Prepartum body condition score affects milk yield, lipid metabolism, and oxidation status of Holstein cows.
In the transition period, dairy cows experience oxidative stress and are susceptible to metabolic disorders and immunologic challenges [1,2]. At the time of early lactation, cows go through a period of negative energy balance (NEB) which may lead to oxidative stress and health problems in these animals . Early lactation NEB not only decreases milk yield but also increased concentrations of non-esterified fatty acids (NEFA) and beta-hydroxybutyrate (BHBA) [4,5]. NEFA in the blood is mobilized from adipose tissue while BHBA is an intermediate metabolite of fatty acid oxidation . NEFA and BHBA are considered to be biomarkers of NEB, and oxidative stress during the transition period [7,8]. The body condition score (BCS) is an assessment of body fat and reflects the NEB of Holstein dairy cows [9,10]. It was reported that the BCS of cows were associated with differences in milk production and composition, reproduction, and health [7,11]. Cows with higher BCS at calving had higher concentrations of NEFA [12,13] and BHBA  in early lactation compared these with lower BCS. Cows with higher BCS are more sensitive to oxidative stress [14,15]. Oxidative stress is mainly derived from an imbalance between reactive oxygen metabolites and antioxidants and the concentration of some oxidative status indices such as malondialdehyde (MDA) was higher in cows with higher BCS before calving .
But the change of BCS during the transition period and their effects on the health and subsequent performance of dairy cows was few systematically studied. Therefore, the relations between the BCS and milk production, lipid metabolism, oxidative status of dairy cows were investigated in the present study. Consequently, this study may be used as reference for the dairy farms to improve the animals' health status and performance by adjusting prepartum BCS.
MATERIALS AND METHODS
Animals and experimental design
The trial was carried out at a commercial dairy farm with about 5,000 lactating cows in Dongying City, Shandong Province, P.R. China. The average milk yield per lactation of the cows was more than 40 kg (305 day). The BCS (5-point scale) was individually recorded 21 days before calving, on the calving day and 21 days after calving . Multiparous Holstein cows (second or third lactation) were selected according to their BCS at 21 days before calving and divided into 4 groups (28 animals per group): medium BCS (3.0 to 3.25, MBCS), high BCS (3.5 to 3.75, HBCS), higher BCS (4.0 to 4.25, HerBCS), and highest BCS (4.5 to 5.0, HestBCS). The cows were given access to total mixed ration and water ad libitum. The cows received a far-off diet (1.33 Mcal/kg) from -60 d to -22 d, and a close-up diet (1.50 Mcal/kg) was offered during the last 21 d. From 4 to 6 days postpartum, cows were supplemented with propylene glycol (PG, 300 mL) as a gluconeogenic precursor for both treatment and prevention of ketosis during transition. Cows were fed lactation diet I until 21 d (1.78 Mcal/kg) and lactation diet II (1.83 Mcal/kg) from 22 d to 100 d and milked four times at approximately 6:00, 12:00, 18:00, and 0:00; the individual milk yield was recorded every 3 days. The compositions of the diets are shown in Table 1 . All of the animal experimental procedures were approved by the Institutional Animal Care and Use Committee at Jilin Agricultural University.
Blood and milk samples
Blood was sampled via the coccygeal vein after morning feeding at days 21, 14, and 7 prepartum (precalving), day 0 (calving), and days 7, 14, and 21 postpartum (after calving). Serum was collected in (1.5 mL) after centrifuging at 2,000xg at 4[degrees]C for 10 min and stored at -20[degrees]C until analytical determination. Colostrum was taken immediately after calving, and the levels of lactoprotein, lactose, solid-not-fat, and ash were analyzed by a milk analyzer (Foss Electric, Hillerod, Denmark) while the density and immune globulin concentration were analyzed by a refractometer (Yucheng To You Optical Instruments Co. Ltd., Shandong, China). The concentrations of NEFA, BHBA, superoxide dismutase (SOD), MDA, catalase (CAT), vitamin A (VA) and vitamin E (VE) in serum were analyzed using commercial bovine specific enzyme-linked immuno-sorbent assay kits (Shanghai Enzyme-linked Biotechnology Co. Ltd., Shanghai, China) according to the instructions. Reaction is terminated by sulphuric acid. The color change is measured spectrophotometrically at a wavelength of 450 nm (Multiskan FC, Thermo scientific, Waltham, MA, USA) and calculated by comparing the optical density of the samples to the standard curve, respectively.
