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Egill Gautason Goutam Sahana Guosheng Su Baldur Helgi Benjamínsson Gumundur Jhannesson Bernt Guldbrandtsen 《Journal of animal science》2021,99(7)
Icelandic Cattle is a local dairy cattle breed in Iceland. With about 26,000 breeding females, it is by far the largest among the indigenous Nordic cattle breeds. The objective of this study was to investigate the feasibility of genomic selection in Icelandic Cattle. Pedigree-based best linear unbiased prediction (PBLUP) and single-step genomic best linear unbiased prediction (ssGBLUP) were compared. Accuracy, bias, and dispersion of estimated breeding values (EBV) for milk yield (MY), fat yield (FY), protein yield (PY), and somatic cell score (SCS) were estimated in a cross validation-based design. Accuracy () was estimated by the correlation between EBV and corrected phenotype in a validation set. The accuracy () of predictions using ssGBLUP increased by 13, 23, 19, and 20 percentage points for MY, FY, PY, and SCS for genotyped animals, compared with PBLUP. The accuracy of nongenotyped animals was not improved for MY and PY, but increased by 0.9 and 3.5 percentage points for FY and SCS. We used the linear regression (LR) method to quantify relative improvements in accuracy, bias (), and dispersion () of EBV. Using the LR method, the relative improvements in accuracy of validation from PBLUP to ssGBLUP were 43%, 60%, 50%, and 48% for genotyped animals for MY, FY, PY, and SCS. Single-step GBLUP EBV were less underestimated (), and less overdispersed () than PBLUP EBV for FY and PY. Pedigree-based BLUP EBV were close to unbiased for MY and SCS. Single-step GBLUP underestimated MY EBV but overestimated SCS EBV. Based on the average accuracy of 0.45 for ssGBLUP EBV obtained in this study, selection intensities according to the breeding scheme of Icelandic Cattle, and assuming a generation interval of 2.0 yr for sires of bulls, sires of dams and dams of bulls, genetic gain in Icelandic Cattle could be increased by about 50% relative to the current breeding scheme. 相似文献
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Practical feeds for juvenile Nile tilapia (Oreochromis niloticus) prepared by replacing Rastrineobola argentea fishmeal with freshwater shrimp (Caridina nilotica) and mung bean (Vigna radiata) meals 
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下载免费PDF全文 G.K. Kubiriza A.M. Akol J. Arnason Ó. Sigurgeirsson S. Snorrason T. Tómasson H. Thorarensen 《Aquaculture Nutrition》2018,24(1):94-101
This study examined the potential of using the freshwater shrimp, Caridina nilotica (CNM), and mung beans, Vigna radiata (VRM), to replace Rastrineobola argentea fishmeal (RAF) as the primary protein source in fish feeds in East Africa. Six diets with varying proportions of RAF, CNM, VRM and full fat soybean meal were tested on Nile tilapia (initial body mass ± SD: 3.30 ± 0.27 g). The growth performance was best in groups fed diets containing either R. argentea or C. nilotica or a combination of the two. Growth was poorest in the fish fed a combination of C. nilotica and V. radiata, and intermediate in the groups fed the commercial formulation and a diet containing a combination of R. argentea and V. radiata. The cost of feed per kg of fish produced decreased with increasing inclusion of C. nilotica. The price of feed per kg fish produced was comparatively high in feeds containing V. radiata due to poor feed conversion ratio. Of all the diets tested, the price of feed per kg of fish produced was highest in the commercial formulation. Caridina nilotica is a good candidate to substitute R. argentea fishmeal in practical diets for Nile tilapia. 相似文献
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Underyearling coho salmon fry were subjected to three initial photoperiod treatments (6L18D, 10L14D, 14L10D) for two months and subsequently to three final treatments (16L8D, 9L6D1L8D, 10L14D) in a factorial design. Growth rates and seawater adaptability were monitored regularly. The groups that were exposed initially to 6L18D or 10L14D and then to 16L8D grew faster and had lower plasma sodium ion levels after seawater challenge tests than any of the other groups. Fish which were initially exposed to 6 L or 10 L daylength and then to a 9L6D1L8D skeleton photoperiod, showed a slightly lower growth rate and seawater adaptability than those given the corresponding complete 16L8D photoperiod. However fish maintained on skeleton photoperiods had significantly greater growth rates and seawater adaptability than those kept on the 10L14D photoperiod. This indicates that it is not the accumulated number of hours of exposure to light that initiates smolting, but rather the time during the day when light is experienced. Fish exposed initially to 14L10D showed little or no response to subsequent changes in photoperiod, suggesting that responsiveness to inductive photoperiods depends on the initial photoperiod treatment. 相似文献
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J. Johannsdottir H.L. Heimisdottir K. Hakonardottir L. Hrolfsdottir A. Steinarsson A.K. Imsland H. Thorarensen A.B. Bergsson R. Bjornsdottir 《Aquaculture Nutrition》2014,20(3):314-323
