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41年前当我即将毕业时，人们公认雌激素具有促进乳腺管道生长发育的功能；对于乳腺小叶泡发育来说，雌激素和孕酮是必要的成份，催乳素和生长激素也必不可少。对于实验室动物品种来说如果乳腺组织有发育完备的小叶泡系统，那么外源催乳素、糖皮质激素和雌激素就能够起到乳汁分泌，很难确定孕酮是否对这一过程有抑制作用。对于一些动物品种，催乳素和甲状腺素有催乳作用，而糖皮质激素却抑制泌乳。生长激素和胰岛素对泌乳的明确作用尚无定论，研究激素对奶牛乳腺发育及功能影响的文章很少。利用体外方法研究激素对乳腺的作用还不成熟，也很少有人定量研究激素对乳腺细胞数目以及牛乳成份的影响。在对血液激素水平、激素受体、生长因子、结合蛋白定量化方面以及激素的营养分配作用和激素对乳腺细胞的作用机制等方面还有待深入研究。总之，我们要避免过于局限在现有激素调节乳腺发育和泌乳功能的理解范围内，事实上泌乳的最大生理刺激是妊娠，而不是外源激素、生长因子、受体兴奋剂/拮抗物以及基因疗法等。 相似文献
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利用外源激素短处理技术,对青年期转基因山羊(10～12月龄)进行人工诱导泌乳,并分析外源激素的处理对转基因山羊乳房发育、泌乳规律、乳汁成分、身体健康的影响,评估此技术对青年转基因山羊进行人工诱导泌乳的可行性.试验组A:8只转基因母羊联合注射雌激素和孕酮(E2∶P4按1∶8)配以利血平进行人工诱导泌乳;试验组B:另7只转基因母羊采用E2∶P4按1∶3进行人工诱导泌乳;并且选择同龄的10只普通母山羊作为对照组C,人工诱导泌乳方案同试验组A;选择同龄的10只普通母山羊作为对照组D,人工诱导泌乳方案同试验组B.结果表明:①转基因山羊经高比例的雌激素水平(E2∶P4=1∶3)的诱导作用,乳腺发育充分,乳房饱满且内部充盈乳汁,乳房容积率是低雌激素水平组羊(E2∶P4=1∶8)的2倍;②最初1周,经高比例的雌激素水平诱导的转基因山羊产奶量是低比例的雌激素水平组的2倍,差异极显著(182 mL/d±25 mL/d vs 93 mL/d±12 mL/d,P<0.01);③转基因山羊经激素诱导泌乳,在最初1周内乳汁分泌量呈先下降后逐步上升的变化规律;④通过人工激素诱导转基因山羊产生的乳汁,乳糖含量为4.35%～4.66 %,乳脂含量3.71%～4.16%,蛋白质含量4.06%～4.11%,均与对照组乳汁无显著差异;⑤诱导泌乳,对山羊自身的健康无显著影响,试验后,能够恢复情期并产羔.可见外源激素人工诱导泌乳短处理技术在青年转基因山羊上应用是可行的. 相似文献
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外源蛋白水解酶对吸收、消化、瘤胃发酵和牛乳成分的影响 总被引：1，自引：0，他引：1
利用外源蛋白水解酶(EPE)对吸收、消化、瘤胃发酵和泌乳性能的影响进行了研究。8头泌乳黑白花奶牛,采用4×4拉丁方,2×2因子试验设计。日粮以大麦青贮和紫花苜蓿作为干草来源,计算满足不同的饲草和精料比[60:40和34:66,干物质为基础]。研究了4种日粮处理:高草料无外源蛋白水解酶组,高草料加外源蛋白水解酶组,低草料无外源蛋白水解酶组和低草料加外源蛋白水解酶组。外源蛋白水解酶(EPE)含有蛋白水解酶活性(纤维水解酶活性可忽略不计),制粒后以一定比率加到颗粒料中。加有外源蛋白水解酶(EPE)的日粮提高了干物质、有机物、氮、酸性洗涤纤… 相似文献
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“多微蛋白素”是利用配位化学原理生产的新型蛋白补料,含有非蛋白氮(NPN)及多种必需微量元素等。本试验研究用“多微蛋白素”按等能等氮原则取代日粮中豆饼的30%与50%,饲喂62头泌乳奶牛作试验组,与饲喂标准日粮的另62头泌乳奶牛作对照进行饲养试验,并对其中14对(两组配对)奶牛的血、乳样进行组份分析。结果发现,试验组奶牛血液 NPN、Ca、P、泌乳量、乳汁蛋白、乳脂率、比重、总乳固体等与对照组无统计差异(P>0.05)。表明“多微蛋白素”能有效取代豆饼。 相似文献
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补力他蒙是一种甲状腺蛋白(碘化酪蛋白),是由甲状腺所分泌的激素(荷尔蒙)合成的,在动物体内具有下列作用:促进母猪乳汁分泌及小猪发育,改善肉质,且可防止乳房炎、子宫炎和泌乳缺乏的混合 相似文献
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垂体促乳素(Prolactia,简写PRL)又称催乳素或生乳素,是垂体前叶分泌的一种蛋白质激素。顾名思意,PRL是促进乳汁分泌的因素。它是发动母畜泌乳和维持泌乳必不可少的激素。此外,PRL还有其它许多生理作用。早在1928年,stricher和Grueter就发现大鼠垂体提取物能促进乳腺泌乳。到1933年,Riddle和Bate从垂体提纯了那种具有促乳作用的物质,并将其命名为Prolactin。几十年来,随着分析技术的发展,对PRL的研究逐步 相似文献
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Current methods of estimating milk production in beef cows can be time-consuming, labor-intensive, and subject to high variability. The weigh-suckle-weigh (WSW) method requires repeated separation of offspring from their dams. Machine milking requires that animals be acclimated to the equipment prior to the estimation. The objective of Exp. 1 was to validate a deuterium oxide (D2O) dilution method of estimating milk production in cattle. In Exp. 1, Holstein calves (n = 5) averaging 29+/-2 d of age and 52.6+/-2.5 kg (+/- SE) were used as the model. Blood was collected for baseline D2O measurements followed by an injection of 300 mg D2O/kg BW. Syringes were weighed before and after the injection to gravimetrically determine the dose. Another blood sample was collected after D2O was allowed to equilibrate with body water for 2 h, and on each of the next five consecutive days, prior to feeding. Actual milk intake was measured by disappearance (i.e., amount of milk replacer offered to the calf minus the amount refused). Deuterium oxide in plasma was measured by mass spectrometry and milk intake was computed from the disappearance curve of D2O in blood plasma for each calf. Accumulated milk intake estimated by D2O dilution was highly correlated (y = 0.9x + 0.6; R2 = 0.99; P < 0.001) with actual milk intake. The objectives of Exp. 2 were to determine whether 1) D2O dilution was comparable to a standard measure of milk production in beef heifers and 2) growth hormone (GH) response to GH-releasing hormone (GHRH) in heifers at weaning is predictive of subsequent milk production. Deuterium oxide dilution and WSW were compared using 14 first-calf Angus heifers and their calves. Deuterium oxide dilution was used to estimate milk production of 40 first-calf Angus heifers that had been challenged with GHRH at weaning. Results indicate that the D2O dilution method is correlated (R2 = 0.89; P = 0.04) to the WSW estimation of milk production. Growth hormone response to GHRH in weanling heifers is positively related (R2 = 0.22; P = 0.03) to their subsequent milk production. Deuterium oxide dilution in calves offers an additional approach to the estimation of milk production of the dam in typical beef cattle production settings. 相似文献
