Ram Singh Bibyan
Culling is the identification and removal of the non-laying or low producing hens from a laying flock. Knowledge of culling reasons on an organized poultry farm is important because it aids in making rapid improvement in poultry farm performance through effective selection. Unless the birds are diseased, they are suitable for marketing or home cooking. Removing the uneconomic birds reduces the cost of egg production as hens eat feed whether or not they are laying, reduces disesase incidences, and provides more space for productive hens. The culling process includes: sight culling at the time of housing; culling by individual inspection of birds ability to lay; general condition; body characteristics; identification of poor layers; molt and its duration; and Checking the Culling Technique.
Sight culling: Sight culling of pullets when being placed in the laying house removes the undersized, underdeveloped, weak, crippled, or diseased birds which have very little chance of becoming good layers. The number of birds culled partly depends on space available in the laying house. Allow 2.5 to 3.0 square feet of floor space for each hen for light breed and 3.0 to 4.0 square feet for each hen for heavy breeds of chickens. Do not be too critical when evaluating the pullet’s size and development, since some good laying hens mature late. Give the birds a chance to mature if they show characteristics that they may develop into good layers. Remove any bird which has a permanent genetic or injury-produced deformity such as crossed beak, slipped wing, one or both eyes blind, or any leg deformity that can interfere with the bird’s ability to mate or to reach feed, water, or the laying nest. It is most economical to remove these birds from the flock as soon as you notice them. Thus feeding birds with little or no chance of becoming good layers can be avoided. Sick or unthrifty birds will often have short, narrow, emaciated bodies and appear listless or droopy. Small, pale combs and wattles generally indicate chronic poor health. Remove these birds from the flock as soon as possible to avoid disease problems that may spread to the flock.
Culling by individual inspection: The commercial layers are not usually culled after being placed in the laying house unless the birds become diseased or crippled. In the small laying flock the hens should be culled about eight to ten weeks after being placed in the laying house. This allows the birds plenty of time to adjust to their new surroundings and reach peak production. It also provides extra time for the development of the slower maturing pullets. Culling at night is recommended, since the birds are less likely to be frightened and reduce egg production. A flashlight with the lens covered with blue cellophane will make it easier to detect poor layers without disturbing the flock. Handle the birds as little as possible so that production will not be greatly reduced. Delay culling if a significant portion of the flock is suffering or recovering from a minor disease or molt. Culling a diseased or molting flock often removes some of the better laying birds. The following body characteristics will indicate if the bird is capable of being a good layer.
The following characteristics differenciate between layers and non-layers
|Comb and Wattles
|Large, bright red, glossy
|Small, dull, shriveled
|Deep, soft, pliable
|Shallow, tough, tight
|Flexible, wide apart
|Stiff, close together
|Large, moist, bleached
|Small, dry, puckered, yellow
General condition: The general condition of a good layer will reflect in health and vitality. The comb and wattles will be large, bright red, and glossy. The head will be trim and refined with large, bright eyes that reflect proper health. The eye rings will be bleached, indicating an onset of lay. The beak may either be fully bleached or becoming bleached. In contrast to the good layer, the poor layer usually has smaller, poorly coloured wattles and comb as well as dull, sunken dyes which reflect low vitality. The eye rings and beak of yellow skinned breeds of chickens will be yellow tinted.
Body characteristics: A good layer will have a large, smooth, moist, almost white vent. The two small bones at the sides of the vent are called the pubic bones. They should be flexible and wide apart, with at least two finger widths between them (one finger width = ¾ inch). The abdomen should be deep, soft, and pliable without an accumulation of body fat. The depth of the abdomen is measured between the tip of the keel or breast bone and the pubic bones. Laying hens should have a depth of three or four finger widths (2½ to 3 inches). The non-layer will usually have a smaller body with a shallow, firm abdomen. Pullets and non-laying hens have a depth of about two finger widths (1½ inches) between the pubic bones and keel. The pubic bones are usually stiff and close together when the hen is not laying. The distance between the pubic bones is one finger width or less. The vent of a non-layer is usually small, puckered, and round.
