Every pigeon producer
wants to keep the kind of stock that pays the best dividends for the purpose
for which it is kept. To the fancier, beauty and fineness of feather or
the ability to home from long distances are often the most important factors
determining the value of their stock. The beauty of birds is still an important
item to many, but to the majority of squab producers, success in business
depends upon the ability of pigeons to produce heavy squabs, full breasted,
plump and meaty with light colored flesh. Birds that combine superior fleshing
ability and high squab production are rated as birds of good stock. Of
course, you want to keep good stock from poor stock. To be good, a flock
of pigeons must be equal to or better than the average flocks of that squab
producing region. From the standpoint of developing more profitable squabbing
pigeon loft, two important problems face the squab industry. The first
problem is how to replace the present flocks with flocks noted for their
squabbing ability. The second problem is how to improve the squabbing ability
of the moderately good flocks.
Eliminate unremarkable
Flocks
Average number of marketable
(mongrel) squab produced per pair of squabbing pigeon varies from as low
as six to as high as 16. One reason is that many of the flocks are composed
of mongrel stock. These flocks of mongrels represent no particular breeding.
They usually consist of birds varying greatly in body size and plumage
color. They lay eggs lacking uniformity size and produce squabs varying
in size and fleshing ability. A flock that produces eggs and squabs lacking
uniformity is handicapped, because highest prices for produce of any kind
can be obtained only when it is of uniform quality.
Fortunately, during the past
few years the number of mongrel flocks in California has been decreasing,
but there are still far too many of them. They should be replaced by more
profitable flocks of standard bred pigeons. The rising generation of squab
producers can do much to hasten the change by encouraging the purchase
of standard bred breeding stocks from reliable sources instead of breeding
from flocks of mongrel parents.
Select Standard bred
Stock
Since the purchase of standard
bred pigeons is the first step toward securing better stock, you should
know what standard bred are. In selecting standard bred stock, you should
also know the answer to such questions as the following:
Are all flocks that meet the
standards of a breed profitable?
Is the uniformity of standard
bred flocks of any economic value to the squab producer?
How are breed standards set?
What are the most popular standard
bred breeds?
What defects of pigeons should
you guard against when selecting standard bred stock?
Your study of this
section will be
aided by keeping in mind
the five questions listed above.
The term "standard bred"
refers to pigeons that belong to breeds that have been developed according
to certain standards of type, color and economic characteristics. Standard
bred pigeons are represented by a large number of breeds, some of which
are economically important, while others are of interest largely as a novelty.
More squab producers than ever keep standard bred for squab production.
They have found that standard bred are uniform in size and color and produce
progeny that are uniform in size and production efficiency than mongrels.
Because of the increased demand for standard bred squabbing pigeons during
recent years, many owners of standard bred flocks have found that by producing
standard bred breeders for replacement the income from the pigeon loft
can be increased considerably, as compared with the production of mongrels.
Since there is such a popular
demand for standard bred stock, it is important to know the qualities,
that standard bred must possess in order to make them profitable. The fact
that a flock is composed of standard bred does not necessarily mean that
it is a profitable flock. An important problem facing the squab industry,
therefore, is how to improve the laying ability of most of the standard
bred stocks of squab industry. Another important problem facing the squab
industry is how to improve the fleshing ability of most of the standard
bred stock because rapid growth and excellent fleshing increase the profitability
of the squabbing pigeons.
Before discussing the qualities
that standard bred must possess in order to make them profitable, it is
necessary to point out what constitutes a standard bred and what are some
of the outstanding characteristics of some of the more important breeds
and varieties.
Breed standards
There has always been a keen
interest in breeding pigeons according to certain standards. One of the
first standards adopted for distinguishing one group of pigeons from another
group was the shape of the bird as shown by the outline made by the plumage.
Each group of pigeons thus developed became recognized as a breed. All
members of a breed are supposed to conform to the standard shape adopted
for the breed. It is well to remember the old saying, "Shape makes the
breed."
The recognized authority
for establishing standards for different breeds of pigeon is the National
Pigeon Association [NPA], an organization of private pigeon breeders
in the United States (and Canada). The association publishes the "Book
of Pigeon Standards," a book issued about every so often, which gives a
description of the standards adopted for each of the breeds recognized
by the association. Although the shape of the bird is the outstanding feature
of a breed, there are certain other characteristics, which a bird must
possess before it is recognized as standard bred which means bred according
to the standards of a breed.
Defects and Disqualification
Practically all pigeon breeders
want their birds to conform reasonably well to standard bred requirements.
This is important to those who sell breeding stock. Pigeon producers prefer
birds that excel in shape, color, and other standard characteristics and
at the same time are noted for squab production.Birds that excel in standard
bred and production qualities are rare, especially if too much attention
has been paid to many characteristics of minor importance, such as the
number of color of feathers and extra fine feathering. Too much "fancy"
and too little "utility" has resulted in several different varieties of
pigeons losing favor in recent years. On the other hand, as long as the
maintenance of breed and variety standard is considered to be in the best
interests of the pigeon industry and as long as purebred stock is in such
popular demand, it is necessary to maintain the standards that have been
adopted for breeds and varieties.
