This study investigated the effects of low potassium diets with different levels of Ca compared to two diets low in dietary cation–anion difference (DCAD) fed prepartum as a strategy to prevent hypocalcemia on sorting behaviour, total tract digestibility, oxidative status and energy and protein metabolism of transition cows. Forty‐eight pregnant dairy cows were assigned to 4 treatment groups: Low Ca, low K (LCLK), High Ca, low K (HCLK), Supplementation with anionic mineral mixture (AMS) supplementation with SoyChlor (CAS). After parturition, all animals were fed a standard postpartum diet. Data were collected until 21 DIM. Prepartum urinary pH was significantly reduced by the low DCAD diets, while postpartum Ca homeostasis was affected by the HCLK ration. Feeding AMS induced sorting against particles <1.18 mm in favour of particles >19 mm prepartum. In contrast, cows fed CAS showed an increase in selective consumption of fine particles and sorted against longer particles similar to the HCLK and LCLK groups. Postpartum sorting activity was not affected by the dietary treatments. After calving, apparent digestibility of NDF was significantly reduced in the HCLK group. Prepartum, we observed effects on serum concentrations of non‐esterified fatty acids were higher and insulin sensitivity was lower in the AMS group. Blood urea nitrogen (BUN) was decreased in cows fed the CAS ration. Postpartum, we found serum protein to be decreased with the low DCAD diets while BUN was decreased in the CAS group. The low DCAD rations increased prepartum serum malondialdehyde concentrations, while postpartum total antioxidant capacity was lower in the HCLK and the AMS group. From these data, we conclude that AMS decreased prepartum intake due to compromised palatability. Intermediate protein metabolism was affected by the low DCAD diets, while parameters of oxidative stress were probably affected by acid–base balance and Ca homeostasis.

中文翻译：

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与饲喂产前奶牛的不同阴离子日粮相比，含不同钙水平的低钾日粮：对分选行为、总消化道消化率、能量代谢、氧化状态和激素反应的影响。

本研究调查了不同钙含量的低钾饮食与两种低阳离子 - 阴离子差异 (DCAD) 产前喂养的饮食相比，作为预防低钙血症的策略对分选行为、总消化道消化率、氧化状态以及能量和蛋白质的影响过渡奶牛的新陈代谢。48 头怀孕奶牛被分配到 4 个处理组：低钙、低钾 (LCLK)、高钙、低钾 (HCLK)、阴离子矿物混合物 (AMS) 补充和大豆氯 (CAS)。分娩后，所有动物都喂食标准的产后饮食。收集数据直到 21 DIM。低 DCAD 饮食显着降低了产前尿 pH，而产后 Ca 稳态受 HCLK 定量的影响。进料 AMS 诱导分选颗粒 <1.18 mm 有利于颗粒 > 19 毫米产前。相比之下，喂食 CAS 的奶牛表现出对细颗粒的选择性消耗增加，并针对类似于 HCLK 和 LCLK 组的较长颗粒进行分类。产后分拣活动不受饮食处理的影响。产犊后，HCLK 组中 NDF 的表观消化率显着降低。产前，我们观察到 AMS 组对非酯化脂肪酸的血清浓度的影响更高，胰岛素敏感性更低。饲喂 CAS 日粮的奶牛的血尿素氮 (BUN) 降低。产后，我们发现低 DCAD 饮食会降低血清蛋白，而 CAS 组的 BUN 降低。低 DCAD 定量增加了产前血清丙二醛浓度，而 HCLK 和 AMS 组的产后总抗氧化能力较低。从这些数据来看，我们得出结论，由于适口性受损，AMS 减少了产前摄入量。中间蛋白质代谢受低 DCAD 饮食的影响，而氧化应激参数可能受酸碱平衡和 Ca 稳态的影响。