Thiobarbituric acid reactive substances and plasma antioxidative capacity in dairy cows at different lactation stages

The aim of the present experiment was to investigate the level of the lipid peroxidation and plasma antioxidative capacity in plasma of dairy cows at different lactation stages. Twenty six healthy dairy cows were used in our experiment. The groups: I - dry cows (n = 7), II - dairy cows < 1 month after calving (n = 9), III - dairy cows 4 - 5 months after calving (n = 10). The highest level of lipid peroxidation (TBARS) was recognized in dairy cows in early lactation (II - 0.58+/-0.42 micromol/l) with significant differences between the groups (p < 0.05). In contrast, there was a tendency (p > 0.05) to the lowest plasma antioxidative activity in cows in the same group (158 +/- 44 micromol/l). The strongest trend to metabolic imbalance was found in the dairy cows in early lactation (group II). In conclusion, the metabolic stress of dairy cows associated with early lactation resulted in an increased level of plasma lipid peroxidation.     

The comparison of thiobarbituric acid reactive substances (TBARS) concentrations in plasma and serum from dairy cattle

The aim of this study was to compare thiobarbituric acid reactive substances (TBARS) concentrations in serum, plasma with heparin (heparin plasma), and plasma with ethylenediaminetetraacetic acid disodium salt (EDTA plasma) as anticoagulants from dairy cattle. Serum, heparin plasma, and EDTA plasma TBARS were not sufficiently strongly correlated to allow accurate prediction of one set of values from the other. Heparin plasma TBARS concentrations were found to be lower, and were affected by the duration of mixing during the assay process. The results suggest that it is necessary to differentiate TBARS concentrations between different sample types such as serum, heparin plasma, and EDTA plasma. For measurements of TBARS concentrations in cattle, EDTA plasma samples may be more suitable than the other samples.     

Plasma thiobarbituric acid reactive substances,vitamin A and vitamin E levels and resumption of postpartum ovarian activity in dairy cows

Vitamins with antioxidative functions are commonly used as supplements to improve fertility in dairy cows. However, according to field test results uncertainty exists about the effect of these vitamins, especially in vitamin A and vitamin E, on ovarian functional activity. This study was performed to reveal the physiological characteristics of cows receiving enough feed and the ovaries of which were activated in the early postpartum period. Six of 12 primiparous cows showing the corpus luteum on 25 to 27 days after parturition were classified as early responders (PER); the remaining six were classified as late responders (PLR). Among 11 multiparous cows, nine were early responders (MER), and the remaining two were late responders (MLR). Plasma concentration of thiobarbituric acid reactive substances (TBARS) in the PER were lower than those in the PLR (P < 0.01). The ratio of plasma all‐trans‐retinol to intake α‐tocopherol or β‐carotene were increased in the following order: MER < PER < PLR (P < 0.01). The milk lactose (P < 0.025) and plasma glucose (P < 0.01) of the early responders tended to be lower than those of the late responders. These may have been associated with the availability of vitamins or energy balance. Thus, we suggest the possibility that the cows which were able to utilize antioxidants and energy from the feed efficiently may have earlier resumption of ovaries postpartum.     

Effects of genetic capacity on milk production and on plasma metabolites in dairy cows during post-ruminal or intravenous carbohydrates or amino acid infusions

