Browsing by Subject "Dual-purpose chicken"

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The potential of gene editing and genomic selection in improving quantitative traits: A simulation study regarding dual-purpose chicken
(2024) Chuang, Edward; Bennewitz, Jörn
The practice of chick culling is the killing of day-old chicks of the layer line chicken. Because of their inability to lay eggs and inefficiency to grow meat, killing them instead of raising them is more economically efficient. In recent years, this practice has raised ethical concerns and led to the ban of this practice in several countries, including Germany and France. One of the several possible solutions is the use of dual-purpose chicken. Unlike the commercial layers, the dual-purpose chicken has abilities in both egg laying and meat production. Even though dual-purpose chicken has better meat growth performance compared to the commercial layers, the use of dual-purpose chicken is still challenging. One of the major challenges to improve dual-purpose chicken is the negative correlation between egg production and meat production. To cope with this negative correlation, some have proposed that gene editing could be a helpful tool to mitigate the problem. The aim of this simulation study is to explore the potential of gene editing to improve negatively correlated quantitative traits. To be more specific, given the aforementioned reasons, the negative correlation between the meat and egg production traits in chicken was chosen as the topic of this study. That is, chicken breeding programs that develop and improve dual-purpose chicken were simulated to discuss the potential of gene editing in animal breeding programs. Chapter 1 begins this thesis with a general introduction of the background to the problem of chick culling, the challenge of developing dual-purpose chicken, and the use of gene editing. Some previous simulation studies on the use of gene editing to improve quantitative traits in animal breeding programs is also introduced in this chapter. Chapter 2 presents a literature review that discusses how gene editing technologies could change the breeding and production of farm animals. In accordance with this thesis's aim, a specific focus was placed on improving quantitative traits. By reviewing the technical and social limitations of gene editing, this review provides a basis for further discussion of the feasibility of the gene-editing implementation as presented in the next chapters. Chapter 3 introduces the simulation framework to explore the potential of gene editing in chicken breeding programs. This framework first simulates two divergently selected lines that reflect the commercial layers and broilers. Based on these two lines, two alternative breeding programs were simulated. One is to develop a dual-purpose line from a layer line (the L-Pure Scenario), while the other selects and improves a synthetic line obtained from a cross between a layer line and a broiler line (the L-B cross scenario). In both breeding schemes, gene editing was integrated into the genomic selection scheme applying optimal contribution selection. The simulation presented in Chapter 4 considers multiplex genome editing that could edit five to one hundred single nucleotide variants at a time. These variants include the causal variants and other falsely edited variants. The results suggest that multiplex gene editing is beneficial in both the L-Pure and the L-B cross scenarios. It also demonstrated that when the risk of negative off-target effect exists, editing more nucleotides does not guarantee extra genetic gain. The simulation presented in Chapter 5 considers the introduction of major genes that would have larger effects on meat production. Here, only the L-Pure scenario is considered. Different to Chapter 4, in this chapter, editing is only possible with only one gene at a time. This chapter aims to study the effects of the numbers of major genes and the pleiotropy (on egg production and meat production). The results suggest that gene editing would be beneficial in dual-purpose chicken breeding programs when the gene is mildly pleiotropic. Chapter 6 ends the thesis with a general discussion that covers the limitations of this study and the possibilities to further expand the simulation study.
Zweinutzungshuhn – was ist das? Umfrage unter Landwirt*innen und Geflügelhalter*innen in Deutschland 2022
(2023) Gebhardt, Beate; Bermejo, Gabriela; Imort-Just, Annik; Kiefer, Lukas; Zikeli, Sabine; Hess, Sebastian
To comply with the ban on chick culling that has been in effect since January 2022, the Federal Ministry of Food and Agriculture proposes three alternatives, including the hatching of dual-purpose chickens. In addition to the breeding and economic challenges of establishing dual-purpose animals in the value chain, the inconsistent understanding of what a dual-purpose chicken actually is and how its characteristics can be successfully communicated to consumers are seen as challenges. The goal of this working report is to present what a dual-purpose chicken is and what understanding farmers have of it. The German nationwide online survey among farmers and poultry farmers regarding the understanding and future of dual-purpose chickens was conducted in autumn 2022 as part of the EIP-Agri project "ZweiWert." The EIP project titled "Building Value Chains for Dual-Purpose Chickens in Baden-Württemberg" (ZweiWert) is funded by the Ministry of Food, Rural Areas and Consumer Protection of Baden-Württemberg from 01/2022 to 12/2024. Project partners include the Naturland Association of Baden-Württemberg, several departments of the University of Hohenheim, and many partners from agricultural production and marketing.
Zweinutzungshuhn – wie schmeckt das? Sensorische Beurteilung von Hühnerfleisch und Eiern von vier Zweinutzungshuhn-Genetiken
(2023) Gebhardt, Beate; Maute, Jutta; Kiefer, Lukas
Research into the sensory properties of meat and eggs from dual-purpose chickens has so far been a niche from a scientific point of view. In cooperation with the EIP-Agri project "ZweiWert", students at the DHBW Heilbronn therefore tasted, analysed and evaluated several dual-purpose chicken genetics in the integration seminar "Dual-purpose chickens: How to communicate the added value" in summer 2023. The genetics “Coffee" from the Ökologische Tierzucht (ÖTZ), "Sundheimer" from the Öko2Huhn project, "RegioHuhn" and "Lohmann Dual" as well as a control group from a classic laying or fattening line were assessed. The aim was to find out how different dual-purpose chickens taste and whether there are sensory differences or special features in meat and eggs Sensory attributes, including appearance, taste and smell, were recorded using a multi-methods assessment sheet. In short, the results of this explorative study show that dual-purpose chickens taste better. However, according to the testers judgement, there are differences not only between the different genetics, but also between the individual parts - breast, drumstick, wings or broth. The sensory profiles of the four dual-purpose chickens tested are varied and do not allow a clear sensory "ranking". The meat from Lohmann Dual apparently corresponds best to consumer preferences, while their eggs (cooked) are the least appealing. Overall, however, there is a consistent sensory superiority of the dual-purpose chickens over the specialised fattening or laying breed. These results - should they be confirmed in further studies - could contribute to increasing consumer acceptance of dual-purpose chickens and addressed in market communication to their further spread. The EIP project titled "Building Value Chains for Dual-Purpose Chickens in Baden-Württemberg" (ZweiWert) is funded by the Ministry of Food, Rural Areas and Consumer Protection of Baden-Württemberg from 01/2022 to 12/2024. Project partners include the Naturland Association of Baden-Württemberg, several departments of the University of Hohenheim, and many partners from agricultural production and marketing.