Pigeon breeders, therefore,
must ever be on the alert in guarding against having undesirable characteristics
become established in their flocks. Undesirable characteristics that are
sometimes found in purebred birds are called "defects" or "disqualification."
There are many factors, which should be considered in developing a sound
pigeon breeding program. All of these affect the number of squabs that
can be produced, and a high level of all these points is essential for
efficient production. Success in squab business depends very largely
upon the economic qualities of the breeding stocks.
1. Disposition
The disposition of pigeons
plays a major role in the success of squab production. It is best noted
during brooding when both parents spend much of their time on eggs and
squabs. Generally, efficient breeders are also devoted parents with highly
developed parental instincts. Losses due to broken eggs, crushed squabs
or poorly fed squabs are exceptionally low in the birds with calm disposition.
For example, the French Monadic is known to be very prolific, raising its
squabs almost the year around. The devotion of the bird to its eggs is
exceedingly strong. I have been told that crossing docile pigeon to "normal"
parents may improve the behavior of their offspring. If that is true than
by breeding for calm disposition many causalities that can lower reproductive
performance may be minimized.
2. Good provider/feeder
There are wide variations
in feeding skills by parents in different strains and breeds of pigeons.
Some parents are excellent providers and will place their squab's nourishment
above everything else. They feed their squabs down to the last grain of
feed in their crops. Selecting for those parents who feed their squab well
is desirable for commercial squab production.
3. Good speed
Commonly known as "speed",
the tendency to rapid reproduction is an inheritable quality of pigeons
and substantial improvements can be made by selection. Pigeons in the wild
state produce no more than two or three clutches of eggs per year. Additional
clutches are important in a good breeding program. Egg production is not
a single character: age at maturity, pauses, and persistency may all have
to be selected for to insure improvement in egg records. Several environmental
and physiological factors affect rate of lay and the total number of clutches
of eggs produced by pigeons. Squab producers must keep these factors in
mind in attempting to appraise the relative laying ability of pigeons year
after year during a long range breeding program. The principle objective
in breeding for high egg production is to increase the efficiency of the
laying stock in the utilization of feed, since feed cost amount to over
one half to two thirds of the total cost of squab production.
4. Viability:
Losses from diseases in pigeon
lofts are of paramount importance. Primary losses are due to the loss of
birds that die plus the loss of feed it consumed various. The monetary
loss also occurs from retarded growth, lower meat value of squabs, and
decreased egg production of many of the birds, which survive the attack
of disease organisms. It is possible to reduce mortality by selection,
provided the parents are selected on the progeny test basis and enough
families of sufficient size are available from which prospective breeders
are selected. Mortality should be considered as essential as egg production,
hatch ability, rate of growth, and other qualities of economic importance.
Squab producers whose lofts are plagued with high mortality from whatever
cause must consider the possibility of reducing the level of mortality
and keeping it within reasonable bounds from year to year. Since the factors
for viability may be specific; that is selection against mortality from
one cause will not necessarily lower mortality from other causes, only
a well planed selection and breeding program offers the best hope.
5. Fertility
Fertility: The economic
loss resulting from poor fertility in breeding flocks in the squab industry
amounts to several thousand dollars every year. Except for their use as
a fertilizer, infertile eggs have practically no salvage value. Whatever
can be done, therefore, to secure a higher percentage of the fertility
in hatching eggs should be of direct benefit to squab producer. Many factors
affect fertility, several of them under the control of the squab producer
including husbandry, environment, nutrition, etc. The problem of determining
whether fertility is inherited is complicated by the fact that fertility
is affected by several environmental factors and by the individuality of
the breeding males and females. Nevertheless, the fertility of mating appears
to be a property of the parents. At any rate, eliminate all low- fertility
individual males and females from breeding lofts.
6. Hatchability
Hatchability means
the number of squabs hatched per 100 fertile eggs. Hatchability and fertility
are biologically independent. There is a relationship between hatchability
and egg size, shell strength and thickness, egg weight loss during incubation,
and rate of laying and all of that are hereditary. Many genes determine
the percentage of fertile eggs that hatch. Progeny testing and selecting
future breeding pigeons from among the best families is the most practical
suggestion that can be offered to improve hatchability. Because of the
apparently large number of genes involved, in order to make much progress
over the years, a large number of pairs should be maintained and a reasonable
number of offspring should be secured from each parents. The percentage
of losses in pigeon lofts from infertile eggs, dead germs, and infant squab
mortality is often high. The loss does not strike the eye forcibly if record
is not kept. For an egg that does not hatch or a squab that dies in the
shell or shortly after hatching appears inconsequential. Such losses could
be as high as 20-25% and constitute a drain upon the business and may be
eliminated partially at least by proper selection of breeding stocks.
7. Feed efficiency:
The primary purpose of raising
pigeons and squabs is to convert feed into food of animal origin for human
consumption. Since the cost of feed represents from one half to over two
thirds of the total cost of raising squabbing pigeons, it is obvious that
any increased efficiency of feed utilization that can be brought about
by breeding should be of great interest to squab producers. Feed consumed
by pigeons is used for body maintenance, for any increase in body weight
that may occur, for egg production and for feeding squabs. Most of the
feed that pigeons consume is used for maintenance. Large birds use relatively
more of their feed for maintenance than small birds. Of two birds of the
same size and production, the one producing plump squabs consume slightly
more feed than the other does. A bird that lay no eggs and feed no squabs
yield any profits to squab producers because all the feed consumed is used
for maintenance. That is why regular culling of the breeding flock is desirable.