All of the data are presented as the means [+ or -] standard error and were subjected to one-way analysis of variance (colostrum composition) and general linear model by SPSS computer software (SPSS Inc., Chicago, IL, USA). The specify model included BCS (MBCS, HBCS, HerBCS, and HestBCS), Time (precalving, calving, postcalving) and their interactions (BCSx time) as fixed effects and cow within the treatment as random effect. Statistical significance is defined when p values are less than 0.05. Pearson correlation coefficients among the detected parameters were also calculated.
Colostrum composition, milk yield, and body condition score loss
The density of colostrum and the levels of immune globulin and lactoprotein of cows in the HestBCS group were higher (p<0.05) than those in the other groups (Table 2). The milk yields of cows in the MBCS, HBCS, HerBCS, and HestBCS groups peaked ([greater than or equal to]50 kg/d) at days 19 to 82, 22 to 100, 25 to 73, and 31 to 97, respectively. The average milk yields (0 to 100 days) were 52.35 kg/d, 50.94 kg/d, 48.59 kg/d, and 48.78 kg/d, respectively (Figure 1; Table 2). In addition, the present data showed that the animals in the HestBCS group had a greater BCS loss after calving (Figure 2). The percentages of lost BCS were 23.62% (HestBCS), 14.36% (HerBCS), 13.33% (HBCS), and 5.53% (MBCS) (Figure 2).
Lipid metabolism and oxidative status
NEFA was affected by both BCS (p<0.01) and time (p<0.01), while BHBA was only affected by BCS (p<0.01). There were no BCSxtime effects on NEFA (p = 0.21) or BHBA (p = 0.97) during the transition period (Table 3). The serum levels of NEFA in cows in the HestBCS group on the calving day and after calving were all higher than those observed in other groups (p<0.05). In addition, the concentrations of BHBA were the highest (p<0.05) in HestBCS on precalving, calving, and postcalving days. Table 4 shows that MDA, SOD, and VA were affected by both BCS and time (p<0.05). There were BCSxtime effects on SOD and VA during the transition period (p = 0.05). The concentrations of MDA, SOD, CAT, VA, and VE (except during precalving) in HestBCS (4.5 to 5.0) cows were all higher (p<0.05) than those in the other groups. Positive Pearson correlation coefficients were observed for NEFA (r = 0.260), BHBA (r = 0.496), MDA (r = 0.700), SOD (r = 0.606), CAT (r = 0.342), VA (r = 0.245), and VE (r = 0.448) to BCS (Table 5).
In early lactation, dairy cows experience a period of NEB due to the sudden increase in requirements of the mammary glands for milk production . The mobilization of adipose tissue is associated with decreasing body weight (BW), and cows in transition with higher BCS lose more BW [18,19]. Similar results were observed in our study as the cows in the HestBCS group had the greatest BCS loss at 21 d after calving. Loker et al  suggested that lower production is associated with greater BCS. In our study, animals in the HestBCS group had a delayed peak milk yield. However, Dechow et al  found that fatter cows with more loss of BCS in early lactation have greater milk production. Milk composition is positively associated with BCS, and higher calving BCS means more protein and lactose during early lactation [22,23]. In our research, a higher level of lactoprotein was observed in HestBCS cows.
