乳牛产后期生理性免疫状态的研究

为了研究乳牛在产后期的生理性免疫状态，检测了产后期乳牛淋巴细胞及其亚群数量和淋巴细胞增殖活化功能及其变化。结果发现，乳牛淋巴细胞及其亚群数量和淋巴细胞增殖活化功能在分娩后第1d最低，然后表现出缓慢上升的总体趋势。CD3细胞数在产后第15d低于产后第1d，到产后第30d时达到最高值；CD4细胞数一直多于CD8细胞数；CD21细胞数在产后第15d时达到最高值，以后缓慢下降；淋巴细胞的增殖活化能力在产后第30d最高，未观察到淋巴细胞有明显的凋亡和增生现象。结果表明，乳牛免疫状态在产后第1d最低，以后逐渐升高，第15d时细胞免疫最低而体液免疫最高，第30d时细胞免疫最强。     

慎防乳牛产后瘫痪

产后瘫痪病又称生产瘫痪，是母牛产后突然发生的一种急性神经机能障碍疾病。其特征是脸、咽、舌、肠道麻痹、失去知觉及四肢瘫痪等。１病因母牛产后瘫痪与血中钙和糖的含量急剧下降有关。血钙的急剧下降是由于钙质随着初乳大量排出和副甲状腺机能障碍所致。血糖过少是由于胰腺活动增强的结果。２症状通常发生在乳牛产后２天～５天。主要表现在食欲减退或废绝，反刍及排粪停止，步态摇摆，站立不稳，后肢交替踏脚，四肢和全身肌肉发抖，随后倒地不起。产乳减少，体温降低至３５℃～３６℃，瞳孔散大，卧地，不时将头弯向胸部一侧，颈部呈特征…     

乳牛产后瘫痪的病因及治疗

乳牛产后瘫痪的病因,以产后急性缺钙之说。由来久远,但各种文献很少说明有关生化指数,作者多年来对瘫痪牛用补钙疗法,总是感到效果不尽人意,因此近年来在临床工作中,应用现代医疗设备,检测患牛和健康牛的血清含钙量,以及心肌酶谱,心电图等进行分析后,确认过去的观点有待商讨,本文认为产后瘫痪是由产犊时急剧阵痛,及其它临产因素等等造成心动过速,引发心肌缺血性损伤变性,或其它原因（如消耗性的营养疾病,疑似感冒的高温,病毒性肝炎等）引发心肌炎症变性所造成,现述如下：1病例作者从80年代初,对我场125头经产牛群的血钙含…     

乳牛产后瘫痪的诊治

乳牛生产瘫痪是高产乳牛生产后突然发生的以低血钙、低血糖、低血磷和低血钾等为主要特征的一种急性代谢疾病。多发生于第2～3胎和高产乳牛产犊后1～3d内,病牛表现四肢瘫痪,卧地不起,头颈向后侧转,丧失知觉等。     

乳牛产后瘫痪的综合防治

阐述现代乳牛场常见的乳牛产后瘫痪发生机理、临床症状、诊断、治疗和预防,通过采取综合防治措施能取得明显疗效。该病会造成乳牛淘汰,将给乳牛场带来严重损失,日常应注重加强饲养管理,尽量减少该病发生。     

八珍汤治疗牛产后缺乳两例

八珍汤由四物汤和四君子汤组成,具有补益气血的功效。牛产后虚弱,常气血亏损,造成了乳汁来源不足。本实验选用八珍汤灌喂产后缺乳病牛两例,以观察八珍汤对产后缺乳的疗效。实验所用中药药材购自广州市清平路中药材市场,每味中药单独粉碎成80目细粉。八珍汤方为:党参60g、炒白术     

运输引起乳牛产后瘫痪的诊疗报道

奶牛瘫痪一般认为主要与血钙过少有关。常见于高产奶牛，多发生在分娩后１２～７２ｈ。但２００１年５月笔者诊治的１头奶牛瘫痪却发生于产后１个月。查其原因是因为运输引起，后经治疗取得较满意的效果。现将诊疗情况报道如下。１发病情况２００１年５月下旬，我市城区奶牛饲养户林某从南平市延平区郊区购进１头６岁左右黑白花奶牛。该奶牛于１个月前分娩。在被购地畜主曾观察过该牛的体况、健康状况及产乳量。该奶牛３天的产乳量分别是２１ｋｇ、２０ｋｇ、２１．５ｋｇ，畜主认为较理想。奶牛从被购地用农用车于下午３点３０分起运至晚上…     

