CHICKEN & EGG
An egg-centric guide to raising poultry
Andy Cawthray
&
James Hermes
If you’ve ever dreamed of waking up to fresh eggs or given thought to the idea of keeping chickens at home but don’t know where to start, fear no more; Chicken & Egg offers a complete reference to raising chickens and other poultry purely for their eggs, from choosing the best-laying breeds, to understanding broody behaviour and producing the most colourful egg selections. Featuring artworked guides to the top twenty breeds, and “Why Did The Chicken...?” problem-solving panels, it is the essential reference.
First published in the UK in 2015 by
Ivy Press
210 High Street
Lewes
East Sussex BN7 2NS
United Kingdom
www.ivypress.co.uk
Copyright © 2015 Ivy Press Limited
All rights reserved. No part of this book may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage-and-retrieval system, without written permission from the copyright holder.
British Library Cataloguing-in-Publication Data
A catalogue record for this book is available from the British Library
Print ISBN: 978-1-78240-200-8
EPUB ISBN: 978-1-78240-209-1
MOBI ISBN: 978-1-78240-210-7
This book was conceived, designed and produced by
Ivy Press
Creative Director: Peter Bridgewater
Publisher: Susan Kelly
Editorial Director: Tom Kitch
Art Director: James Lawrence
Editor: Jamie Pumfrey
Design: JC Lanaway
Paintings: Kate Osborne
Colour origination by Ivy Press Reprographics
Distributed worldwide (except North America) by Thames & Hudson Ltd, 181A High Holborn, London WC1V 7QX, United Kingdom
Contents
Preface
PART 1
INTRODUCING THE CHICKEN & THE EGG
Chickens: What Are They?
The Science of Egg Formation
Introduction to Egg Quality
Feeding Chickens for Egg Production
PART 2
BREEDS DEVELOPED FOR EGG-LAYING
Ancona
Araucana
Australorp
Barnevelder
Lakenvelder
Legbar
Leghorn
Marans
Minorca
New Hampshire
Orpington
Plymouth Rock
Rhode Island Red
Welsummer
Wyandotte
PART 3
KEEPING CHICKENS FOR EGGS
Getting Started
Pitfalls & Potholes
Choosing Your Henhouse
Your Egg-Laying Flock
Laying & Brooding
Diet & Health
Glossary
Index
Picture Credits
Preface
When considering chickens, the question always arises: “Which came first, the chicken or the egg?” This single conundrum has plagued the great thinkers of human civilization for millennia. Of course, it has no real answer because its purpose is simply to illustrate that some questions don’t have answers, and yet the debate will continue long into the future. However, while the debate rages with little chance of any resolution, we have chickens and eggs to fill our lives with both pleasure and nutrition.
The chicken has become entwined in the lives of most of the world’s population. In any restaurant or café, chicken and eggs are prominent fare on the menu. In knick-knack and general-household stores, chickens of all shapes and sizes are prominently on display, immortalized in stylized paintings and sculptures, and chicken feathers are found in many crafts, hats, pillows, and fishing flies. Chickens have also become part of our language, in sayings such as “Don’t put all your eggs in one basket,” “Don’t count your chickens before they’ve hatched,” “You’ve got egg on your face,” “The hen-pecked husband flew the coop,” and “Don’t get your hackles up.”
In recent years, the poultry and egg industries have become the primary producers of protein consumed by over half of the population of the world. The chickens used to produce these foodstuffs have developed into the most efficient traditional livestock species on the planet, returning the highest level of product—meat and eggs—for the least amount of feed.
In small farms and even in urban settings, chickens have gained in popularity. Small flocks of a handful of hens are supplying eggs to many families and their neighbors while providing life lessons, responsibility, and the hard realization of life and death to countless numbers of children.
This book will lead the reader through the origins and history of the birds we know as chickens. The complexity of the lowly egg is explained, including how it is formed, its quality criteria, and the conditions that result in baby chicks. Potential and new small producers will learn of the variety of egg-laying breeds and their temperaments, as well as the basic management conditions and practices required to house a small flock, including the proper care and feeding of these impressive animals.
