Department of Animal Sciences, College of Agriculture, Isfahan University of Technology, Isfahan, Iran.
Institute of Physiology and Cell Biology, University of Veterinary Medicine, Foundation, Hannover, Germany.
J Anim Physiol Anim Nutr (Berl). 2021 Jan;105(1):14-25. doi: 10.1111/jpn.13438. Epub 2020 Aug 25.
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.
本研究调查了与两种低日粮阳离子-阴离子差 (DCAD) 相比，不同水平钙的低钾饮食对围产期奶牛分类行为、全肠道消化率、氧化状态以及能量和蛋白质代谢的影响，旨在预防低钙血症。将 48 头怀孕奶牛分为 4 个处理组：低钙低钾（LCLK）、高钙低钾（HCLK）、阴离子矿物质混合物补充（AMS）和大豆氯化物补充（CAS）。产后，所有动物均喂食标准产后日粮。数据收集至 21 天泌乳日（DIM）。低 DCAD 日粮显著降低了产前尿液 pH 值，而产后 HCLK 日粮影响了钙平衡。产前 AMS 诱导了对 <1.18mm 颗粒的分类偏好，而对 >19mm 颗粒的分类偏好减少。相比之下，饲喂 CAS 的奶牛表现出对细颗粒选择性采食的增加，并对长颗粒进行分类，类似于 HCLK 和 LCLK 组。产后的分类活动不受日粮处理的影响。产后，HCLK 组的 NDF 表观消化率显著降低。产前，AMS 组的非酯化脂肪酸血清浓度较高，胰岛素敏感性较低。饲喂 CAS 日粮的奶牛血尿素氮（BUN）降低。产后，我们发现低 DCAD 日粮降低了血清蛋白，而 CAS 组的 BUN 降低。低 DCAD 日粮增加了产前血清丙二醛浓度，而产后 HCLK 和 AMS 组的总抗氧化能力降低。根据这些数据，我们得出结论，AMS 降低了产前采食量，因为适口性降低。低 DCAD 日粮影响了中间蛋白代谢，而氧化应激参数可能受到酸碱平衡和钙平衡的影响。
