Genetic Aspects of Reproduction in Sheep     

DR Notter 《Reproduction in domestic animals》2008,43(S2):122-128

Maintenance of high levels of realized fertility (defined as the percentage of ewes that lamb) and appropriate levels of fecundity are critical for efficient sheep production. The optimal level of fecundity in most situations is well below the maximum attainable level and can be targeted by combining selection among and within breeds with use of an expanding array of single-gene mutations affecting ovulation rate and litter size. The heritability of litter size is approximately 0.10, allowing changes of up to 2%/year from simple mass selection. Mutations in several genes associated with the transforming growth factor β superfamily ( BMPRIB , GDF9 and sex-linked BMP15 ) can increase ovulation rates by 0.7–1.5 ova in heterozygous ewes. However, ewes that are homozygous for BMP15 or GDF9 mutations are sterile, so use of these mutations requires carefully structured breeding programmes. Improvements in fertility may be critical for autumn lambing or programmes that aspire to lamb throughout the year. Selection to improve fertility in spring matings has been successful; selected adult ewes have lambing rates of 80–85% in October and early November. The selected ewes have a dramatically reduced seasonal anestrus, and many ewes continue to cycle during spring and summer. Major genes affecting seasonal breeding have not been identified in sheep. Polymorphisms in the melatonin receptor 1a gene appear to be associated with seasonal breeding in some, but not all breeds. However, functional genomic studies of genes associated with circadian and circannual rhythms have potential to reveal additional candidate genes involved in seasonal breeding.  相似文献   

Anaplasma phagocytophilum infection in horses in the Netherlands   总被引：1，自引：0，他引：1  

Butler CM  Nijhof AM  Jongejan F  van der Kolk JH 《The Veterinary record》2008,162(7):216-217

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Horse Advisory Committee III--Infectious complications--digestion (part II)     

Picavet T  Butler CM  Daha TJ  van Dooam DC  van Duijkeren E  Goehring LS  Houwers DJ  Laan TT  van Maanen C  Sloet van Oldruitenborgh-Oosterbaan MM 《Tijdschrift voor diergeneeskunde》2008,133(5):190-195

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Efficacy of meloxicam in a pain model in sheep     

IG Colditz  DR Paull  JB Lloyd  L Johnston  AH Small 《Australian veterinary journal》2019,97(1-2):23-32

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Effects of ultraviolet radiation on the growth and morphology of Hymenolepis microstoma (Cestoda)     

J H Butler  F H Whittaker  H T Spencer 《Folia parasitologica》1972,19(2):113-120

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Comparison of radiography and computed tomography to evaluate fractures of the canine tarsus          下载免费PDF全文

Danielle Butler  Sarah Nemanic  Jennifer J. Warnock 《Veterinary radiology & ultrasound》2018,59(1):43-53

Detection and accurate classification of traumatic tarsal fractures are important for identifying cases requiring surgical intervention. The aim of this prospective, experimental, methods comparison study was to directly compare the accuracy, sensitivity, and specificity of tarsal computed tomography (CT), ten‐view and two‐view digital radiographs for detecting traumatic fractures of the canine tarsus. The working hypothesis was that tarsal fractures would be detected with higher accuracy, sensitivity, and specificity using CT imaging compared to radiography, and a ten‐view would be superior to a two‐view radiographic study. Ten cadaver hind limbs of medium to large dogs received a CT scan and ten‐view radiographic study before and after induction of fractures with a hydraulic press. All bones included in the radiographic images were assessed for fractures by two observers and gross dissection was used as the gold standard. The two‐view radiographic study (dorsoplantar, lateromedial) was created from the ten‐view study and reviewed 2 years later. All limbs sustained fractures, the most common locations were the talus and calcaneus (n = 7). The sensitivity of CT was greater than ten‐view radiographic study (77% vs. 57%), while the specificity was similar (97% vs. 98%). The sensitivity and specificity of the ten‐view and two‐view radiograph studies were similar (57% vs. 55%; both 98%). Computed tomography images were reassessed postdissection to determine if failure to identify fractures resulted from observer error. Overall, CT was better than radiography for detecting fractures of the canine tarsus, however there was little improvement with ten‐view compared to two‐view radiographic studies.  相似文献   

Prevalence of Theileria orientalis types in beef cattle herds on the North Coast of New South Wales          下载免费PDF全文

AKK Proctor  M Ball  P Freeman  C Jenkins  DR Bogema 《Australian veterinary journal》2016,94(4):117-120

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Exogenous paraoxonase‐1 during oocyte maturation improves bovine embryo development in vitro          下载免费PDF全文

JAA Rincón  EM Madeira  FT Campos  B Mion  JF Silva  VA Absalón‐Medina  WR Butler  MN Corrêa  LMC Pegoraro  A Schneider 《Reproduction in domestic animals》2016,51(5):827-830

Paraoxonase‐1 (PON1) is an enzyme found in serum and follicular fluid that protects cell membrane and circulating lipids against oxidative damage. The aims of this study were to measure the direct effects of recombinant PON1 (rPON1) on bovine oocyte maturation at the molecular level (gene expression) and to measure the carry‐over effects of PON1 on pre‐implantation embryo development in vitro. COCs were submitted to IVM with the addition of 0.0, 0.02, 0.04 and 0.08 mg ml^?1 of rPON1, corresponding to an average PON1 arylesterase enzyme activity of 2.2 ± 0.4, 15.5 ± 1.5, 30.2 ± 3.0 and 57.9 ± 5.0 U ml^?1, respectively. The results indicated that addition of rPON1 during IVM improved embryo development in a dose‐dependent manner as D7 embryo development was 22.2%, 29.4%, 32.2% and 37.0% for the treatment groups, respectively (p = 0.02). In conclusion, addition of PON1 enzyme during IVM exerted dose‐related positive effects on embryo development rates to blastocysts.  相似文献   

Major compositional units of the moon: lunar prospector thermal and fast neutrons   总被引：2，自引：0，他引：2  

WC Feldman  BL Barraclough  S Maurice  RC Elphic  DJ Lawrence  DR Thomsen  AB Binder 《Science (New York, N.Y.)》1998,281(5382):1489-1493

Global maps of thermal and fast neutron fluxes from the moon suggest three end-member compositional units. A high thermal and low fast neutron flux unit correlates with the lunar highlands and is consistent with feldspathic rocks. The South Pole-Aitken basin and a strip that surrounds the nearside maria have intermediate thermal and fast neutron flux levels, consistent with more mafic rocks. There appears to be a smooth transition between the most mafic and feldspathic compositions, which correspond to low and high surface altitudes, respectively. The maria show low thermal and high fast neutron fluxes, consistent with basaltic rocks.  相似文献   

Evidence against hydrogen-based microbial ecosystems in basalt aquifers     

RT Anderson  FH Chapelle  DR Lovley 《Science (New York, N.Y.)》1998,281(5379):976-977

It has been proposed that hydrogen produced from basalt-ground-water interactions may serve as an energy source that supports the existence of microorganisms in the deep subsurface on Earth and possibly on other planets. However, experiments demonstrated that hydrogen is not produced from basalt at an environmentally relevant, alkaline pH. Small amounts of hydrogen were produced at a lower pH in laboratory incubations, but even this hydrogen production was transitory. Furthermore, geochemical considerations suggest that previously reported rates of hydrogen production cannot be sustained over geologically significant time frames. These findings indicate that hydrogen production from basalt-ground-water interactions may not support microbial metabolism in the subsurface.  相似文献