We may not answer the questions as to why the chicken crossed the road or whether the chicken or the egg came first, but we will lead you on an exciting journey into the world of the chicken and the egg.
1
INTRODUCING
THE CHICKEN & THE EGG
CHAPTER ONE
CHICKENS
What Are They?
Chickens are a group of domestic birds that have been associated with man for millennia. Since their domestication for use as livestock animals, they have been a source of wonder and amazement, as well as becoming one of the primary protein sources in the human diet, in the form of chicken meat and eggs.
A Brief History
Chickens are essentially a domesticated pheasant native to Southeast Asia. They are classed with similar birds in the taxonomic order Galliformes (commonly called gamebirds or galliforms), which, in addition to the chicken and its wild progenitor, the jungle fowl, include turkeys, pheasants, quail, partridges, guinea fowl, and peafowl. Galliforms in general are adapted to life on the ground. While they can fly, none is a strong flyer, and most species use this ability for the primary purpose of avoiding predators; an explosion of wing-flapping to take off (the flush) startles the predator and lasts for only a few moments, with the bird landing a short distance away and the predator standing confused and without a meal.
In the beginnings of their association with man, early “pre-chickens” were relegated to a recreational role. It is generally accepted that jungle fowl were originally taken into captivity for fighting contests, with the winning roosters gaining the right to produce the next generation. As jungle fowl morphed into chickens during the ensuing millennia, fighting skills remained high on the priority list for selection. Egg and meat production were inconsequential during the domestication and early development of the chicken.
Over the centuries, as chickens continued to be bred for their fighting ability, many of the traits that are important in breed identity today arose merely as the result of mutations brought about by selective breeding. Traits such as feather color and pattern, comb type, feathered shanks, polydactyly (extra toes), and skin, egg, and earlobe color were identified by these early chicken enthusiasts and selected for during breeding in addition to fighting skill. This selection of groups of birds with similar traits could be considered the beginning of breed development. It is suggested that the Dorking breed, which has the distinguishing trait of five toes, was described as early as the first century ad. However, it wasn’t until the middle of the 19th century that chicken breeds, based on body shape and size, comb type and skin, and leg, egg, and earlobe color, among other traits, began to be categorized in an official way. At the same time, cockfighting began to lose favor with the public, with the sport outlawed first across most of Europe (it was banned in England and Wales in 1835), and finally in the US in 2006. While cockfighting remains a source of recreation in many parts of the world, chicken enthusiasts are increasingly turning to “fancy chickens,” competing by exhibiting them in shows rather than allowing them to fight in pits.
With the advent of showing, breed development intensified and breed standards were developed. Breeds were required to “breed true”—produce offspring similar to their parents—and had to conform to specific standards (see box) for weight, shape, color, and many other traits.
Breed standards
In about 1863, the first Poultry Club of Great Britain was established, publishing the first standard of poultry breeds in 1865. The club was disbanded shortly after, only to be resurrected in 1877 to the current Poultry Club of Great Britain. In 1873, the American Poultry Association was founded; it published its first Standard of Perfection in 1874, which has been updated ever since, with a new edition every few years.
From their domestication until the early years of the 20th century, chickens were not an important part of the human diet. Birds were bred for fighting or their appearance, and only culls or hens past their prime were consumed.
Eggs were readily consumed but were not a large part of the diet either. However, a small segment of poultry breeders began to disregard breed characteristics in favor of economic traits such as egg number, size, and quality, or meat traits such as growth rate, body size, and feed conversion.
Commercial egg production began as a few extra birds laying eggs for sale or barter. Flocks rarely exceeded a couple of hundred birds, and hens laid only a few dozen to a hundred or so eggs annually. In 1913, after several years of selective breeding for egg number, James Dryden, professor of poultry husbandry at Oregon State University, produced Lady McDuff, the first hen that was recorded to lay more than 300 eggs in a single year. A few years later, Dryden bred Oregona, a hen that was documented as laying more than 1,000 eggs in five years. Both hens were white-egg-laying single-comb white Leghorns and marked the beginning of the egg-laying strains of chicken in the modern era.