Effect of nutrient levels during the far‐off period on postpartum productivity in dairy cows

The present study aimed to determine the effects of differing nutrient levels during the far‐off period on postpartum metabolism and milk production in lactating cows. Twenty‐six multiparous cows were assigned to three dietary treatments in the far‐off period: a low‐energy diet (L, n = 9, 80% intake of the total digestible nutrients requirement), a moderate‐energy diet (M, n = 8, 105%) and a high‐energy diet (H, n = 9, 130%). During the close‐up period, all cows were provided with 105% intake. After parturition, all cows were fed a lactation diet. The BCS recovery was slow, and low milk yield was found in the H group. In the L group, BCS recovery was favorable after parturition, and lactation persistence was increased. The L group had low rumen endotoxin activity and a high initial ovulation rate after parturition. These findings indicate that a high‐energy diet during the far‐off period has a deleterious effect on milk production. In contrast, the restricted diet in the far‐off period increased adaptability with respect to peri‐parturition metabolic changes, improved the post‐parturition nutritional state, and increased milk production. Furthermore, it suggests that the nutrient levels in the far‐off period affect rumen endotoxin activity and reproductive function after parturition.     

Characterization of ruminal dynamics in Holstein dairy cows during the periparturient period

We used four pregnant Holstein cows to delineate ruminal adaptations as cows transitioned from one lactation to the next. Cows were fed typical diets through far-off and close-up dry periods and lactation. We measured ruminal characteristics on day 72 (late lactation), 51 (far-off dry), 23 and 9 (close-up dry) prepartum and on days 6, 20, 34, 48, 62, 76 and 90 postpartum (early lactation). Measurements included: ruminal fill (weight of actual contents), ruminal capacity (volume of rumen when fully filled), digestibilities and ruminal passage rates. Ruminal capacity tended to increase linearly during early lactation but was stable during dry and transition periods. Both total and liquid fill decreased linearly during the dry period, increased across parturition, and increased linearly through early lactation. Dry matter fill decreased as cows were fed the close-up diet at day 23 prepartum then increased near parturition and continued to increase across early lactation. Solid passage rate was greatest when cows were fed the close-up diet, and decreased throughout the transition period. In lactation, solid passage rate responded quadratically with peak at day 48 followed by decreases through day 90 postpartum. Liquid passage increased linearly across the transition period. Total tract organic matter digestibilities increased linearly over the dry period with significant increases prior to or immediately after parturition, then they remained relatively stable over early lactation until they increased at day 90. Fibre digestibilities demonstrated quadratic responses over early lactation, being higher on day 6 and day 90 than at other times. Starch digestibilities decreased linearly across both the dry and transition periods with decreases in lactation until day 62 followed by increases until day 90. High producing lactating dairy cows go through a multitude of ruminal adaptations, in terms of digestion, passage, capacity and fill, as they transition from one lactation to the next.     

Influence of a marine algae supplementation on the oxidative status of plasma in dairy cows during the periparturient period

This study was part of a larger study that addressed the effects of marine algae (ALG) supplementation in the ration of high yielding periparturient dairy cows. The objectives were to induce milk fat depression (MFD) in early lactation by feeding docosahexaenoic acid (DHA) from ALG and to determine the effects on milk production, milk components and metabolic status early post partum. This study focuses on the oxidative status in the plasma during the ALG supplementation. Plasma samples were collected from 16 Holstein Friesian cows at the day of parturition and at −1, 2, 4 and 6 weeks relative to calving with half of the cows receiving the ALG supplement (44 g DHA/d) from 3 weeks pre partum on. The following parameters were measured in plasma: ferric reducing ability of plasma (FRAP), α-tocopherol level, glutathione peroxidase activity (GSH-Px) and thiobarbituric acid reactive substances (TBARS) concentration. There was a significant effect of time for FRAP and α-tocopherol indicating changes in the plasma oxidative status around parturition. The ALG supplementation was successful in creating a milk fat depression (MFD) but could not improve the energy balance. Feeding of ALG significantly increased lipid peroxidation as measured by TBARS, probably through their high content of n-3 polyunsaturated fatty acids.     