Unprofitable producers if in good physical condition should be sold for
their meat value, thus reducing the cost of feeding the flock.
8. Growth:
One of the most important
factors affecting the efficiency of feed utilization in raising squabs
is rate of growth. The faster that a squab grows, the more efficiently
is feed utilized during the growing period. Rapid growth, good body type,
and superior breast fleshing are very desirable in squab raised for meat
production. Increase in body size involves an increase in the size of organs
and muscles and in the growth of bones of the body, this true growth being
distinguished from the increase in size that results from the deposition
of fat, in the reserve tissue. True growth implies, therefore, an increase
in water, protein, and mineral matter and involves an adequate supply of
energy producing nutrients, to support the various growth processes, and
vitamins of various kinds, which are essential for the attainment of physiological
well-being and the most efficient utilization of feed. Rate of growth is
naturally affected by such environmental conditions as overcrowding, chilling
or excessive heat, drafty lofts, improperly balanced diets and parasites
and disease. These facts are mentioned primarily for emphasizing the importance
of maintaining uniform conditions for different lofts or pigeon houses
that are being compared with respect to their inherent growth rates. A
squab makes greater gains in live weight per unit of feed consumed during
the early growth stages than during the later growth stages. In other words,
as the squab increases in weight, the gain in weight that it makes per
pound of feed consumed decreases. This is because, as the squab increases
in weight, relatively more of the feed it consumes is used for maintenance.
During the first few weeks of growing period, environment has a greater
influence than heredity on rate of growth. However, most of the differences
in efficiency of feed utilization are due to inherent differences in the
rate of growth.
9. Body type and size
Body type in squabs is of
considerable importance in the squab industry because it affects prices
paid for market squab and may influence consumer appeal for dressed squab.
Where as growth involves a simultaneous and coordinated growth of all the
structural features, form is the visible expression of biological organization.
Therefore, the ultimate size and shape of body attained by squabs is determined
largely by the duration of growth, the rate of growth of the leg bones
and their development in relation to the development of the keel, the extent
of development of the breast muscle, and the amount of distribution of
stored fat. During the growth period, the variability in skeletal growth
is relatively much less than the variability in body weights. Shank length
serves as a reliable index of body weight during most of the growing period
and shank length and body weight are more closely correlated during various
growing periods than after the birds have attained mature body weight.
Several genes, a few of major importance, including at least one sex linked
gene, are involved in the inheritance of body size in birds. Selection
based on body size and type of birds should be quite effective in increasing
body size in most strains of birds.
10. Flashing
Variability in body shape
and degree of fleshing is evident in different strains and breeds of pigeons.
The live bird outline is of some value in selecting breeding stock to produce
well proportioned and well fleshed squabs. Increase in body length and
depth and increase in length of legs is inversely correlated with the percentage
of edible meat. On the other hand, length of keel is positively correlated
with percentage of edible meat. Differences in body confirmation of live
birds could be determined quite accurately by comparing body weight, shank
length, keel length, and anterior body depth. The most desirable index
of body shape in live birds is the relationship between shank length and
cube root of body weight.
Cock's body shape is transmitted
to his progeny to a high degree. The shape as well as the location of the
keel in its longitudinal axis, has more influence on the conformation of
dressed birds than the length of the keel. The relative proportion of edible
meat, fat and skin to bone and inedible viscera varies due to breed differences.
The percentage of flesh is influenced by the size of the birds in relation
to period of growth. However, relative fleshing is not necessarily a good
criterion of plumpness of breast fleshing. A well fleshed bird might have
a poor appearance as a dressed bird because of relatively great depth of
body. In addition, shallow- bodied bird might by quite plump in appearance
but actually have relatively less flesh than the deep bodied bird. For
that reason, body depth should be taken into consideration in relation
to degree of breast fleshing.
Thickness of breast muscle,
or roundness (plumpness) of breast is a character separate from and independent
of skeletal width of the thoracic cavity. Plumpness of breast in birds
is negatively correlated to depth but since breast plumpness is apparently
inherited from the male, it should be possible to develop strains of
PLUMP BREASTED, DEEP BODIED, FAST GROWING SQUABS by progeny testing. The
fastest growing birds, with relatively the longest shanks and keels, also
have the widest breasts and tend to grade the best. It is possible to select
and breed for increased width of breast without materially affecting shank
length, keel length and body weight. In addition, improvement in breast
width is attained more rapidly when body weight, shank length and keel
length and breast width are considered than when breast width alone is
considered in selecting future breeding stock. The phenotypic selection
of future breeding stock should be quite effective in a selection and breeding
program to develop rapid- growing strains.
