DOCSLIB.ORG

Meat and Egg Production with Dual-Purpose Poultry: Biological Background, Feed Requirements and Efficiency, Meat and Egg Quality

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Meat and Egg Production with Dual-Purpose Poultry: Biological Background, Feed Requirements and Efficiency, Meat and Egg Quality Research Collection Doctoral Thesis Meat and egg production with dual-purpose poultry: biological background, feed requirements and efficiency, meat and egg quality Author(s): Müller, Sabine Karin Publication Date: 2018 Permanent Link: https://doi.org/10.3929/ethz-b-000340446 Rights / License: In Copyright - Non-Commercial Use Permitted This page was generated automatically upon download from the ETH Zurich Research Collection. For more information please consult the Terms of use. ETH Library DISS. ETH NO. 25564 Meat and egg production with dual-purpose poultry: biological background, feed requirements and efficiency, meat and egg quality A thesis submitted to attain the degree of DOCTOR OF SCIENCES of ETH ZURICH (Dr. sc. ETH Zurich) presented by Sabine Mueller MSc ETH Agrarwissenschaften, ETH Zurich born on 02.12.1986 citizien of Amriswil, TG accepted on the recommendation of Prof. Dr. Michael Kreuzer, examiner Dr. Ruth E. Messikommer, co-examiner Dr. Barbara Eichenberger, co-examiner 2018 Unsere Leidenschaften sind nicht zufällig, sie sind unsere Berufung. Fabienne Frederickson ________________________________________________________________Table of contents Table of contents Table of contents ....................................................................................................................... 1 Abbreviations ............................................................................................................................ 6 List of figures ............................................................................................................................ 7 List of tables .............................................................................................................................. 8 Summary ................................................................................................................................. 10 Zusammenfassung .................................................................................................................. 12 Chapter 1 General introduction .............................................................................................................. 15 1.1 Possible alternatives to chick culling ......................................................................... 17 1.1.1 Dual-purpose poultry .......................................................................................... 18 1.1.2 Fattening the male layer cockerels ..................................................................... 18 1.1.3 In ovo sex determination .................................................................................... 19 1.1.4 Altering the secondary sex ratio ......................................................................... 19 1.2 The situation in Switzerland ...................................................................................... 19 1.3 Dual-purpose poultry and the feed no food concept .................................................. 20 1.4 Product quality ........................................................................................................... 23 1.5 Thesis outline and aim of the project ......................................................................... 23 1.6 Design of the project .................................................................................................. 24 Chapter 2 Carcass and meat quality of dual-purpose chickens (Lohmann Dual, Belgian Malines, Schweizerhuhn) in comparison to broiler and layer chicken types ................................... 25 2.1 Abstract ...................................................................................................................... 26 2.2 Introduction ............................................................................................................... 26 2.3 Materials and methods ............................................................................................... 28 2.3.1 Experimental design, animals and housing ........................................................ 28 2.3.2 Measurements and sampling .............................................................................. 31 2.3.3 Feed and excreta analysis ................................................................................... 32 2.3.4 Bone analysis ...................................................................................................... 32 1 Table of contents _______________________________________________________________ 2.3.5 Meat analysis ...................................................................................................... 32 2.3.6 Calculations and statistical analysis ................................................................... 33 2.4 Results ....................................................................................................................... 33 2.4.1 Growth performance .......................................................................................... 33 2.4.2 Carcass characteristics ........................................................................................ 35 2.4.3 Bone characteristics ............................................................................................ 36 2.4.4 Meat quality ........................................................................................................ 37 2.5 Discussion .................................................................................................................. 39 2.5.1 Growth Performance and Feed Efficiency ......................................................... 39 2.5.2 Carcass Quality .................................................................................................. 40 2.5.3 Meat Quality ....................................................................................................... 41 2.5.4 Bone Characteristics ........................................................................................... 43 2.6 Conclusion ................................................................................................................. 44 Chapter 3 Growth, carcass and meat quality of two dual-purpose chicken types and a layer type fattened for 67 or 84 days compared with a slow-growing broiler .................................... 