The objectives of this study were to investigate the effects of genetic capacity on abomasal and intravenous infusions of wheat starch or glucose (CHO) or a mixture of amino acids (AA) on milk production, nitrogen utilization efficiency, plasma metabolites and hormones of dairy cows in early and late lactation. Eight cows from two genetic lines selected for low (L) and high (H) milk production were used in a 4 × 4 Latin square design. The mean differences in pedigree index between the two groups were 1639 kg milk and 55 kg protein yield based on 305 days lactation. Infusions were: 1) starch in the abomasum (SP), 2) glucose in the blood (GB), 3) AA in the abomasum (AP), and 4) AA in the blood (AB). The experiment was conducted in early lactation (start: 57 ± 4 and 52 ± 2 days postpartum, 31.3 ± 2.8 and 34.7 ± 1.4 kg milk for L and H cows, respectively) and repeated with the same animals and treatments in late lactation (start: 168 ± 4 and 163 ± 2 d postpartum, 21.0 ± 1.9 and 23.8 ± 0.7 kg milk for L and H cows, respectively). Daily amounts infused were on average 354 and 258 g in early and late lactation, respectively. The cows were restrictively fed a basal diet consisting of concentrate mixture and grass silage (55:45 on DM basis). Differences in milk yield and ECM between the genetic groups were 3.7 and 3.3 kg in early lactation and 2.9 and 2.0 kg in late lactation, respectively, but the difference was not significant (P > 0.10). Minor effects of genetic group were found in milk production and plasma metabolite concentrations. However, the extraction rates of EAA, BCAA, NEAA and TAA were higher (P < 0.05) in H cows than in L cows in early lactation but not in late lactation. OM and CP digestibility and hormones were affected by genetic group or genetic group × treatment interaction. It is concluded that genetic capacity is important for digestion and metabolism of nutrients, and particularly, how hormone levels are influenced by different nutrient supply.     

异丁酸钠对奶牛泌乳性能和血液指标的影响

文章旨在研究异丁酸钠对奶牛泌乳性能和血液指标的影响。选用20头体重为(567±11.8)kg、已产奶(148±4.5)d且日均产奶量为(22.3±0.81)kg的的健康中国黑白花奶牛进行一项重复4×4拉丁方饲养试验。处理为:对照(不做添加)和低[LIB,20g(/头·d)]、中[MIB,40g(/头·d)]、高[HIB,60g(/头·d)]添加量。试验每个阶段为期30d(预饲15d,正饲15d)。本试验条件下,异丁酸钠的添加对干物质采食量(DMI)没有影响,MIB添加组的产奶量最高,但处理组之间差异不显著;除乳脂中各处理之间差异不显著外,乳蛋白、乳糖、乳非脂固形物和乳灰分的HIB添加组的均低于其他3个处理的,且差异显著(P0.05);其中,均以LIB添加组的最高。血中葡萄糖和生长激素的浓度呈线性增加(P0.05),而游离脂肪酸的浓度呈线性下降;LIB、MIB和HIB三个添加水平的血清总胆固醇浓度均低于对照,以MIB组的最高;MIB组的血浆总蛋白(P0.01)、白蛋白含量最低;LIB组的血清尿素氮水平低于对照,但随着添加量的增加提高了;但对血浆甘油三酯没有影响。结果表明,该日粮中添加异丁酸钠时,MIB组的泌乳母牛产奶量最高,且不会影响到下一胎次的繁殖性能。因此建议异丁酸钠的最适添加量为40g(/头·d)。     

有机硒对奶牛血硒含量和抗氧化能力的影响

选用35头处于干奶期40d，泌乳期相近和上胎平均日产奶量20kg的中国荷斯坦奶牛，采用完全随机区组设计分为7组，即：对照组、亚硒酸钠（7．5mg／d、15mg／d和22．5mg／d）和有机硒（7．5mg／d、15mg／d和22．5mg／d），研究有机硒和无机硒对血硒含量和抗氧化能力的影响。结果表明：试验前各组体细胞数、全血谷胱甘肽过氧化物酶活性、血硒差异不显著，试验期有机硒较无机硒显著降低体细胞数，提高了全血谷胱甘肽过氧化物酶活力和血硒含量。由此推断有机硒提高机体的抗氧化能力，降低了体细胞数。     

Effects of repeated jugular puncture on plasma cortisol concentrations in loose-housed dairy cows

