CONCEPT OF MATING & ARTIFICIAL INSEMINATION IN POULTRY
by-DR RAJESH KUMAR SINGH, JAMSHEDPUR, JHARKHAND
9431309542,rajeshsinghvet@gmail.com
Introduction
The importance of AI in breeder flock ,we know very well but at the same time its importance can’t be denied in our native local poultry breeds like Kadaknath, Assel etc.Our native breeds are at the verge of extinction , it is high time to adopt the AI technique in Deshi murgi or Backyard poultry farming too. In order to understand this we must know the mating technique among poultry. Although this mating technique has been in vogue since time immemorial among tribal people who use the Deshi murgi for cock fighting in states like Jharkhand, Odissa, Chhatisgarh,WB etc.In this post i have tried to give a nutshell of mating n AI know how in poultry.
Artificial Insemination (AI) is an important tool to improve the reproductive performance of birds especially broiler breeders and turkey where fertility is low due to heavy body weight. Eventhough AI is well developed technique in cattle, is not so well developed in poultry because no standard technique is available to store poultry semen for a long period. The techniques available at present permits to collect semen and use it for insemination immediately with or without dilution using semen diluents at 1: 2 ratio. Semen collected from one cock is sufficient for inseminating 5 to 10 hens depending upon the semen volume and sperm concentration.
At farms, where AI is practiced the males are kept separately in individual cages where sufficient space is available for movement of the birds. There should be a particular team of workers to associate collection and insemination of semen. Frequent changes of personnel in the team may affect the normal behaviour of birds. Rough handling should be avoided, if not it may develop fear reaction, which affects the semen volume during ejaculation.
The number of females to be mated to each male varies depending upon the breed, age, health, and sexual activity of the male. In general, the males of light breeds like leghorns are more active and vigorous than the males of heavier breeds such as white Plymouth Rock and Rhode Island Reds. Older males are usually capable of caring for fewer females than cockerels. Spermatozoa are able to live in the oviduct for at least 5-11 days in ducks, geese or fowl and three weeks in turkeys, and during this period a succession of eggs in a hen is fertilized after a single insemination.
Methods of mating:——
The following methods of mating are generally used:
[A] Natural mating
1. Pen mating
2. Flock mating
3. Stud mating
4. Shift mating.
[B] Artificial insemination
[A] Natural Mating———-
Fertilization in commercial chickens is usually the result of natural mating. However, in some cases, artificial insemination is commonly practised. The turkey industry especially depends on artificial insemination since natural mating is virtually impossible as a result of intense genetic selection for conformation and body weight.
The completed mating in chickens is the culmination of a sequence of behaviours. The rooster will initiate mating by exhibiting courtship behaviour: dropping one wing and dancing in a circle (the lowered wing will be on the inside of the circle dance). The hen will crouch (dip her head and body) to indicate receptiveness to the male. The rooster will then mount the hen and grab her comb, neck feathers, or the skin on the back of her head or neck to help hold onto the hen’s back.
The next behaviour is the tread (the rooster walks quickly in place on the hen’s back) and finally the completed mating of the behavioural sequence. The completed mating occurs when the rooster dips his tail to the side of the hen’s tail and spreads his tail feathers so that their cloacae come into contact. At this point the rooster’s ejaculate is released directly into the hen’s vagina via her cloaca.
In the typical breeder house with thousands of birds, the entire sequence of behaviors do not always occur, and the courtship dance is frequently left out of the sequence. Chickens are polygynous but certain males and females selectively mate regularly. Some females in the flock will show avoidance to specific males, and therefore are rarely mated by those males.
The rooster usually ejaculates between 100 million and five billion sperm at a time with greater concentrations produced at the beginning than at the end of the day, when depletion occurs after many matings. First ejaculates average about 1 ml but after several ejaculations, the average volume will be reduced to 0.5 ml or less. These data were obtained from semen collection as done in artificial insemination. The numbers of sperm per ejaculate and the volumes of semen should be lower in natural matings than semen collection by artificial stimulation and abdominal massage. The frequency of mating follows a diurnal pattern with mating frequency reaching peaks early and late in the day.