Relationship between parity and mineral status in dairy cows during the periparturient period

Data from 65 cows were collected to clarify the relationship between parity and mineral status in Holstein cows during the periparturient period. Milk fever occurred in a second‐ and a fourth‐lactation cow at parturition. Bodyweight of cows decreased immediately after parturition, and the decreased weights of cows from 1 to 6 days after parturition ranged from 11 to 27 kg. Milk yield of multiparous cows was higher than that of primiparous cows, but Ca and P concentrations in colostrum were not affected by the parity. Plasma glucose of primiparous cows was higher than that of multiparous cows, and plasma nonesterified fatty acids of fourth‐and‐more‐lactation cows at parturition was highest. Plasma Ca concentration of cows at parturition decreased with advancing parity, and plasma inorganic P concentration of third‐and‐more‐lactation cows was lowest at parturition. Plasma parathyroid hormone of fourth‐and‐more‐lactation cows at parturition was highest, but plasma hydroxyproline and alkaline phosphatase was lowest. These results suggest that the large transfer of Ca and P to colostrum is a factor in the development of milk fever in third‐and‐more‐lactation cows.     

Association of rumen fill score and energy status during the close‐up dry period with conception at first artificial insemination in dairy cows

Recent studies have shown significant associations between prepartum energy status and postpartum fertility in dairy cows; therefore, the assessment of energy status by blood metabolites and metabolic hormones and suitable improvement of management during the prepartum period may enhance reproductive performance. Rumen fill score (RFS) is associated with feed intake; however, it is unknown whether RFS is also related to blood parameters. Therefore, this study investigated the relationship between RFS and energy status during the prepartum period, and their associations with conception at first artificial insemination (AI) after parturition. In 42 multiparous Holstein cows, RFS assessment and blood sampling were carried out twice a week during 3 weeks of the peripartum period. Ovarian cycles until AI were evaluated by measuring milk progesterone levels. Before calving, positive correlations were observed between RFS and total cholesterol, and RFS did not change in pregnant cows at first AI after parturition, whereas in non‐pregnant cows, RFS decreased gradually as the calving day approached. After calving, non‐pregnant cows showed lower energy status compared with pregnant cows, and some non‐pregnant cows showed anovulation and cessation of estrous cycle. In conclusion, RFS during the close‐up dry period is related to real‐time energy status, and is associated with postpartum energy status and conception at first AI in dairy cows. © 2016 Japanese Society of Animal Science     

Expression of fibroblast growth factor 21 in the liver of dairy cows in the transition period and during lactation

Fibroblast growth factor 21 (FGF21) has been identified as a novel hormonal factor involved in the regulation of metabolic adaptations during energy deprivation. The present study aimed to investigate the expression of the FGF21 gene in the liver of dairy cows during the transition from pregnancy to lactation. Therefore, the relative mRNA abundance of FGF21 in liver biopsy samples of 20 dairy cows in late pregnancy (3 weeks pre‐partum) and early lactation (1, 5, 14 weeks post‐partum) was determined. It was observed that hepatic mRNA abundance of FGF21 at 1 week post‐partum was dramatically increased (110‐fold) compared to 3 weeks pre‐partum (p < 0.001). With progress of lactation, mRNA concentration of FGF21 was declining; nevertheless, mRNA abundance at 5 and 14 weeks post‐partum remained 25‐ and 10‐fold increased compared to 3 weeks pre‐partum (p < 0.001). Using a gene array technique, it was found that many genes involved in fatty acid oxidation, gluconeogenesis and ketogenesis were up‐regulated during early lactation compared to late pregnancy. Moreover, there were positive linear correlations between hepatic mRNA concentration of FGF21 and mRNA concentrations of genes involved in ketogenesis as well as carnitine synthesis and carnitine uptake at various time‐points during lactation, indicating that FGF21 could play a role in ketogenesis and carnitine metabolism in the liver of dairy cows (p < 0.05). In overall, the present study shows that expression of the FGF21 gene is strongly up‐regulated during the transition period. It is assumed that the up‐regulation of FGF21 might play an important role in the adaptation of liver metabolism during early lactation in dairy cows such as in other species.     