High larval mortalities and anatomical deformities are among the major obstacles restricting the development of Atlantic cod (Gadus morhua) aquaculture. The immune system of cod larvae is poorly developed at hatch, and innate immune parameters are therefore of importance for defence against environmental microorganisms. Two separate experiments were conducted with bioencapsulation of the live feed of cod larvae using a pollock (Pollachius virens) protein hydrolysate. Offering peptide enhanced live feed to larvae during the first weeks of exogenous feeding promoted larval development, with reduced incidence of severe deformities to 3.0% as compared with 9.6% deformities observed in the control group at 160 days posthatch. The production and distribution of IgM and lysozyme were furthermore increased in larvae fed peptide enhanced feed compared with control larvae. IgM was predominantly detected in the foregut and the epithelial lining of the digestive tract as well as in the epidermal mucus of the skin. Lysozyme was mainly detected in the epidermal mucus of the skin and in the foregut. Overall, the results indicate that live feed enhancement using a protein hydrolysate derived from pollock may reduce deformities and promote normal development during early production stages of cod larvae. 相似文献
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Arnþór Gústavsson Albert K. Imsland Snorri Gunnarsson Jón Árnason Ingólfur Arnarson Arnar F. Jónsson Heiðdís Smáradóttir Helgi Thorarensen 《Aquaculture International》2010,18(3):433-445
In order to study the possible interactive effects of salinity and photoperiod on growth, feed conversion, and blood chemistry
in juvenile halibut, 2,604 (initial mean weight 26.8 g ± 0.2 SEM) juvenile halibut were exposed to six different combinations
of salinities (13, 21, or 27‰) and photoperiods [continuous light, C and simulated natural photoperiod (65°N), SNP] for 129 days.
Improved (10–20%) growth and 10–24% higher feed conversion efficiency were observed at low and intermediate salinities compared
to the high salinity groups. Improved feed conversion efficiency (20%) and temporary growth enhancing effects (10%) of continuous
light were observed, but effects faded out as day length in the simulated natural photoperiod group increased. No interactive
effects of photoperiod and salinity on growth feed conversion or measured blood chemistry variables (blood sodium, pH level,
haematocrit, bicarbonate content, and total carbon dioxide). It is suggested that juvenile Atlantic halibut should be reared
at low and intermediate salinities and at continuous light, as this will improve growth and increase feed conversion efficiency. 相似文献
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Snorri Gunnarsson Sindri Sigurdsson Helgi Thorarensen Albert K. Imsland 《Aquaculture International》2009,17(4):385-389
The effects of different concentrations of cryoprotectant (dimethyl sulfoxide; DMSO), cooling rate and straw size on the post-thaw
motility of frozen sperm from spotted wolffish, Anarhichas minor, were studied. There was no significant difference in the post-thaw motility of sperm treated with three different concentrations
of DMSO (10, 20 and 30%). Similarly, there was no significant difference in the post-thaw motility of spermatozoa when using
different freezing rates (i.e. distance of straws from the surface of liquid N2, 4.7, 5.5 and 7.1°C min−1) and the straw size (0.5 and 1.0 ml) did not affect survival. The cryopreservation of sperm can be used to make up for the
frequent lack of sperm and/or the unsynchronised timing of sperm production in spotted wolffish males and the ovulation time
in females. The results show that sperm from spotted wolffish can be frozen to secure access to viable sperm, but further
experiments are needed in order to reveal the effect of different parameters on the post-thawing mortality and define the
optimum conditions for cryopreservation. 相似文献
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Prevelence and severity of coronary arteriosclerosis of rainbow trout is consistently and significantly related to the absolute size of the heart. Treatment of immature and mature and female trout with natural and synthetic sex streroids had the effect of increasing the relative size of the heart by an average of 54%. The disease state of the coronary arteries was not significantly affected by streroid treatment, sex of the fish or season during which the experiments were conducted. 相似文献
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Hlmfrídur Sveinsdttir Helgi Thorarensen gústa Gudmundsdttir 《Aquaculture (Amsterdam, Netherlands)》2006,260(1-4):307-314
Proteases play a key role in yolk formation and degradation during embryogenesis of marine fish. This study presents the first clear data on the involvement of trypsin and chymotrypsin activities in the embryogenesis of Atlantic cod (Gadus morhua). Both enzyme activities were shown to be present in unfertilized eggs followed by a significant decline (P < 0.01) in trypsin activity during the first 4 days post fertilization (dpf). Thereafter, the trypsin- and chymotrypsin activities increased to a maximum around day 9 pf. A decline in trypsin and chymotrypsin activities was observed from day 10 pf with minimal activity just prior to first feeding (day 15 pf). Western blot analysis, using polyclonal antibodies raised to Atlantic cod trypsins I and Y, mostly coincided with the trypsin activity profile. The novel trypsin Y was previously shown to have both trypsin- and chymotrypsin-like activities. Thus, some of the chymotrypsin activity observed in the samples may be originated from trypsin Y. The low trypsin and chymotrypsin activities just prior to first feeding (13–15 dpf) may indicate insufficient digestive function as trypsin has been shown to be a suitable short-term indicator reflecting the nutritional quality of marine fish larvae. 相似文献