共查询到19条相似文献，搜索用时 125 毫秒
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<正>维生素D通过调节钙、磷吸收维持动物机体正常功能。养殖生产中,通常采用维生素D3来满足畜禽维生素D的需要。维生素D3吸收入机体后,首先在肝脏中转化成25-羟基钙化醇(25-OH-D3)然后到达肾脏被羟化成激素形式的代谢物1,25-(OH)2-D3实现维生素D的生物学功能。研究认为Hy.D(25-OH-D3)不受肠道胆酸分泌和脂肪的影响,比维生素D3更易吸收;而且可避免维 相似文献
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早在60年前人们就已经知道维生素D是善食中的一种必要成分。1968年以来的研究表明维生素D必须在第25位和第1位碳原子上进行羟化,转化为1,25—二羟维生素D才能有力地刺激肠内钙、磷的吸收和骨吸收。由于种种原因,人们对于维生素D在反刍动物体内的代谢还所知不多。反刍动物体内维生素D代谢的复杂性及其调节钙代谢的 相似文献
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饮水添加25-OH-D3对肉仔鸡胫骨质量的影响 总被引：1，自引：0，他引：1
维生素D是促进动物机体钙磷吸收的主要因素，对动物骨骼生长有重要意义；而动物从日粮中摄取的维生素D必须转化为25-OH-D3、1,25-（OH）2-D3、25，26-（OH）2-D3等代谢物后才具有生物活性，并有效地发挥其生理生化功能。 相似文献
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25-羟D3不同添加水平对罗曼父母代种鸡生产性能的影响 总被引：2，自引：0，他引：2
25-羟基维生素D3是维生素D3的代谢物，它与维生素D3不同，更容易吸收，很少受肠道中脂肪和胆汁存在与否的影响，是维生素D3的一种活性产物。它能有效的降低蛋鸡的破蛋率、腿病发病率，提高鸡的生产性能，种蛋的受精率、孵化率和健雏率。维生素D3彼家禽或动物采食后，需要在肝脏经羟化作用转变为25-羟基维生素D3，25-羟D3经血液运送到肾脏后，在1-α-羟化酶作用下，转变为1，25-二羟基维生素D3，1，25-二羟基维生素D3为维生素D3的活性形式，可调节钙和磷结合蛋白的合成，继而调节钙和磷自小肠的吸收、运送血液钙和磷的浓度． 相似文献
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《国外畜牧学(猪与禽)》2017,(10)
<正>在养猪领域,9月展示了很多活动。全球范围内正在推出许多新举措。1 DSM公司在美国市场推出Hy·D产品化学巨头DSM公司在美国市场推出了猪用的Hy·D产品。该产品已经在其他国家/地区销售,是维生素D的一种代谢物25-OH-D3,用于补充维生素D3。该公司表示,该产品可以被动物持续有效地吸收,消除了在肝脏转化的需要,从而可以更快地达到最佳的维生素D水平。该产品有助于获得更强的骨骼结构,较高 相似文献
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1营养因素 蛋壳中91.1%的成分为无机成分,其中碳酸钙占98.4%,碳酸镁占0.75%,磷酸钙占0.75%,此外还含有微量的钾和钠。蛋壳中钙元素的直接来源为血液中的钙离子,当血液中的钙离子浓度降低时,产蛋鸡会通过胃肠道吸收钙或动员骨骼中的钙来补充。钙元素不足时,蛋鸡会产软壳蛋、薄壳蛋,蛋壳颜色变浅,骨骼变薄易断,低血钙,严重时甚至抽搐死亡。蛋鸡产蛋期应给予含钙3%~4%的日粮。如果钙含量偏高,可能会造成蛋壳表面出现碳酸钙颗粒,反而影响蛋壳质量。钙摄入严重偏高还可能导致痛风等问题。通常鸡蛋产出之前要在输卵管的子宫部停留18~20小时,并在此形成蛋壳,蛋壳的形成速度在开始时逐渐加快,大约6个小时之后达到最大速度,然后进入匀速阶段。可以看出蛋壳主要是在夜间形成的,因此下午补钙可以增加钙离子的利用率,从而提高蛋壳强度和厚度。在饲料中添加的作为钙源的石灰石粒度在3.3毫米最为合适,粉碎过细的石灰石可能在夜晚到来之前已经完全代谢掉,当血钙和骨钙都得到满足之后,多余的钙便会被排出体外而没有用于蛋壳形成。磷和钙都是骨骼的主要成分,单纯的缺磷也能够引起佝偻病和骨软症。但是磷在蛋壳中的含量极低,只有0.116%。当饲料中磷水平在0.5%以上时,会影响蛋壳质量。钙主要从十二指肠吸收进入血液。1,25-二羟胆钙化醇（1,25-二羟维生素D3）能刺激小肠黏膜合成钙结合蛋白,促进钙主动吸收。1,25-二羟维生素D3一般从维生素D2和维生素D3转化而来,因此维生素D缺乏会严重影响蛋壳质量。需要注意的是虽然在哺乳动物维生素D2和维生素D3的生物活性相等,但是在家禽体内,维生素D3的活性要比维生素D2高50~100倍。尽管太阳光可使鸡皮肤中的7-脱氢固醇转变为维生素D,但其生成量远不能满足产蛋鸡的需要。通常产蛋鸡饲料中维生素D的含量应高于2000国际单位/千克,在应激和病理状态下,应为鸡群额外补充维生素D。此外,维生素C、锌和锰等微量元素缺乏也会造成蛋壳质量下降。 相似文献
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乳牛口服大量β-胡萝卜素对维生素D3及钙磷代谢的影响 总被引：1，自引：0，他引：1
６头健康成年荷斯坦乳牛被随机均分为２组。试验组牛第１周每头口服β－胡萝卜素２３．０ｇ,以后每周每头口服１１．５ｇ,对照组不做任何处理。试验期共８周。结果表明,试验组乳牛血清钙及无机磷水平呈下降趋势;血清维生素Ｄ３活性代谢产物２５－ＯＨ－Ｄ３和１,２５－（ＯＨ）２－Ｄ３均呈现明显下降;至第５周末,血液β－胡萝卜素水平最高,２５－ＯＨ－Ｄ３水平下降非常明显。据此认为,乳牛对β－胡萝卜素的吸收存在一阈值,大剂量的β－胡萝卜素进入机体,可能直接干扰维生素Ｄ３的羟化,使其活性代谢产物呈下降趋势,但由于吸收阈值的存在,其对维生素Ｄ３和骨骼钙磷代谢的干扰作用可得到一定程度的减缓。 相似文献
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乳牛口服过量维生素A对维生素D3及钙磷代谢的影响 总被引：9，自引：0，他引：9
从北京郊区某农场选取１０头健康成年黑白花乳牛，随机分为试验（５头，每周每头口服维生素Ａ１００万单位）和对照（５头，不作任何处理）两组。８周以后检测发现，试验组血清钙和无机磷水平呈下降趋势；尾椎骨皮质变薄，密度下降，呈现骨质吸收现象；血清碱性磷酸酶显著下降（Ｐ＜０．０５）；其活性代谢产物２５－羟维生素Ｄ３（２５－ＯＨ－Ｄ３）极显著下降（Ｐ＜０．０１）；１，２５－二羟维生素Ｄ３［１，２５－（ＯＨ）２－ 相似文献
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维生素D(VD)与骨代谢的钙磷吸收有着非常密切的关系,其体内活性形式为1,25 (OH)2D3。而VD受体（VDR）是介导1,25 (OH)2D3发挥生物效应的核内生物大分子。近年来,随着对骨病研究的深入,对VDR基因与骨代谢关系的研究越来越受到国内外学者的重视。在不同群体甚至不同个体中,VDR基因极容易表现出多态性。目前大量的研究集中在VDR基因4个单核苷酸多态性（single nucleotide polymorphism,SNP）位点FokI、BsmI、ApaI、TaqI与骨代谢之间的关系。作者分别从钙吸收、骨量、骨密度、骨质疏松、佝偻病等方面对VDR基因与骨代谢关系进行综述。 相似文献
