What are the technical points for sexing day-old chicks?

Poultry farmers all know that after chicks hatch, sexing the newborn chicks and promptly culling or fattening the male chicks can improve flock uniformity and feed conversion, with clear economic benefits. So how do you distinguish male from female chicks? What are the key technical points for sexing?

1. Vent-sexing or touch method

1. Male chicks

Near the anal opening, at the junction of the second and third folds on the center of the lower wall of the cloaca, there is a spherical protrusion about the size of a sesame seed, flanked on both sides by regular folds in a splayed shape, also called “splayed folds”. The spherical protrusion is called the “genital protrusion”. The genital protrusion and splayed folds are white with a slight luster, elastic, and when pressed and rubbed they feel full, are not easily deformed, are tough, and have clear outlines

2. Female chicks

Under normal conditions, the genital protrusions of newborn female chicks are almost completely degenerated, which is called the normal type, but in a small number of female chicks the genital protrusions are not completely degenerated. They can be identified based on the following points.

(1) Appearance and feel: the genital protrusions of female chicks have indistinct outlines, are shrunken, and the surrounding tissue provides weak support, giving an isolated impression.

(2) Luster: the genital protrusions of female chicks are soft and transparent.

(3) Elasticity: the genital protrusions of female chicks have poor elasticity and deform easily under pressure or stretching.

(4) Degree of congestion: the blood vessels of the genital protrusions of female chicks are not well developed, and they do not easily become congested when stimulated; whereas the blood vessels of the genital protrusions of male chicks are well developed, with fine blood vessels on the surface, and they become congested.

(5) Shape of the front end of the protrusion: the front end of the genital protrusion of female chicks is pointed, while the front end of the genital protrusion of male chicks is round.

3. Vent-sexing method

(1) Catching and holding chicks: the commonly used methods are the clamp-hold method and the cup-hold method, with the clamp-hold method being commonly used; the following uses that method as an example.

(2) Defecation and vent opening: before opening the vent, first expel the droppings; use the left thumb to gently press the lower edge of the left hip bone of the abdomen, and with the chicken's breathing squeeze the droppings into the droppings container. The thumb pressure must be moderate; if too light, the droppings will not be fully expelled. If too heavy, it will seriously injure the chick, or even squeeze out unabsorbed yolk, causing death.

(3) Opening the vent: hold the chick in the left hand, place the left thumb to the left of the vent, bend the left index finger against the chick's back, while placing the right index finger to the right of the vent and the right thumb at the chick's navel area. Push the right thumb upward in a straight line while pulling the right index finger downward, gathering them at the vent; the left thumb should also gather inward, so that the three fingers form a triangular area where they come together, and with a squeeze of the three fingers brought together, the vent opens

(4) Identification: judge based on the presence or absence of genital protrusions and differences in shape. If water or droppings obstruct the view, quickly and gently wipe it away with the left thumb, then observe with the naked eye; if the genital protrusions are difficult to distinguish at once, use the left thumb to touch them, observing their degree of elasticity and congestion, and carefully distinguish them in combination with the above differences between male and female.

(5) Releasing chicks: when releasing chicks, be gentle and quick.

Under normal circumstances, this method has a 1.4-1.8% misjudgment rate, and it easily harms the chicks, causing a 0.5-1.0% mortality rate. Therefore, this method is considered the most complex sexing method, requires specialized technicians, and is highly labor-intensive and extremely tedious.

2. Sex-linked trait identification method

Using the principle of sex-linked inheritance, specific breeds or strains are crossed, and the commercial day-old chicks produced show clear differences between males and females in feather color, feather type, or skin, allowing accurate sex identification on that basis.

This method is both accurate and convenient, and is commonly used in the modern poultry industry. There are mainly the following 2 types:

(1) Silver-white feather color is dominant over golden-yellow feather color; white is dominant and golden-yellow is recessive. When a silver-white rooster is mated with a golden-yellow hen, in the first generation the silver-white chicks are roosters and the golden-yellow chicks are hens.

(2) Slow-feathering versus fast-feathering: slow-feathering (slow feather) means the primary wing feathers are equal in length to the primary covert feathers, or the primary covert feathers are longer than the primary wing feathers; fast-feathering type (fast feather) means the primary wing feathers are longer than the primary covert feathers. Slow feathering is dominant and fast feathering is recessive. When a slow-feathering hen is mated with a fast-feathering rooster, in the first generation the fast-feathering type are hens and the slow-feathering type are roosters.