45 3.1 Abstract ...................................................................................................................... 46 3.2 Implications ............................................................................................................... 46 3.3 Introduction ............................................................................................................... 47 3.4 Material and methods ................................................................................................ 48 3.4.1 Birds, housing and experimental conditions ...................................................... 48 3.4.2 Fattening and slaughter ...................................................................................... 49 3.4.3 Carcass and meat quality analysis ...................................................................... 49 3.4.4 Statistical analysis .............................................................................................. 50 3.5 Results ....................................................................................................................... 51 3.5.1 Growth performance .......................................................................................... 51 3.5.2 Carcass characteristics ........................................................................................ 53 3.5.3 Meat quality ........................................................................................................ 53 2 ________________________________________________________________Table of contents 3.6 Discussion .................................................................................................................. 57 3.6.1 Competitiveness of dual-purpose types with slow-growing broilers depending on fattening period .................................................................................................. 57 3.6.2 Differences between the two dual-purpose types slaughtered at 67 or 84 days . 59 3.6.3 Competitiveness of the male layer type in growth, carcass and meat quality .... 59 3.7 Conclusions ............................................................................................................... 60 3.8 Supplementary material ............................................................................................. 60 3.8.1 Materials and Methods ....................................................................................... 60 3.9 Results and Discussion .............................................................................................. 61 3.9.1 Effects of extending the fattening period of the layer type to 126 days ............. 61 Chapter 4 Do dual-purpose and male layer chickens have a greater resilience against a low-protein- low-soybean diet than slow-growing broilers? .................................................................... 65 4.1 Abstract ...................................................................................................................... 66 4.2 Introduction ............................................................................................................... 66 4.3 Material and methods ...............................................................................................
Load more

Recommended publications
  • How Does Respeggt Gmbh Live up to the Promise of “Free of Chick Culling”?
    FAQ What does the respeggt GmbH do? We, the respeggt GmbH, hold the rights to the respeggt label “Free of Chick Culling”. The label represents the promise that the table eggs and the egg products in foodstuffs have been produced free of the usual “chick culling” of day-old male chicks. This product promise is based on the implementation of a method for gender identification in the hatching egg. At the end of the 21-22 days incubation period, the laying hen chicks hatch from the fertilised hatching eggs. Usually, the male chicks, who hatch alongside the females, are killed in the hatcheries since they are unable to lay eggs. Only the female chicks are reared and later lay the table eggs as adult laying hens. Gender identification in the hatching egg allows the male hatching eggs to be identified and sorted out during the incubation period. As a result, only the female hatching eggs are incubated until the end. This way we avoid killing the day-old male chicks. We offer all hatcheries the service of gender identification in the hatching egg to sort their hatching eggs. This service is offered to hatcheries at no extra cost. Only when the subsequently produced table eggs are sold, do we charge the packing centres a licence fee per table egg. A major advantage of this approach is that smaller hatcheries will still be able to compete in the market. No extra investment is required in order to implement the process of gender identification in the hatching egg and to sell female chicks with the label “Free of Chick Culling”.
    [Show full text]
  • News & Views January/February 2020 Edition
    January / February 2020 VIEWS & Hinton, Chairman of USPOULTRY USPOULTRY Recognizes Mark Waller as Workhorse of the Year Dr. Maricarmen Garcia Receives 2020 Dr. Charles Beard Research Excellence Award 2020 IPPE Has Great Turnout NEWS The All Feather Association serving the industry through education, research, communication and technical assistance. TABLE OF CONTENTS BOARD OF DIRECTORS Bernie Adcock TYSON FOODS, AR Brian Barrett FEATHER CREST FARMS, TX ASSOCIATION 1 President’s Column Bob “Pic” Billingsley 2 Hinton, Chairman / 2020 USPOULTRY Board of Directors SANDERSON FARMS, MS 3 USPOULTRY Recognizes Mark Waller as Workhorse of the Year Lance Buckert 3 Dr. Garcia Receives 2020 Dr. Charles Beard Research Excellence Award KOCH FOODS, IL 4 Six Industry Leaders Receive USPOULTRY Lamplighter Award Jonathan Cade 5 Lamplighter Awards (cont’d) HY-LINE INTERNATIONAL, IA 6 Seminar Committee Receives USPOULTRY Lamplighter Award Dr. Tom Frost 11 Research Results DSM NUTRITIONAL PRODUCTS, GA 11 USPOULTRY and the USPOULTRY Foundation Sponsor $200,000 for FFAR-Funded Research That Benefits the Poultry Industry Mikell Fries 12 Bill Lovette, Keynote Speaker at USPOULTRY Foundation Executive Luncheon CLAXTON POULTRY FARMS, GA 17 $5,998 USPOULTRY Foundation Student Recruiting Grant Awarded to the University of Florida Ben Harrison AMICK FARMS, SC EDUCATION Tom Hensley 13 Ergonomic Improvements in the Poultry Industry Highlighted at the 2020 IPPE FIELDALE FARMS, GA 14 Broiler and Layer Production, Processing Issues Focus of 2020 Latin American Poultry Summit
    [Show full text]
  • LAYING HENS: the INSIDE STORY a Viva! Report by Juliet Gellatley, Bsc Zoology, Founder & Director, Viva!