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Turkey poults were fed a vitamin D-deficient diet and examined for clinical signs and structural changes of bone and parathyroid glands. Vitamin D-deficient poults developed ricketic changes during days 10 to 14. Control poults (deficient diet plus vitamin D) did not develop rickets. In deficient poults, lengths of proliferating-prehypertrophied zones of growth plates increased significantly in the proximal tibiotarsus but were only slightly elongated in the distal tibiotarsus. Unmineralized hypertrophic chondrocyte zones increased in length rapidly in conjunction with a decrease in the length of mineralized hypertrophic degenerative zones; this occurred more rapidly in proximal than in distal tibiotarsus. Other ricketic changes included decreases in bone ash, total femoral bone ash (calcium, phosphorus, magnesium), bone length, and body weight. Plasma alkaline phosphatase was increased, calcium was normal, and phosphorus was normal or elevated. Parathyroids were hyperplastic and had foci of degeneration. Vitamin D3 metabolites 25OHD3, 1,25(OH)2D3, and 24,25(OH)2D3 were rapidly depleted. Increase in bone ash Ca/P ratios in deficient poults suggests that phosphorus may be selectively released from ricketic bone. Low 25OHD3 and 1,25(OH)2D3 of control poults early in the experiment suggests that 1,400 IU of vitamin D3/kg of feed may not be an adequate level of vitamin D3 for growing turkey poults. 相似文献
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Corbee RJ Tryfonidou MA Meij BP Kooistra HS Hazewinkel HA 《Domestic animal endocrinology》2012,42(1):43-49
Both spontaneous hypercortisolism and chronic glucocorticoid treatment are associated with osteoporosis and low circulating concentrations of 1,25-dihydroxy-vitamin D in humans. Pituitary-dependent hypercortisolism (PDH) is a common disorder in dogs, but little is known about the vitamin D status of affected dogs. Pituitary-dependent hypercortisolism in dogs can be treated effectively by hypophysectomy and subsequent hormone supplementation. Because hormone supplementation does not include GH, dogs that have undergone hypophysectomy have low circulating concentrations of GH and IGF-1, which may result in low plasma 1,25-dihydroxy-vitamin D concentrations and consequently increased parathyroid hormone secretion. The aim of this study was to determine whether dogs with PDH need vitamin D supplementation before and/or after hypophysectomy. To this end, we measured plasma concentrations of GH, IGF-1, parathyroid hormone, calcium, phosphate, and vitamin D metabolites in 12 dogs with PDH before and 8 wk after hypophysectomy and in 12 control dogs. Although plasma GH concentrations were lower in dogs with PDH than in control dogs both before and after hypophysectomy, the vitamin D status was similar. In conclusion, there is no need for vitamin D supplementation in dogs with PDH, either before or after hypophysectomy. 相似文献
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Mellanby RJ Mellor PJ Roulois A Baines EA Mee AP Berry JL Herrtage ME 《The Journal of small animal practice》2005,46(7):345-351
Protein-losing enteropathies were diagnosed in two dogs that were initially presented with diarrhoea and weight loss. Plasma biochemistry in both cases revealed low concentrations of albumin, calcium and ionised calcium. Both dogs had an elevated plasma parathyroid hormone concentration and low serum 25-hydroxyvitamin D (25[OH]D) concentration. The first dog was diagnosed with lymphangiectasia on postmortem examination, and the second dog was diagnosed with chronic lymphocytic/ plasmacytic enteritis and severe cystic mucoid changes based on endoscopic duodenal biopsies. While a causal effect was not demonstrated, the protein-losing enteropathies may have caused reduced intestinal absorption of vitamin D leading to low plasma concentrations of ionised calcium and secondary hyperparathyroidism. To the authors' knowledge, this is the first report of low ionised calcium concentrations, low 25(OH)D and 1,25-dihydroxyvitamin D concentrations, and high parathyroid hormone concentrations in dogs with protein-losing enteropathies. 相似文献