The NEFA and BHBA are commonly measured as indices of NEB and fat oxidization, and their concentrations during the early postpartum period are associated with BCS [10,19, 24,25]. The NEFA concentration in blood can be a reason for adipose tissue mobilization due to excess acetyl CoA generated from [beta]-oxidation into ketone bodies, this leads to the loss of BCS [26,27]. In the present study, more rapid BCS loss and higher levels of NEFA and BHBA after calving were found in HestBCS cows, which is consistent with the results of Adrien et al . Barletta et al  indicated that cows that lost BCS during the transition period had higher concentrations of NEFA and BHBA and more health events during the lactation. However, Mansouryar et al  fund that there was no significant differences in concentrations of NEFA and BHBA in high and normal BCS cows in early lactation. A BCS of 3.5 or higher at calving is associated with increased risk for ketosis , and a concentration of BHBA [greater than or equal to]1,200 [micro]mol/L is considered as a sign of clinical ketosis [29,30]. However, no cows in the present study were diagnosed as ketotic at 1 week postpartum, as the BHBA concentrations were all lower than 1,200 [micro]mol/L. This may be because choline (STACHOL) was added in the close-up diet  and PG was orally fed to cows at 4 days postpartum [32,33].
The MDA is the end product of the oxidative destruction of lipids, and its content can indicate the oxidative status of dairy cows [34,35]. In the present study, the highest level of MDA was found in HestBCS cows and MDA were increased on the calving day and decreased after calving. These data demonstrate that cows suffered the most serious oxidative stress on calving day and cows with higher BCS suffered much more serious oxidative stress than the other BCS cows before or after calving. It is probable that a negative association between BCS and dry matter intake in early lactation . To maintain the requirements for milk production, prepartum cows with higher BCS experience more serious NEB .
The SOD is considered to be the first defense against pro-oxidants that convert the superoxide ([O.sup.-.sub.2]) to hydrogen peroxide ([H.sub.2][O.sub.2])  and Bernabucci et al  used SOD in blood to assess the oxidative status of transition dairy cows. In the current study, HestBCS cows had the highest SOD concentrations. And the concentration of SOD was commonly higher on calving day which was similar to the report of Bernabucci et al . CAT is a critical antioxidant enzyme that prevents the accumulation of [H.sub.2][O.sub.2] and is considered to be an index of antioxidative status [39,40]. In the present study, CAT and MDA showed positive correlations, which is consistent with a previous study .
The VA and VE are fat-soluble membrane antioxidants that are important for enhancing antioxidant defense systems against oxidative stress [41,42]. Jin et al  reported that a diet supplemented with VA increases the concentration of serum SOD and CAT, which is consistent with the results of the current study. The VE supplementation reduces oxidative damage in the livers of heifers  and mitigates oxidative stress in crossbred cows . In the present study, an oxidative (NEFA, BHBH, MDA)-antioxidative (SOD, CAT, VA, VE) balance was obviously observed in the cows, which might be the result of homeostatic control.
This study indicates that the milk yield, lipid metabolism, and oxidative status of Holstein cows are related to prepartum BCS and BCS loss during the transition period. Holstein cows with MBCS have better milk yield performance after calving whereas the animals with HestBCS suffer greater BCS loss and higher oxidative stress. Our data may provide some theoretical basis for improving the postpartum health and performance of dairy cows by adjusting prepartum BCS.
CONFLICT OF INTEREST
We certify that there is no conflict of interest with any financial organization regarding the material discussed in the manuscript. https://doi.org/10.5713/ajas.18.0817
Submitted Oct 30, 2018; Revised Jan 23, 2019;
Accepted Mar 22, 2019
The study was financially supported by Jilin Province Science and Technology Key Project (20160301003NY) and Jilin Province Feed Engineering and Technology Research Center (20170623075TC). The authors would like to thank Dr Yang Zhi Liu and Dr Zhe Sun for their helps during the submission.