    LAYING HENS: THE INSIDE STORY A Viva! report by Juliet Gellatley, BSc Zoology, Founder & Director, Viva! Viva! is a reg charity 1037486 LAYING HENS: THE INSIDE STORY LAYING HENS: THE INSIDE STORY A Viva! report by Juliet Gellatley, BSc Zoology, Founder & Director, Viva! Written by Juliet Gellatley, with additions by Claire Palmer, Viva! [email protected] www.facebook.com/juliet.gellatley Copyright: Viva! 2017 Viva! 8 York Court Wilder Street Bristol BS2 8QH 0117 944 1000 www.viva.org.uk Viva! is a reg charity 1037486 ISBN 978-0-9571874-7-4 2 CONTENTS EXECUTIVE SUMMARY 4 FREE RANGE EGG FARMS 31 QUALITY ASSURANCE SCHEMES: A life inside 31 WHAT THEY REALLY MEAN 51 INTRODUCTION 6 ‘Happy Egg’ farms 32 RSPCA Assured 51 The Chicken (Gallus gallus CASE STUDY: FREE British Lion Quality Mark 51 domesticus) 7 RANGE FARMS 33 Soil Association 51 Chickens behaving naturally 7 ‘HAPPY EGG’ FARM Housing On Modern-Day Farms 10 A. 2010 investigation THE GLOBAL EGG INDUSTRY 52 Battery (or conventional) cage 10 (Strathruddie Farm and Retailers 53 Enriched cage 11 Bishophill Farm) 33 Cage Egg Company Suppliers 53 Percheries/barn 12 ROWBOTTOM FARM 34 Noble Foods 54 Free range farms 12 Stonegate 54 Organic 12 ORGANIC 35 Supermarket Policies 54 Antibiotics and vaccination 35 Ingredients 55 FROM BIRTH TO DEATH IN Impacts on welfare 36 Vegan Lines 55 JUST A YEAR AND A HALF 13 Egg replacer 55 Chick Production 13 CASE STUDY: Vegan egg replacers chart 56 Baby chicks 13 ORGANIC FARMS 37 Male chicks 13 MAC’S FARM 37 EGGS AND YOUR HEALTH 57 Viva! Investigates UK Hatcheries
    [Show full text]
  • Discussionpaper1906komplett
    Department für Agrarökonomie und Rurale Entwicklung 2019 Diskussionspapiere Discussion Papers Societal attitudes towards in ovo gender determination as an alternative to chick culling Corrina Reithmayer Michael Danne Oliver Mußhoff Department für Agrarökonomie und Rurale Entwicklung Universität Göttingen D 37073 Göttingen ISSN 1865-2697 Diskussionsbeitrag 1906 Societal attitudes towards in ovo gender determination as an alternative to chick culling Abstract In ovo gender determination of incubated eggs can be a large-scale substitute to the culling of male chicks in layer hen production. However, the technology raises new ethical concerns which relate to the sensitivity of the embryo, as well as how the screened out eggs will be used afterwards and the accuracy of gender determination. In order to comprehensively investigate consumer attitudes towards this new technology, a questionnaire including a choice experiment was distributed to a representative sample of 482 German consumers between December 2018 and March 2019. The data was analyzed by an explorative factor analysis and a latent class analysis. Results indicate that the sample can be divided into four segments, which differ in preferences for production attributes, attitudes and price sensitivity. Attitudinal differences are found regarding respondents’ approval of the technical advances in agricultural production, confidence in legal regulations and the endorsement of enhanced livestock production conditions. Both a meaningful usage of by-products and a high rate of accuracy are crucial factors for the acceptance of in ovo gender determination for the majority of respondents. However, response behavior of one segment, representing 11% of the sample, indicates the disapproval of both chick culling and in ovo screening.
