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排序方式: 共有229条查询结果,搜索用时 15 毫秒
201.
JL Yániz F López‐Gatius I García‐Ispierto G Bech‐Sàbat B Serrano C Nogareda JA Sanchez‐Nadal S Almeria P Santolaria 《Reproduction in domestic animals》2010,45(4):699-705
The aim of this study was to determine if the factors affecting the abortion rate in dairy herds with high incidence of Neospora‐associated abortions are different in pregnancies of cows and heifers chronically infected with Neospora caninum. In heifers (n = 229), an increase in the cumulative number of days with a mean relative humidity (RH) lower than 60% during the second trimester of gestation increases the risk of abortion. Yet, the likelihood of abortion was 7.6 times lower for pregnant heifers inseminated with Limousin bull semen, compared with those inseminated with Holstein‐Friesian bull semen. In pregnancies of parous cows (n = 521), an increase in rainfall and in the cumulative number of days with a mean RH lower than 60% during the second trimester of gestation increased the abortion rate. However, in contrast, an increase in the lactation number produced a decrease in the abortion rate, with a likelihood of abortion 4.8 times lower for pregnant cows inseminated with Limousin bull semen, and three times lower for those inseminated with Belgian Blue bull semen, compared with dairy cows inseminated with Holstein‐Friesian bull semen. Finally, the likelihood of abortion was 3.2 times lower for pregnancies of parous cows with low antibody titres against N. caninum (6–30 units) as compared to those with high antibody titres (≥30 units), whereas in heifers this variable had no effect. The practical recommendations of the present study include the control of the cow environment during the second trimester of gestation, the priority of culling for parous cows with higher antibody titres against N. caninum and the insemination of Neospora‐seropositive cows with semen from the Limousin breed. 相似文献
202.
RW Graham EL Lundelius MA Graham EK Schroeder RS Toomey E Anderson AD Barnosky JA Burns CS Churcher DK Grayson RD Guthrie CR Harington GT Jefferson LD Martin HG McDonald RE Morlan HA Semken SD Webb L Werdelin MC Wilson 《Science (New York, N.Y.)》1996,272(5268):1601-1606
Analyses of fossil mammal faunas from 2945 localities in the United States demonstrate that the geographic ranges of individual species shifted at different times, in different directions, and at different rates in response to late Quaternary environmental fluctuations. The geographic pattern of faunal provinces was similar for the late Pleistocene and late Holocene, but differing environmental gradients resulted in dissimilar species composition for these biogeographic regions. Modern community patterns emerged only in the last few thousand years, and many late Pleistocene communities do not have modern analogs. Faunal heterogeneity was greater in the late Pleistocene. 相似文献
203.
204.
Effects of Serum Deprivation and Cycloheximide on Cell Cycle of Low and High Passage Porcine Fetal Fibroblasts 总被引:1,自引:0,他引:1
MD Goissis HVA Caetano MG Marques FRO de Barros WB Feitosa MP Milazzotto M Binelli MEOA Assumpção JA Visintin 《Reproduction in domestic animals》2007,42(6):660-663
Arrest of cells in G0/G1 cell cycle phase is desired for nuclear transfer procedures. Serum starvation and cell cycle inhibitors are different ways to induce synchronization of the cell cycle. This study investigated the effects of serum starvation and cycloheximide (CHX) on the cell cycle of low (5th) and high (15th) passages fetal porcine fibroblasts. Cell cycle phases were determined using fluorescent activated cell sorting. Fifth passage fibroblast cultures had higher (p < 0.05) proportion of cells in G0/G1 only after 72 h of serum starvation (77.60 ± 0.65) when compared with non‐starved cells (71.44 ± 1.88). Serum starvation for all periods tested induced an increase (p < 0.05) on proportion of cells in G0/G1 on the 15th passage. No significant differences were observed on the 5th passage cultures exposed to CHX, although, on the 15th passage an increase on proportion of cells was observed after all periods of exposure (p < 0.05). These data indicates that high passage cells in vitro are more susceptible to serum starvation and CHX G0/G1 synchronization. 相似文献
205.
