奶牛产乳热的预防

文章介绍了产乳热和亚临床低血钙的发病机理,强调调整奶牛产犊前后钙磷代谢是降低代谢紊乱的关键环节.在几种传统的解决方案基础上着重介绍了阴离子盐在预防产乳热方面的作用和在生产上的应用.     

The effect of intramuscularly administered vitamin D3 on serum vitamin D metabolites and electrolytes in vitamin D3 deficient dairy cows

The effect of intramuscular administration of vitamin D₃ (1×10⁶ IU D₃/100 kg bodyweight) to 3 different dairy breeds on the serum levels of vitamin D₃, 25-OH-D₂, 25-OH-D₃, Ca, inorganic P and Mg was studied.The vitamin metabolites and the electrolytes were analysed on 9 occasions during a 36-day period. Vitamin D₃ was analysed on 6 occasions during the same period. No significant breed differences were observed except for 25-OH-D₃ (P ≤ 0.05). The D₃ level rose in 1 day from < 2 ng/ml to 906 ng/ml and decreased to below 50 % of the peak level after 6 days. At the end of the experiment (day 36) vitamin D₃ was < 2 ng/ml. 25-OH-D₃ rose from < 2 ng/ml to 106 ng/ml in 6 days and stayed at this level during the whole experiment. 25-OH-D₂ decreased from 16 ng/ml to 5 ng/ml during the observation period.     

Fat-soluble vitamin nutrition for dairy cattle

The need for supplementation of dairy cow diets with fat-soluble vitamins depends on the amount of vitamins naturally present in the diet, the availability of dietary vitamins, and the vitamin utilization rate of the animal. Fresh forage contains ample amounts of the vitamin A precursor beta-carotene as well as vitamin E. Irrespective of the dietary amount, however, the availability of vitamins A, D, and E, as well as beta-carotene, can be adversely influenced by poor fat digestion, as commonly occurs due to enteric disease in young calves. In addition, high-grain diets appear to increase the amount of ruminal vitamin destruction and may thus increase vitamin requirements. The vitamin utilization rate may be increased by inflammation as well as dietary and environmental factors. The factors influencing vitamin availability and utilization rate should be considered when formulating rations. Because the vitamin requirement is variable, blood concentrations of vitamins should be monitored when conditions such as poor fertility, weak calves, and poor immune response are present.     

The monitoring, prevention, and treatment of milk fever and subclinical hypocalcemia in dairy cows

The periparturient cow undergoes a transition from non-lactating to lactating at calving. The animal is tremendously challenged to maintain calcium homeostasis. Those that fail can develop milk fever, a clinical disorder that is life threatening to the cow and predisposes the animal to a variety of other disorders. Guidelines for monitoring the incidence of hypocalcemia and methods for treating milk fever are reviewed. The physiological factors that cause milk fever and strategies for prevention of milk fever are discussed, focusing on the effects diet cation-anion difference can have on tissue sensitivity to parathyroid hormone. Another major risk factor for milk fever is hypomagnesemia, which is observed when animals are fed inadequate amounts of magnesium, or some factor is present in the diet that prevents adequate absorption of magnesium. Moderate hypomagnesemia impairs the ability of the cow to maintain calcium homeostasis and hypocalcemia occurs.     

Oral 1,25-dihydroxyvitamin D3 in prevention of milk fever

The effect of daily oral doses of 1,25-dihydroxy vitamin D₃ (1,25-(OH)₂D₃) on plasma mineral concentrations and incidence of milk fever was tested in 39 aged cows. Three dose levels of 1,25-(OH)₂D₃ (0, 100 and 200 µg/d) were compared in cows supplemented with 100 g Ca/d (250 g CaCO₃) and in cows receiving no Ca supplement. 1,25-(OH)₂D₃ treatments were given from day 5 before expected calving (day –5) until the day after calving (Calving = day 0).Expected minima in Ca concentrations in plasma were seen on day 1 in placebo treated cows, while Ca concentrations in 1,25-(OH)₂D₃ treated cows were normal or increased in the period from start of treatment until day 3–5. In the parturient period (day –1 to +2) 1 of 21 treated cows developed milk fever, as compared to 4 of 18 untreated. A pronounced hypocalcaemia developed, however, in the 1,25-(OH)₂D₃ treated cows from day 3 to 5 onwards, culminating day 8–11 with 7 cases of milk fever. Ca supplements reduced the development of hypocalcaemia in the 1,25-(OH)₂D₃ treated cows, but could not completely prevent the occurrence of milk fever.     