In three experiments, the effects of venipuncture on plasma cortisol concentrations were studied in loose-housed dairy cows. In Exp. 1, two blood samples were collected 18 min apart on three alternate days from 20 dairy cows for studying their adrenocortical response to a single venipuncture. To further evaluate the effect of cows anticipating venipuncture, in Exp. 2, 15 dairy cows were sequentially venipunctured once daily on 12 successive days in a randomized order in groups of five, starting 15 min apart. In Exp. 3, 10 primiparous cows were used on three alternate days to study habituation to serial sampling (i.e., collection of five blood samples by venipuncture, 15 min apart). In cows accustomed to handling, jugular puncture did not affect cortisol concentrations in plasma collected 18 min later. Average daily cortisol concentrations varied between 2.07 +/- .38 and 3.81 +/- .56 ng/mL in the first (t = 0) and between 1.43 +/- .15 and 2.61 +/- .72 ng/mL in the second (t = 18) blood samples. Likewise, when cows were sampled sequentially once a day, the order of sampling between and within groups did not influence (P > .05) plasma cortisol concentrations. In contrast, primiparous dairy cows that were less used to being handled showed an average increase in cortisol concentrations when five samples were collected by venipuncture 15 min apart. During successive sampling sessions, however, the cows did not decrease or increase plasma cortisol concentrations in response to repeated serial sampling at the group level (P > .05). Between individuals, the maximum effect of repeated venipuncture on cortisol concentrations (4.5 to 22.6 ng/mL), the time at which the effect reached its maximum (30 to 60 min), and the consistency of the response pattern over successive series varied largely. The results of this study show that in cows that were accustomed to handling and to being restrained, baseline cortisol concentrations can be measured in single blood samples that are collected by jugular puncture within 1 min after first approaching the cow. When successive blood samples need to be collected within 15 to 20 min, jugular puncture may induce an increase in cortisol concentration, which seems to depend on the handling experience of the animals and on individual differences.     

外源性金属硫蛋白对奶牛泌乳性能和抗氧化状况的影响

选取24头中国荷斯坦奶牛经产泌乳母牛,随机等分为A、B、C、D四组,分别每头静脉注射经生理盐水溶解的Zn-MT 0 (对照),4.0,8.0和12.0 mg,以探讨外源性金属硫蛋白(MT)对奶牛泌乳性能和血清抗氧化状况的影响。结果表明,C和D组的4％标准乳产量均显著高于对照组(P<0.05),但各组间的乳脂率无显著差异(P>0.05)。B、C和D组血清谷胱甘肽过氧化物酶(GSH-Px)活性均显著高于对照组(P<0.05)。D组血清过氧化氢酶(CAT)活性分别显著高于B组(P<0.05)和对照组(P<0.01);C组血清CAT活性也显著高于对照组(P<0.05)。C和D组总抗氧化能力(T-AOC)分别显著高于对照组和B组(P<0.05)。B、C和 D组血清丙二醛(MDA)含量均显著低于对照组(P<0.05)。说明MT不失为一种能够有效调控奶牛泌乳量和抗氧化能力的生理活性物质和高效抗氧化剂。     

产褥期子宫炎对奶牛抗氧化能力、部分细胞因子、结合珠蛋白的影响

通过检测顺产后患产褥期子宫炎奶牛抗氧化能力、细胞因子变化和结合珠蛋白变化情况,为后期产褥期子宫炎治疗保健研究提供参考。选用20头产后健康荷斯坦奶牛为对照组(N组),产褥期子宫炎5例(PM),产后前10d检测体温;分别在产后3、7、14、21d经颈静脉采血,用试剂盒检测抗氧化能力、部分细胞因子和结合珠蛋白。结果显示:PM组体温在4~10d之间高于N组,其中第5、8天差异显著;PM组CAT、T-AOC、GSH-Px分别在3、7、7d显著高于N组,2组SOD、MDA差异不显著;N组IL-6、TNF-α分别在21、14d显著高于PM组。结果表明:产褥期子宫炎奶牛CAT、T-AOC、GSH-Px等抗氧化指标升高,细胞因子IL-6、TNF-α降低,进行药物对奶牛产褥期子宫炎的治疗保健效果评价试验时可参考上述变化显著的指标。     