Breeding chickens specifically for their meat didn’t take off until as recently as the 1920s, when Cecile Steele first raised chickens for the purpose in Delaware. However, the quality remained poor until Charles Van Tress of California crossed Dark Cornish and New Hampshire breeds, selected for their growth and meat characteristics. The result, the Cornish Cross, won the A&P supermarket chain’s Chicken of Tomorrow contest in 1948 and gave rise to the modern broiler chicken.
From these beginnings, through many generations of selection and further crossing with the white Plymouth Rock to bring in white feathering, the Cornish Cross remains a non-standard breed. Nonetheless, it has ideal meat characteristics of growth and feed conversion, and to the present day remains the most efficient traditional livestock species, growing to nearly 7 lb. (3.2 kg) in as many weeks while consuming about 12 lb. (5.4 kg) of feed.
In recent years, chicken has become the primary meat of choice for much of the western world, and with the addition of eggs in our diet, the bird itself has arguably become the most important livestock animal throughout the world.
Origins of the Chicken
The chicken, which is arguably the most numerous bird on the planet, began its existence as an obscure pheasant in the jungles of Southeast Asia. It was most probably Charles Darwin who first proposed that the bird was the domestic ancestor of the red jungle fowl (Gallus gallus).
This species is among a group of 4 extant and as many as 13 extinct pheasant-type species that are found from western India through the southern reaches of Asia and into the island chains of Indonesia and the Philippines. The birds generally dwell on the jungle floor and into the margins of grasslands at the edge of forested areas in these regions. The ranges of these closely related species rarely intersect, so there is little possibility of natural hybridization between them.
Comb characteristics
Both the Sri Lankan and green jungle fowl vary in appearance from the more common red and gray jungle fowl, especially in terms of their comb. The combs of these more isolated types are variable in color, with not only the typical red but also patterns of blue and yellow. In addition, the Sri Lankan jungle fowl’s comb has even smaller and less distinct serrations when compared with that of the gray jungle fowl, and the serrations are completely lacking in the comb of the green jungle fowl.
The red jungle fowl, which has the broadest range—from India in the west through Southeast Asia and into the many of the Indonesian and Philippine islands—has at least five subspecies groups that are somewhat isolated from one another. In appearance and behavior, it most resembles the domestic chicken; in fact, many novice and even some experienced poultry enthusiasts could mistake it for a chicken. Truly wild examples of red jungle fowl are probably difficult to obtain today because the birds have been breeding with domestic chickens for centuries as their habitat has been infiltrated by man.
The other jungle fowl species have relatively small ranges and are mostly isolated. The gray jungle fowl (Gallus sonneratii), sometimes called Sonnerat’s jungle fowl, is found in the westernmost part of the overall range of jungle fowl, generally in peninsular India. It differs most strikingly from its red jungle fowl cousin in its comb—the flesh appendage that resides on the top of the head, used for courtship display and probably for cooling. Most prominent in the males, the small points and minimal serrations of the gray jungle fowl’s comb are clearly in contrast with the more chicken-like “single comb” of the red jungle fowl. (The single comb is the typical comb of most breeds of chicken; it mostly stands erect with “sharp” points forward and on top, and a broader “blade” projecting rearward.)
The remaining two jungle fowl species are isolated to some of the islands that lie within the overall range of the Gallus genus. The Sri Lankan jungle fowl (Gallus lafayetii; previously called the Ceylon jungle fowl) is found only on the island of Sri Lanka off the eastern tip of southern India, while the green or Javan jungle fowl (Gallus varius) is found on a few islands in western Indonesia, including Java and Bali.