    [Show full text]
  • Farm Animal Welfare Factsheets
    Farm Animal Welfare Factsheets Meat Issues in chicken meat production Breeders Chickens Breeder birds in the meat chicken industry lay the eggs that will hatch into chickens grown for meat. Breeder birds gain weight rapidly, to the point of obesity, and therefore develop an increased prevalence of health Chicken is the most popular problems, reproductive problems and a decrease in sexual activity. To address these issues, access to food meat consumed by Australians. is restricted for breeder birds. This creates animal welfare concerns as birds experience chronic hunger and On average, Australians eat 47 stress, and may display abnormal repetitive behaviours, aggression and injurious pecking which can cause harm to their fellow birds.⁴ RSPCA knowledge base kg of chicken each year, ¹ RSPCA knowledge base with over 650 million Conventional housing meat chickens slaughtered Meat chickens raised in conventional systems spend their life in barren, cramped and dimly-lit environments. every year in Australia for Birds are discouraged from moving about and eat continuously, gaining weight rapidly which causes severe human consumption. These welfare problems, including weak legs, eye and respiratory issues, and in some cases, heart failure. Weak birds have been selectively legs means increased contact with often damp litter, causing foot pad burns, hock burns and breast blisters.⁵ bred over many generations to RSPCA Approved grow and gain weight in a short period of time, and both male Catching and transport and female meat chickens are Once the chickens are ready for processing, they are placed into crates and transported to the processing farmed. plant. Chickens can be caught by hand or gathered up by a machine for placing into the transport crates.
    [Show full text]
  • Animal Rights and Food : Beyond Regan, Beyond Vegan
    This is a repository copy of Animal rights and food : beyond Regan, beyond vegan. White Rose Research Online URL for this paper: http://eprints.whiterose.ac.uk/157942/ Version: Accepted Version Book Section: Milburn, J. orcid.org/0000-0003-0638-8555 (2016) Animal rights and food : beyond Regan, beyond vegan. In: Rawlinson, M. and Ward, C., (eds.) The Routledge Handbook of Food Ethics. Routledge . ISBN 9781138809130 https://doi.org/10.4324/9781315745503 This is an Accepted Manuscript of a book chapter published by Routledge in The Routledge Handbook of Food Ethics on 1st July 2016, available online: https://www.routledge.com/The-Routledge-Handbook-of-Food-Ethics/Rawlinson-Ward/p/bo ok/9781138809130 Reuse Items deposited in White Rose Research Online are protected by copyright, with all rights reserved unless indicated otherwise. They may be downloaded and/or printed for private study, or other acts as permitted by national copyright laws. The publisher or other rights holders may allow further reproduction and re-use of the full text version. This is indicated by the licence information on the White Rose Research Online record for the item. Takedown If you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing [email protected] including the URL of the record and the reason for the withdrawal request. [email protected] https://eprints.whiterose.ac.uk/ Animal Rights and Food: Beyond Regan, Beyond Vegan Josh Milburn This is a draft version of a paper appearing in The Routledge Handbook of Food Ethics, edited by Mary C.
    [Show full text]
  • A Critical Discourse Analysis of the Animals Farmed Series in the Guardian
    “It Would Be Kinder to Shoot Them” A Critical Discourse Analysis of the Animals Farmed Series in The Guardian Lukas Leitinger Supervisor: Núria Almiron Academic Year: 2019/20 Research project of the MA in International Studies in Media, Power, and Difference Department of Communication Universitat Pompeu Fabra, Barcelona Abstract This study conducted a critical discourse analysis on the Animals farmed series in The Guardian. To this end, the messages of the 196 articles from the launch of the series until April 20, 2020 and 8 articles from outside the series were analysed. Predominantly, the language of the series reinforces animal oppression by only asking how, not if, we should farm nonhuman animals. Some articles in the series show farmed animals’ suffering and workers’ ethical dilemmas, yet thorough challenges to animal oppression were only found outside the series. Thus, the study identified an underlying welfarist ideology throughout Animals farmed. Additionally, this study conducted a political economy analysis to explore the economic pressures behind the series. This analysis revealed links to the animal industry and philanthropy, which helps explain the findings. With these findings, the study contributes to critical animal and media studies and to journalism fighting animal oppression. Keywords: farmed animals, animal oppression, newspapers, critical animal and media studies, critical discourse analysis, political economy, philanthropy Type of Project: Research Report 2 Table of contents 1 Introduction .....................................................................................................................
