Uniformity refers to how consistent the body weights of all birds in a flock are. It is an important indicator for evaluating a replacement pullet flock. Uniformity not only reflects the quality of rearing during the growing period, but also determines the flock’s future peak production and how long it sustains peak production.

We recommend that poultry farmers implement strict disease prevention and hygiene measures and a scientific vaccination program, maintain appropriate stocking density and adequate access to feed and water, regularly sample and monitor flock body weights, and adjust feeding based on the monitoring data. These measures help ensure that flock uniformity meets the target and improve the profitability of layer production.

I. Strict Disease Prevention and Hygiene Measures and a Scientific Vaccination Program

Establish a sound, science-based biosecurity system and a comprehensive vaccination program. If a flock becomes ill, its condition may deteriorate and its uniformity may decline. Therefore, chicks should be kept under strict isolation as soon as they arrive, using closed brooding, to prevent or reduce illness in the flock. Without this measure, or if it is not implemented strictly, birds may vary in size if the flock contracts a disease, even if none die. Therefore, strict hygiene and disease prevention measures are essential to improving flock uniformity.

II. Appropriate Stocking Density and Adequate Access to Feed and Water

Stocking density and the number of feeding and drinking spaces have a significant effect on flock uniformity. Therefore, replacement pullets should be appropriately grouped during rearing.

During the rearing period, the flock is generally divided into two or three weight groups once or twice. When sorting, weigh the entire flock, divide it into large, medium, and small birds, and house each group separately.

Set an appropriate amount of housing space according to the flock's age:

1-4 days: ensure at least 167 cm2 of cage-floor area per bird, and 2.7 cm of feeder length per bird;

4 days-3 weeks: 334 cm2 of cage-floor area per bird, and 5.4 cm of feeder length per bird;

4 weeks-14 weeks: 400 cm2 of cage-floor area per bird and 8 cm of feeder length per bird;

After 15 weeks: 450 cm2 of cage-floor area per bird and 12 cm of feeder length per bird.

III. Weigh the flock regularly and conduct random sampling

The main purpose of weighing is to assess the effectiveness of feed restriction and monitor flock uniformity. Therefore, the flock must be weighed on the last feed-withdrawal day of each week.

　　Generally, randomly sample 1-2%, calculate the average body weight, and determine the feed quantity for the following week based on body weight (compared with the standard). The flock uniformity is then determined by calculating the percentage of sampled chickens whose body weights are within an average body weight ±10% of the total number of sampled chickens.

　　To ensure effective weighing, we must take random samples when weighing.

　　IV. Strengthen daily management and promptly identify abnormalities

　　Do not disturb the flock while it is eating. Observe from a distance how actively the flock is eating and the percentage of birds coming forward to eat. 1 hours after the flock starts eating, inspect the flock and observe the feather color, fecal color, and activity of the chickens, and promptly monitor the flock’s condition.

　　During daily inspections, select chickens that are too heavy or too light and raise them separately. In addition, chickens can be selected during immunization to improve overall flock uniformity.

　　By applying the above measures together, the uniformity of breeding chickens can be effectively improved, thereby increasing the flock’s egg production rate and production performance.