Infertile eggs are a problem that affects all of us from time to time, but seems to be most common in the first round of eggs in the breeding season. A typical pigeon breeder pairs his birds in late December or early January. Everyone wants the oldest, most mature young birds at show time. The problem with this is that we are fighting a battle with Mother Nature that we have created for ourselves. If left together pigeons will reproduce year round with a break in mid winter. This is the same time we are trying to force mate our breeders, a problem which is compounded by the fact that by keeping the sexes separated their reproductive cycles are at an annual low. The widowed hens have a low hormonal level due to the absence of a cock, the lessened daylight hours and the cold weather. When mated with a cock at the beginning of the breeding season the hen's reproductive system (hormones) must come out of the low level of activity into egg production, a process which normally takes about 10 days.

What about the cocks? Members of an all male social group of monogamous animals have a lower level of the hormone testosterone (critical for sperm production) than male members of the same species that are in contact with females of their own kind. Therefore all the stock cocks that have been roaming the cock pen for several months have a low testosterone level and therefore low sperm count. The sperm count will rise slowly after contact with the hens but this again takes time.

Tying this all together at mating time, the hen is in a low reproductive cycle and must gear up for egg production, which as mentioned is usually 10 days. Fertilization can only occur 3 to 6 days before the first egg is laid (4th to 7th day after pairing). The cocks already have a low sperm count at pairing time and repeated courtship copulations during the first 3 to 4 days after pairing further reduces the amount of sperm available for fertilization on the 4th, 5th and 6th days, exactly when the hen is in the critical stages of ovulation. Because of the unnatural pairing process during the low reproductive cycles of both the cock and the hen, we have hens that need to be fertilized at a time in which the cocks have the lowest sperm count of the year!

The obvious solution to this problem is to get a high sperm count copulation 3 to 6 days before the first egg is laid. To do this we must keep the pair from copulating excessively during the first 3 days after pairing, while at the same time providing sufficient stimulation to commence the hen's ovulation cycle. The easiest way is on the morning of the mating day to put the cock and the hen in adjoining show coops where they can see but not get at each other. The cock will go through the mating ritual and the hen will likely be receptive to his advances. In the afternoon the hen is put in the cock's cage for an hour or so. After they have mated the hen is returned to her cage where she can continue to see her mate. During their time together the hen's reproductive cycle will have been set in motion. After 3 or 4 days (with plenty of clean feed and fresh water) the birds are removed from the show coops and placed together in their nest box. This method will go a long way toward making sure the cock has enough sperm left to fertilize the hen during the optimum fertilization time of her ovulation cycle.

After the first round there should be no further problem due to the fact that the cock's sperm count will rise to and remain at a higher level because of the stimulation afforded by the raising of young and the reduced courtship copulations.

- Vaughn Suhling

It is an accepted fact that all fertile eggs will not produce a live healthy squab although hatchability rates for pigeons are higher (95-96%) than most other domestic birds such as chickens, turkeys, ducks and geese. The reasons why fertile eggs do not hatch can be divided into three categories: management, genetic and physiological.

Management

The first reason usually mentioned when discussing hatching problems is lack of proper feeding. To give strength to the egg germ the parent birds must be properly nourished. Improperly balanced rations will cause low vitality which in turn causes weakened egg germs. The result is that though the germ may assume life in the shell and grow into a squab, it does not have the strength to pick its way out of the shell and therefore dies. When proven feeding programs are followed, this problem is minimal. All the nutrients essential for life, except oxygen, must be contained in the egg so a complete diet is essential.

Sanitation, when it involves spraying to control external parasites or hydrated lime to help with odours, can cause embryo mortality.

Mated pairs of pigeons incubating eggs and raising youngsters do a better job if left alone. Traffic through pens, particularly at night, will upset many birds and their constant movement on and off the nest can create problems. It is not uncommon for both parents to leave the nest for short periods of time, however if the nest is left for a longer time the eggs can become chilled. Birds have been known to desert their nest and build a nest in a new location with good subsequent hatchability. Faulty nest construction in which eggs roll away from the parents, interrupting incubation, may have difficulty hatching.

Genetic

Hatchability of eggs is inherited. Studies indicate that several genes are involved for this single trait. The larger the number of genes involved in the inheritance of a particular character, the greater the difficulty in determining the mode of inheritance. Moreover, environment plays an important part in the full development of the various physiological characters, the genes sometimes being unable to exercise their full affects. Genes for high hatchability may be present but incubation conditions being faulty with only poor results following. Studies have shown that hens whose eggs are of high hatchability tend to transmit this character to their daughters and, likewise, hens whose eggs are of low hatchability tend to transmit this character to their daughters. Similar studies with cock birds have shown that they have relatively less influence on egg hatchability. One must always keep in mind that hatchability is an inherited trait and as such high levels can only be maintained if the breeding in the loft is controlled.

Physiological

Even though conditions of incubation are ideal, all fertile eggs will not hatch. This failure to hatch can usually be traced to a malfunction or malformation in the developing embryo. There are two periods during incubation where high levels of embryo mortality are observed. The first period is about 2 to 3 days during the early growth of embryonic tissues and a change in the nutrition of the embryo from simple carbohydrates to more complex proteins. Improper development of the tissues may make it difficult for the embryo to handle the complex protein molecule which would be fatal. The second peak in embryo mortality is near the end of the incubation period as the embryo shifts its position in the egg. In preparation for hatching the embryo must shift its head to the area near the air cell. If this is not accomplished or the head is malpositioned so that the embryo cannot puncture the air cell and eventually pick its way through the shell, then death will surely follow.

In summary there are many reasons why fertile pigeon eggs fail to hatch. Management and genetic factors are tools which the loft owner can employ to improve his operation and realize a higher percentage hatch of fertile eggs. Physiological reasons, however, are another problem and little can be done to change them except to say that they may closely tied in with genetics.

- John J. Dowling Jr