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Wei Zhao (1,2), Xue Chen (1,2), Jun Xiao (2), Xiao Hui Chen (1), Xue Feng Zhang (1,2,3,4), Tao Wang (1,2,3,4), Yu Guo Zhen (1,2,3,4) *, and Gui Xin Qin (1,3,4) *
* Corresponding Authors:
Yu Guo Zhen
Tel: +86-431-8453-3231, Fax: +86-431-8453-2992, E-mail: firstname.lastname@example.org
Gui Xin Qin Tel: +86-431-8453-3231, Fax: +86-431-8453-2992, E-mail: email@example.com
(1) College of Animal Science and Technology, Jilin Agricultural University, Changchun 130118, China
(2) JLAU-Borui Dairy Science and Technology R&D Centre of Jilin Agricultural University, Changchun 130118, China
(3) Key Laboratory of Animal Production, Product Quality and Security, Ministry of Education, Jilin Agricultural University, Changchun 130118, China
(4) Key Laboratory of Animal Nutrition and Feed Science of Jilin Province, Jilin Agricultural University, Changchun 130118, China
Xiao Hui Chen
Xue Feng Zhang
Yu Guo Zhen
Gui Xin Qin
Caption: Figure 1. Average milking yield of Holstein cows after calving (0 to 100 days).
Caption: Figure 2. Body condition score of Holstein cows before calving, at calving, and after calving. a-d Means in the same row followed by different superscripts differ at p<0.05. The same letter or no letter indicates no significant difference.
Table 1. Ingredients (kg/head/d) and chemical composition (% of dry matter) of the experimental diets Items Far-off diet Close-up diet (-60 d to -22 d) (-21 d to calving) Ingredients Corn silage 6.00 12.00 Fermented rice straw 7.00 -- Alfalfa hay -- -- Wet distilled -- 3.00 grain solubles Oat grass 6.00 3.80 Steam-flaked corn -- -- Corn -- 1.40 Urea 0.04 0.05 Soybean 0.70 0.50 Spouting corn bran 0.50 -- Soybean hull 0.50 0.70 Rapeseed meal 1.30 1.00 Extruded soybean -- -- Premix I (1) 0.20 -- Premix II (2) -- 0.80 Premix III (3) -- -- Fat powder -- Rumen bypass protein -- 0.50 Diamond V XPC -- 0.025 STA-CHOL -- 0.056 Rumen-protected -- 0.02 nicotine KHC[O.sub.3] -- -- Molasses -- -- Wet matter 22.24 23.85 (kg/head/d) Dry matter intake 13.40 13.10 (kg/head/d) Chemical composition Acid detergent 32.92 22.41 fiber NEl (Mcal/kg dry 1.33 1.50 matter) (4) Neutral detergent 49.00 36.60 fiber Crude protein 13.00 13.85 Starch 13.50 23.30 Non-fiber 30.00 37.85 carbohydrates Calcium 0.51 1.20 Phosphorus 0.39 0.44 Items Lactation diet I Lactation diet II (calving to 21 d) (22 d to 100 d) Ingredients Corn silage 14.00 -- Fermented rice straw -- -- Alfalfa hay 3.70 4.00 Wet distilled 2.00 5.00 grain solubles Oat grass 0.50 -- Steam-flaked corn 2.50 4.40 Corn 1.40 2.20 Urea 0.04 0.07 Soybean 1.50 2.30 Spouting corn bran -- -- Soybean hull 0.80 -- Rapeseed meal -- 0.50 Extruded soybean -- 0.50 Premix I (1) -- -- Premix II (2) -- -- Premix III (3) 0.68 0.68 Fat powder 0.15 0.30 Rumen bypass protein 