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SUMMARY Thirty-six, 2- to 4-day-old Friesian bull calves were divided into 4 groups and fed milk replacer and calf starter pellets ad libitum in separate pens. Four treatments were applied; lasalocid in milk (1 mg/kg body weight/day) (M), lasalocid in starter (F), lasalocid in both milk and starter (M+F) and untreated (C). When the calves were about 2 weeks old they were each dosed orally with 550 000 sporulated Eimeria sp oocysts, mainly E zurneii and E bovis. The infection, detected by faecal excretion of oocysts, was suppressed in the M+F and M groups. There was significant excretion of oocysts in the F group but these calves did not show any clinical signs of coccidiosis. Untreated calves were affected with diarrhoea containing blood on the 24th day after inoculation. Body weight gain and intake of starter pellets was also depressed in the untreated calves during the time they were clinically affected. It is concluded that mixing lasalocid in milk replacer (or fresh milk) is an effective method of protecting young calves against early infection with coccidia. 相似文献
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Calves (n = 2) born to dams with experimentally induced brucellosis, and calves (n = 4) born to dams with naturally occurring infection were examined by the delayed-type hypersensitivity (DTH) test for possible B. abortus infection. The results were compared with the serum agglutination test, complement fixation test, and Coombs test. Five calves were nursed by their dams for 8-10 weeks after birth. One calf was separated from its dam and fed artificial milk. Three to five months after birth, four calves tested seropositive in the serologic tests. Antibodies were detected in one calf as early as 1 week after birth. The calf fed on artificial milk was seronegative 4-5 weeks after birth. All calves reacted to the DTH test antigen from week 12 until the end of the experiment, even though serologic tests were negative. We conclude that the DTH test is a valuable technique for diagnosing Brucella in calves born to infected dams. 相似文献
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J L Sartin R J Kemppainen K A Cummins D N Marple J C Williams 《American journal of veterinary research》1991,52(9):1397-1400
A study was initiated to determine whether development of a functional ruminant digestive system was associated with alterations in plasma growth hormone (GH) concentration. Holstein bull calves were fed milk or milk with grain until studied at the age of 1 month (n = 12). Calves placed on pasture with some grain supplementation were studied at the age of 3 months (n = 6) to determine plasma GH concentration in an animal with fully developed ruminant metabolism. Blood samples were taken at 10-minute intervals for 5 hours, followed by administration of bovine GH-releasing factor (0.075 micrograms/kg of body weight) and subsequent blood sample collection for 1 hour. On the following day, a blood sample was collected via jugular cannula, clonidine (10 micrograms/kg) was administered, and blood samples were subsequently obtained. Data indicated that milk-fed calves had higher mean plasma GH concentration than did either milk/grain-fed or older calves. The difference in mean plasma GH concentration was related to higher secretory pulse amplitude. Pituitary responses to bovine GH-releasing factor did not differ among the 3 groups, but response to clonidine were greater in milk-fed calves than in calves of the other groups. These data indicate that the change from a nonruminant to a ruminant-type gastrointestinal tract, perhaps attributable to subsequent changes in metabolism, may induce changes in hypothalmic function to decrease GH concentration. 相似文献
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Protection of colostral antibodies against bovine leukemia virus infection in calves on a California dairy. 总被引：1，自引：1，他引：0 