The amount of fat
in the flesh of pigeons undoubtedly affects the flavor. The fatness of
the squab is also used in grading birds for the market; hence, the amount
of fat in the muscles is of considerable interest. In poultry, the breast
muscles (light meat) contain less fat than the leg muscles; the other edible
portions of the carcass contain more fat than the leg muscles. However,
in pigeons, like other flying birds, the wings and breast muscles are the
same like drumstics.
Table 3:
Composition of Squab meat
____________________________________________________________
Meat
Water Energy Protein
Fat Fiber Ash
%
kcal gm
gm gm
gm
-----------------------------------------------------------------------------------------------
Total edible
58.0 279
18.6 22.1 0
1.5
Flesh and skin
56.6 294
18.5 23.8 0
1.4
Flesh only
72.8 142
17.5 7.5
0 1.2
Light meat (no skin)
74.0 125
20.7 4.2
0 1.2
Giblets
69.8 154
19.8 7.2 1.2
2.0
_____________________________________________________________
Source: Composition
of foods: Agricultural Handbook No. 8.
Agriculture Research Service,
USDA, 1963.
FACTORS
THAT INFLUENCE
THE MARKETABILITY
OF SQUABS
The following factors influence
the marketable qualities of squabs:
Down feathers are soft,
hairy, yellow, infant feathers to be found on most newly hatched squabs.
The down of squabs is simple filaments and much more feather like and fluffy.
Some nestling have a greater amount of down feathers than others do. These
infants down feathers drop off as the squab grows older. At three to four
weeks of age, several of them may remain attached to the outer ends of
the contour feathers of the neck. They are one of the means of identifying
a young pigeon three to five weeks of age. There is a considerable variation
in the age at which different plumage appear and are replaced, if not in
the number of successive plumage's, in different breeds or strains
of pigeons.
Rate of feathering depends
to some extent on the growth and general well being of the birds. This
is shown by the relatively slow feathering of runt birds where the same
factor (such as unfavorable environment) causes slow growth and slow feathering.
Well grown birds of normal size also differ among themselves in rate of
feathering and rate of growth. The differences are inherited.
The best known inherited
differences between breeds in rate of feathering are determined by sex
linked genes. Rapid feathering breeds carry a sex linked recessive gene
for rapid feathering.
The simplest method of insuring
well feathered squabs at marketing age would seem to be to introduce the
recessive sex linked gene for early feathering into all breeds and varieties
used for squab production.
Considerable success can
be achieved by selecting for early feathering on back and other parts of
body in strains carrying the dominant sex linked gene for slow feathering.
These strains apparently carry genes, which modify the expression of feathering
to such an extent that some birds feather out more rapidly the others.
Probably the most favorable
period for selection in strains of the sex linked slow feathering type
is after an age at which majority of the squabs would not show considerable
feather growth. Certainly, the selection for feathering should be made
before any of the squabs reach a marketable weight. This would mean selection
for rate of feathering at 3 to 5 weeks of age or earlier.
-
Breast defects
The commonest breast defects
are crooked keel and breast blister. Others, for instance, split keels,
presumably an accidental developmental deformity, are so rare that they
are of negligible economic importance and will not be discussed in this
paper.
Crooked Keel: Crooked
keel may result from nutritional deficiencies, particularly insufficient
minerals or vitamin D in the diet of pigeons not exposed to sunlight; and
from a hereditary tendency to develop crooked keels. Obviously, only straight
keeled birds should be used for breeding. Care should be taken to feed
an adequate diet.
Breast blisters: Breast
blisters are characterized by the collection of viscous fluid under the
skin over the keel. Small blisters usually are not noticed and have no
effect on the market value of the squab, but large blisters detract from
the appearance of the birds and thereby reduce their market value.Prevention
is a more desirable method of avoiding breast blisters, but not enough
is known about their cause to do this effectively.
Dark meat differs from white
or light-colored meat for the pigments called myoglobin and cytochrome.
In addition to these pigments, birds that have a black coloring in the
feathers may also have it in the flesh, particularly in the abdominal region.
Black pigments do not occur in the flesh of white feathered birds or in
the flesh of birds with relatively light plumage. Black pigment does not
harm except to detract from the appearance of the bird. Because of the
unattractive appearance some fastidious people will not buy squabs exhibiting
this pigment but will pay a premium for well fleshed birds free from it.
-
Economy of gain
The producer of squab meat
is interested not only in the type and in quantity of yield, but in the
cost at which such yield is obtained. Generally, this question resolves
itself into the efficiency of food utilization by the growing squabs or
feed efficiency. The life cycle of pigeon production is such where we can
not separate the feed consumption of the parents from the squabs and must
include the total amount of feed consumed by the parents while calculating
the feed conversion or feed efficiency in squab production. The feed efficiency
can be measured by the ratio of pounds of gain in weight of squabs over
pounds of feed consumed by the pigeons. Actually, a major part of
food consumed by parents is used for their own maintenance , productive
and reproductive needs and remainder portion is used for feeding
squabs.
For practical purposes, the
" total weight efficiency " may be used provided comparison between pigeons
of the same age and size is made. This is due to the fact that maintenance
requirements depend on a function of body size, so that if the total weight
efficiency of one pair of squabbing pigeons is compared with another pair,
any size difference between them will introduce an error. From the standpoint
of the practical squab producer, it should be remembered that the total
weight efficiency definitely depends upon the amount of squabs produced
by the squabbing pigeons. Regardless of how many pounds of squabs are produced
by the parents, feed requirements for their body maintenance remains the
same.
