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排序方式: 共有78条查询结果,搜索用时 46 毫秒
31.
J. Ertl C. Edel E.C.G. Pimentel R. Emmerling K.‐U. Götz 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2018,135(3):151-158
Single‐step models including dominance can be an enormous computational task and can even be prohibitive for practical application. In this study, we try to answer the question whether a reduced single‐step model is able to estimate breeding values of bulls and breeding values, dominance deviations and total genetic values of cows with acceptable quality. Genetic values and phenotypes were simulated (500 repetitions) for a small Fleckvieh pedigree consisting of 371 bulls (180 thereof genotyped) and 553 cows (40 thereof genotyped). This pedigree was virtually extended for 2,407 non‐genotyped daughters. Genetic values were estimated with the single‐step model and with different reduced single‐step models. Including more relatives of genotyped cows in the reduced single‐step model resulted in a better agreement of results with the single‐step model. Accuracies of genetic values were largest with single‐step and smallest with reduced single‐step when only the cows genotyped were modelled. The results indicate that a reduced single‐step model is suitable to estimate breeding values of bulls and breeding values, dominance deviations and total genetic values of cows with acceptable quality. 相似文献
32.
Laura Plieschke Christian Edel Eduardo C. G. Pimentel Reiner Emmerling Jörn Bennewitz Kay‐Uwe Götz 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2018,135(4):286-292
Genotyping females and including them into the reference set for genomic predictions in dairy cattle is considered to provide gains in reliabilities of estimated breeding values for selection candidates. This should especially be true for low heritability traits. By the use of simulation, we extended a genomic reference set for an existing trait by including a fixed number of genotyped first‐crop daughters for one or two generations of reference sires. Moreover, we calculated results for the effects of a similar strategy in a situation where for a new trait the recording of phenotypes has recently started. For this case, we compared the effect of two different genotyping strategies: first, to phenotype cows but to genotype their sires only, and second, to collect phenotypes and genotypes on the same cows. We studied the effects on validation reliabilities and unbiasedness of predicted values for selection candidates. We found that by extending the reference set with genotyped daughters it is possible to increase the validation reliability of genomic breeding values. In the case of a new trait, it is always better to collect and use genotypes and phenotypes on the same animals instead of using only sire genotypes. We found that the benefits that can be achieved are sensitive to the sampling strategy used when selecting females for genotyping. 相似文献
33.
Marilene de Farias Brito Alessandra dos Santos Belo-Reis José Diomedes Barbosa Daniel Guimarães Ubiali Ana Paula de Castro Pires Elizabeth Sampaio de Medeiros Renata Pimentel Bandeira de Melo Pedro Paulo Feitosa de Albuquerque Elise Yamasaki Rinaldo Aparecido Mota 《Tropical animal health and production》2016,48(7):1497-1501
34.
35.
Guilherme Gomes Verocai Lauro Nogueira Lopes Leonardo Burlini Thaís Ribeiro Correia Clarissa Pimentel de Souza Katherina Coumendouros 《Tropical animal health and production》2009,41(7):1241-1242
This paper reports the occurrence of parasitism by the Oriental eye-fluke, Philophthalmus gralli in ostriches reared in a commercial flock from the State of Minas Gerais State, Southeastern Brazil. The two affected birds
presented lacrimation, inflammatory reaction and loss of body condition. After physical examination the birds revealed, 17
and 15 trematodes each, only in the right eyes. The economic impact of this parasite on Brazilian ostrich industry is still
undetermined, requiring further studies. 相似文献
36.
The infrared spectra recorded by Mariner 6 and 7 show reflections at 4.3 microns. which suggest the presence of solid carbon dioxide in the upper atmosphere of Mars. 相似文献
37.
38.
Land degradation: effects on food and energy resources 总被引:1,自引:0,他引:1
Pimentel D Terhune EC Dyson-Hudson R Rochereau S Samis R Smith EA Denman D Reifschneider D Shepard M 《Science (New York, N.Y.)》1976,194(4261):149-155
39.
Zoila Abad Raúl Gonzlez Irian Mendoza Aym Oliva Eulogio Pimentel Rafael Pimentel Rebeca Martínez Mario Pablo Estrada Yamilka Ramirez Amilcar Arenal 《Aquaculture (Amsterdam, Netherlands)》2007,270(1-4):541-545
Gene transfer has offered a new tool for the development of improved fish strains for aquaculture. Monosex fish populations could minimize the impact of genetically modified organisms in the environment. In Oreochromis aureus, the use of pseudofemale spawners (sex-reversed male with a female phenotype) is an alternative technique for producing genetically male tilapia offspring. O. aureus fry were treated with 17β-estradiol at 100 mg/kg of food for 45 days. We obtained 77.1% females and 45.9% in the control group. Females randomly taken from the treated group were crossed with normal males. Fry from pseudofemales producing more than 90% male progenies were submitted to 17 β-estradiol treatment to obtain F2 pseudofemales. The results of the sex-reversal were low and variable ranging between 66.0 and 84.3% females. F2 pseudofemales were crossed with transgenic males from the F70 line (O. aureus × O. urolepis hornorum) and non-transgenic (O. aureus) males. The sex ratio of progeny of F2 pseudofemale deviated significantly (P < 0.01) in favor of males in the crosses with transgenic (90.2%) and non-transgenic (89.3%) males compared to the results observed with normal females (51.0 and 52.3%, respectively). The mean fry production with pseudofemales (per m2/day) was similar to the normal females in the crosses with transgenic and non-transgenic males. To our knowledge this is the first report on the production of a near monosex population in genetically modified fish. 相似文献
40.
The effect of photoperiod and feeding frequency on larval of the Amazonian ornamental fish Pyrrhulina brevis (Steindachner, 1876)
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Galileu Crovatto Veras Marcos Ferreira Brabo Joel Artur Dias Higo Andrade Abe Zélia Maria Pimentel Nunes Luis David Solis Murgas 《Aquaculture Research》2016,47(3):797-803
This study aimed to evaluate the performance of Pyrrhulina larvae, Pyrrhulina brevis, under different photoperiods and feeding frequencies. A completely randomized design was used, with four replicates in a 5 × 2 factorial, with five photoperiods (6L:18D, 12L:12D, 16L:8D, 20L:4D, 24L:0D) and two feeding frequencies (two or four times a day). Four hundred larvae with an initial length of 4.6 ± 0.09 mm were randomly distributed in 40, 1‐L containers at a density of 10 larvae/L. Feeding was performed with Artemia nauplii in the ratio of 150 Artemia nauplii/larva/feeding. After 15 days, all larvae were euthanized for measurements of length (mm), final weight (mg), survival rate (%) and larvae uniformity in weight an length (%). The data were subjected to analysis of variance and subsequently, in case of significance, a Tukey test was performed to compare means. There was no interaction between photoperiod and feeding frequency on studied variables (P > 0.05). Likewise, there was no influence of feed rate on the same variables (P > 0.05). There was only influence of photoperiod, where the larvae subjected to longest photoperiods (24L:0D and 20L:4D) showed improved weight and length (P < 0.05). Therefore, a photoperiod of 20L:4E, with feeding twice a day is recommended. 相似文献