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下载免费PDF全文 M L Lassauzet W O Johnson M C Thurmond F Stevens 《Canadian journal of veterinary research》1989,53(4):424-430
A three-year prospective study involving 244 calves was undertaken on a California dairy to evaluate the protective role of colostral antibodies against bovine leukemia virus (BLV) infection in calves. Calves were followed from birth to the time they left their individual hutch (TLIH), at about 90 days of age. The probability of being infected at TLIH and the daily risk of infection between birth and TLIH were modelled using the logistic and the Cox models, respectively. Calves with no detectable antibodies during the first week of life were up to 2.00 and 2.75 times more likely to be infected at TLIH compared to calves with low and high concentrations of antibodies during the first week of life, respectively (p = 0.01). When the daily risk was modelled, calves without antibodies at the estimated day of infection were up to 3.4 and 11.6 times more likely to become infected than calves with low and high concentrations of antibodies on that day, respectively (p less than 0.001). Results indicated that calfhood infection may be reduced by about 45% through the feeding of colostrum with BLV antibodies. Further reduction in infection may be possible by feeding calves milk powder, milk replacer, and/or milk from noninfected cows. Results also indicated that quantification of the effect of a time-dependent risk factor, such as colostral antibody concentration, might be affected if treated as a fixed factor. 相似文献
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Miyazaki T Miyazaki M Yasuda J Okada K 《Veterinary journal (London, England : 1997)》2009,179(1):109-116
The aim of this study was to determine whether ultrasonography could be used to evaluate curd formation in the abomasum of preruminant calves. Holstein-Friesian calves were fed one of three milk replacers: clotting (five calves), non-clotting (four calves) and pH-dependent clotting (clots form at pH 5.5, but not at pH 6.5; six calves). Ultrasonography was performed until 6h after feeding the milk replacers. In calves fed the clotting milk replacer, a large clot of curd was visualised by ultrasonography as a clearly outlined echogenic image and whey as an anechoic image. In calves fed the non-clotting milk replacer, abomasal contents were visualised as a uniform, entirely echogenic image, indicating the absence of curd formation. In calves fed milk replacer with pH-dependent clotting properties, several small curds and whey were visualised by ultrasonography. It was concluded ultrasonography can be used to visualise abomasal curd and to distinguish the presence and absence of curds in the abomasum of calves. 相似文献
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Two milk feeding systems were investigated as influencing the health and development of calves. After the termination of colostrum feeding, the ten animals of the experimental group were given whole milk whereas the control group (also ten calves) was given the Laktosan milk replacer. By the age of three months, blood was collected from the calves for biochemical examination in weekly intervals, later once a month. The content of urea, determined in the blood plasma of the calves of the experimental group was significantly lower in the fourth to seventh week. The plasma levels of nitrogen, potassium, calcium and magnesium were about the same in the experimental and control groups, being within the limits of the reference values. At the age of six to nine weeks, the content of inorganic phosphorus in the blood plasma of the tested animals was statistically significantly higher. Vitamin A concentration in the blood plasma was about the same in both groups. The content of vitamin E in the blood plasma of the calves of the experimental group was statistically significantly higher in the fourth to eight week of age. No significant differences between the two groups were observed in the plasmatic activities of aspartate aminotransferase (AST) and gamma-glutamyl transferase (GMT). The activities of alkaline phosphatase (ALP) were significantly higher in the third to fifth week of life. From the fifth to eighteenth week of age, the average daily weight gains were significantly higher in the calves given whole milk. 相似文献