A rooster may mate from 10 to 30 or more times per day, depending on the availability of hens and competition from other roosters. However, the number of sperm per ejaculate is seldom less than 100 million which is the minimum required to maintain high fertility. With natural mating, better fertility will result when mating occurs after the hen has laid a hard shell egg. However, if the hens are mated frequently (daily), there is unlikely to be a noticeable difference in fertility regardless of when the matings occur.
The rooster has a small phallus that becomes engorged with lymph to form a copulatory organ. The copulatory organ is rudimentary and at the time of mating there is practically no penetration. The hen everts her vagina during copulation, which helps to transfer the semen into the oviduct. Ducks, geese and some other birds have more well-defined copulatory organs.
An understanding of the natural mating behaviour in chickens can help the breeder manager and producer to observe the mating behaviour sequences in their flocks to assess whether their flock fertility should be good, average or poor.
Since mating behaviour generally follows a diurnal pattern, the best times to observe the flock for mating behaviour are early in the morning and late in the afternoon.
In a broiler breeder house, pay attention to the frequency of females coming off the slats so that they can be mated.
When a large percentage of females is reluctant to enter the litter area, it is a sign that the males may be overly aggressive and fertility will suffer.
A good practice would be to walk the outside perimeter of the slats in the time before and shortly after egg production begins. This forces the hens to move toward nests and to become accustomed to the litter area.
In this method of mating males are allowed to mate with females naturally. This mating method can be categorized as following:
[1] Pen Mating ——-
1. Usual method of mating used for pedigree hatching.
2. A group of hens are allowed to mate with a cock in a pen.
3. The mating pens are of 8ft x 6ft size.
4. The male to female ratio is 1: 10 or 12 for light breeds and 1: 8 or 10 for heavy breeds.
5. The fertility is lower in this mating compare to flock mating due to preferential matings i.e. a male may mate more frequently with certain females than with others. The preference for mating is generally attributed to plumage colour etc.
[2] Flock Mating——-
1. It is mass mating system wherein two or more males are mated with several females housed in single pen.
2. Male to female ratio is generally higher in this method i.e. one male for 12 to 15 females of light breeds and 10 to 12 females of heavy breeds.
3. From pedigree hatching point of view, the eggs cannot be identified for their parentage.
4. Under this system, sometimes the aggressive males scare away other males preventing them from mating. Such aggressive males should be removed from the flock.
5. This method also provides an opportunity for the birds to mate with the mates of their choice whereas there is no such choice in stud or pen mating.
6. The fertility is generally high and, therefore, much desirable for producing chicks meant for commercial purpose.
[3] Stud Mating——-
1. In this type of mating the male is kept separately in coop or pen (2 ft * 3 ft size).
2. The females are picked up from the pen one by one and put into the coop. After the mating is accomplished, another female and so on replace the female.
3. In comparison to flock or pen mating, it involves more work and labor.
4. More offspring’s can be obtained from sire of high merit.
5. By this method it is possible to mate one male to many females.
6. To ensure good fertility, the hen should be stud mated at least once a week.
7. As compared to flock or pen mating this method results in higher fertility.
8. This method of mating can also be employed if the birds are kept in the cages.
[4] Shift Mating——
1. In this type of mating the sires are shifted in breeding pens.
2. This method can be employed in breeding programs (family breeding) where the breeding value of more number of males needs to be tested for locating really superior males.
3. At the same time by shifting the male, a female can be mated with several males and her breeding worth can be evaluated more precisely.
4. The major hindrance in shifting of males in a breeding pen during the season is the problem of accuracy of the parentage of the progeny since the fertility is maintained for 2-3 weeks even after removing the cock.
