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Kristinn Hugason Thorvaldur Arnason Jón V Jónmundsson 《Livestock Production Science》1985,12(2):161-167
Mating results of 5649 pairings taking place in the years 1978 and 1979 were analysed. The average fertility rate for 316 stallions was found to be 85.6%. On average, 17.9 mares were mated to each stallion during the breeding season. The overall fertility (conception) rate was estimated to 82.1%, the apparent fertility rate 81.1% and the numerical productivity rate 78.0%. The sex ratio for the newborn foals was found to be 52.5% males vs 47.5% females, which is significantly different from an equal ratio of the two sexes. The generation interval from parent's birth to birth of offspring, LPO, was estimated to be 9.7 years. The generation intervals for the four different paths were: LSS=8.6, LSD=8.7, LDS=11.4 and LDD=11.6. 相似文献
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Santiago R Butron A Arnason JT Reid LM Souto XC Malvar RA 《Journal of agricultural and food chemistry》2006,54(6):2274-2279
The stem borer Sesamia nonagrioides (Lefèbvre) is the most important insect pest that attacks maize, Zea mays L., in northwestern Spain. Host plant resistance to this borer was investigated in relation to the cell wall phenylpropanoids content in the pith. Eight inbred lines that differ in resistance were analyzed. Three major simple phenolic acids, p-coumaric, trans-ferulic, and cis-ferulic acids, and three isomers of diferulic acid, 8-5', 8-O-4', and 8-5'b (benzofuran form), were identified. The amount of all these compounds was correlated with the resistance level in the genotypes, with the resistant inbreds having the highest concentrations. The role of these compounds in cell wall fortification and lignification is well-documented, suggesting their possible intervention in S. nonagrioides resistance. Future studies that focus on these compounds could be useful to enhance S. nonagroides resistance. 相似文献
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David Borchers Tiago Marques Thorvaldur Gunnlaugsson Peter Jupp 《Journal of Agricultural, Biological & Environmental Statistics》2010,15(3):346-361
Distance sampling methods assume that distances are known but in practice there are often errors in measuring them. These
can have substantial impact on the bias and precision of distance sampling estimators. In this paper we develop methods that
accommodate both systematic and stochastic measurement errors. We use the methods to estimate detection probability in two
surveys with substantial measurement error. The first is a shipboard line transect survey in the North Sea in which information
on measurement error comes from photographically measured distances to a subset of detections. The second is an aerial cue-counting
survey off Iceland in which information on measurement error comes from pairs of independently estimated distances to a subset
of detections. Different methods are required for measurement error estimation in the two cases. We investigate by simulation
the properties of the new estimators and compare them to conventional estimators. They are found to perform better than conventional
estimators in the presence of measurement error, more so in the case of cue-counting and point transect estimators than line
transect estimators. An appendix on the asymptotic distributions of conditional and full likelihood estimators is available
online. 相似文献
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M Tryland L Kleivane A Alfredsson M Kjeld A Arnason S Stuen J Godfroid 《The Veterinary record》1999,144(21):588-592
Between 1983 and 1996 a total of 1386 samples of serum were taken from four species of seal and three species of whale in the waters west of Iceland, the area of pack-ice north-west of Jan Mayen, the northern coast of Norway and the Kola Peninsula, the waters west of Svalbard, and the Barents Sea; they were tested for the presence of anti-Brucella antibodies with an indirect ELISA (protein G conjugate). The positive sera were re-tested with classical brucellosis serological tests, such as the serum agglutination test, the EDTA-modified serum agglutination test, the Rose Bengal test, and the complement fixation test, as well as an anti-complement ELISA. Anti-Brucella antibodies were detected in all the species investigated, except for the bearded seal (Erignathus barbatus), with the following prevalences: hooded seals (Cystophora cristata) 35 per cent; harp seals (Phoca groenlandica) 2 per cent; ringed seals (Phoca hispida) 10 per cent; minke whales (Balaenoptera acutorostrata) 8 per cent; fin whales (Balaenoptera physalus) 11 per cent; and sei whales (Balaenoptera borealis) 14 per cent. An isolate belonging to the genus Brucella was obtained from the liver and spleen of one of the seropositive minke whales. The findings suggest that antibodies against the surface lipopolysaccharide of Brucella species are widely distributed among marine mammals in the North Atlantic Ocean. 相似文献
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Tarduno JA Duncan RA Scholl DW Cottrell RD Steinberger B Thordarson T Kerr BC Neal CR Frey FA Torii M Carvallo C 《Science (New York, N.Y.)》2003,301(5636):1064-1069
The Hawaiian-Emperor hotspot track has a prominent bend, which has served as the basis for the theory that the Hawaiian hotspot, fixed in the deep mantle, traced a change in plate motion. However, paleomagnetic and radiometric age data from samples recovered by ocean drilling define an age-progressive paleolatitude history, indicating that the Emperor Seamount trend was principally formed by the rapid motion (over 40 millimeters per year) of the Hawaiian hotspot plume during Late Cretaceous to early-Tertiary times (81 to 47 million years ago). Evidence for motion of the Hawaiian plume affects models of mantle convection and plate tectonics, changing our understanding of terrestrial dynamics. 相似文献
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Attempts to eliminate Sarcoptes scabiei var. suis were made in 2 naturally infested sow herds, by intramuscular (i.m.) injection of doramectin (Dectomax, Pfizer, New York, USA). A single injection strategy was used. In one of the herds, the environment was treated with an acaricide following dry cleaning of floors, walls and equipment. In the second herd, no environmental treatment was performed. Results were measured by skin lesion scoring, ear scrapings to show Sarcoptes scabiei var. suis, and calculating rubbing index throughout the observation period of 20 months following treatment. Skin lesion scores decreased and stayed low following treatment for the entire observation period. Live Sarcoptes scabiei var. suis mites were isolated prior to treatment from both herds, but not following treatment. Rubbing index decreased following treatment, but was occasionally at or above 0.4. The results of these studies indicate that elimination of Sarcoptes scabiei var. suis from 2 naturally infested herds was successful, using doramectin in a single injection strategy. Precautions must be taken to ensure adequate dosing of every pig, and to avoid reinfestation due to poor biosecurity. 相似文献
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Studbook performance records for 2734 Swedish standardbred trotter broodmares have been analysed. Transformation of most variables was necessary in order to approach normality of the records. The heritability for the traits varied between 0.10 and 0.68, the lowest value for transformed “number of starts” and highest for transformed “earnings per start”. Genetic correlations were very high or high between all traits except for transformed “number of starts”. Transformed “earnings” was found to be genetically almost identical with transformed “best life-time racing time”, but more suitable for selection purposes. Several selection indices were constructed and their use in mass-selection and for adjusting for non-random distribution of dam genotypes when progeny-testing stallions is discussed. 相似文献