For example, if a pair produced
20 lb.. of squab and consumed 120 pounds of feed in a year time ,its total
weight efficiency is 1:6. That means for every pound of squab they produced
they have consumed 6 pounds of feed. On the other hand, if they produced
10 lb of squabs during the same time and consumed 110 lb of feed their
efficiency is 1:11. Since their feed requirement forbody maintenance
remained almost constant level, their feed consumption did not drop
proportionately and reflected a reduced feed efficiency. Obviously, the
gain per pound of feed consumed is so low for squabbing pigeons that they
become unprofitable to produce unless they produce 12 or better marketable
squabs per year.
HOW TO CHOOSE
REPLACEMENTBREEDING
STOCK
Pigeons that combine
superior fleshing ability and high egg production are rated as birds of
choice in squab production. The ultimate goal of any breeding program is
to have a high proportion of pigeons with the most desirable
characters . The success of such breeding program is largely dependent
upon the wisdom with which the prospective parents are chosen. The best
should be saved for breeding purposes in order that each year's flock may
be better than the flock of the year before. Selection of breeding parents
involves a great deal more than being able to tell which pairs are doing
well at the time of observation. In selecting young birds to replace the
flock, it is best to choose from nests containing two squabs of nearly
equal size, age and from the same mating. By following a careful system
of selection for size, shape, and vigor, the type of the squabs can be
improved greatly.
The desired type will usually
involve not one but several economic characters. Since no one pigeon ever
combines all the best characters, we must be reconciled from the beginning
to compromise in the selection of future breeding pigeons. Each individual
constitutes a new and temporary combination of genes, which are taken
as "samples" from the genes of parents. In this sampling process, the squab
producer is able to exercise some degree of control, thus changing the
new population so that it is a little different from the preceding one.
Take, for example, the case of body size of the squab. If no selection
is practiced, the gene frequency for each pair of genes and the body
size as a whole remains approximately the same. The flock of
pigeons as a whole does not change with respect to the proportion of genes,
which it carries for large size and those, which it carries for small
size.
There are still large and
small pigeons in the loft because of the chance combination of genes for
body size. However, the mean of the population remains about the same.
When selection is applied, the squab producer no longer takes his sample
of genes from the whole population but only from that portion of the population
having, the greatest assumed concentration of the desired genes. This results
in a change in the gene frequency in the population of pigeons for
the body size.
When selection is exercised
to change the gene frequency for any single character, the squab producer
may be unconsciously selecting for or against another character. For example,
egg size and egg numbers have a physiological relationship, an attempt
to increase number of eggs may result into a decrease in egg size.
FACTORS
DETERMINING
A
CHANGE THAT CAN BE MADE IN
THE GENE
REQUENCYOF A CHARACTER
The amount of change that
can be brought about in the gene frequency of a particular character is
dependent upon several factors including:
-
The number of individuals that
are available. For instance, if a character is influenced by as few as
five genes, one would expect that 243 individuals would be required to
have all possible combinations (genotypes) represented. Any number less
than that means few of the possible extremes in genotypes might be secured.
-
The proportion of the individuals
that can be discarded from each generation . If it is possible to use as
breeders only 10 % of the population, then the sample of genes for the
new generation will come from a source in which the desirable genes predominate.
-
The accuracy with which individuals
with a desirable genotype can be identified. The phenotypic expression
of all characters is influenced by both environment and heredity.
It is helpful to know something
about the heritability of a character in determining whether the record
of an individual can be wisely used in estimating its breeding value.
WHAT IS
HERITABILITY?
Heritability may be defined
as the percentage of the variation of a given character due to genetic
forces. Suppose we are dealing with a character such as body weight of
squab at market age of 28 days. The number of gene pairs contributing to
it is probably very large. Ordinarily, when more than two or three pairs
of gene are involved in the inheritance of a character, it is not practical
to isolate and measure the effects of each. We can weigh a squab at the
age of 28 days and determine that it has a phenotype of 1.5 pounds
or what ever it may be for any specified age.
The phenotype is the product
not of the bird's genetic constitution acquired from its parents, but of
the interaction between its genes with various non genetic or environmental
forces. The more the actions of the genes involved are susceptible to environmental
modification, the less accurate will be our judgment as to the bird's actual
genotype.
Statistical methods have
been devised to measure approximately, what percentage of the variation
of a given character is due to genetic forces and what to environmental
influences. In body weight, the percentage of genetic variation is about
40%, and the environmental percentage about 60%.
The figure expressing the
percentage of genetic variation is known as the "degree of heritability".
Heritability for body weight is thus about 40%, usually written 0.40.
The degree of heritability
is a exceedingly important figure for us. It determines the amount of gain
which breeding selection can accomplish. More important, its magnitude
governs the choice of an efficient selection method.
HERITABILITY
40% OF A SQUAB'S BODY WEIGHT
IS DUE TO HEREDITARY
AND 60% TO ENVIRONMENT
Heritability does not mean
that 40% of a squab's body weight is due to hereditary and 60% to environment.
