The novel use of proximal photogrammetry and terrestrial LiDAR to quantify the structural complexity of orchard trees     

Murray  Jon  Fennell  Joseph T.  Blackburn  George Alan  Whyatt  James Duncan  Li  Bo 《Precision Agriculture》2020,21(3):473-483

Precision Agriculture - Within the agrifood sector, the production of high yields is a driver for UK orchard husbandry. Currently, orchard tree management is typically a non-discriminatory method...  相似文献   

Control of western corn rootworm via RNAi traits in maize: lethal and sublethal effects of Sec23 dsRNA     

Ana M Vlez  Elane Fishilevich  Murugesan Rangasamy  Chitvan Khajuria  David G McCaskill  Adriano E Pereira  Premchand Gandra  Meghan LF Frey  Sarah E Worden  Shannon L Whitlock  Wendy Lo  Karl D Schnelle  Jamie R Lutz  Kenneth E Narva  Blair D Siegfried 《Pest management science》2020,76(4):1500-1512

  相似文献   

Mitochondrial Activity, Distribution and Segregation in Bovine Oocytes and in Embryos Produced in Vitro   总被引：7，自引：0，他引：7  

AM Tarazona  JI Rodríguez  LF Restrepo  M Olivera-Angel 《Reproduction in domestic animals》2006,41(1):5-11

Contents Bovine oocytes and embryos produced in vitro were studied to determine the mitochondrial pattern of distribution, segregation and activity using DIOC 6 and Jc-1 fluorescence. The highest fluorescence level observed in mature oocytes was taken as 100% activity and six activity levels were estimated as follows: (1) 0%, (2) 1-15%, (3) 16-30%, (4) 31-50%, (5) 51-75% and (6) 76-100%. Three patterns of mitochondrial distribution were found: (1) diffused throughout the cytoplasm in oocytes and embryos, (2) pericytoplasmic in oocytes and embryos, and (3) perinuclear only in embryos. The segregation of mitochondria in blastomeres showed two distinct patterns: (1) symmetrical with an even mitochondrial population, and (2) asymmetrical with different numbers of mitochondria in each blastomere. In immature oocytes, mitochondrial activity was very low and the distribution was diffuse or negligible, while in mature oocytes the activity was high and the distribution was diffuse or pericytoplasmic. Competent embryos up to the 16-cell stage showed intermediate levels of activity (16-50%) but activity decreased thereafter up to the blastocyst stage. Non-competent embryos showed low levels of activity (1-15%) at all stages. These results suggest that mitochondria might play an important role during early development and that a minimum threshold of activity regulates the potential competence for reaching the blastocyst stage.  相似文献   

Simulation of lean lamb production systems     

H D Blackburn  G D Snowder  H Glimp 《Journal of animal science》1991,69(1):115-124

A series of simulations were performed to evaluate the effects of mature size (WMA; 60, 70, 80 and 90 kg), slaughter weight (SW; 55, 60 and 65 kg) and three diets fed to feedlot lambs. Rations included a traditional diet (C2L) or placing weaned lambs on alfalfa for either 30 (A30) or 60 (A60) d before placing them on the C2L diet (A30-C2L and A60-C2L). Two lamb pricing schemes were used in the financial analysis of the biological results: sale price based on weight with or without adjustment for carcass fat. Placing lambs on alfalfa pasture increased ownership by 22 d on average compared to C2L. As WMA and SW increased, ownership increased from 3 to 11 d. Across nutritional treatments, fat decreased by 5.8 to 9.0% as WMA increased from 60 and 90 kg. When market lambs were priced on weight, net returns per lamb were greatest for A30-C2L or A60-C2L ($2.34 and $5.21, respectively above C2L) and for greater SW ($4.77 and $7.16 greater for SW 60 and 65 kg than for SW 55). The combination WMA of 90 kg, a SW of 65 kg and nutritional treatment of A60-C2L proved most profitable. However, when sale price was discounted for excessive fat content, the combinations WMA of 60 or 70 with a SW of 65 and A60-C2L were most profitable. The rank correlation between biological efficiency (weight gain/dry matter feed consumption) and net return, when sale price was based on weight, was found to be -.51. This was because lambs slaughtered at lighter weights had high biological efficiencies but low net returns due to a negative price margin. With negative price margins but positive feeding margins, net returns are greatest for heavier, fatter lambs fed longer.  相似文献   

