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1.
The morphology of 16–17 days old embryos from virgin heifers (VH) and repeat breeder heifers (RBH) was compared using light and electron microscopy. In addition some embryos transferred from one heifer category to the other were studied. Embryos from VH were elongated blastocysts and the oval embryonic disc had three germ layers. The ectoderm was stratified and many mitoses were seen. The endoderm lining the blastocoelic cavity consisted of almost squamous cells conjoined by tight junctions. Between the ectoderm and the endoderm the mesoderm had developed and expanded laterally and the coelom had formed. The trophoblastic cells adjacent do the embryonic disc were cylindrical, whereas those more peripheral located were cuboidal. The trophoblastic cells were conjoined by tight junctions and they had numerous long microvilli on their peripheral surface. Except in the embryonic disc region, the endodermal cells had filopodial processes towards the trophoblast. The embryos from RBH varied in appearance. One was similar to those from VH whereas the others were, more or less retarded, without formation of mesoderm. The smaller one consisted ot trophoblastic cells only. The transferred embryos (representing surviving embryos: 2 out of 9 in VH-RBH and 5 of 6 in RBH-VH) had a morphology similar to that of VH blastocytes two though, appeared somewhat retarded. It is suggested that the retarded embryos lack the ability to complete embryonic development and that the uterine environment of RBH is not favourable to sustain normal embryonic development. 相似文献
2.
山羊传染性胸膜肺炎支原体和绵羊肺炎支原体对抗菌药物敏感性的研究 总被引:4,自引:0,他引:4
测定了环丙沙星、氧氟沙星、单诺沙星、红霉素、罗红霉素、泰乐菌素、泰妙菌素、四环素等8种药物对羊肺炎支原体两个标准株Y-98和Y-goat的体外抑菌浓度以及红霉素与氧氟沙星、泰乐菌素对Y-goat和四环素与氧氟沙星、泰乐菌素对Y-98的联合药敏作用.结果表明,这8种抗菌药物对Y-goat和Y-98的MIC(μg/mL)分别为:环丙沙星0.223、0.002 23,氧氟沙星0.281、0.014 0,单诺沙星0.136、0.014 0,红霉素0.021 8、无效,罗红霉素0.032 7、无效,泰乐菌素0.042 2、0.039 0,泰妙菌素0.021 7、0.052 0,四环素0.195、0.052 0.红霉素与氧氟沙星的联合药敏指数为1,是相加作用;红霉素与泰乐菌素对Y-goat的联合药敏指数为1.5,是无关作用;四环素与氧氟沙星、泰乐菌素对Y-98的联合药敏试验指数均为0.375,是协同作用. 相似文献
3.
In vitro studies of Norwegian Red bovine semen immobilized and cryopreserved in alginate solid gel network
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AH Alm‐Kristiansen ER Gaustad G Bai FB Standerholen G Klinkenberg E Kommisrud KE Waterhouse 《Reproduction in domestic animals》2018,53(2):365-370
Development of new semen cryopreservation techniques improving sperm survival and ensuring availability of viable spermatozoa for a prolonged time‐period after AI is promising tools to reduce sensitivity of timing of AI and enhance overall fertility. The SpermVital® technology utilizes immobilization of bull spermatozoa in a solid network of alginate gel prior to freezing, which will provide a gradual release of spermatozoa after AI. The objective of this study was to compare post‐thaw sperm quality and in vitro sperm survival over time of Norwegian Red bull semen processed by the SpermVital® (SV) technology, the first commercialized production line of SpermVital® (C) and by conventional procedure applying Biladyl® extender (B). Post‐thaw sperm motility was not significantly different between SV, C and B semen (p > .05). However, sperm viability and acrosome intactness were higher for SV than C and B semen (p < .05). Small differences in DNA quality were observed (p < .05). Sperm viability after storage in uterus ex vivo was higher for SV than for C semen (p < .05). Furthermore, sperm survival in vitro over time at physiological temperature was significantly higher for SV semen than C semen as well as B semen during the incubation period of 48 hr (p < .05). In conclusion, the SpermVital® technology is improved and is more efficient in conserving post‐thaw sperm quality and results in higher sperm viability over time in vitro for SV than for C and B semen. 相似文献
4.