5. This difficulty may be overcome by discarding the eggs for one week after the change of males.
6. The main advantage of this system is that a large number of males can be tested in a limited space.
7. The pen mating doesn’t differ from this system except the mates are shifted from one pen to another in a sequence.
[B] Artificial Insemination——-
Artificial insemination (A.I.) means the deposition of semen into reproductive tract of female by some means other than natural mating. In various poultry breeding projects the artificial insemination has gained considerable attention. Artificial insemination (AI) involves the deposition of semen into female reproductive tract manually. It starts from the collection of the semen from the male and its evaluation in terms of motility, viability and concentration followed by its deposition into female reproductive tract. Sexual maturity in both male and female bird occurs at 18 weeks of age. One ejaculate of a male can cover up 20 female birds by using AI. Dose of semen is 100–200 million spermatozoa/insemination in 50 microliter volume. Poultry semen shows poor response for cryopreservation so AI is done as soon as semen is collected
History—-
Artificial insemination has been widely applied to poultry. Semen collection, processing, and AI have been reviewed by Sexton (1979) and Lake (1986) and more recently by Donoghue and Wishart (2000). Pioneers in the poultry field were Burrows and Quinn (1937), who developed the method of abdominal massage and pres-sure to collect semen. With the ease of collecting poultry semen, and proximity of hens on large breeding farms, AI is used extensively with freshly collected semen. It is used 100% for turkey breeding because mating is difficult. Freshly collected chicken semen was among the first type of semen to be frozen (Shaffner et al., 1941; Polge et al., 1949). However, cryopreserved poultry sperm are less fertile and freezing poultry sperm still is experimental (Gill et al., 1999).
This procedure consists of collecting semen from males and inseminating into females. The major use of A.I. is in heavy birds whose fertility is generally low under pen mating. It is also practiced when the layers are kept in cages. Adopting A.I. as well as service of a valuable male can be extended can increase fertility. The practice of A.I. requires some training on the part of both operator and the male.
It is a valuable technique in avian species. It is ordinarily practiced when the flock presents an apparent fertility problem. Excellent fecundity has been obtained by the use of artificial insemination (A.I.), better in many instances, than that obtained by natural mating. The A.I. of domestic fowl is not widely used on commercial farms. On the other hand, turkey breeders use A.I. extensively to propagate their stock, especially the large Broad Breasted Bronze strains that experienced difficulty in mating naturally. Technique for artificially breeding ducks and geese are available but large-scale breeding programme using such methods have not been applied except perhaps with certain breeds of ducks in the far east.
Psychology:—-
Psychological factors influence the amount of semen that can be extracted from the reproductive tract. The extent, to which an operator has to struggle with a male, before it is captured and restrained, varies tremendously. In general, the greater the struggle the smaller the amount of semen obtained.
Turkeys, ducks and geese require more training for handling than most breeds of domestic fowl, even without a struggle. Occasionally some males never respond properly to stimulation for semen collection. How far this is due to psychological factors or to inherent defects of physiology is not known. To bring the males into maximum semen production, it may be desirable to train them by handling on alternate days for a period of a week or more before the first insemination date.
Advantages of Artificial Insemination in Poultry—–
1. Efficient use of males: – Requirement of males is lesser in A.I. compared to natural mating which will reduce the rearing cost of males and increases the intensity of selection.
2. Multilocational testing of outstanding sires.
3. Avoidance of preferential mating and physical incompatibility.
4. Production of fertile eggs from layers in cages is possible.
5. Accurate recording of pedigree is possible.
6. Fertility is 5-10% higher in A.I. as compare to natural mating.
7. Interspecies hybridization is possible.
8. Use of large male with small female and vice versa is possible.
The Process of Artificial Insemination Includes
1. Preparation of Males
2. Preparation of Equipments
3. Collection (Milking) of semen from Males
4. Evaluation of Semen
5. Dilution of Semen and
6. Deposition of Semen in Vagina of Female
Characteristics of Poultry Semen——
Semen consists of spermatozoa and seminal plasma. Fowl semen is generally highly concentrated (3 to 8 billion spermatozoa per ml for broiler fowl). This is due to the presence of limited amount of seminal plasma since the accessory reproductive organs are absent in avian species. The seminal plasma is derived from the testes and excurrent ducts. At the time of ejaculation a lymph-like fluid (also known as transparent fluid) of cloacal origin may be added to the semen in varying amounts. The addition of transparent fluid to semen at the time of ejaculation act as an activating medium for the previously non-motile spermatozoa, thus ensuring their transport from the site of deposition to the sites of sperm storage tubules in the utero-vaginal junction of the hen’s oviduct.