1.20 1.20 Diamond V XPC 0.025 0.025 STA-CHOL 0.060 -- Rumen-protected 0.02 -- nicotine KHC[O.sub.3] 0.05 -- Molasses 0.80 1.00 Wet matter 29.42 45.18 (kg/head/d) Dry matter intake 17.30 24.40 (kg/head/d) Chemical composition Acid detergent 18.69 16.64 fiber NEl (Mcal/kg dry 1.78 1.83 matter) (4) Neutral detergent 27.87 26.28 fiber Crude protein 16.40 17.36 Starch 26.37 30.90 Non-fiber 43.81 46.06 carbohydrates Calcium 1.09 0.85 Phosphorus 0.45 0.45 (1) Nutrients provided/kg of additive: vitamin A, 700 kIU; vitamin [D.sub.3], 200 kIU; vitamin E, 8,500 IU; Cu, 650 mg; Zn, 1,656 mg; Mn, 1,335.6 mg; Co, 40 mg; I, 80 mg; Se, 32 mg; CaC[O.sub.3], 122 g; CaHP[O.sub.4]-2[H.sub.2] O, 34 g; NaCl, 120 g. (2) Nutrients provided/kg of additive: vitamin A, 400 kIU; vitamin [D.sub.3], 100 kIU; vitamin E, 5,000 IU; Cu, 375 mg; Zn, 345 mg; Organic Zn, 225 mg; Mn, 508.8 mg; Co, 6 mg; I, 24 mg; Organic Se, 24 mg; Ca, 143.8 g; P, 13.6 g; Cl, 158.8 g; S, 49.6 g. (3) Nutrients provided/kg of additive: vitamin A, 400 kIU; vitamin [D.sub.3], 150 kIU; vitamin E, 3,000 IU; Cu, 650 mg; Zn, 2,415 mg; Mn, 1,303.8 mg; Co, 24 mg; I, 60 mg; Se, 24 mg; Ca, 157.7 g; P, 32.3 g; NaCl, 130 g. 4) NEl (Mcal/kg DM) was calculated according to NRC . Table 2. Influence of body condition score on the colostrum composition (%) and average milking yield (kg/d, 0 to 100 d) of Holstein cows Variables MBCS (3.0 to 3.25) HBCS (3.5 to 3.75) Density (%) 19.49 [+ or -] 4.07(a) 20.30 [+ or -] 3.19(a) Immune 18.77 [+ or -] 3.08(a) 18.31 [+ or -] 3.22(a) globulin (%) Lactoprotein (%) 6.06 [+ or -] 1.08(a) 5.75 [+ or -] 1.38(a) Lactose (%) 8.84 [+ or -] 1.14 8.26 [+ or -] 1.88 Solid-not- 16.52 [+ or -] 2.18 17.12 [+ or -] 2.05 fat (%) Ash (%) 1.19 [+ or -] 0.20 1.12 [+ or -] 0.29 Average milking 52.35 [+ or -] 7.03 50.94 [+ or -] 7.42 yield (kg/d) Variables HerBCS (4.0 to 4.25) HestBCS (4.5 to 5.0) Density (%) 20.11 [+ or -] 4.15(a) 29.39 [+ or -] 2.77(b) Immune 19.59 [+ or -] 3.63(a) 27.34 [+ or -] 3.92(b) globulin (%) Lactoprotein (%) 6.57 [+ or -] 0.99(ab) 7.59 [+ or -] 0.62(b) Lactose (%) 9.21 [+ or -] 1.38 9.22 [+ or -] 1.61 Solid-not- 18.64 [+ or -] 1.52 20.06 [+ or -] 1.45 fat (%) Ash (%) 1.27 [+ or -] 0.18 1.33 [+ or -] 0.27 Average milking 48.59 [+ or -] 3.83 48.78 [+ or -] 5.43 yield (kg/d) MBCS, medium BCS (3.0 to 3.25); HBCS, high BCS (3.5 to 3.75); HerBCS, higher BCS (4.0 to 4.25); HestBCS, highest BCS (4.5 to 5.0). (a,b) Means in the same row followed by different superscripts differ at p <0.05. Table 3. Influence of body condition score on the levels of non-esterified fatty acid (NEFA) and beta-hydroxybutyrate (BHBA) of Holstein cows Variables Treatments (1) MBCS (3.0 to 3.25) NEFA Precalving 1,372.50 [+ or -] 309.31(b) ([micro] Calving 871.14 [+ or -] 101.89(aA) mol/L) Postcalving 1,510.20 [+ or -] 270.87(bB) BHBA