When during the pullet rearing phase should lighting duration be increased to stimulate sexual maturity, and what weight thresholds are required?

Photostimulation—the process of increasing day length to trigger the pituitary gland to release reproductive hormones—must be timed based on pullet development rather than chronological age. For commercial brown layers, photostimulation should ideally begin between 17 and 18 weeks (119 to 126 days). Crucially, the flock must have achieved a minimum uniform body weight threshold of 1400 to 1450 grams, with at least 85% uniformity. Starting light stimulation too early in underweight or non-uniform pullets leads to a high incidence of prolapse, small egg sizes, a double-peak production curve, and early flock exhaustion. If pullets are underweight, lighting must remain at the rearing baseline (e.g., 9 hours) until the target weight is achieved. Rearing managers can study pullet light stimulation charts in the Poultry Encyclopedia, buy automated astronomical light timers on Poultry Plaza, monitor daily pullet market rates on Poultry Rates, and trade point-of-lay pullets on Murghi Mandi.