Historical and current perspectives on the treatment, control and pathogenesis of milk fever in dairy cattle

Milk fever has been recognised in cattle for about 215 years and its clinical signs have not changed since they were described by Victorian veterinary surgeons in the mid-nineteenth century. It was only 80 years ago that abnormal parathyroid gland function was associated with the pathogenesis of the hypocalcaemia characteristic of the disease, and the current basis for its treatment with intravenous calcium salts was established. Although this treatment is effective, most recent research has focused on preventing the disease through an understanding of the endocrine control of extracellular calcium homeostasis. In the 1970s the synthetic vitamin D analogue 1alpha-hydroxycholecalciferol was developed for intramuscular injection before a cow calved, but variable results encouraged other preventive strategies to be considered, including restricting the dietary intake of calcium, and manipulating the dietary cation-anion balance of cows before they calved. Currently, the role of extracellular calcium receptors in the parathyroid gland is under investigation as a preliminary step to devising more effective treatments and/or preventive methods for milk fever.     

奶牛流行热的临床治疗初探

奶牛流行热是由牛流行热病毒引起的一种暴发、急性、热性传染病。此病传播迅速 ,呼吸、消化器官严重卡他性炎症 ,多数病牛伴随运动障碍、产奶停止 ,特别是高产牛病情尤为严重 ,死亡率也高。一般发病都在 7～ 1 0月 ,蚌埠市郊区上一次奶牛暴发流行此病是在1 991年 7月中旬到 9月下旬 ,给饲养奶牛的村集体和农户造成很大的经济损失。到 1 997年 7月下旬至 9月下旬本病又在市郊饲养奶牛的施徐、张公山、和戴湖村再次暴发流行 ,经统计 5 2户村民饲养奶牛 347头 ,染病 2 6 5头 ,其中成母牛 2 6 3头 ,犊牛 2头 ,发病率73.8%。死亡 1 4头 ,因瘫痪淘…     

奶牛流行热的防治

牛流行热是由牛流行热病毒引起的急性、热性传染病,一般发生于夏季或夏秋之交,潜伏期一般为3～5天。流行热传播速度快、流行面广、发病率高,但死亡率低。1流行病学牛流行热是由节肢动物传播的一种病毒性传染病。蚊和库蠓是牛流行热的媒介昆虫。在自然条件下,通过吸血昆虫的叮咬     

The use of milk progesterone profiles for assessing the response to cloprostenol treatment of non-detected oestrus in dairy cattle

Post-partum milk progesterone profiles from 1400 dairy cows were used to identify 296 animals which had ovulated 50 or more days post partum without being observed in oestrus. Of these, 165 cows were left as untreated controls, being inseminated at any observed oestrus after 60 days post partum. Fixed time insemination three and four days after a single cloprostenol injection (74 cows) resulted in a short calving-to-conception interval and a lower culling rate than in control cows, while insemination at observed oestrus after cloprostenol (57 cows) resulted in an even greater improvement in these parameters. The fixed-time insemination group required significantly more services per conception than either of the other groups (P < 0.005). A study of the profiles suggested that not all of the cows had ovulated within four days of injection and that those ovulating later had a greater chance of being observed in oestrus and becoming pregnant if insemination was carried out only at observed oestrus after cloprostenol injection.     