What it means is that in a population of pigeons there will be differences
between individuals, partly caused by the fact that each bird has somewhat
different genetic makeup, and partly by the fact that each bird has been
under an environment to some extant peculiar to itself. The degree of heritability
is the fraction of the total of such VARIATION, which is traceable to genetic
differences. If the birds in a population are deliberately subjected to
different environments, the total variation among them will be increased.
However, the absolute amount of genetic variation will remain unchanged.
In other words, heritability will drop. By the degree of heritability we
means the proportion of the variation in a flock in which males and females
are mated together without regard to their genotype or phenotype resemblance
to each other ( random bred ). The higher the heritability, the greater
is the correlation between the genotype and the phenotype. If the heritability
of a character is 100% (or simply 1), it means that the genotype value
of a bird coincides with its phenotype value. At the other extreme, a heritability
of zero would mean that the genotype and phenotype are not at all correlated
and all of the variation in the phenotype is due to non genetic or environmental
sources.
Degree of heritability is
shown in different characteristics-- some have high and some low heritability.
For characters having high heritability, individual selection of pigeons
can be efficient in raising the average level of performance. For characters
of low heritability, resort to family selection must be made. In both situations,
combined selection of using information on both individual and family characters
will make for a more reliable breeding program than would reliance on either
method alone. Below is a list of some of the qualities for which information
on the degree of heritability is available.
TABLE 4:
HERITABILITY
OF SOME CHARACTERS.
He can decide which birds of
those available will become the parents of the next generation. This is
SELECTION
It is in his power to decide
which particular male will be mated to a given female. This involves a
choice of a MATING SYSTEM.
-
He can within certain limits
determine what proportion of the next generation will originate from each
of the birds selected to be parents. This is his power to control REPRODUCTIVE
RATES.
Any progress in the breeding
of squabbing pigeons has to come about through the conscious or unconscious
use of the principles of heredity . It should be apparent that a given
bird's breeding value depends upon the genes it carries . However, there
is no practical means available to pigeon producer to determine with certainty
an individual's genetic makeup. His problem is to weigh such evidence
as is available, and form discriminating decisions.
DETERMINING
THE
BREEDING
VALUE OF SQUABBING PIGEONS
The evidence concerning a
given bird's breeding value falls naturally into five categories. These
are:
1. Individuality
2. Pedigree
3. Family or sibs
4. Reproductive performance
5. Progeny
Of these, the last two are by
far the most dependable and, therefore, the most important. However, they
are available only after an individual has been bred and is a proven breeder.
INDIVIDUALITY:
The individuality of a bird
refers to the sum total of its characters. It includes every detail of
its make-up, what it does and the way it does it. When the character being
selected for has a high degree of heritability, that is, when the phenotype
is closely representative of the genotype, selection on an individual basis
assures that desirable genotype are being used. For example, if one were
breeding for a highly heritable character such as body size, then the most
rapid progress would result if one selected all of the superior individuals
(approximately 10% of the population can be saved for breeding purposes).
It is a safe practice to base selections on individuality first, and upon
pedigree and family later. If one is purchasing a bird for breeding purposes
he should look over the group for sale, select the few which appear most
satisfactory under careful scrutiny, and then investigate their pedigree
and ,if available, their respective family or siblings.
PEDIGREE
That a good individual with
a good pedigree is preferred to an equally good individual with a poor
pedigree .The reason is that the chances that the first bird is pure for
the genes responsible for the characters desired are better than
for the second. A good pedigree only betters the chances; it does
not guarantee purity. Therefore, if one has good loft of pigeon
with a good pedigree record, that does not provide practical assurance
regarding breeding value. Progress in breeding always has been and probably
always will be more or less a matter of chance. Selection is a powerful
aid in improving the chances, and pedigree should be a very strong consideration
in selection.
FAMILY OR SIBS:
A further evidence as to
the likelihood that a given bird carries certain genes, and is pure for
them, is given by the trait of his brothers and sisters. In making, use
family records ,the question always presents itself what to do about
the superior individuals in the poor or mediocre families and inferior
individuals in the superior families. In breeding for low heritable characters
such as egg production, neither of these categories should be selected
for breeding purposes. The probability that the pigeon under consideration
is pure for the genes for the qualities he carries is greater when his
siblings are equally and uniformly good in those traits than when is he
is an outstanding individual among mediocre siblings. This line of evidence
is not always available to squab producer unless the parents of the
individuals under scrutiny have been mated together for more than one breeding
year and the performance data of their siblings of other years is available
for comparison. When one is selecting for a character such as egg production,
which has a low degree of heritability and is exhibited in only one sex,
it is necessary to use measures other than the individual's record to estimate
genotype. In this case, the record of the family as a whole becomes more
important than the record of the individual in determining which bird to
use as breeders determine. The most efficient kind of a continuous breeding
program is one in which emphasis shifts from individual selection to family
selection as more attention is given to characters that are less and less
heritable.