Precalving 322.13 [+ or -] 49.80(a) ([micro] Calving 345.75 [+ or -] 34.87(a) mol/L) Postcalving 369.01 [+ or -] 50.22(a) Variables Treatments (1) HBCS (3.5 to 3.75) NEFA Precalving 1,412.50 [+ or -] 311.67(b) ([micro] Calving 774.00 [+ or -] 159.33(aA) mol/L) Postcalving 900.50 [+ or -] 147.92(aA) BHBA Precalving 347.96 [+ or -] 64.95(a) ([micro] Calving 324.50 [+ or -] 52.98(a) mol/L) Postcalving 343.23 [+ or -] 47.27(a) Variables Treatments (1) HerBCS (4.0 to 4.25) NEFA Precalving 1,535.00 [+ or -] 351.96(b) ([micro] Calving 833.00 [+ or -] 126.91(aA) mol/L) Postcalving 889.75 [+ or -] 124.59(aA) BHBA Precalving 409.32 [+ or -] 58.72(a) ([micro] Calving 345.83 [+ or -] 60.62(a) mol/L) Postcalving 388.38 [+ or -] 83.62(a) Variables Treatments (1) HestBCS (4.5 to 5.0) NEFA Precalving 1,730.00 [+ or -] 446.29 ([micro] Calving 1,369.0 [+ or -] 137.25(b) mol/L) Postcalving 1,632.50 [+ or -] 153.60(b) BHBA Precalving 571.37 [+ or -] 68.07(b) ([micro] Calving 549.92 [+ or -] 89.82(b) mol/L) Postcalving 559.71 [+ or -] 66.13(b) Variables p-vale BCS Time BCSxtime NEFA Precalving <0.01 <0.01 0.21 ([micro] Calving mol/L) Postcalving BHBA Precalving <0.01 0.61 0.97 ([micro] Calving mol/L) Postcalving BCS, body condition score. (1) MBCS, medium BCS (3.0 to 3.25); HBCS, high BCS (3.5 to 3.75); HerBCS, higher BCS (4.0 to 4.25); HestBCS, highest BCS (4.5 to 5.0). (a,b) Means in the same row followed by different superscripts differ at p <0.05. (A,B) Means in the same column followed by different superscripts differ at p <0.05. Table 4. Influence of body condition score on oxidative status of Holstein cows Variables Treatments (1) MBCS (3.0 to 3.25) MDA Precalving 8.75 [+ or -] 2.37(a) (nmol/mL) Calving 9.13 [+ or -] 1.19(a) Postcalving 8.59 [+ or -] 1.97(ab) SOD Precalving 177.40 [+ or -] 27.52(a) (U/mL) Calving 191.46 [+ or -] 32.91(a) Postcalving 183.98 [+ or -] 24.94(b) CAT Precalving 139.96 [+ or -] 27.46(a) (U/mL) Calving 126.49 [+ or -] 18.16(a) Postcalving 148.05 [+ or -] 27.20(a) VA Precalving 79.45 [+ or -] 15.02(aB) (ng/mL) Calving 65.60 [+ or -] 11.42(aB) Postcalving 62.22 [+ or -] 12.64(aA) VE Precalving 35.24 [+ or -] 5.99(b) (ug/mL) Calving 33.55 [+ or -] 5.79(aB) Postcalving 26.09 [+ or -] 5.21(aA) Variables Treatments (1) HBCS (3.5 to 3.75) MDA Precalving 8.84 [+ or -] 1.49(aAB) (nmol/mL) Calving 9.48 [+ or -] 1.16(aB) Postcalving 6.93 [+ or -] 1.96(aA) SOD Precalving 171.08 [+ or -] 22.67(aB) (U/mL) Calving 177.01 [+ or -] 23.70(aB) Postcalving 125.09 [+ or -] 19.07(aA) CAT Precalving 137.81 [+ or -] 28.03(a) (U/mL) Calving 120.44 [+ or -] 18.30(a) Postcalving 122.45 [+ or -] 45.15(a) VA Precalving 61.36 [+ or -] 20.36(aA) (ng/mL) Calving 64.89 [+ or -] 13.09(aA) Postcalving 108.88 [+ or -] 11.37(bB) VE Precalving 29.54 [+ or -] 6.51 (ug/mL) Calving 32.15 [+ or -] 2.34(a) Postcalving 30.14 [+ or -] 8.91(a) Variables Treatments (1) HerBCS (4.0 to 4.25) MDA Precalving 9.05 [+ or -] 1.28(aAB) (nmol/mL) Calving 9.54 [+ or -] 2.1(aB) Postcalving 6.69 [+ or -] 1.52(aA) SOD Precalving 180.14 [+ or -] 18.03(aB) (U/mL) Calving 192.71 [+ or -] 25.65(aB) Postcalving 131.74 [+ or -] 20.74(aA) CAT Precalving 132.66 [+ or -] 18.75(a) (U/mL) Calving 119.56 [+ or -] 13.79(a) Postcalving 144.79 [+ or -] 59.91(a) VA Precalving 62.24 [+ or -] 21.59(aA) (ng/mL) Calving 71.44 [+ or -] 13.44(aA) Postcalving 123.63 [+ or -] 24.73(bB) VE Precalving 29.12 [+ or -] 6.43 (ug/mL) Calving 36.17 [+ or -] 9.96(a) Postcalving 31.93 [+ or -] 8.32(ab) Variables Treatments (1) HestBCS (4.5 to 5.0) MDA Precalving 12.64 [+ or -] 1.81(bB) (nmol/mL) Calving 17.17 [+ or -] 2.42(bC) Postcalving 10.03 [+ or -] 1.23(bA) SOD Precalving 256.79 [+ or -] 25.84(bA) (U/mL) Calving 348.58 [+ or -] 23.43(bB) Postcalving 216.57 [+ or -] 26.10(cA) CAT Precalving 196.25 [+ or -] 32.81(b) (U/mL) Calving 198.61 [+ or -] 20.01(b) Postcalving 207.02 [+ or -] 45.58(b) VA Precalving 113.15 [+ or -] 25.84(bA) (ng/mL) Calving 123.20 [+ or -] 19.61(bAB) Postcalving 135.30 [+ or -] 9.55(cAB) VE Precalving 36.90 [+ or -] 9.51 (ug/mL) Calving 46.70 [+ or -] 9.31(b) Postcalving 40.62 [+ or -] 9.39(b) Variables p-value BCS Time BCSxtime MDA Precalving <0.01 <0.05 0.16 (nmol/mL) Calving <0.01 Postcalving <0.01 SOD Precalving <0.01 <0.05 0.05 (U/mL) Calving <0.01 Postcalving <0.01 CAT Precalving <0.01 0.51 0.47 (U/mL) Calving <0.01 Postcalving <0.01 VA Precalving <0.01 <0.05 0.05 (ng/mL) Calving Postcalving VE Precalving <0.01 0.13 0.37 (ug/mL) Calving Postcalving BCS, body condition score; MDA, malondialdehyde; SOD, oxidase dismutase; CAT, catalase; VA, vitamin A; VE, vitamin E. (1) MBCS, medium BCS (3.0 to 3.25); HBCS, high BCS (3.5 to 3.75); HerBCS, higher BCS (4.0 to 4.25); HestBCS, highest BCS (4.5 to 5.0). (a,b) Means in the same row followed by different superscripts differ at p <0.05. (A,B) Means in the same column followed by different superscripts differ at p <0.05. Table 5. Pearson correlation coefficients of the levels of non-esterified fatty acid and beta-hydroxybutyrate, and indices of oxidative status and body condition score of Holstein cows NEFA BHBA MDA SOD NEFA -- BHBA 0.572** -- MDA 0.468** 0.764** -- SOD 0.379** 0.624** 0.781** -- CAT 0.524** 0.750** 0.585** 0.594** VA 0.354** 0.636** 0.375** 0.487** VE 0.417** 0.788** 0.741** 0.671** BCS 0.260* 0.496** 0.700** 0.606** CAT VA VE BCS NEFA BHBA MDA SOD CAT -- VA 0.512** -- VE 0.527** 0.639** -- BCS 0.342** 0.245* 0.448** -- NEFA, non-esterified fatty acid; BHBA, beta-hydroxybutyrate; MDA, malondialdehyde; SOD, oxidase dismutase; CAT, catalase; VA, vitamin A; VE, vitamin E; BCS: body condition score. * p<0.05, ** p<0.01.