S. Nyman S. E. Malm H. Gustafsson B. Berglund 《Acta Agriculturae Scandinavica, Section A - Animal Sciences》2016,66(3):135-144
The presence and importance of visual oestrous symptoms and the relation to conception, breed, housing system and milk yield were studied. Data were collected from a Swedish research herd during a 16-year period. Local, secondary and primary oestrous symptoms and an overall oestrus intensity score (OI) were studied. Decreasing trends in oestrous expression and conception rates (CR), and an increase in CR with more intensive oestrus, from 24% at OI score one (very week) to 54% at OI score five (very strong) were observed. The mean interval from first to last observed oestrus symptom was long with a large variation (54?±?SD?=?32?h). Generally, irrespectively of housing system, Swedish Red cows had higher CR, more intensive oestruses and longer oestrus durations compared to Swedish Holstein cows. Local oestrous symptoms, with CR of 24–28%, were most frequently detected, which is why more attention should be paid to local oestrous symptoms. 相似文献
5.
J. P. Gustafsson D. Berggren M. Simonsson M. Zysset & J. Mulder 《European Journal of Soil Science》2001,52(4):655-665
The processes controlling the retention and release of aluminium in acid forest soils are still subject to controversy, and therefore a universal hypothesis as to what mechanisms are operating has not been firmly established. By studying the Bs horizons of Swedish and Swiss podzolized soils, and by analysing data in the literature, we have found that aluminium hydroxide, and in some cases also poorly ordered imogolite, may control Al solubility in moderately acid (pH > 4.2–4.3) Bs horizons. The strongest evidence in support of the presence of a quickly reacting Al(OH)3 pool came from the temperature dependence of Al solubility in a Bs horizon, which was consistent with the reaction enthalpy of an Al(OH)3 phase such as gibbsite, and from the observation that the ion activity product for Al(OH)3 was the same regardless of whether equilibrium was reached from over‐ or undersaturation. The pool of Al(OH)3 is commonly small and may be completely dissolved after large additions of acid. This may be explained by the continuing redissolution of reactive Al(OH)3 to form less soluble imogolite‐type phases. By using the same methods it was found that soil suspensions did not reach equilibrium with poorly ordered imogolite even after 17 days. Thus, imogolite probably does not control Al solubility in the short term in many soils despite the common occurrence of this mineral. This is due to the relatively slow kinetics of imogolite formation and dissolution, especially at low temperatures and at small solution H4SiO4 concentrations. 相似文献
6.
Paula Cederberg Jan-Gunnar Gustafsson 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(1):19-32
Abstract The potential for extending organic wine production in Chile is discussed in relation to its history and present situation. The main objective is to present an overview of the production of organic wine in Chile, its certification, and national and international markets. During the wine harvesting season in March and April 2006, the authors visited and interviewed staff at four Chilean organic wineries. The wineries were all situated in the wine-producing centre of the country and were of variable sizes. One of the certification bodies in Chile was also interviewed. In addition to the field studies and interviews in Chile, various written information has been used. Second to Argentina, Chile is the country that produces most wine in Latin America. Vineyards cover a total of 110 000 hectares of the country's two million hectares of arable land. A study carried out in 2005 showed that 2000 hectares (almost 2%) of vineyards are organically cultivated. The organic production is operated by 32 different companies, which produce organic wine mainly for exportation to the international market. In Chile, the number of certified organic wine producers has increased in recent years in a trend directed by international demand and possible competitive advantages for Chilean wines. In order for a wine to be called ‘organic’ or ‘wine made from organically grown grapes’, the cultivation and final product must be approved by a certification company. In Chile there are three main active certification bodies; one national (Certificadora Chile Orgánico, CCO) and two international (the Swiss company IMO and the German company BCS). The study reveals a country with innovation and energy but facing strong pressures from the international market and its jungle of laws and directives, and the differing prestige of different certifications and labels. Chile as a wine-producing country has many competitors, and the production of organic wine could be a way to find diversity and exploit new market ground where environmental consideration concerns and sustainability are important targets. 相似文献
7.
