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排序方式: 共有412条查询结果,搜索用时 46 毫秒
81.
82.
Michele R. S. Simões Joal J. B. Leal Alessandro P. Minho Cláudia C. Gomes Michael D. MacNeil Rodrigo F. Costa Vinícius S. Junqueira Patrícia I. Schmidt Fernando F. Cardoso Arione A. Boligon Marcos J. Yokoo 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2020,137(2):177-188
Our goal was to define a breeding objective for Brangus beef cattle in Brazil. Bioeconomic models were produced and used to estimate economic values (EVs). The scenarios simulated were typical full-cycle beef production systems that are used in tropical and subtropical regions. The breeding objective contained pregnancy rate (PR), warm carcass weight (WCW), mature cow weight (MCW), number of nematode eggs per gram of faeces (EPG) and tick count (TICK). Two models were used in series to estimate the EV. A deterministic model was used to simulate effects of PR, WCW and MCW on profitability with a constant parasite load. Subsequently, stochastic models were used to estimate economic values for TICK and EPG as consequences of their environmental effects on weight gains, mortality and health costs. The EV of PR, WCW, MCW, EPG and TICK, was US$1.59, US$2.11, −US$0.24, −US$5.35 and −US$20.88, respectively. Results indicate positive emphasis should be placed on PR (12.49%) and WCW (65.07%) with negative emphasis on MCW (13.92%), EPG (2.77%) and TICK (5.75%). In comparison with the indexes usually used, these results suggest a reformulation in the selection indexes of the beef production system in tropical and subtropical regions in order to obtain greater profitability. 相似文献
83.
Stefano P. Marelli Michela Beccaglia Alessandro Bagnato Maria G. Strillacci 《Reproduction in domestic animals》2020,55(Z2):4-9
Pedigree dogs and cats are bred aiming to conform breed standards with very poor consideration for breeding stock fertility. At the same time, the genetic asset underlining reproductive traits could be effectively analysed like in other species under selection. The definition of selection targets is very important in breeding protocols determination. The aim of the present work is to present an overview of the different correlations between reproduction and genetics, starting from selection procedure and inbreeding coefficient moving to genomic and the application of SNPs and GWAS on population study and identification of genes involved in phenotypical variation of reproductive traits in dogs. Particular relevance has been given to the concept of inbreeding which effects on canine reproduction have been presented. The use of genomic information in inbreeding coefficient calculation can be considered an improved effective procedure in the evaluation of the genetic variability loss in canine population and its negative effects on reproductive traits. 相似文献
84.
Stefania Uccheddu Eliana Pintus Jose Julian Garde Lidia Fleba Marco Muzzeddu Flavia Pudda Luisella Bogliolo Alessandro Strina Stefano Nieddu Sergio Ledda 《Reproduction in domestic animals》2020,55(10):1294-1302
Habitat degradation leads to small and fragmented populations, lower genetic variability and fertility overtime. Assisted reproductive techniques represent important tools to cope with the dramatic loss of biodiversity. Fallow deer (Dama dama), beyond its high commercial value and wide distribution, may represent the most suitable model to study endangered cervids. In this study, oocytes were recovered post-mortem from fallow deer during the breeding and no breeding seasons and were in vitro matured (IVM). The ability of cryopreserved thawed sperm samples recovered by electroejaculation from four adult males was tested by in vitro fertilization of IVM oocytes. The number of oocytes collected per ovary did significantly vary across seasons from 6.2 ± 0.92 during breeding season to 10.4 ± 1.26 during no breeding season (p = .006). Oocytes collected during the breeding season showed higher in vitro fertilization rate compared to the no breeding season (p = .045). However, no embryos reached the blastocyst stage. Semen samples obtained by electroejaculation were successfully cryopreserved, although the cryopreservation process negatively affected most kinetic parameters, mainly at 2 hr post-thawing. Moreover, the percentage of rapid spermatozoa significantly decreased between fresh samples and at 2 hr post-thawing, whereas the percentage of slow spermatozoa increased across the same period (p < .05). Our study provides the logistic steps for the application of assisted reproductive techniques in fallow deer and might be of great interest for genetic resource bank planning. 相似文献
85.