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1. Two experiments were carried out to investigate responses in performance and bone compositional and structural characteristics in broilers fed diets containing 4 concentrations of vitamin D3 (5, 20, 125 and 250 microg cholecalciferol/kg) at different concentrations of calcium, available phosphorus and vitamin A. 2. In experiment 1, body weight and tibia breaking strength were maximised at 14d with 250 microg vitamin D3/kg, tibia ash was maximised with 125 microg vitamin D3/kg. A high incidence of tibial dyschondroplasia (TD) was decreased to very low levels with 125 microg vitamin D/kg. 3. At 42d, performance and bone characteristics showed no response to vitamin D3 concentrations above 20 microg/kg. 4. Dietary vitamin A within the range 2-4 to 4.5 mg retinol/kg did not show any interaction with vitamin D3 status at either age. 5. In experiment 2, responses to vitamin D3 were strongly influenced by dietary calcium/available phosphorus. With 13 g calcium and 5 g available phosphorus/kg, performance and bone characteristics responded to vitamin D3 concentrations up to 125 microg/kg but more was needed at less optimal concentrations of calcium and available phosphorus. TD incidence was minimised with 250 microg/kg. 6. This study shows that high dietary concentrations of vitamin D3 can prevent TD. It is concluded that the vitamin D3 requirement of broilers up to 14 d of age at optimal dietary calcium and available phosphorus concentrations may be in the range 35 to 50 microg/kg for cortical bone quality and up to 250 microg/kg for prevention of TD. The vitamin D3 requirement for cortical bone quality after 14 d is not higher than 20 microg/kg. These requirements are much higher than earlier estimates and may be related to higher calcium requirements of modern broiler genotypes. Current regulations limiting maximum vitamin D3 concentrations in broiler starter diets may need to be reviewed. 相似文献
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Effects of vitamin or mineral deficiency on the morphology of medullary bone in laying hens. 总被引：2，自引：0，他引：2
Adult laying hens were fed diets deficient in phosphorus, calcium, calcium and phosphorus, and vitamin D3 to determine their effects on bone histology and parathyroid gland size. The phosphorus deficient diet caused an insignificant decrease in parathyroid size while the other diets caused significant increases. A considerable amount of individual variation in medullary bone volume and osteoid seam width was observed in all groups but, despite this, the calcium, calcium and phosphorus and vitamin D3 deficient diets clearly resulted in increased osteoid. Birds receiving diets deficient in calcium and phosphorus, and in vitamin D3 for longer periods were observed to have partially or completely resorbed medullary bone. Osteodystrophia fibrosa was noted in vitamin D3 deficient birds which had no follicular activity. 相似文献