Parturition and retention of fetal membranes were induced with PGF2 alpha in 3 primiparous dairy cows. Starting on day 12 post partum (PP) the cows were treated with 500 micrograms i.m. of ACTH-analogue (tetracosactid) every 6 h for 6 times. Changes in plasma concentrations of cortisol, progesterone and 15-ketodihydro-PGF2 alpha were evaluated immediately after treatment. The effects on the resumption of ovarian activity were evaluated by clinical and ultrasound examinations and by progesterone and 15-ketodihydro-PGF2 alpha analyses for 56 days after parturition. Treatment was able to induce a statistically significant (p < 0.01) similar increase in cortisol and progesterone after both the 1st and the 6th injections, in all cows. No changes in 15-ketodihydro-PGF2 alpha concentrations were seen after any of the injections of ACTH-analogue. The first corpus luteum (CL) was seen on day 18 PP (cow A), and 28 (cow B) and in both cases it was followed by a normal ovarian cyclicity. No CL was observed during the whole period of study in cow C. Progesterone profiles confirmed these clinical and ultrasonographic findings. The steroid output, especially progesterone, induced by the ACTH-analogue might be a stimulus for the onset of ovarian cyclicity, since 2 of the 3 animals ovulated earlier than expected. These findings point to the fact that interference with the stress system might have a positive effect on ovarian cyclicity. The different pattern of response does however demand further studies. 相似文献
8.
Day 7 bovine embryos were microsurgically bisected and replaced into surrogate zonae pellucidae. They were fixed immediately after bisection and at various intervals of in vitro incubation at 35 °C in modified Dulbecco's medium. At the light microscopical level, the bisected embryos restored the prebisection morphology within 30 min. after splitting. The electron microscopy confirmed these findings, suggesting that day 7 bovine demi-embryos for transfer purposes, should be cultured for 30 min before morphologically evaluated. Eleven pairs of bisected day 7 bovine embryos were transferred to 11 synchronized heifers. The recipient heifers were slaughtered at day 15, and the recovered embryos evaluated. Nine of the demi-embryos developed to morphologically, normal spherical to elongated, embryos. 相似文献
9.
10.
Among the machinery found in wood manufacturing industries, routers and planers are the most commonly used. These tools, which many times are mounted on metal cylinders, actually operate only briefly, i. e., when a chip is cut from a piece of wood under process. The rest of the time the knife follows the cylinder surface and a cycloid is formed relative to the work piece, which in turn is fed into the machine. A number of knives are mounted on the cutter, which ascertain that the planed surface will become sufficiently planed and does not show too a wavy pattern. This works fine for high revolutions and low feeding speeds even if problems sometimes occur. Factories, however, naturally want to increase the overall manufacturing speed, which means that at the same time more defects are introduced at the planed surface. These defects are the result of the cutting process. In this paper, we examine, by use of a load cell, how the cutting forces vary during the formation of a wood chip. Wood is not an isotropic material and knots and other anomalies make the evaluation harder. In order to simplify the conditions, experiments are also shown from the cutting of a plastic polymer material as well as Medium Density Fibreboard (MDF). It is shown that the work piece vibrated intensely which littered all output data from the cell. Experience from the experiments however made it possible to design a computerised filter which saved only those registrations which were of interest while the others were set to zero. For beech, the forces were found to be of the magnitude 50 N/cm opposite to the feeding direction while the tranverse forces changed signs and had a magnitude of about 5 N/cm. 相似文献