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Bittrich S Morel C Philipona C Zbinden Y Hammon HM Blum JW 《Journal of animal physiology and animal nutrition》2002,86(5-6):185-198
Morbidity and mortality of preterm neonatal calves are higher than of calves born at normal term, possibly and in part due to immaturity of physiological functions. Physiological parameters were therefore studied during the first week of life in seven preterm calves, born on day 277 of gestation after dams were injected prostaglandin F2alpha and flumethason. Calves were fed colostrum of the first milking for the first 3 days and from day 4 to day 7 the same colostrum diluted with milk replacer. Body weight increased during the first week of life by 2.2 kg. Heart rate and respiratory rate were always relatively high, whereas values of rectal temperature, blood gases, haematological, metabolic and endocrine traits were in the range and behaved similarly as is the experience in full-term neonatal calves. Major exceptions were glucose and insulin, the concentrations of which barely rose postprandially, and growth hormone, the responses of which to growth hormone releasing factor analogue 1-29 were extremely variable and in part very small. In conclusion, calves born 2 week before normal term that survived the first week of life, although physiologically immature, were well able to handle ingested nutrients and to control their metabolism. 相似文献
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S W Owens J L Sartin R J Kemppainen K A Cummins F F Bartol M A Bowman 《American journal of veterinary research》1986,47(2):263-269
Twenty-one Holstein bull calves were randomly assigned at birth to 3 groups. Two groups (each of 7 calves) were raised as follows: fed a milk diet alone or fed milk with grain supplementation after 2 weeks of age; studies were done when calves reached 4 weeks of age. The 3rd group was fed on milk with grain supplementation until weaning after which the calves were maintained on grain and pasture. These calves (older calves) were studied at 12 weeks of age. Either propionate (0.28 mmol/kg) or glucose (0.56 mmol/kg) was injected IV in a random order. Samples of blood were obtained from the calves before and immediately after injections were done and at 2, 5, 10, 15, 30, 45, and 60 minutes after secretagogue injection. Plasma was examined for glucose by a glucose oxidase procedure and for immunoreactive insulin (IRI) and glucagon (IRG) by radioimmunoassay. The IRI response to the injection of glucose was greater in older calves (P less than 0.02). Patterns of IRI secretion, as determined by heterogeneity of regression, showed age differences for both secretagogues (P less than 0.05). Base-line IRG was greater in milk/grain-fed calves than in milk-fed calves (P less than 0.05). Mean IRG response to propionate injection was higher (P less than 0.05) in milk/grain-fed calves than in milk-fed calves. Plasma glucose concentration increased in older calves, but decreased in milk-fed calves after propionate injection. The data indicate that maturation in the ruminant is accompanied by altered regulation of insulin and glucagon secretion.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
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Correction of metabolic acidosis in diarrheal calves by oral administration of electrolyte solutions with or without bicarbonate 总被引：5，自引：0，他引：5
Acid-base balance was evaluated in calves with experimentally induced viral diarrhea. When blood pH decreased to less than 7.200, calves were assigned to treatment groups and fed milk replacer, electrolyte solution without bicarbonate, or electrolyte solution containing bicarbonate. Calves in the electrolyte treatment groups had lower mortality (P less than 0.05), were better hydrated (P less than 0.05), and were less acidotic (P less than 0.05) than calves fed milk replacer. Bicarbonate-containing electrolyte solution restored acid-base balance (P less than 0.05) and corrected depression better (P less than 0.05) than electrolyte solution that did not contain bicarbonate. Both electrolyte solutions were equally good at correcting dehydration. 相似文献