    [Show full text]
  • Purpose Poultry Products
    CONSUMERS' ACCEPTANCE AND WILLINGNESS TO PAY FOR DUAL- PURPOSE POULTRY PRODUCTS Isabelle D. M. Gangnat1*, Sabine Müller1, Michael Kreuzer1, Michael Siegrist2 and Vivianne H. M. Visschers2 1 Institute of Agricultural Sciences, ETH Zurich, 8092 Zurich, Switzerland 2 Institute for Environmental Decisions, ETH Zurich, 8092 Zurich, Switzerland *Corresponding author email: [email protected] Abstract – Alternatives to mass culling of male layer broilers costs about 13% more at the grocery [3]. chicks are dual-purpose poultry and egg sexing. The The extra costs observed at the grocery for organic first goes along with higher costs and smaller eggs from dual-purpose hens are about 20% higher chicken and eggs. Consumers’ acceptance of both than that of regular organic eggs [3]. The eggs are alternatives remains unknown. A survey was also 6 to 12% lighter [4, 5]. therefore conducted with 402 consumers in Swiss groceries. Results enlighten the ignorance of most Chicken and eggs from dual-purpose poultry have consumers about mass culling of male layer chicks. arrived just recently in Swiss grocery stores as a A gap between consumers’ willingness to pay and response to welfare concerns about the practice of the actual price of dual-purpose poultry products culling day-old chicks only because of their retrieved in groceries was also observed. The economic non-profitability. However, no smaller size of dual-purpose chicken and eggs did information is available yet on consumers’ not appear as a concern. Egg sexing was moderately willingness to pay (WTP) for the higher cost of preferred to chick culling but not to dual-purpose producing dual-purpose products, and little is poultry.
    [Show full text]
  • Tulsa Vegan Guide
    Tulsa Vegan Guide Photo courtesy of Oliver and Friends Farm Rescue and Sanctuary in Luther, Oklahoma. Check out their facebook to donate/volunteer. The Tulsa Guide for eating out/shopping compassionately and environmentally-friendly. (Check out the Tulsa Vegan Guide Facebook Group or email [email protected] for updates) 1 TVG The Tulsa Vegan Guide A Guide in Progress Here you will find a few detailed lists of some different restaurants in the Tulsa area that provide vegan-friendly dishes as well as product alternatives found in our city. I am also subject to human error, if you find anything incorrect in this guide, please contact me via the Facebook Group or [email protected] CAUTION: These are not allergen menus. Make sure to communicate with the various restaurants on any cross- contamination issues. For more support: -Tulsa Vegan Guide’s Facebook Group for updates. -Tulsa Vegan Network (Facebook Group) -New Vegan Support (Facebook Group) -Vegan Amino (Phone App) It’s like a vegan Facebook! -www.Challenge22.com (22 Day Vegan Challenge Website for a free nutritionist) “Our unwillingness to see personhood in nonhuman animals does not diminish their personhood; it diminishes our humanity.”- The Abolitionist Vegan Society 2 Table of Contents Highlights……………………………………………………………………………….….….4 Drive Thrus…………………………………………………………………….……….……..6 Sandwiches/Subs………………..…………………………………………..…………...12 Mexican Food…………………………………………………………………………..……20 Asian Food………………………………………………………………………………….….27 Pizza/Italian Food…………………………………………………….……………….……41
    [Show full text]
  • The Business Benchmark on Farm Animal Welfare Report 2018 Nicky Amos & Dr Rory Sullivan
    The Business Benchmark on Farm Animal Welfare Report 2018 Nicky Amos & Dr Rory Sullivan 1 The Business Benchmark on Farm Animal Welfare Report 2018 The Business Benchmark on Farm Animal Welfare The Business Benchmark on Farm Animal Welfare (BBFAW) is the leading global measure of farm animal welfare management, policy commitment, performance and disclosure in food companies. It enables investors, companies, NGOs and other stakeholders to understand corporate practice and performance on farm animal welfare, and it drives – directly and through the efforts of others – corporate improvements in the welfare of animals reared for food. BBFAW maintains the Global Investor Statement on Farm Animal Welfare and convenes the Global Investor Collaboration on Farm Animal Welfare, a collaborative engagement between major institutional investors and food companies on the issue of farm animal welfare. In addition, BBFAW manages extensive engagement programmes with companies and with investors and provides practical guidance and tools for companies and for investors on key animal welfare issues. The programme is supported by the BBFAW’s founding partners, Compassion in World Farming and World Animal Protection, who provide technical expertise, guidance, funding and practical resources. More information on the programme can be found at www.bbfaw.com Compassion in World Farming Compassion in World Farming is the leading farm animal welfare charity advancing the wellbeing of farm animals through advocacy, political lobbying and positive corporate engagement. The Food Business programme works in partnership with major food companies to raise baseline standards for animal welfare throughout their global supply chains. The team offers strategic advice and expert technical support for the development, implementation and communication of higher welfare policies and practices, and increasingly frameworks for a more humane sustainable food system.
