131.5 and 124.8 ± 2.4 mM in AC and BL calves, respectively, and increased with age and time after feeding. Dry matter intake was lower in AC calves at wk 4 and remained lower through wk 16. Rate of starter consumption was also lower in AC calves at wk 16. Body weight also was also lower for AC calves from wk 5 through 16. Blood hemoglobin and hematocrit were lower in AC calves, but other blood characteristics were not different. Rumen volume increased with age and tended to be greater in BL calves. Passage rate and papillae length and width were not different between diets, but AC calves experienced a greater degree of tissue degradation. Ruminal acidosis symptoms in calves appear similar to those in adult cattle, and the etiology of the disease seems to follow similar mechanisms. It is clear from this study that symptoms can be moderated by diet, but further research is needed to determine whether symptoms can be nutritionally prevented or whether calves that experience ruminal acidosis are more susceptible to the disease as adults.

中文翻译：

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断奶前，断奶中和断奶后，初学者诱发的小牛瘤胃酸中毒的生理效应。

目的是在营养上诱发或抑制幼小犊牛瘤胃酸中毒，并比较瘤胃和全身健康指标。在3周龄时将10只小牛（n = 5 /饮食）瘤胃插管，并接受代乳品和2种犊牛初学者日粮中的1种，这些日粮旨在引起（AC；造粒，42.7％淀粉，15.1％中性洗涤剂纤维，57.8）瘤胃酸中毒：钝性（BL；膨化； 35.3％淀粉； 25.3％中性清洁剂纤维； 48.1％非纤维碳水化合物）；瘤胃酸中毒。平均出生体重为38.7±1.3千克。每周测量体重和小腿起动器摄入量。相对于起动饲料，在年龄的第6、8、10、12、14和16周龄时，在-8，-4、0、2、4、8、12和24 h取样瘤胃含量。在同一周从颈静脉收集血液，以进行全血细胞计数，血液pH，氧气和二氧化碳的分压。在第16周期间评估了起动剂的消耗速率。使用标记系统估算液体通过率和挥发性脂肪酸吸收率。在第17周屠宰小牛，收集瘤胃组织并评估其乳头长度，宽度和组织降解程度。AC和BL犊牛的平均瘤胃pH±标准误差分别为5.37±0.24和5.63±0.24。断奶后一周观察到最低的pH值。AC和BL犊牛的总瘤胃挥发性脂肪酸浓度分别为131.5和124.8±2.4 mM，并随着年龄和进食时间的增加而增加。AC小牛在第4周时的干物质摄入量较低，而在16周到第16周时仍保持较低水平。从5周到16周，AC犊牛的体重也较低。AC犊牛的血红蛋白和血细胞比容较低，但其他血液特征没有变化。瘤胃体积随着年龄的增长而增加，并且在BL犊牛中往往更大。饮食之间的通过率和乳头长度和宽度没有差异，但是AC小牛的组织降解程度更高。犊牛的瘤胃酸中毒症状看起来与成年牛类似，该病的病因似乎也遵循类似的机制。从这项研究中可以明显看出，饮食可以缓解症状，但是还需要进一步研究以确定症状是否可以通过营养预防，或者成年后患有瘤胃酸中毒的犊牛是否更容易患该病。AC犊牛的血红蛋白和血细胞比容较低，但其他血液特征没有差异。瘤胃体积随着年龄的增长而增加，并且在BL犊牛中往往更大。饮食之间的通过率和乳头长度和宽度没有差异，但是AC小牛的组织降解程度更高。犊牛的瘤胃酸中毒症状看起来与成年牛类似，该病的病因似乎也遵循类似的机制。从这项研究中可以明显看出，饮食可以缓解症状，但是还需要进一步研究以确定症状是否可以通过营养预防，或者成年后患有瘤胃酸中毒的犊牛是否更容易患该病。AC犊牛的血红蛋白和血细胞比容较低，但其他血液特征没有差异。瘤胃体积随着年龄的增长而增加，并且在BL犊牛中往往更大。饮食之间的通过率和乳头长度和宽度没有差异，但是AC小牛的组织降解程度更高。犊牛的瘤胃酸中毒症状看起来与成年牛类似，该病的病因似乎也遵循类似的机制。从这项研究中可以明显看出，饮食可以缓解症状，但是还需要进一步研究以确定症状是否可以通过营养预防，或者成年后患有瘤胃酸中毒的犊牛是否更容易患该病。饮食之间的通过率和乳头长度和宽度没有差异，但是AC小牛的组织降解程度更高。犊牛的瘤胃酸中毒症状看起来与成年牛类似，该病的病因似乎也遵循类似的机制。从这项研究中可以明显看出，饮食可以缓解症状，但是还需要进一步研究以确定症状是否可以通过营养预防，或者成年后患有瘤胃酸中毒的犊牛是否更容易患该病。饮食之间的通过率和乳头长度和宽度没有差异，但是AC小牛的组织降解程度更高。犊牛的瘤胃酸中毒症状看起来与成年牛类似，该病的病因似乎也遵循类似的机制。从这项研究中可以明显看出，饮食可以缓解症状，但是还需要进一步研究以确定症状是否可以通过营养预防，或者成年后患有瘤胃酸中毒的犊牛是否更容易患该病。