本试验旨在探讨不同泌乳阶段的高产与低产奶牛血清营养状况指标与抗氧化指标的变化规律，并建立血清营养状况指标与抗氧化指标的多元线性回归模型。采用2×6（产奶量：高产≥35 kg/d和低产< 35 kg/d；泌乳阶段：围产前期、围产后期、泌乳前期、泌乳中期、泌乳后期和干奶期）双因素完全随机试验设计，将240头体重[（550±10）kg]、胎次[（2.08±0.47）胎]、体况（3.0~3.5分）、饲养管理相似的荷斯坦奶牛随机分为12组，每组20头。结果显示：高产奶牛血清β-羟丁酸（β-HB）、维生素A（VA）含量及过氧化氢酶（CAT）活性显著高于低产奶牛（P≤0.05）。奶牛围产前期的血清维生素E（VE）、锌（Zn）含量及硫氧还蛋白还原酶（TrxR）活性较低，总超氧化物歧化酶（T-SOD）、谷胱甘肽过氧化物酶（GSH-Px）、CAT活性较高；围产后期的血清葡萄糖（GLU）、VA、VE、硒（Se）含量及T-SOD、GSH-Px活性较低，游离脂肪酸（NEFA）、β-HB、丙二醛（MDA）含量及CAT活性较高；泌乳前期的血清GLU、VA、Se、铜（Cu）含量及总抗氧化能力（T-AOC）、T-SOD、GSH-Px、CAT活性较低，MDA含量较高；泌乳中期的Se含量较低，Zn含量较高；泌乳后期的血清Se、Zn、MDA含量较低，GLU含量与TrxR活性较高；干奶期的血清NEFA、Zn含量较低，GLU含量及GSH-Px活性较高。泌乳阶段与产奶量对奶牛血清Se、Zn含量及T-AOC与GSH-Px、TrxR活性的影响存在显著的互作效应（P≤0.05）。多元回归分析结果表明，在围产后期和泌乳前期，血清抗氧化指标MDA含量与血清营养状况指标NEFA及β-HB含量呈显著正相关（P≤0.05），与VA、VE、Se、Zn、Cu含量呈显著负相关（P≤0.05），而血清其他抗氧化指标T-AOC以及T-SOD、GSH-Px活性与上述血清营养状况指标间的多元回归关系正好与MDA含量相反。综上，泌乳阶段对奶牛血清营养状况指标与抗氧化指标有显著影响，在围产后期与泌乳前期，血清营养状况指标NEFA、β-HB、VA、VE、Se、Zn、Cu含量与抗氧化指标T-AOC及T-SOD、GSH-Px活性和MDA含量间呈显著的多元线性回归关系。

This experiment was aimed to investigate the variations of serum nutritional status indexes and antioxidant indexes in different lactation stages of dairy cows, and a multiple linear regression model on the nutritional status indexes and antioxidant indexes was established. The experiments were conducted as a 2×6 (milk yield:high yield, ≥ 35 kg/d or low yield, <35 kg/d; lactation stage:prepartum, postpartum, early-lactation period, mid-lactation period, late-lactation period and dry period) double-factor completely randomized experiment design. A total of 240 Holstein cows with similar body weight[(550±10) kg], parity[(2.08±0.47) parities], body condition (3.0 to 3.5 points) were randomly divided into 12 groups with 20 cows per group. The results showed that the serum β-hydroxybutyric acid (β-HB), vitamin A (VA) contents and catalase (CAT) activity of high-yield dairy cows were significantly higher than those of low-yield dairy cows (P ≤ 0.05). The serum vitamin E (VE), zinc (Zn) contents and thioredoxin reductase (TrxR) activity in prepartum of dairy cows were lower, while the total superoxide dismutase (T-SOD), glutathion peroxidase (GSH-Px) and CAT activities were higher. The serum glucose (GLU), VA, VE, selenium (Se) contents and T-SOD, GSH-Px activities in postpartum were lower, while the non-esterified fatty acids (NEFA), β-HB, malondialdehyde (MDA) contents and CAT activity were higher. The serum GLU, VA, Se, copper (Cu) contents, total antioxidant capacity (T-AOC), and T-SOD, GSH-Px, CAT activities were lower in early-lactation period, while the MDA content was higher. The serum Se content was lower in mid-lactation period, while the Zn content was higher. The Se, Zn and MDA contents in late-lactation period were lower, while the GLU content and TrxR activity were higher. The NEFA and Zn contents in dry period were lower, while the GLU content and GSH-Px activity were higher. The lactation stage and milk yield had significantly interaction effects on the serum Se, Zn contents, T-AOC, GSH-Px and TrxR activities of dairy cows (P ≤ 0.05). The results of multiple regression analysis showed that serum antioxidant index such as MDA content had a significantly positive correlation with serum nutritional status indexes such as NEFA and β-HB contents (P ≤ 0.05), and had a significantly negative correlation with VA, VE, Se, Zn and Cu contents in the postpartum and early-lactation period (P ≤ 0.05). However, the multiple regression relationships between serum antioxidant indexes such as T-AOC, T-SOD and GSH-Px activities with the above nutritional status indexes showed the opposite results to MDA content. In summary, the serum nutritional status indexes and antioxidant indexes of dairy cows are significantly affected by the lactation stage, and there are significant multivariate regression relationships between the serum nutritional status indexes such as NEFA, β-HB, VA, VE, Se, Zn, Cu contents and the antioxidant indexes such as T-AOC, T-SOD and GSH-Px activities, and MDA content.