Usually cock start producing semen from the age of 16 weeks but the fertilizing capacity of the semen is low. So the cocks from 22 or 24 weeks of age are used for semen collection. The natural colour of poultry semen is white or pearly white. Heavy breed male can produce 0.75 to 1 ml semen and light breed male can produce 0.4 to 0.6 ml of semen. A male can be used thrice in a week for semen collection with a gap of one day. Although every day semen collection will not change the fertilizing capacity but the volume of semen will be low.
1] Preparation of males—–
Males used for A.I. should be healthy vigorous and free from any physical abnormality or disability. They should be placed on balanced breeder ration a month before actual collection is to be practiced. The male birds can be housed in individual cages, but they need to have enough room to be able to crow. A suggested cage size is 45 cm wide, 60 cm deep and 60 cm high. The feed and water containers should be hung on the outside of the cage. Male birds respond to the people handling them and a quiet, unhurried approach is necessary with careful handling. During the collection of semen, it is essential that visitors remain outside the shed. This will prevent the birds from becoming frightened. It is a good idea that the males are housed in close- proximity to the hens so that the time between collection and insemination is kept to a minimum. Prior to use, the selected male birds should be examined for external parasites, particularly poultry lice, and treated accordingly. It is also a good idea to clip the feathers from around the vent area to give easy access to the male organ. This applies particularly to loose-feathered breeds of poultry. Each and every male should be tested for production and evaluation of semen before used for A.I.
2] Preparation of equipments—-
The equipments required for A.I. are-
1. Semen collection funnels/cups: – Glass or plastic funnel of 3cm diameter with stem blocked with paraffin.
2. Glass/ tuberculin syringe.
3. Test tube stand/ rack for holding of funnel/cup
Figure 1. Artificial Insemination Equipment: From top, clockwise: Syringe with inseminating tube and rubber connection. Ringer’s Solution. Glass Tube
3] Collection of semen from males (milking)——-
The cock should be held in the left hand, head extending under the arm. The soft sides of its abdomen between the gizzard and the pelvic bones should be massaged with right hand in order to stimulate the ejaculatory organ. The fingers of the right hand are outspread at the start of the stroke but brought together at the end of the stroke so as to converge on the vent. The stroking of males back should be done moving the hand in the direction of the birds vent only. Such a stimulus causes the trained male to evert or protrude the vent region. When this occurs, a quick motion of strokes will cause the male to ejaculate. The squeezing pressure is applied by the thumb and index finger inward and downward at a point just above the vent. The semen is collected by an assistant in an A.I. funnel by holding it under the vent.
Precautions while collecting the semen—–
1. The males should be separated from females at least one week before an attempt is made to collect the semen.
2. The feathers around the males vent should be plucked off to obtain the semen easily.
3. Collection of semen may be carried out daily depending upon the need. However, thrice a week collection will give maximum number of spermatozoa over a long period of time.
4. The semen contaminated with foreign material like urine and faeces should not be used.
4] Evaluation of semen——
Semen is a mixture of sperm cells and carrying fluids. In domestic birds the ejaculate is characteristically highly concentrated and low volume. The composition of semen obtained while artificial collection is quite variable, the sperm cells being mixed with secretary fluid from the engorged phallic apparatus and some time mixed with digestive & urinary tract wastes. The contributions of these factors are not easily controlled & consequently considerable variation in semen composition has been reported.
The fertilizing ability of semen depends upon its quality. Semen can be evaluated on the basis of volume, colour, pH, motility of the spermatozoa, sperm concentration, percentage of live, dead, and abnormal spermatozoa etc. Good quality chicken semen is pearly white and opaque. The semen volume is about 0.5-0.75 ml/ejaculate with sperm concentration 4 billion per milliliter.