植物甾醇对泌乳前期奶牛生产性能及血浆生化指标的影响

本试验旨在研究添加不同剂量植物甾醇对泌乳前期荷斯坦奶牛生产性能及血浆生化指标的影响。选用泌乳期相近的健康荷斯坦奶牛24头,随机分成4组,每组6头,Ⅰ组为空白对照组,饲喂基础日粮,Ⅱ、Ⅲ、Ⅳ组分别在基础日粮中添加200、400和800 mg/d植物甾醇,研究不同添加量的植物甾醇对奶牛生产性能及血液生化指标的影响。结果表明：①各试验组血浆生化指标Ⅱ组变化最为明显。较Ⅰ组而言,Ⅱ组血浆雌激素、孕酮、催乳素、卵泡刺激素、黄体生成素、干扰素、白细胞介素2、高密度脂蛋白胆固醇均显著提高（P＜0.05）,丙二醛含量显著下降（P＜0.05）。②较Ⅰ组而言,Ⅲ组血浆白细胞介素2、高密度脂蛋白胆固醇均显著提高（P＜0.05）。③与Ⅰ组相比,Ⅳ组血浆甘油三酯含量明显下降（P＜0.05）,总超氧化物歧化酶显著提高（P＜0.05）。添加植物甾醇可提高奶牛的泌乳量,改善奶牛内源激素不平衡的状况,并促进奶牛发情,改善奶牛脂类代谢情况,改善奶牛体质,其中200 mg/d植物甾醇添加量为最适添加量。     

Effects of tryptophan supplementation on plasma tryptophan and related hormone levels in heifers and dairy cows

This study was conducted to investigate the effects of rumen-protected tryptophan (125 g tryptophan per day) in heifers and dairy cows. Blood samples from dairy cows and heifers were collected for 24h in 3-h intervals on the day before tryptophan supplementation, on day 2, 5 and 7 of tryptophan supplementation, and in heifers additionally on d 14 after tryptophan supplementation was ceased. Plasma tryptophan, melatonin, serotonin, and prolactin concentrations were determined. Tryptophan plasma concentrations on d 5 were augmented at day (11:00 h) and nighttime (02:00 h), (P<0.05) in response to tryptophan supplementation in heifers by 119% and in dairy cows by 47%, respectively, as compared with d 0. Melatonin increased (P<0.05) in response to tryptophan supplementation in heifers, but not in cows. The effect of tryptophan supplementation on plasma tryptophan and melatonin was reversible as demonstrated in heifers on d 14 after cessation of tryptophan supplementation. Serotonin and prolactin in plasma did not respond to tryptophan supplementation. However, milk yield during morning milking increased significantly in tryptophan supplemented cows on d 1, 3 and 4 as compared to the day before tryptophan supplementation. Additional blood samples were taken during afternoon milking in cows at 1-min intervals for the analyses of oxytocin and prolactin on the day before the start and on d 7 of tryptophan supplementation. Milk flow curves were recorded during milking. No effect of tryptophan supplementation on the milking related release of oxytocin and prolactin and on any characteristic of milk flow was observed. In conclusion, tryptophan supplementation caused increased plasma tryptophan in cows and heifers and plasma melatonin in heifers. However, plasma serotonin, prolactin and oxytocin release in cows remained unchanged by tryptophan supplementation. Milk yield at morning milking increased slightly and transiently in response to tryptophan supplementation.     

Effects of nutrition on reproduction in dairy cows

It is clear that nutrition is closely related to reproduction in the dairy cow. In addition to classic nutrient deficiency and excess, dry cow body condition and postpartum energy balance have a major impact on fertility. Dry cow rations must be designed to prevent milk fever, dystocia, retained placenta, other calving problems, and metritis. Most importantly, milk yield and reproductive performance should be regularly monitored to detect nutritionally associated health and performance changes that precede impairment of reproductive function.     