REPRODUCTIVE PERFORMANCE:
The evidence concerning a
bird's breeding value so for has had to do with its own or with proceeding
generations. For the most part, this evidence is available before it goes
into the breeding loft. Its reproductive performance and performance of
its progeny are not available until a later date. No matter what a bird's
individuality or pedigree may be, or indeed, what genes for high production
it may be known to carry, its value as a breeder is seriously limited if
a reasonable number of progeny is not forthcoming. In order that this may
occur, a female must first lay a large number of eggs during her breeding
life. The reproductive performance will include several things, which
are discussed elsewhere.
PROGENY:
In contemplating a given
bird for the first time as a possible breeder, individuality, pedigree,
and family are all one has to go by. Hopes are built upon these but predictions
are quite uncertain. However, one reasonably sure basis for making a decision
about the bird's ability to transmit genes for desired characters to most
or all of its progeny would be by breeding it. The progeny test is the
decisive test of breeding value. By progeny testing is meant a careful
analysis of the results secured from various mating that have been made,
in order that future mating may be made with greater assurance of desirable
results. Any mating that has given unusually good results should be repeated,
if possible. On the other hand, any male or female whose progeny have been
uniformly unsatisfactory should be discarded. It should always be remembered,
however, that the progeny are the products of two parents. Uniformity and
productiveness under given environmental conditions depend upon the genes
from both parents, unless it is assumed that one parent is pure for all
dominant genes concerned. The most accurate estimate of a pigeon's breeding
worth is an evaluation of its progeny when it is mated with several different
mates. This is the best proof that those pigeons have desirable genotype,
and they and their progeny should be used in future breeding operations.
Ideally, each male should be mated to eight or more females representing
several full sister families.
The performance of each male's
progeny under such system is highly representative of his breeding worth.
In making use of superior progeny tested males, they may be re-mated with
the females with which they produced superior families , as well as the
full sisters of these superior pigeons. However, in pigeon breeding it
is not possible without artificial insemination. In using family selection
or the progeny test, all individuals of a family must be considered and
not just a few selected individuals. If some individuals of a family have
died or have been culled, this fact must be taken into consideration when
determining the relative merit of the family. Besides giving evidence concerning
the genetic makeup of the parents, the progeny also witness to the pigeon
breeder's skill or good fortune in mating.
HOW
TO TEST THE
GENETIC
CONSTITUTION OF THE PIGEONS
The general rule
for testing the genetic constitution of a bird is to mate it with a bird
that carries the pure recessive character. The individual is pure for the
dominant character, if none of the offspring show the recessive character.
Sometimes a recessive character may be carried in a flock for some time
without being detected, if mating happen to be made with birds, which are
pure for the dominant gene. The impurity is discovered when two impure
individuals are mated.
WHAT IS INBREEDING?
Inbreeding is the mating
of related birds to fix some desirable quality or character. Close inbreeding
is the mating of closely related birds, such as brother to sister
or sire to daughter. It is one of the quickest ways of fixing and intensifying
characters. This at once make it a dangerous system to use unless great
care is exercised in selecting the birds to be mated, for the bad as well
as for the good characters may be intensified. Inbreeding is like any high-powered
implement; when properly used, it is an excellent aid to human effort,
but in the hands of the ignorant and careless it is a source of danger.
WHAT IS LINE
BREEDING ?
Line breeding is systematic
inbreeding. It involves the repetition of certain desirable individuals
and their offspring in successive generations for the production of inbred
strains. By this method, a male may be mated to his daughters and then
later females offspring resulting from the mating with his daughters.
Similarly a female may be mated to her son and later to a male produced
from the mating with her son.The system aims to reduce the danger of arising
from the promiscuous mating of closely related individuals.
The success of line breeding
depends on the skill of the squab producer in making his selection, and
his knowledge of the laws of breeding. Line breeding, if properly conducted,
makes it possible for a producer to develop several families of birds within
the same flock which are similar in breeding and of common ancestors but
not closely related. By such a plan, a strain can be established without
using any outside blood for several years, unless flock is small. Even
in such mating, harmful effects may be produced in some cases. However,
if the stock is vigorous and has previously been selected for desirable
characters associated with hatchability, growth and viability, successful
mating may be expected.
WHAT IS OUT
CROSSING ?
Out crossing is the mating
together of individuals of two different strains or families of the same
breed or variety. It is the opposite of inbreeding. This is done for new
blood, usually to improve the vigor, to correct some outstanding defect,
which the producer has not been able to overcome, or to introduce some
desirable factor, which is not present in the stock. When new blood is
introduced, the effect on the offspring should be noted carefully to see
whether the results are what are desired. It is never advisable to use
new blood extensively without first trying it in a small way to see if
it produces the results expected of it. Out crossing should not be regularly
practiced, as it tends to break down and scatter the definite bloodlines
established by years of line breeding.
WHAT IS GRADING?
Grading is mating of a mixed
flock with a purebred male and is the method commonly followed to improve
a mongrel flock. The offspring of such a mating are called "grades" because
they come from purebred sire and common stock. The first cross generally
shows marked improvement over the native stock. If the females of this
mating are again bred to a male of the same breed, greater uniformity of
type results. The continual use of males of the same breed results in a
flock, which is practically purebred. Improvement by grading is slow and
tedious . Many quicker and better results may be obtained at very little
extra cost by purchasing a few purebred pigeons from a well bred flock.