    [Show full text]
  • Cetology and Crustaceology in Moby-Dick and “Consider the Lobster”
    Ethics and Semiogenic Construction of Other Animals: Cetology and Crustaceology in Moby-Dick and “Consider the Lobster” By Eva Natalia Kasprzycka A Thesis submitted to the Faculty of Graduate Studies of The University of Manitoba in partial fulfilment of the requirements of the degree of MASTER OF ARTS Department of English, Film, Theatre and Media University of Manitoba Winnipeg Copyright © 2019 by Eva Kasprzycki i Abstract This thesis brings together a ten-page essay on lobsters and a 700-page book on whales to scrutinize the semiogenic construction of creatures floating in the political animal menagerie. Herman Melville’s novel Moby-Dick and David Foster Wallace’s essay “Consider the Lobster” are texts that are fundamentally concerned with the ethical stakes of textual and historical representations of cetaceans and crustaceans. Both these works explore the intersection between the unknowability of nonhuman animal subjectivity and the industrial rendering of nonhuman animal bodies —an intersection paved and maintained by biopolitical agents that emphasize the former so that the latter can occur without criticism. Despite being published 154 years apart, both these works use the New England coastline to portray industries of death and devouring, both of which are centres of epistemological ambiguity for Wallace and Melville. By theoretically unpacking the political, cultural and historical portrayal of crustaceans and cetaceans in these two literary works, this thesis pursues some of the intra-active networks —in particular those of speciesist ideology— that encase and weave together the industrialized biocapital of nonhuman bodies to the aesthetic representation of them. ii Acknowledgements First, I would like to thank the Department of English, Film and Theatre for the financial support that made this endeavour a lot easier.
    [Show full text]
  • Rearing Male Layer Chickens: a German Perspective
    agriculture Brief Report Rearing Male Layer Chickens: A German Perspective Mona Franziska Giersberg * and Nicole Kemper Institute for Animal Hygiene, Animal Welfare and Farm Animal Behaviour, University of Veterinary Medicine Hannover, 30173 Hanover, Germany; [email protected] * Correspondence: [email protected]; Tel.: +49-511-856-8963 Received: 19 October 2018; Accepted: 6 November 2018; Published: 9 November 2018 Abstract: The killing of male layer hybrids in the hatcheries, at a day-old, is common practice but it also raises strong socio-ethical concerns. In recent years, three different approaches to avoid this killing have been developed—the in ovo sex determination, the rearing of male layers for meat, and the use of dual-purpose breeds. In Germany, about one million male layers are raised each year in the organic and conventional sector. Regarding animal health and welfare, this concept seems favourable. However, the main challenge, that is, to what extent these animals can be kept in a resource-friendly and ecologically sustainable way, remains yet to be solved. Currently, for a niche, this approach contributes to the diversification of the German market. It serves as an example for reacting to societal concerns immediately, before feasible solutions are available for the entire system of modern poultry production. Keywords: animal welfare; animal ethics; poultry; culling; day-old chickens; sustainability 1. Introduction The genetically-determined antagonism between reproduction and fattening performance in chickens has led to specialised hybrids for egg and meat production. In broiler hybrids, both sexes are used for meat production. However, since male layer chickens are not suitable for economic fattening purposes, they are usually killed by maceration or carbon dioxide, in the hatcheries, at a day-old.
    [Show full text]