Domestication of the Chicken
While the exact date and place of chicken domestication is impossible to determine, it is clear when comparing the genetic evidence from domestic chickens and jungle fowl that the vast majority of the chicken genome is quite similar to that of the red jungle fowl and dissimilar to the other extant Gallus species. Genetic studies also reveal that there were probably two major domestication events: one in the Indus Valley of western India, and the other in Southeast Asia, in the region of Vietnam.
In 2008, following the completion of the sequencing of the complete chicken genome in 2004, it became clear that at least some of the DNA from the gray jungle fowl had made its way into the chicken. The gene that imparts yellow color to a chicken’s skin, which is a common trait in many chicken breeds, is found only in the DNA of the gray jungle fowl. It is unknown whether the addition of this single known gene (more may be discovered in the future) occurred prior to domestication as a natural hybridization or as a result of “domestic” red jungle fowl breeding with gray jungle fowl sometime after the original domestication event.
The domestication of the chicken was apparently contemporary with the domestication of other major animal species. The dog was arguably first in the domestication parade, followed by pigs, cattle, sheep, goats, horses, and, much later, turkeys, with chickens coming on the scene around 8,000 years ago, between the times goats and horses were domesticated.
While food and fiber were probably of primary concern for the domestication of most traditional animal species, it seems that the chicken was originally domesticated for the propensity of the roosters to fight. It is surmised that early man watched red jungle fowl roosters fighting off other roaming roosters in short but dramatic wing-flapping battles, leading to the banishment of one and the reproductive success of the other.
Fighting is a natural behavior of the polygamous red jungle fowl. The birds are harem breeders, meaning that each rooster will select a string of between 8 and 12 hens to constitute his harem. He protects his harem from predators and from marauding stag roosters looking for a harem of their own. This natural process assures that only the strongest males produce the next generation.
Once these birds were captured and forced to live in captivity, their ultimate fate was assured—domestication. Over the succeeding centuries, populations of jungle fowl/chickens made their way north to China, arriving there as early as 5,000 BC, and west into the Middle East, Europe, and Africa, which they reached by the first century AD. The birds also moved east, island-hopping throughout the Pacific Ocean with the Polynesians, until they made their first landfall in the Western Hemisphere in the 12th century on the coast of South America. At some point during their travels, jungle fowl became chickens.
CHAPTER TWO
The Science of Egg Formation
Egg-laying (oviparity) is a reproductive strategy in many animals. Of the mammals, only the platypus and four known species of spiny anteater (echidna) are classed as monotremes (egg-laying mammals), but among the reptiles, amphibians, and fish, many species are egg-layers. The eggs of all of these non-avian egg-laying species have a soft shell, which is either leathery or coated in jelly. Only bird eggs have a hard shell. The question many people ask is why do chickens lay eggs, or, more appropriately, what is the stimulus that causes them to lay eggs?
Reproductive Maturity
Eggs are the natural response of birds—in this case chickens—to reproduce. In general, pullets (young hens less than one year old) begin laying eggs at about 20 weeks of age and will continue to lay well for a year or so. As they age, their egg production begins to subside, increasing in the spring and summer and reducing in the fall and winter. But why do hens begin laying at 20 weeks?
As with all animals, age is a critical factor for reproduction. Maturity of the reproductive system, as well as of other organ systems and even a minimum body weight, are essential for successful reproduction. In mammals, puberty is attained at a certain age, which differs depending on the species. When puberty is reached, the brain signals the hypothalamus (the “master gland”) and pituitary to release certain hormones directly into the bloodstream. When these hormones reach the gonads (the ovary in females and testis in males), they respond by maturing into their functional reproductive state.
Days of the estrous cycle
In female mammals, the ova that migrated to the ovary during embryonic development begin to complete their maturation, a process that occurs either one or a few at a time, depending on the species. In addition, the ovary releases hormones of its own, which target other sexual organs and trigger morphological changes to assure a successful reproductive event. After a few weeks, an ovum is released to meet with sperm from the male, which have undergone a similar maturation event. If fertilization is unsuccessful, the hormone levels subside for a period of about three to four weeks, when the process repeats. This is a simplistic review of the estrous or heat cycle in mammals.