Selenium, thiobarbituric acid reactive substances, and thyroid hormone activation in broilers supplemented with selenium as selenized yeast or sodium selenite

The objective of this experiment was to compare the efficiencies of sodium selenite (SS) and selenized yeast (SY) supplemented at different doses (0.05 and 0.30 mg Se/kg feed) with respect to plasma glutathione peroxidase (Gpx) activity, extent of oxidative lipid injury, and thyroid hormone activation in broilers during the first four weeks of growth. Results indicate a significant increase in plasma Gpx activity and reduction in thiobarbituric acid reactive substances (TBARS) in all supplemented groups at 4 weeks of age compared to 2-week-old chicks. Plasma thyronine activation was highest in SY supplemented broilers. It can be concluded that in the first 4 weeks of broiler life selenite has a more efficient antioxidative effect which is reflected in lower plasma and liver TBARS values. However, broiler feed supplementation with selenized yeast results in a more proficient conversion of T4 to T3.     

日粮添加富硒益生菌对奶牛硒吸收转化、抗氧化能力与生产性能的影响

将36头经产荷斯坦奶牛随机分成4组,对照组喂基础日粮,富硒益生菌(Se-Pro)组每头牛添加108.2 g/d,益生菌(Pro)组每头牛添加20.8 g/d,亚硒酸钠(Na2seO3)组每头牛添加5 mg/d.试验期为产前30 d至产后3个月.于试验0、30、60、90、120 d,采血样测定全血se含量、GPx活性和血浆丙二醛(MDA)含量;于产后2(初乳)、30、60、90 d,采乳样测定se含量;产后每个月测定产奶量1次.结果显示,Se-Pro组和Na2SeO3组的全血、初乳、常乳Se含量和GPx活性均显著高于对照组和Pro组(P<0.05);Se-Pro组的全血、常乳Se含量和GPx活性(30 d除外)均显著高于Na2SeO3组(P<0.05);Se-Pro组和Na2SeO3组的血浆MDA含量均显著低于对照组和Pro组(P<0.05);Se-Pro组的血浆MDA含量均显著低于Na2SeO3组(P<0.05);与对照组相比,Se-Pro组、Pro组、Na2SeO3组的泌乳期前3个月的平均日产奶量(4%FCM)分别增加了2.96 kg/d(P=0.069)、1.64 kg/d(P>0.05)、0.69kg/d(P>0.05).结果表明,Se-Pro的作用效果优于Pro和Na2SeO3.     

鞣酸对奶牛饲料利用、产奶和抗氧化状态的影响

本研究旨在探讨日粮中添加富含鞣酸的柿子皮对泌乳期奶牛饲料利用、产奶和抗氧化状态的影响.试验将平均体重为(348.85±8.98)kg、泌乳量为(7.20±0.56)kg/d的8头奶牛随机分为2组,每组4个重复,每个重复1头奶牛.对照组饲喂玉米-米糠-菜粕型日粮,处理组在日粮中添加10％柿子皮(鞣酸含量为1.2?mg/k...     

Stability of plasma metabolites and hormones in lactating dairy cows

Plasma concentration stability of glucose, free fatty acids, ketone bodies, growth hormone, insulin were determined in lactating dairy cows. Concentrations of these metabolites and hormones were measured during a 36- to 48-hour period in 3 normal, mature dairy cows in the 2nd month of lactation. Samples were taken at 30-minute intervals; also, intensive sampling (every 10 minutes) was done at varying times in relation to feeding and milking. Of the 5 components measured, glucose concentration was the most stable, easiest to assay, and most reliable for use as a diagnostic aid in assessing metabolic carbohydrate disturbances in dairy cattle.     