Meat production in Africa: the case for a new domestic species     

J T Blackburn 《The Veterinary record》1972,90(12):349-350

  相似文献   

A comparative study of the complement fixation test for mycoplasma hyopneumoniae in SPF and non-SPF herds of swine in Illinois     

George T. Woods  Herbert S. Wright  Billie O. Blackburn 《Veterinary microbiology》1976,1(4):459-465

Serum samples from 458 swine from eight specific pathogen-free (SPF) herds swine were compared to samples from 178 swine from eight non-SPF herds in Illinois using the complement fixation (CF) test for Mycoplasma hyopneumoniae antibodies. In SPF herds, 9.4% of the samples gave positive test results, compared to 51.7% of the samples from non-SPF herds. The range of reactor rates in SPF herds was 0–26.9% and in non-SPF herds 3.4–100%. Used on herd basis with some modification, the CF test should be useful in monitoring state and nationally accredited SPF swine herds.  相似文献   

Genetic diversity in and conservation strategy considerations for Navajo Churro sheep     

Maiwashe AN  Blackburn HD 《Journal of animal science》2004,82(10):2900-2905

The objectives of this study were to 1) evaluate the genetic diversity of Navajo-Churro sheep using pedigree information; 2) examine the distribution of the Navajo-Churro population; and 3) evaluate the effect of breeder dynamics on genetic conservation of the breed. Pedigree data and breeder information (city and state) were obtained from the Navajo-Churro Sheep Breed Association. Inbreeding coefficients were calculated for each individual animal using pedigree information. A geographic information system program was used to divide the United States into four regions and overlay breeder locations, flock size, and flock inbreeding level. The small correlation between level of inbreeding and flock size (r = -0.07, P = 0.07) indicated that inbreeding levels are not different across flock sizes. The mean flock inbreeding levels ranged from 0 to 11% across regions. The level of inbreeding did not differ among regions (P = 0.15), except for Region 4 (Kansas and Missouri; P = 0.001). The number of breeders registering sheep averaged 34 per year. Most of the breeders were transient, with only eight breeders maintaining ownership for more than 7 yr. Average inbreeding level for 2000 was found to be 1.2%, with a linear increase in inbreeding of 0.1%/yr over the period studied, suggesting a minimal loss of genetic diversity for the Navajo-Churro. However, given the relatively small effective population size (92) and the transient nature of the breeders, development of an ex situ cryo-preserved germplasm bank may be the best long-term strategy for maintaining this breed's genetic diversity.  相似文献   

Changes in Blood and Semen Quality of Bulls after Artificial Infection with Mycoplasma wenyonii     

高光平  高桂生  李正苯  史秋梅  张艳英  邵新华  梁银聚 《农业科学与技术》2014,(2):261-264

[目的]验证温氏枝原体对种公牛血液和精液品质的影响。[方法]将10头健康的鲁西黄牛的种公牛随机分成2组,试验组分别于试验当天和第28天静脉注射温氏枝原体,从临床症状、血液涂片镜检、血液生理生化、精液品质和阴囊变化等方面,综合评价温氏枝原体对种公牛的影响。[结果]除个别指标外,试验组临床检查基本正常,未出现明显的血液和精液品质异常。[结论]该研究表明人工感染温氏枝原体对种公牛毒力较低,致病性不强,对血液和精液品质无明显异常。  相似文献   

Harmful moratorium on stem cell research     

Rowley JD  Blackburn E  Gazzaniga MS  Foster DW 《Science (New York, N.Y.)》2002,297(5589):1957

  相似文献   

Metapopulation dynamics, abundance, and distribution in a microecosystem     

A Gonzalez  JH Lawton  FS Gilbert  TM Blackburn  I Evans-Freke 《Science (New York, N.Y.)》1998,281(5385):2045-2047

The experimental fragmentation of landscapes of a natural ecosystem resulted in declines in the abundance and distribution of most species in the multispecies animal community inhabiting the landscapes and the extinction of many species. These declines caused the deterioration of the positive interspecific relation between local population abundance and distributional extent in this community. However, when patches were connected by habitat corridors, an immigration "rescue effect" arrested declines in both abundance and distribution and maintained the observed positive relation between them. These results demonstrate the importance of metapopulation dynamics and landscape connectivity for the persistence of populations in fragmented landscapes.  相似文献