THE STIMULUS: LIGHT
In chickens, and most birds in general, the process is similar but with a few dramatic differences. The first and most obvious difference is that chickens do not undergo puberty. Instead, it is a specific stimulus—the photoperiod, or light/dark cycle—that begins the process. The hen’s brain remains the controlling organ, but in this case the pineal gland is key. The pineal is directly light sensitive (it is sometimes called “the third eye”), responding to changes in day length and controlling the circadian rhythm by releasing the hormones melatonin and serotonin. The hen will begin laying eggs when the day length reaches the threshold level of 12 hours.
When this level is reached and the hen is receiving at least 12 hours of light per day, its pineal gland is stimulated to release hormones that begin the cascade of events through the hypothalamus and pituitary and ending in egg production. For young pullets, the first egg will be laid after about two to three weeks, while older hens that have laid in the past will respond more quickly.
A second obvious difference with mammals is that rather than having an estrous cycle lasting three to four weeks, the hen will continue to lay eggs essentially daily for months while the stimulus of long day length remains. The pause in chickens occurs during fall each year, when the days become shorter. When day length drops below 12 hours, pineal hormones change and egg production slows and often ceases. During this lull in egg production, the hen will also molt, a process of losing and regrowing feathers. This natural process is much more severe in wild birds, which completely cease egg production in late summer and replace all their feathers by mid-fall. Some waterfowl find themselves flightless during the molt. Following centuries of breeding, the domesticated chicken often continues to lay during the molt and replaces only a portion of its feathers each year.
By taking advantage of the hen’s biological response to light, farmers are able to increase substantially the number of eggs laid. Placing 18–20-week-old pullets under 14–16 hours of light per day will bring them into production in about two weeks, no matter what the season of the year. In addition, keeping the lights on a long-day schedule will keep them laying through the fall and winter months. Eventually the birds will need to molt, which can easily be accomplished during their second winter. This is done simply by providing them natural short-day photoperiods, starting in about mid-November and continuing through the end of December. This period of short days (less than 12 hours) will give the hens plenty of time to molt and rejuvenate their egg production. Restoring long days of 16 hours of light (and even a little more, as they are older now) from January onward will restore their egg production.
What about the rooster?
The question often arises: What about the rooster? What is his role in egg production? Unlike mammalian males that breed with the females only when they are in heat, the rooster, like the hen, responds to photoperiod and will breed with hens daily as long as the stimulus of long day length is present. So, while the rooster is obviously important for reproduction, he has no role in egg production.
Egg Formation: The Process
Biologically, eggs are the female’s contribution to the reproduction process. Chickens, like all birds, produce a hard-shelled egg in which development of their offspring occurs without any outside contribution throughout the 21-day process.
The egg begins as a germ cell that has resided in the hen’s ovary since the time the hen was an embryo developing in its own egg. Once a pullet reaches sexual maturity, ovulation begins. As previously explained, birds do not experience puberty but are instead stimulated into sexual maturity by an environmental stimulus—photoperiod in temperate regions. Long days, with more than 12 hours of light, stimulate the brain and pituitary gland to release hormones that in kind stimulate the ovary to begin the process of ovum (yolk) formation. From the ovary, the formation of the egg passes through several stages, described as follows.
Reproductive system of the hen
OVARY
Chickens have only one active ovary, always on the left. This contains as many as 3,000–10,000 germ cells, only a few of which develop at any one time. The germ cells that will eventually become yolks develop in order, so that only one is mature enough for ovulation (release). Occasionally, more than one yolk ovulates at a time, resulting in a double-yolk or multiple-yolk egg. Once the yolk is released from the ovary, the process of egg formation begins in the hen’s oviduct.