A Van Zyl J Daniel J Wayne C McCowan R Malik P Jelfs CJ Lavender JA Fyfe 《Australian veterinary journal》2010,88(3):101-106
Two horses were diagnosed as having Mycobacterium ulcerans infections. The first was a 21-year-old Quarterhorse-cross mare living in Mallacoota (a coastal town near the border of New South Wales and Victoria, Australia) that presented with lichenification, hair-loss and oedema on a fetlock, which subsequently ulcerated, as well as a non-healing ulcer on the wither. The second horse was a 32 year-old Standardbred gelding from Nicholson, near Bairnsdale, Victoria, that had an ulcerated lesion on its caudal thigh. Histologically, there were characteristic changes seen with M. ulcerans infections in other species, including extensive necrosis without associated granulomatous inflammation. The organisms were seen in Ziehl-Neelsen-stained smears or sections of the lesions from both horses and were isolated in culture from the first horse. A definitive diagnosis was provided by real-time polymerase chain reaction targeting the M. ulcerans-specific insertion sequence, IS2404. Delayed identification of the infectious agent in the first case led to the use of suboptimal antimicrobial therapy, resulting in failure to control the infection and the horse was subsequently euthanased. The second horse was successfully treated following surgical debulking of the centre of the lesion and one session of aggressive cryosurgery. Mycobacterium ulcerans should be considered in the differential diagnosis of unexplained lichenification with oedematous and ulcerated skin lesions in horses living in regions where this organism is endemic. 相似文献
206.
B Macías García L González Fernández C Ortega Ferrusola C Salazar‐Sandoval A Morillo Rodríguez H Rodríguez Martinez JA Tapia D Morcuende FJ Peña 《Reproduction in domestic animals》2011,46(1):141-148
Lipids were extracted from ejaculated spermatozoa from seven individual stallions to distinguish neutral lipids (NL) and polar lipids (PL) and determine their variation among stallions and their relationship with sperm quality and sperm susceptibility to lipid peroxidation. The isolated fatty acids were correlated with sperm quality (membrane integrity, mitochondrial membrane potential (ΔΨm) and expression of active caspases) and the sensitivity of the sperm plasma membrane to LPO. The miristic (C14: 0), palmitic (C16: 0), stearic (C18: 0) and oleic (C18: 1n9) acids were predominant among the NLs. Within the phospholipid fraction, the docosapentanoic acid (C22: 5n6) was dominant, albeit varying among stallions. Surprisingly, the percentage of polyunsaturated fatty acids was positively correlated with sperm quality and a low propensity for LPO, probably because these particular fatty acids provide a higher fluidity of the plasma membrane. The stallion showing the poorest sperm membrane integrity plus a high level of LPO in his ejaculate had a lower percentage (p < 0.05) of this fatty acid in his sperm plasma membranes. 相似文献
207.
208.
C Sosa A Gonzalez‐Bulnes JA Abecia F Forcada A Meikle 《Reproduction in domestic animals》2010,45(6):1033-1038
The objective of this study was to determine, in sheep, the effect of a short‐term undernutrition on growth dynamics and competence of pre‐ovulatory follicles. Synchronization of sexual cycles and induction of ovulation were performed, with progestagens and gonadotrophins, in 14 adult female sheep. Morphological characteristics and developmental competence of ovarian follicles to achieve ovulation were determined by imaging techniques (ultrasonography and laparoscopy) and blood sampling. All the animals ovulated and mean ovulation rates were similar between groups (2.0 ± 0.6 corpora lutea in control ewes and 2.2 ± 0.8 in undernourished sheep). However, nutritional restriction, even during a short period, was related to the presence of large follicles in static growing phase which, despite reaching ovulation, persisted static during the induced follicular phase and evidenced functional alterations as there was no inhibition of the development of subordinate follicles. Thus, this study suggests the existence of deleterious effects from short‐term undernutrition on functionality of pre‐ovulatory follicles, which can compromise fertility. 相似文献
209.
210.
Pingyang Liu Neil Ravenscroft Marie K. Harder Xingyi Dai 《Agriculture and Human Values》2016,33(2):291-304
This paper presents an oral history of farming in the Southern Yangtze Valley in China, covering the period from pre-liberation to recent market liberalization. Using the stories and observations of 31 elderly residents of a small water town, the paper describes the hard labor of traditional farming practices and the acquiescence of many when, post-liberation, they could leave farming for better-paid factory work. However, in a departure from conventional analyses, these oral histories suggest that the co-dependency culture of traditional farming has broken down, and farmers are unwilling to return to the land and continue farming. The changes in knowledge cultures of local farmers in recent decades are not likely to lead to pathways to working with incoming modern “outsider farmers,” nor able to be blended with potential new “urbanite” knowledges of those who might wish to increase organic farming. The current knowledge cultures of these farmers has shifted as needed to the optimization of family unit needs, naturally leading them to urbanization and the relinquishing of their ties to the land. For cultural rather than economic reasons, these farmers see themselves as the last peasant farmers of Tianshanzhuang. 相似文献