Identification of poor layers: After peak egg production, check the flock is to be checked for poor producers. These poor producers have highly pigmented (yellow) beaks and shanks. As the hen produces eggs, she diverts yellow colour from certain portions of her body and deposits it into the yolks of the eggs. Bleaching of various parts of the hen’s body is a very good indicator of the time the hen has been in production. The loss of colour is easily seen in yellow-skinned breeds such as the white leghorns and birds on diets containing sources of the coloring agents. In the white-skinned breeds the bleaching effect is less pronounced and more difficult to detect. The vent is the first site of colour bleaching. When a pullet begins to lay, the colour fades from the vent within the first week of lay. A good producing hen will have a white, pink, or bluish-white vent.
Time after first egg taken for bleaching of yellow coloring
|Time after first egg
|Ear Lobes (white Leghorn)
|Base of beak
|Tip of beak
|Bottom of feet
|Front of shanks
|Rear of shanks
|About 24 weeks
After vent, eye rings start bleaching and are completely bleached within the first two weeks of lay. In leghorn strains the eye ring bleaching is closely followed by bleaching of the ear lobes. The beak is the first significant portion of the body generally used to judge the bleaching effect of egg production. The beak will lose its colour, progressing from the base to the tip. It takes from four to eight weeks for the beak to bleach after the hen begins laying eggs. The beak will often have a striped appearance then. The lower beak loses colour more rapidly than the upper beak. If is often used as a bleaching indicator when the upper beak has a heavy brown or black pigment. A hen whose beak is fully pigmented has not laid for at least four weeks. Bleaching of pigment from the shanks is a good indicator of a long production time. The pigment bleaches from the shanks in this order: bottom of feet, front of shank, back of shank, and hock joint. The shanks have no colouring between two and six months after the onset of continuous lay. When the hen ceases to lay, the body parts are recoloured in the same order as they were bleached, with the vent first and the shanks last. The speed at which the colour returns depends on the type of feed and the state of the bird’s health, but it usually returns in about half the time required to bleach.
Recycling of layer stock: The layers can be kept for another year for egg production based on their performance and market demand. However, the intensity of production decreases as the age increases. The birds can be kept for one cycle (18-72 wks) or for two cycle ( 18-65wks then molting at 65 wks and egg production from 70-110 wks) or for three cycles (18-65wks then molting at 65 wks and egg production from 70-105 wks then second molting and then egg production from 110-140 wks)
Estimating duration of molt: The molting time can be determined by examination of bird’s large primary wing feathers. Length of molt can be estimated by allowing six weeks for the first mature group of primaries and two weeks for each additional feather or group of feathers. If the primary feathers are not fully grown, the time of molt can be estimated based on the feathers’ present stage of growth. A primary feather reaches half its full length after two weeks, two-thirds its growth after three weeks, and completes its growth six weeks after the old primary is lost. The growth rate of the replacement feathers is the same for both early and late molting hens. Often pullets undergo a partial molt, involving the neck and tail feathers. This condition can usually be eliminated by purchasing pullets hatched in April or later in each year and by following proper management practices. The length and incidence of a molt are influenced considerably by the bird’s body weight, physical condition and environmental conditions such as nutrition and management.
Check the culling technique: Avoid culling the flock for fear that you might eliminate good hens and be sure of your culling ability. If a wire-bottomed broody coop or extra laying cages are available, you can check your culling technique by separating the hens and observing their egg production for a few days. Give the birds plenty of feed and water. Be careful when culling to avoid upsetting the hens and affecting their normal rate of egg production.
Culling is all about removing uneconomical birds from the flock. Culling reduces feeding cost, prevents the spread of diseases at farm, gives more room to healthy birds, and thus, leads to uniform flock. Each poultry farm is recommended to have a definite culling schedule for better productivity. The culling schedule depends upon the flock size and the reasons of the culling process, which can be weekly or monthly.