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Closing the Yield Gap : = Improving Production Efficiency in Smallholder Farms of Nile Tilapia Through Selective Breeding.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Closing the Yield Gap :/
其他題名:	Improving Production Efficiency in Smallholder Farms of Nile Tilapia Through Selective Breeding.
作者:	Mengistu, Samuel Bekele.
面頁冊數:	1 online resource (199 pages)
附註:	Source: Dissertations Abstracts International, Volume: 84-05, Section: B.
Contained By:	Dissertations Abstracts International84-05B.
標題:	Aquaculture. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=29877833click for full text (PQDT)
ISBN:	9798352982044

Closing the Yield Gap : = Improving Production Efficiency in Smallholder Farms of Nile Tilapia Through Selective Breeding.
Mengistu, Samuel Bekele.

Closing the Yield Gap :Improving Production Efficiency in Smallholder Farms of Nile Tilapia Through Selective Breeding. - 1 online resource (199 pages)

Source: Dissertations Abstracts International, Volume: 84-05, Section: B.

Thesis (Ph.D.)--Wageningen University and Research, 2022.

Includes bibliographical references

The aim of this thesis was to optimise the breeding program of Nile tilapia for a smallholder production system, thereby contributing to closing the yield gap. From Chapter 2 to 4, we generated information that can be used to optimize the current GIFT breeding program for Nile tilapia. Identifying the major factors contributing to the current yield gap in smallholder Nile tilapia farms is crucial and the first step to any intervention. In Chapter 2, based on meta-analysis of literature, dissolved oxygen was identified as one of the major environmental factors contributing to reduced growth and FCR. In the presence of substantial dissolved oxygen differences between the environments, genotype by environment (GxE) interaction can be expected. The output from Chapter 2 was used to design the GxE interaction experiment (Chapter 3). In Chapter 3, heritabilities for harvest weight (HW 0.18 and 0.23), thermal growth coefficient (TGC, 0.21 and 0.26), survival days (0.03 and 0.04) and size traits (0.08 to 0.45) were estimated, in an attempt to indicate that these traits can be improved by selective breeding. We estimated the genetic correlation for these traits between aerated and non-aerated ponds. The genetic correlations (rg) between the aerated and non-aerated ponds for harvest weight (0.80±0.30) and growth (0.81±0.27) indicate some GxE interactions. The less than unity genetic correlation implies that the genetic improvements gained in aerated ponds will not be fully expressed in non-aerated ponds. Therefore, breeding programs should consider GxE interaction. In Chapter 4, genetic parameters for log-transformed variance of deviations (LnVar), a good indicator of resilience, were estimated. Heritable genetic variation was found for LnVar and it was noted that LnVar is more expressed in the non-aerated pond compared to the aerated pond. Finally, in Chapter 5, we estimated genetic parameters for critical swimming speed (Ucrit) and the genetic correlation between Ucrit and harvest weight of fish raised in a non-aerated pond. Substantial heritable variation was found for Ucrit. The estimated genetic correlations between Ucrit early in life and HW after grow-out in non-aerated pond, and Ucrit and growth were negative, implying that Nile tilapia with higher Ucrit early in life had lower HW and growth later in life. In this Chapter 6, the findings from the previous chapters combined and discussed their implications for breeding programs.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2023

Mode of access: World Wide Web

ISBN: 9798352982044Subjects--Topical Terms:

545878
Aquaculture.
Index Terms--Genre/Form:

542853
Electronic books.

Closing the Yield Gap : = Improving Production Efficiency in Smallholder Farms of Nile Tilapia Through Selective Breeding.
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040 $a MiAaPQ $b eng $c MiAaPQ $d NTU
100 1 $a Mengistu, Samuel Bekele. $3 3695350
245 1 0 $a Closing the Yield Gap : $b Improving Production Efficiency in Smallholder Farms of Nile Tilapia Through Selective Breeding.
264 0 $c 2022
300 $a 1 online resource (199 pages)
336 $a text $b txt $2 rdacontent
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500 $a Source: Dissertations Abstracts International, Volume: 84-05, Section: B.
500 $a Advisor: Komen, J.; Mulder, H.A.; Benzie, John A.H.
502 $a Thesis (Ph.D.)--Wageningen University and Research, 2022.
504 $a Includes bibliographical references
520 $a The aim of this thesis was to optimise the breeding program of Nile tilapia for a smallholder production system, thereby contributing to closing the yield gap. From Chapter 2 to 4, we generated information that can be used to optimize the current GIFT breeding program for Nile tilapia. Identifying the major factors contributing to the current yield gap in smallholder Nile tilapia farms is crucial and the first step to any intervention. In Chapter 2, based on meta-analysis of literature, dissolved oxygen was identified as one of the major environmental factors contributing to reduced growth and FCR. In the presence of substantial dissolved oxygen differences between the environments, genotype by environment (GxE) interaction can be expected. The output from Chapter 2 was used to design the GxE interaction experiment (Chapter 3). In Chapter 3, heritabilities for harvest weight (HW 0.18 and 0.23), thermal growth coefficient (TGC, 0.21 and 0.26), survival days (0.03 and 0.04) and size traits (0.08 to 0.45) were estimated, in an attempt to indicate that these traits can be improved by selective breeding. We estimated the genetic correlation for these traits between aerated and non-aerated ponds. The genetic correlations (rg) between the aerated and non-aerated ponds for harvest weight (0.80±0.30) and growth (0.81±0.27) indicate some GxE interactions. The less than unity genetic correlation implies that the genetic improvements gained in aerated ponds will not be fully expressed in non-aerated ponds. Therefore, breeding programs should consider GxE interaction. In Chapter 4, genetic parameters for log-transformed variance of deviations (LnVar), a good indicator of resilience, were estimated. Heritable genetic variation was found for LnVar and it was noted that LnVar is more expressed in the non-aerated pond compared to the aerated pond. Finally, in Chapter 5, we estimated genetic parameters for critical swimming speed (Ucrit) and the genetic correlation between Ucrit and harvest weight of fish raised in a non-aerated pond. Substantial heritable variation was found for Ucrit. The estimated genetic correlations between Ucrit early in life and HW after grow-out in non-aerated pond, and Ucrit and growth were negative, implying that Nile tilapia with higher Ucrit early in life had lower HW and growth later in life. In this Chapter 6, the findings from the previous chapters combined and discussed their implications for breeding programs.
533 $a Electronic reproduction. $b Ann Arbor, Mich. : $c ProQuest, $d 2023
538 $a Mode of access: World Wide Web
650 4 $a Aquaculture. $3 545878
650 4 $a Feeds. $3 659935
650 4 $a Food. $3 551593
650 4 $a Disease. $3 705846
650 4 $a Mortality. $3 533218
650 4 $a Hypoxia. $3 3561738
650 4 $a Biomass. $3 1013462
650 4 $a Metabolism. $3 541349
650 4 $a Fish production. $3 3688049
650 4 $a Climate change. $2 bicssc $3 2079509
650 4 $a Farm buildings. $3 3688430
650 4 $a Environmental conditions. $3 3550086
650 4 $a Ponds. $3 3564818
650 4 $a Birth weight. $3 3685767
650 4 $a Carp. $3 3687621
650 4 $a Fish. $3 3564374
650 4 $a Agriculture. $3 518588
650 4 $a Animal sciences. $3 3174829
650 4 $a Aquatic sciences. $3 3174300
650 4 $a Biological oceanography. $3 2122748
655 7 $a Electronic books. $2 lcsh $3 542853
690 $a 0404
690 $a 0473
690 $a 0475
690 $a 0792
690 $a 0416
710 2 $a ProQuest Information and Learning Co. $3 783688
710 2 $a Wageningen University and Research. $3 3557914
773 0 $t Dissertations Abstracts International $g 84-05B.
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=29877833 $z click for full text (PQDT)