OVIDUCT
As with the hen’s ovary, only the left oviduct is active. Occasionally a “right oviduct” develops, but it is nearly always vestigial and non-functioning. The oviduct’s function is essentially to package the yolk into what we know of as a chicken egg. The oviduct has five distinct sections, each with a function in the formation of the completed egg: the infundibulum, magnum, isthmus, shell gland, and vagina.
Infundibulum
The released yolk enters the oviduct through the infundibulum, the funnel-shaped end that actively engulfs the yolk. If the hen has mated in recent days, sperm cells that have been stored in “sperm nests” found in the infundibulum are released so that fertilization can occur. The yolk moves through the infundibulum in about 20 minutes.
Magnum
From the infundibulum, the yolk enters the magnum, passing through it in about three hours. It is in the magnum that albumen (egg white) is secreted around the yolk. Albumen is a combination of about 13 known proteins and is deposited around the yolk in distinct layers (see here).
Isthmus
The yolk, which is now surrounded with albumen, then reaches the isthmus, a distinctly thinner and shorter part of the oviduct compared to the magnum. It is here that with the shell membranes, inner and outer, are deposited onto the albumen. During the nearly 90 minutes that the egg spends in the isthmus, water begins to diffuse into the albumen, plumping the overall package and beginning the formation of the ultimate egg shape. The final process in the isthmus occurs as the egg begins to move to the shell gland, and involves the placement of small “seeds” of calcium carbonate (calcite) onto the outer surface of the outer shell membrane. These calcite “seeds” provide the starting point for shell deposition in the shell gland.
Shell Gland
Nearly five hours after ovulation, the nearly formed egg passes from the isthmus into the shell gland. At this stage its overall shape and size have already been partially determined. The egg is still somewhat flaccid, soft, and pliable, yet completely covered by membranes, so if it were to be laid at this time, it would be deemed a “soft shell.”
As the flaccid egg enters the shell gland, the plumping that started in the isthmus continues until the membranes are distended and the egg no longer appears flaccid. During the next 20 hours or so, the rather thick lining of the shell gland secretes about 0.3 oz. (10 g) of calcium carbonate onto the membrane surface, “growing” calcite crystals to a thickness of about 0.007–0.011 in. (0.2–0.3 mm). The crystals are deposited in columns with occasional spaces left vacant, resulting in a porous shell. It is estimated that the pores make up about 0.003 in.2 (2 mm2) of the total surface area of the shell of an average chicken egg. These pores allow exchange of oxygen, carbon dioxide, and water vapor.
Uterus versus shell gland
Many books continue to label the shell gland the “uterus.” The use of this name has, unfortunately, continued for decades, with seemingly only avian purists having difficulty with its connection to an avian system. The shell gland section of the avian oviduct is not a uterus. A uterus is a mostly mammalian organ, where mammalian embryos implant, receive nourishment by way of a placenta, and develop from a few cells to a fully formed baby mammal, until “forced” out during parturition (birth). In a bird, the section erroneously called the uterus but more properly termed the shell gland has the biological function of secreting mainly calcium carbonate to create the hard eggshell, a distinctly avian characteristic.
Most breeds of chicken lay eggs with brown shells, a few lay white-shelled eggs, and only a couple lay eggs with blue or green shells. The brown color is deposited on the shell surface as one of the last events in the shell gland. The production of white-shelled eggs is due to a mutation in the biochemical pathway that creates the brown color, disrupting this so that the color is not deposited. The blue or green color of eggs from the Araucana and related breeds comes from the deposition of a different pigment that is “mixed” with the calcium carbonate shell so that the color is throughout the shell material. The difference is evident by examining the inside of the eggs after breaking the shell: Brown eggs are white on the inside surface, while blue and green eggs are blue or green all the way through. The entire process of shell formation takes about 18–22 hours.
Vagina
Once the shell is complete, egg-laying (oviposition) begins. Just prior to laying, the egg, which has been moving through the oviduct pointed-end first, turns so that the egg will be laid blunt end first, a movement that probably relates to ease of laying.