5] Dilution of semen——
The spermatozoa begin to lose their integrity after collection, which results in reduced fertility. As a practical matter it is prudent to use semen within 30-45 minutes of collection. In laboratory conditions excellent fertility levels have been reported with chicken & turkey semen held unfrozen invitro for 24 hours or more.
Diluents increases the volume of semen, retains cell integrity and buffering the detrimental effect arising on storage. In general if semen has to be stored beyond 1 hour after collection, dilution with ideal extender and careful handling is essential.
Successful short-term preservation of unfrozen avian semen requires the collection of clean, high quality samples and careful handling of the semen after collection. Storage condition and diluents used for storage have differed markedly. With most diluents, avian sperm survive best when kept cool (5-15ºC) but excellent fertility has also been reported when chicken sperm were held in minimum essential medium at 41ºC for 24 hours.
Progress towards long-term preservation of frozen chicken & turkey semen is being made. Better fertility has also been obtained with frozen chicken semen than with frozen chicken semen than with frozen turkey semen. Levels of fertility obtained with frozen chicken semen are high enough to allow conservation of selected germplasm by poultry breeding organizations but too low to allow wide spread commercial use.
The some of the diluents used for dilution of chicken semen are
1. Ringer’s solution
2. Simple saline diluent
3. Sodium citrate buffer
4. Glucose citrate solution
5. Lake’s diluent
6. Tris- yolk extender buffer
7. Mac Pherson’s extender
8. Belts ville poultry semen extender
Table 1. Composition of Ringer’s solution (commonly used)
Composition Quantity (g)
Sodium chloride (NaCl) 9.00
Potassium chloride (KCl) 0.25
Calcium chloride (CaCl2) 0.30
Sodium bicarbonate (NaHCO3 ) 0.20
These are dissolved in distilled water to make the total volume 1 liter. The pH of this solution should be 7.
Table 2. Modified Ringer’s solution.
Composition Quantity
Sodium chloride 68 g
Potassium chloride 17.33 g
Calcium chloride 6.4 2 g
Magnesium sulphate 2.50 g
Sodium bicarbonate 24.50 g
Distilled water 10 L
The concentrated semen can be diluted by using extenders to inseminate more number of females. However, the A.I. should be done as early as possible after dilution because fertilizing capacity of avian species is quickly degenerated on storage. The diluent should be added at a ratio of 1: 2 – 4.
6] Insemination of semen——-
The recommended dose for undiluted, good quality semen is 0.03 ml/week but for diluted semen dose varies from 0.03 to 0.05 ml/every 3 – 4 days to maintain good fertility. To obtain optimum fertility 80 to 100 millions sperms / ml is recommended hence; the required quantity of semen is to be taken in syringe for insemination.
The process includes
1. Eversion of vagina
2. Deposition of semen.
The process of insemination requires two men. One man with his left hand holds firmly the lower thighs of the hen and with the right hand applies pressure on the abdomen below the cloaca to evert the vagina. As the vagina is everted the second man gently inserts the inseminating syringe to a depth of 3 cm into the oviduct.
The semen is released from the syringe; simultaneously the pressure on the abdomen is released to allow the oviduct to resume its normal position.
Soon after the insemination, optimum number of spermatozoa enters the primary storage glands (sperm storage glands) at utero – vaginal junction. Sperm are seldom found in the infundibulum storage site unless semen is introduced into the oviduct in such a manner that it bypasses the utero – vaginal glands. Fertilization of egg takes place in infundibulum. Thus after a single mating or insemination eggs received up to 3 to 4 weeks will be fertile but the fertility will be reduced with time advances.
For good results
1. Insemination should be done when no hard-shelled egg is present in the uterus preferably during late afternoon hours.
2. Avoid any kind of stress to the birds before insemination.
3. A.I. equipment should be thoroughly cleaned and properly sterilized before use.
4. The intervals between inseminations should be strictly maintained.
5. For good fertility A.I. should be done twice a week.
