Ovine hereditary chondrodysplasia (spider syndrome) in Suffolk lambs   总被引：1，自引：0，他引：1  

PH PHILLIPS  CM BUNN  CE ANDERSON 《Australian veterinary journal》1993,70(2):73-74

  相似文献   

Polymerase chain reaction‐based national surveillance programme to determine the distribution and prevalence of Taylorella equigenitalis in South African horses          下载免费PDF全文

C. E. May  A. J. Guthrie  B. Keys  C. Joone  M. Monyai  M. L. Schulman 《Equine veterinary journal》2016,48(3):307-311

  相似文献   

Prevalence,differences, and potential correlation to age,sex, breed,coat color,iris color,and geographic location in naturally occurring refractive errors in the normal equine eye from Germany and North Carolina     

Lauren N. Charnock  Michael G. Davidson  Deborah A. Keys  Brian C. Gilger  Richard J. McMullen Jr. 《Veterinary ophthalmology》2023,26(4):297-305

  相似文献   

Cellulose and hemicellulose digestibility in the stomach, small intestine and large intestine of swine   总被引：2，自引：0，他引：2  

J E Keys  J V DeBarthe 《Journal of animal science》1974,39(1):53-56

  相似文献   

Effect of suckling intensity on human growth hormone binding, biochemical composition and histological characteristics of ovine mammary glands     

R.Michael Akers  John E. Keys 《Domestic animal endocrinology》1985,2(4):159-172

Suckling both, or only one contralateral mammary gland during 15 days postpartum was utilized to study lactogenic hormone binding to mammary microsomal membranes and quantitative mammary morphology in ewes. Binding of radiolabeled human growth hormone was specific for lactogenic hormones. Non-radiolabeled human growth hormone, ovine and bovine prolactin and human placental lactogen effectively competed with radiolabeled human growth hormone for binding sites but ovine and bovine growth hormone were completely ineffective. Specific binding of radiolabeled human growth hormone to 600 μg of membrane protein averaged 23 ± 3% in all lactating glands. Neither days postpartum nor treatment of contralateral mammary glands substantially altered hormone binding in lactating glands. Specific human growth hormone binding (6 ± 0.5%) in non-suckled glands (15 days postpartum both udder halves) was significantly lower (P<0.01) than in lactating tissue but only a moderate and variable reduction in specific binding was measured in membranes from glands non-suckled for 15 days but contralateral to a suckled gland (14 ± 4%). Specific binding was approximately doubled in assays with 600 compared with 300 μg of membrane protein and the pattern of binding among variously suckled glands was not changed by treatment of membranes with 4 M MgCl₂ prior to assay. Most secretory cells from all lactating glands had rounded, basally displaced nuclei, apical fat globules, secretory vesicles and abundant densely stained basal cytoplasm (ergastoplasm). Alveolar lumenal area was maximal (50% of tissue area) and stromal tissue area was minimal. After 15 days of non-suckling (both udder halves) mammary cells were engorged with lipid, ergastoplasm was reduced and nuclei were irregularly shaped and randomly displaced compared with lactating tissue. In addition, lumenal area was reduced and stromal tissue more evident. Lack of suckling for 5 days had little apparent effect on mammary cytology. Like lactogenic hormone binding, mammary tissue morphology was only moderately altered by 15 days of non-suckling when the remaining gland was suckled. RNA concentration was lowest (2.1 ± 0.3 mg/g) in mammary tissue from ewes in which neither gland was suckled for 15 days postpartum but non-suckling interval had no significant effect when contralateral glands were suckled. DNA concentration was not significantly influenced by suckling treatments. Relative lactogenic hormone binding closely corresponded to changes in cytological and biochemical indices of secretory cell function.  相似文献   

Culturing freshwater pearl mussel Margaritifera margaritifera: a breakthrough in the conservation of an endangered species     

S.J. Preston  A. Keys  D. Roberts 《水产资源保护:海洋与淡水生态系统》2007,17(5):539-549

• 1. The freshwater pearl mussel Margaritifera margaritifera L. is globally endangered and is threatened by commercial exploitation, pollution and habitat loss throughout its range. Captive breeding would be a valuable tool in enhancing the status of M. margaritifera in the UK.
• 2. We have developed a semi‐natural system for successfully infecting juvenile brown trout with glochidial M. margaritifera, and culturing juvenile mussels in experimental tanks where glochidial M. margaritifera can excyst from fish gills and settle into sediment.
• 3. Infected fish had less than 1% mortality. Levels of infection varied among fish. Two yearly cohorts of juvenile M. margaritifera were identified from samples of sediment taken from each experimental tank. Individuals range in size from 1.4 mm (2000 cohort) to >3 mm in length (1999 cohort).
• 4. The number of juvenile M. margaritifera present in the two experimental tanks are estimated to be between 3600 (tank A) and 0 (tank B) for the putative 1999 cohort and between 6000 (tank A) and 13 000 (tank B) for the putative 2000 cohort.
• 5. This pioneering method for large‐scale cultivation of juvenile M. margaritifera is intermediate between the release of infected fish into rivers and the intensive cultivation systems developed in continental Europe and the USA for other species of unionid. This is the first time that large numbers of M. margaritifera have been cultured and represents a significant breakthrough in the conservation of this globally endangered Red Data List species. The method is straightforward and is most cost‐effective when undertaken alongside established hatchery processes.

Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

Contribution of the natural biota associated with substrates to the nutritional requirements of the post-larval shrimp, Penaeus esculentus (Haswell), inhigh-density rearing systems     

Michele A Burford  Melony J Sellars  Stuart J Arnold  Sandy J Keys  Peter J Crocos  & Nigel P Preston 《Aquaculture Research》2004,35(5):508-515

The contribution of epiphytes associated with physical substrates to the nutritional requirements of post‐larval shrimp, Penaeus esculentus Haswell, was determined in high‐density rearing systems (3000, 6000 and 11 000 m^?3). Stable isotope signatures of epiphytes on polyethylene mesh substrate, AquaMats? and tank walls were compared with shrimp signatures. Two methods were used: the determination of carbon and nitrogen natural abundance ratios; and ¹⁵N‐nitrogen enrichment ratios after the addition of ¹⁵N‐ammonium to tanks. Using the natural abundance technique and a simple mixing model, epiphytes were found to contribute substantially to the carbon requirements of post‐larval shrimp (39–53%). This was despite the addition of formulated feed at satiation levels. There was no indication of a reduced contribution of carbon from epiphytes to shrimp nutrition at higher shrimp densities. The lack of a difference in the ¹⁵N/¹⁴N ratios of the two food sources meant that mixing models could not be used to calculate the contribution of nitrogen from epiphytes vs. artificial feed to shrimp nutrition. Using the ¹⁵N‐nitrogenenrichment method, the amount of nitrogen contributed by epiphytes to shrimp nutrition over 24 h could be determined. This method showed that nitrogen from epiphytes was assimilated by shrimp. ¹⁵N‐enrichment methods provided a more accurate alternative to natural abundance techniques, particularly when the stable isotope signals ofthe food sources are similar. This experiment hasshown the benefits in providing substrates for P.esculentus in high‐density rearing systems to provide an additional food source for shrimp.  相似文献   

Growth, Survival and Reproductive Performance of Domesticated Australian Stocks of the Giant Tiger Prawn, Penaeus monodon, Reared in Tanks and Raceways   总被引：1，自引：0，他引：1  

Greg I  Coman  Peter I  Crocos  Stuart J.  Arnold  Sandy I.  Keys Nigel P.  Preston Brian  Murphy 《Journal of the World Aquaculture Society》2005,36(4):464-479

The growth, survival and reproductive performance of domesticated Australian stocks of the giant tiger shrimp Penaeus monodon were evaluated in trials conducted in 1997 and 2003. The 1997 trials assessed the performance of first generation progeny of wild broodstock from the northeast coast of Australia and fourth generation progeny of pond‐reared broodstock, which also originated from northeast coast wild stocks. In these trials, growth and survival of the shrimp were assessed when reared for 17 mo in tanks. Reproductive performance of the shrimp was assessed at 14.5 mo and 17 mo. The 2003 trials assessed the performance of first generation progeny of wild broodstock from the Gulf of Carpentaria (north coast of Australia). In these trials, growth and survival of shrimp were assessed when reared for 14 mo in tanks and raceways. Reproductive performance of the shrimp was assessed at 11 mo, 12 mo, and 15 mo. Growth and reproductive performance of the stocks varied between trials, families, ages and rearing systems. The most pronounced differences in growth and reproductive performance were between the 1997 and 2003 trials. At 11 mo of age, the average wet weight of the shrimp in the 2003 trials (females 117.1 ± 5.8 g; males 87.9 ± 7.6 g) was 200% greater than the average wet weight of shrimp in the 1997 trials (females 55.2 ± 6.8 g; males 41.2 ± 3.4 g). The reproductive performance of the shrimp was also higher in the 2003 trials in terms of the percentage of spawnings hatching (52.0% in 1997; 77.1% in 2003) and mean hatch rate (21.5% in 1997; 31.6% in 2003). Differences in the growth and reproductive performance of the tank‐reared stocks between years were indicative of significant improvements in the rearing environment, diet and husbandry techniques. Variation in the reproductive performance between families was consistent across rearing environments and at different ages and suggests the potential to improve reproductive performance through genetic selection. Notably, this study identified hatch rates of nauplii from the spawned eggs as a key area for future improvement of domesticated stocks reared in tanks and raceways. Future efforts to improve the growth and reproductive performance of domesticated P. monodon could benefit from integrating incremental improvements to husbandry with genetic selection.  相似文献   

关于内蒙古大兴安岭林区大径材培育的探讨     

策日格  刘科 《内蒙古林业调查设计》2011,34(1):58-59,65

文章通过对内蒙古大兴安岭林区培育大径材的目的、意义、必要性及方法等方面的分析,论述了大径级材培育是促进林区生态、经济和社会协调发展的有力措施。  相似文献   

Isotopic fractionation of stratospheric nitrous oxide     

YL Yung  CE Miller 《Science (New York, N.Y.)》1997,278(5344):1778-1780

We propose an isotopic fractionation mechanism, based on photolytic destruction, to explain the 15N/14N and 18O/16O fractionation of stratospheric nitrous oxide (N2O) and reconcile laboratory experiments with atmospheric observations. The theory predicts that (i) the isotopomers 15N14N16O and 14N15N16O have very different isotopic fractionations in the stratosphere, and (ii) laboratory photolysis experiments conducted at 205 nanometers should better simulate the observed isotopic fractionation of stratospheric N2O. Modeling results indicate that there is no compelling reason to invoke a significant chemical source of N2O in the middle atmosphere and that individual N2O isotopomers might be useful tracers of stratospheric air parcel motion.  相似文献