WHAT IS CROSSBREEDING
?
Crossbreeding is the breeding
together of individuals of different breed or varieties. It usually results
in better hatchability, livability and growth of squabs. Its influence
on egg production may be variable. Two separate breeds must be maintained
for the production of crossbred stock.
WHAT IS A SELECTION INDEX
?
Squab producers are generally
interested in improvement of more than one character at a time. They
must decide whether to try to improve one character at a time or consider
all simultaneously. The latter method will produce the greatest overall
gain but only a small amount of gain in any one character. The greater
the number of characters, the smaller the improvement in each single character.
To help the squab producer with the problem of selection, it is suggested
that some kind of selection index be developed. In its simplest
form, a selection index is merely a system for evaluating an individual
for several characters simultaneously. Consciously or unconsciously, all
squab producers practice this system to a certain extent. If a female lays
a large number of large eggs that hatch well, it probably would not be
discarded because of poor plumage color, although the color condition might
cause it to be discarded if it were mediocre in other characters. The development
of a good selection index is not an easy matter. It is complicated
by the fact that not only are there many characters to be considered but
also they are not all of equal importance. The selection index must be
suited to the individual squab producer considering the weak and
strong points of his strain. The index will require changes as the strain
improves or degenerates in certain characters. A simple index might be
constructed by assigning appropriate values to the following characters:
1. Temperament of the breeding stock,
2. Tendency to rapid reproduction,
3. Persistency in production,
4. Longevity and disease resistance,
5. Heavy feeding of squabs,
6. Hatchability of family,
7. Body conformation.
8. Viability of progeny,
9. Feed conversion , and
10. Age to market.
If the strain is relatively
weak in any one of these characters, it will be necessary to put more emphasis
on that character. As the breeding program progresses, the value assigned
to each character can be altered or a change can be made in the number
of characters considered. Whether an individual is culled or used for breeding
would thus depend on its total score in relation to the score of all other
progeny tested pigeons. Successful breeding involves a succession of compromises.
No single pigeon is apt to bring together as many desirable characters
as possible in the progeny produced.
FOR
A BETTER
UNDERSTANDING
of the material in this paper,
the following is an explanation of some of the primary factors governing
heredity, and a glossary of a few of the terms used in genetics. offspring.
Genes are defined as the determiners of hereditary characters. With few
exceptions, they occur in pairs--one member of the pair being derived from
each of the parents. Thus genes may be:
DOMINANT OR RECESSIVE.
A dominant gene will express
itself whether or not the gene paired with it is like itself or different.
A recessive gene will express itself only when both members of the pair
are alike.
HOMOZYGOUS OR HETEROZYGOUS.
Homozygous means they
will have acquired two like genes and will breed true. Heterozygous
means they will have acquired two unlike genes and will not breed true.
Various genes are usually designated by arbitrary letters-- capital letters
designating dominant and small (lower case) letters designating a recessive
condition. Thus the gene for hatchability, H represents dominant and h
represents recessive.
GENOTYPE:
Genotype is the term designating
the constitutional makeup of an individual with respect to genes.
PHENOTYPE:
Phenotype is the term used
to indicate the visible characteristics of a pigeon's constitutional makeup
or genotype.
INCOMPLETE DOMINANCE
Incomplete dominance is used
to designate cases I which 2 unlike genes are present in a pair governing
a character, but neither gene completely suppresses the expression of its
mate.
MULTIPLE GENES:
In cases where characters
are produced by the action of a large number of genes ,the result is said
to be due to multiple genes.
BREEDS
USED
FOR SQUABBING
PIGEONS
1. CARNEAU
-
- Docile
-
- Fast
producer
-
- Attentive
to its young
-
- Dependable
feeder
-
- Tight
feathered
-
- Dressed
squab has well rounded body and breast and very clear white skin.
2. FLORENTINES
-
- Madonna
like type and shape
-
- Close
hard feathers
-
- Aggressive
-
- Tendency
to fight
3. HOMER- GIANT
-
- Active
and hardy
-
- Fast
breeder
-
- Fine
body size
-
- Fertility
and stamina
-
- Its
blue and blacks mated together often produce dark skinned squabs
4. KINGS- WHITE, SILVER
ETC.
-
- Prolific
like Homer and Mondain
-
- Size
and Short blocky breast like Mondain
-
- Angular
body of dressed squab
-
- Silver
King: more docile, quite
-
- Broad
breasted, deep keeled, well proportioned, blocky, deep and
well rounded body, straight bright red legs of medium
length
5. MONDAIN
-
- Very
prolific, year around
-
- Devotion
to its eggs is exceptionally strong
-
- Fast
maturing squabs
-
- Loose
feathers
-
- Greater
weight, broader rump
6. RUNT
-
- The
largest domestic pigeon- too large to be profitable
-
- Very
tame
-
- Slow
breeder
-
- Quarrelsome
-
- Weigh
and eat twice as much as any other breed
-
- Never
be crowded
7. STRASSER
-
- Vigor
and consistent production
-
- As
large as King
-
- Hard
and tight feathers
-
- Coloration
Copyright
2002 by Azhar Bokhari
Updated: 2002/05/08