Laboratory for Animal Nutrition and Animal Product Quality, Department of Animal Sciences and Aquatic Ecology, Faculty of Bioscience Engineering, Ghent University, 9000 Gent, Belgium.
Laboratory for Animal Nutrition and Animal Product Quality, Department of Animal Sciences and Aquatic Ecology, Faculty of Bioscience Engineering, Ghent University, 9000 Gent, Belgium; State Key Laboratory of Grassland and Agro-Ecosystems, International Centre for Tibetan Plateau Ecosystem Management, School of Life Sciences, Lanzhou University, Lanzhou 730000, China.
J Dairy Sci. 2023 Aug;106(8):5723-5739. doi: 10.3168/jds.2022-22865. Epub 2023 Jun 16.
Metabolic and oxidative stress have been characterized as risk factors during the transition period from pregnancy to lactation. Although mutual relations between both types of stress have been suggested, they rarely have been studied concomitantly. For this, a total of 99 individual transition dairy cows (117 cases, 18 cows sampled during 2 consecutive lactations) were included in this experiment. Blood samples were taken at -7, 3, 6, 9, and 21 d relative to calving and concentrations of metabolic parameters (glucose, β-hydroxybutyric acid (BHBA), nonesterified fatty acids, insulin, insulin-like growth factor 1, and fructosamine) were determined. In the blood samples of d 21, biochemical profiles related to liver function and parameters related to oxidative status were determined. First, cases were allocated to 2 different BHBA groups (ketotic vs. nonketotic, N:n = 20:33) consisting of animals with an average postpartum BHBA concentration and at least 2 out of 4 postpartum sampling points exceeding 1.2 mmol/L or remaining below 0.8 mmol/L, respectively. Second, oxidative parameters [proportion of oxidized glutathione to total glutathione in red blood cells (%)], activity of glutathione peroxidase, and of superoxide dismutase, concentrations of malondialdehyde and oxygen radical absorbance capacity were used to perform a fuzzy C-means clustering. From this, 2 groups were obtained [i.e., lower antioxidant ability (LAA, n = 31) and higher antioxidant ability (HAA, n = 19)], with 80% referring to the cutoff value for cluster membership. Increased concentrations of malondialdehyde, decreased superoxide dismutase activity, and impaired oxygen radical absorbance capacity were observed in the ketotic group compared with the nonketotic group, and inversely, the LAA group showed increased concentrations of BHBA. In addition, the concentration of aspartate transaminase was higher in the LAA group compared with the HAA group. Both the ketotic and LAA groups showed lower dry matter intake. However, a lower milk yield was observed in the LAA group but not in the ketotic group. Only 1 out of 19 (5.3%) and 3 out of 31 (9.7%) cases from the HAA and LAA clusters belong to the ketotic and nonketotic group, respectively. These findings suggested that dairy cows vary in oxidative status at the beginning of the lactation, and fuzzy C-means clustering allows to classify observations with distinctive oxidative status. Dairy cows with higher antioxidant capacity in early lactation rarely develop ketosis.
代谢和氧化应激已被确定为妊娠到哺乳过渡期的风险因素。尽管已经提出了这两种应激之间的相互关系，但很少同时对它们进行研究。为此，共有 99 头个体产奶牛（117 例，18 头牛连续 2 个泌乳期采样）被纳入本实验。在产犊前 -7、3、6、9 和 21 天采集血液样本，并测定代谢参数（葡萄糖、β-羟丁酸（BHBA）、非酯化脂肪酸、胰岛素、胰岛素样生长因子 1 和果糖胺）的浓度。在第 21 天的血液样本中，测定了与肝功能相关的生化指标和与氧化状态相关的参数。首先，将病例分配到 2 个不同的 BHBA 组（酮症组和非酮症组，N：n = 20：33），这两个组由产后平均 BHBA 浓度和至少 4 个产后采样点中的 2 个超过 1.2 mmol/L 或均低于 0.8 mmol/L 的动物组成。其次，使用氧化参数[红细胞中氧化型谷胱甘肽与总谷胱甘肽的比例（%）]、谷胱甘肽过氧化物酶和超氧化物歧化酶的活性、丙二醛浓度和氧自由基吸收能力进行模糊 C-均值聚类。由此获得 2 个组[即较低的抗氧化能力（LAA，n = 31）和较高的抗氧化能力（HAA，n = 19）]，80%的个体归属于聚类成员的截断值。与非酮症组相比，酮症组丙二醛浓度升高，超氧化物歧化酶活性降低，氧自由基吸收能力受损，而 LAA 组 BHBA 浓度升高。此外，LAA 组天冬氨酸转氨酶浓度高于 HAA 组。酮症组和 LAA 组的干物质采食量均较低。然而，LAA 组的产奶量较低，而酮症组的产奶量没有降低。在 HAA 和 LAA 聚类中，只有 19 个中的 1 个（5.3%）和 31 个中的 3 个（9.7%）分别属于酮症组和非酮症组。这些发现表明，产奶牛在泌乳早期的氧化状态存在差异，模糊 C-均值聚类可以对具有独特氧化状态的观察结果进行分类。在泌乳早期具有较高抗氧化能力的奶牛很少发生酮症。