Relationship between overfeeding and overconditioning in the dry period and the problems of high producing dairy cows during the postparturient period

Summary

In dairy cows, overfeeding during the dry period leads to overcondition at calving and to depression of appetite after calving. As a consequence, at calving overconditioned high‐producing dairy cows inevitably go into a more severe negative energy balance (NEB) postpartum than cows that have a normal appetite. During the period of NEB, the energy requirements of the cow are satisfied by lipolysis and proteolysis. Lipolysis results in an increased concentration of non esterified fatty acids (NEFA) in the blood. In the liver, these NEFA are predominantly esterified to triacylglycerols (TAG) that are secreted in very low density lipoproteins (VLDL). In early lactation in cows with a severe NEB, the capacity of the liver to maintain the export of the TAG in the form of VLDL in balance with the hepatic TAG production is not always adequate. As a result, the excess amount of TAG accumulates in the liver, leading to fatty infiltration of the liver (hepatic lipidosis or fatty liver). The NEB and/or fatty liver postpartum are frequently associated with postparturient problems. In general, a severe NEB induces changes in biochemical, endocrinological, and metabolic pathways that are responsible for production, maintenance of health, and reproduction of the postparturient dairy cow. These changes include a decrease in blood glucose and insulin concentrations, and an increase in blood NEFA concentrations. High NEFA concentrations caused by intensive lipolysis are accompanied by impairment of the immune system, making the cows more vulnerable to infections. Metabolic diseases such as ketosis, milk fever, and displaced abomasum are related to overcondition at calving. The changes in biochemical, endocrinological, and metabolic pathways are associated with delay of the first visible signs of oestrus, an increase in the interval from calving to first ovulation, a decrease in conception rate, and a prolonged calving interval. It is possible that the increased blood NEFA concentration directly impairs ovarian function.     

Effect of fat supplementation during transition period on plasma leptin and non‐esterified fatty acid concentrations in Holstein cows

The objective of this experiment was to investigate the effect of fat supplementation during the transition period on pre and postpartum body weight (BW), body condition score (BCS), non‐esterified fatty acids (NEFA), glucose and leptin concentrations in Holstein cows. Holstein cows (n = 15) received a low fat diet (LF; 1.61 Mcal net energy for lactation (NEL)/kg of dry matter [DM]), moderate fat diet (MF; 1.68 Mcal NEL/kg DM) or a high fat diet (HF; 1.74 Mcal NEL/kg DM) for 4 weeks prior to calving. All cows were fed similar lactation diets ad libitum (1.74 Mcal NEL/kg DM) for 30 days after calving. Increasing diet energy density during transition period had no effect on prepartum DMI, BCS, BW, glucose and NEFA concentrations (P > 0.05); but leptin concentrations and energy balance (EB) were affected by treatments (P < 0.05). Animals fed HF had less plasma leptin prepartum. After parturition, BW, milk production, milk fat, protein, urea nitrogen and plasma glucose concentrations were affected by prepartum diets (P < 0.05). Fat supplementation prepartum did not affect postpartum NEFA. In conclusion, prepartum fat supplementation decreased leptin concentration prepartum.     

酵母铬对围产前期奶牛抗氧化能力的影响

研究在日粮中添加不同水平的酵母铬对围产前期奶牛抗氧化性能的影响。选用20头体况和预产期相近的中国荷斯坦奶牛,随机分为4组,对照组为基础日粮,3个处理组在基础日粮中分别添加2.4、4.8和7.2g/d的酵母铬。结果显示,与对照组相比,添加酵母铬可以提高血清中总抗氧化能力（T-AOC）,超氧化物歧化酶（SOD）和谷胱苷肽过氧化物酶（GSH-Px）的活力（P〈0.01）;在4.8g/d铬水平下,与对照组相比饲喂酵母铬奶牛血清丙二醛（MDA）含量显著降低（P〈0.01）。结果表明,基础日粮添加酵母铬,0.4mg Cr/kg干物质（DM）可提高围产前期奶牛抗氧化能力。