The use of vitamin D3 and its metabolites to improve beef tenderness

Three experiments were conducted to determine whether feeding 25-hydroxyvitamin D3 (25-OH D3) or 1,25-dihydroxyvitamin D3 (1,25-(OH)2 D3) improves the tenderness of longissimus dorsi (LD), semimembranosus (SM), and infraspinatus (IF) muscles similar to supplemental vitamin D3 without leaving residual vitamin D3 and its metabolites in muscle. In the first two experiments, 24 crossbred steers were used to determine the effects of different oral amounts of 1,25-(OH)2 D3 (Exp. 1; n = 12) and 25-OH D3 (Exp. 2; n = 12) on plasma Ca2+ concentrations. In the third experiment, crossbred steers were allotted randomly to one of four treatments: 1) control placebo (n = 7); 2) 5 x 10(6) IU of vitamin D3/d (n = 9) for 9 d and harvested 2 d after last treatment; 3) single, 125-mg dose of 25-OH D3 (n = 8) 4 d before harvest; or 4) single, 500-microg dose of 1,25-(OH)2 D3 (n = 9) 3 d before harvest. The LD and SM steaks from each animal were aged for 8, 14, or 21 d, whereas steaks from the IF were aged for 14 or 21 d. All steaks were analyzed for tenderness by Warner-Bratzler shear force and for troponin-T degradation by Western blot analysis. Supplementing steers with vitamin D3 increased (P < 0.01) the concentration of vitamin D3 and 25-OH D3 in all muscles sampled. Feeding steers 25-OH D3 increased (P < 0.05) the concentration of 25-OH D3 in meat, but to an amount less than half that of cattle treated with vitamin D3. Supplemental 1,25-(OH)2 D3 did not affect (P < 0.10) shear force values; however, there was a trend (P < 0.10) for supplemental vitamin D3 and 25-OH D3 to produce LD steaks with lower shear values after 8 and 14 d of aging, and lower (P < 0.10) shear force values for the SM aged for 21 d. Analysis of Western blots indicated that LD steaks from cattle supplemented with vitamin D3 and 25-OH D3 had greater (P < 0.05) troponin-T degradation. Antemortem supplementation of 25-OH D3 seems to increase postmortem proteolysis and tenderness in the LD and SM without depositing large concentrations of residual vitamin D3 and its metabolite 25-OH D3.     

日粮中添加硒和维生素E对奶牛产奶性能及牛乳和血浆中硒和维生素E含量的影响

选择32头泌乳中期、胎次一致、泌乳量相近的中国荷斯坦奶牛,随机分为4组,分别为对照组(饲喂基础日粮)、添加有机硒组、添加维生素E组和添加有机硒+维生素E组,试验期60 d。结果显示:(1)日粮中单独添加硒和维生素E及同时添加硒和维生素E对奶牛的产奶量、乳蛋白、乳脂、乳糖和总固形物含量均无显著影响(P0.05);(2)日粮中添加硒显著提高了牛乳和血浆中硒的含量(P0.001);(3)日粮中添加维生素E显著提高了牛乳和血浆中维生素E的含量(P0.001);(4)同时添加硒和维生素E对于牛乳和血浆中硒和维生素E含量未出现增效作用。因此,在奶牛日粮中添加硒和维生素E是生产富硒奶和高维生素E奶的一种有效方法。     

提高乳牛奶产量和奶品质的几项措施

自三鹿奶粉事件以后,人们对牛奶的品质要求更高,养牛户对乳牛的产奶量更加关注,那么我们怎样做才能更好的提高乳牛奶产量和奶品质呢?科学的饲养管理是提高乳牛的奶产量和奶品质的主要途径,喂给丰富的、易消化的饲料,可提高奶中脂肪和蛋白质的含量.     

氧化应激对奶牛的危害及其防治

氧化应激是当机体遭受到体内外各种有害刺激时,氧化系统和抗氧化系统失衡,自由基的产生量超过机体的清除能力,抗氧化系统不能及时清除过多的自由基而造成的。氧化应激与多种疾病的发生相关。奶牛的代谢水平高,更易发生氧化应激。本文就奶牛氧化应激的产生、氧化应激对奶牛的影响以及如何抑制奶牛氧化应激做一综述。     

Evaluation of serum and milk ELISAs for paratuberculosis in Danish dairy cattle

A milk and a serum ELISA for detection of antibodies against Mycobacterium avium ssp. paratuberculosis (MAP) were evaluated against the complement-fixation test (CFT) and culture of faecal samples from 580 cows collected between August 1996 and December 1996. Milk and serum were obtained concurrently from six dairy herds infected with MAP and from two dairy herds without history of infection with MAP.

A cut-off value of 7 OD% was used in the ELISAs. At this cut-off value, all six culture-positive herds were positive in the serum ELISA but one was negative in the milk ELISA. All six culture-positive herds were positive in the CFT. In the two culture-negative herds, the serum and the milk ELISA deemed all serum samples negative at this cut-off value, whereas four serum samples from one of these herds were positive in the CFT. The highest cut-off value enabling the milk ELISA to record all six culture-positive herds as positive was 4 OD%. The highest cut-off value enabling the serum ELISA to record all six culture-positive herds as positive was 17 OD%. Individual-sample relative sensitivities of the ELISAs ranged from 49 to 64% and relative specificities were 80–96% at the cut-off values of 4, 7 and 17 OD%.