Stability of plasma metabolites and hormones in parturient dairy cows

Metabolic changes that accompany the transition from parturition to lactation in dairy cows were studied. To measure these changes, plasma samples were obtained from 20 mature Holstein-Friesian dairy cows 10 days before through 10 days after parturition. They were analyzed for glucose, free fatty acids (FFA), lactic acid, ketone bodies, glucocorticoids, insulin, and growth hormone concentration. Lactic acid and glucocorticoids remained constant during the experiment, except for the day of parturition itself. In the prepartum period, changes were not detected in concentrations of hormones (glucocorticoids, insulin, and growth hormone), whereas, plasma metabolites began changing prior to parturition. Most evident were prepartum increased in FFA, ketones, and glucose. Postpartum plasma glucose concentration rapidly returned to prepartum concentrations. Plasma concentration of FFA and ketone bodies remained elevated for longer periods.     

Impact of metritis on the generation of reactive oxygen species by circulating phagocytes and plasma lipopolysaccharide concentration in peripartum dairy cows

This study examined the relationship between postpartum metritis, reactive oxygen species (ROS) generation, and plasma lipopolysaccharide (LPS) concentration in peripartum dairy cows. Blood was collected twice weekly from 2 weeks prepartum through 6 weeks postpartum. Whole blood chemiluminescence (WBCL) was measured using the luminol‐enhanced zymosan‐stimulated chemiluminescence assay. Cows were examined for uterine health disorders and classified into two groups, healthy (n = 11) and metritis (n = 5). Metritis had a significant effect on WBCL, with cows with metritis having a higher WBCL. Plasma LPS concentrations in cows with metritis were significantly higher than in healthy cows. To examine the effect of LPS on WBCL, blood was sampled in healthy peripartum cows (1 to 2 weeks prepartum, n = 8; 0 to 3 weeks postpartum, n = 11; and 4 to 8 weeks postpartum, n = 8) and incubated with LPS. At 1 endotoxin units/mL of LPS, similar to the plasma LPS concentration in cows with metritis, the WBCL increased in cows at 0 to 3 weeks postpartum. Results indicate that the increase in ROS generation and plasma LPS concentration are associated with metritis, and LPS may be responsible for enhanced ROS generation in early postpartum dairy cows.     

Effect of fasting on plasma metabolites and hormones in lactating dairy cows

Metabolic and pathophysiologic changes of secondary ketosis were studied. Plasma samples were obtained from a group of 8 mature, lactating dairy cows before, during, and after a 48-hour fast. These samples were analyzed for glucose, free fatty acids (FFA), lactic acid, ketone bodies, glucocorticoids, insulin, and growth hormone concentrations. In the prefasting period, metabolites and hormones remained constant. Lactic acid and glucocorticoids also remained stable during the entire experiment, except on the 1st day after termination of the fast, when glucocorticoids increased significantly (P less than 0.05). Glucose values decreased significantly (P less than 0.01) with the onset of fasting, began to rise halfway through the fast, and were elevated following termination of the fast. Plasma glucose concentration returned to normal by the end of the experiment. Plasma FFA concentrations increased during the early portions of the fast and decreased thereafter. Plasma ketone body concentration responded similarly, but the change occurred approximately 12 hours after the plasma FFA changes. A value determined as ketotic was reached during the fast (14.6 +/- 1.3 mg/dl). Insulin concentrations remained low during the fast and increased after fasting. Plasma growth hormone concentration increased to a new plateau in response to fasting and then decreased somewhate after fasting was ended.     

霉菌毒素对奶牛的影响及其控制措施

饲料霉变已成为全球关注的问题,而饲料的安全性将直接影响到动物产品的质量。本文主要概述了3类霉菌毒素对奶牛的危害及饲料、乳的限量标准;同时根据霉菌生活习性并结合生产实际总结霉菌污染控制措施,为合理控制饲料霉菌的污染提供依据。