Alessandro Troisi Lucia Cardinali Laura Menchetti Roberto Speranza John P. Verstegen Angela Polisca 《Reproduction in domestic animals》2020,55(4):454-459
Leptin regulates body weight and several physiological processes including reproduction. We evaluated the circulating levels of leptin in pregnant and non-pregnant bitches as well as their correlation with body weight, food intake and number of foetuses. Nineteen healthy German shepherd bitches were used and divided in two groups (pregnant n = 12 and non-pregnant n = 7). Blood samples were collected every 15 days starting from ovulation (Day 0) throughout pregnancy (pregnant group, P) or throughout luteal phase (non-pregnant group, NP) In pregnant bitches, leptin concentrations increased from the day of ovulation (1.32 ± 0.06 ng/ml) up to day 45 (1.51 ± 0.06 ng/ml; p < .01) and returned to baseline values from day 60 post-ovulation. In non-pregnant bitches, leptin concentrations remained constant throughout the whole observation period (estimated marginal mean ± SE=1.33 ± 0.38 ng/ml). Pairwise comparisons showed significant differences between P and NP at day 45 post-ovulation (p < .05). Multivariable models indicated that, controlling for time and litter size, there was a positive relationship between leptin concentration and BW (p < .05) although Pearson coefficients showed that the correlation between BW and leptin was only significant in NP animals at day 45 (r = 0.76, p < .05). The multivariable approach also suggested that, holding BW and time constant, leptin concentrations tend to increase as the number of puppies increased (p = .06). Our study supports indirectly the contribution of the feto-placental unit to the circulating maternal leptin concentration. 相似文献
86.
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88.
Paolo Fantozzi Alessandro Sensidoni 《Plant foods for human nutrition (Dordrecht, Netherlands)》1983,32(3-4):351-368
The goals of the present studies were: (1) to obtain smoking material from tobacco with reduced toxicity; (2) to use the tobacco leaf, as an alternative to other plants, as a source of food protein. On the grounds of technological, nutritional and agronomical results, the following observations can be made: (1) It is feasible to lower the toxicity of the tobacco smoke by extracting protein from the green leaves before curing. (2) The cured deproteinized tobacco can easily be utilized for the production of smoking material without any important alteration of its taste. (3) The composition of the tobacco protein concentrate is very interesting and is superior to other protein concentrates. (4) Itsin vivo andin vitro digestibility is one of the highest among the vegetable protein sources which have been studied. (5) Use of high planting densities and high levels of nitrogen fertilization per hectare results in high yields of total protein from tobacco (1794 Kg/ha). 相似文献
89.
Understanding the causes determining the radial pattern of sap flux density is important both for improving knowledge of sapwood functioning and for up-scaling sap flow measurements to canopy transpiration and ecosystem water use. To investigate the anatomical connection between whorls and annual sapwood rings, pruning-induced variation in the radial pattern of sap flux density was monitored with Granier probes in a 35-year-old Picea abies (L.) Karst tree that was pruned from the crown bottom up. Modifications in the radial pattern of sap flux density were quantified by a shape index (SI), which varies with the relative contribution of the outer and inner sapwood to tree transpiration. The SI progressively diminished during bottom up pruning, indicating a significant reduction in sap flow contribution of the inner sapwood. Results suggest that the radial pattern of sap flux density depends mainly on the vertical distribution of foliage in the crown, with lower shaded branches hydraulically connected with inner sapwood and upper branches connected with the outer rings. 相似文献
90.
Pellegrini Marco Abbiati Marco Bianchini Augusto Colangelo Marina Antonia Guzzini Alessandro Mikac Barbara Ponti Massimo Preda Giovanni Saccani Cesare Willemsen Albert 《Journal of Soils and Sediments》2020,20(6):2685-2696
Journal of Soils and Sediments - The paper aims to show the preliminary monitoring and field test results of the innovative technology tested in the framework of the MARINAPLAN PLUS LIFE project... 相似文献