SPRING SUMMER BONUS MAGAZINE 2026

These mistakes collectively result in layers that face numerous challenges during the laying period, including poor peak production, inadequate laying, reduced shell quality, and increased mortality due to prolapses and disease challenges from missed vaccinations. Environmental management: Improper house temperature and humidity for age and the ventilation. Why lighting programmes matter Lighting is one of the most powerful environmental factors influencing sexual maturity in laying hens. The lighting programme controls the onset of lay and significantly affects performance throughout the production cycle. As stated in the Lohmann Brown management guide, field results indicate that avoiding an early light increase at 14 or 15 weeks allows the bird to physically develop further before the onset of lay. This can result in better production persistence and better shell quality in the later stages of lay. The fundamental principles that must guide any lighting programme are: • Never increase hours of light during the rearing period before 1,4–1,5 kg BW is achieved. • Never decrease hours of light during the production period • Always account for natural daylight in open or brown-out houses Working with natural day length South Africa presents unique challenges and opportunities for pullet rearing in open- sided houses. The natural day length varies significantly by season and geographic location. In South Africa, the longest day of the year provides approximately 14 to 15 hours of daylight, depending on whether the operation is situated in the northern or southern parts of the country. For open-sided houses that cannot be completely darkened, the lighting programme must be synchronised with the natural day length during placement and at transfer to the layer house. In open-type rearing houses, the lighting programme must take into consideration the seasonal change in natural day length and be set up in such a manner that the total light never increases during the rearing period. When to rear pullets in South Africa The optimal timing for rearing pullets in open- sided houses depends on synchronising the flock’s age with seasonal day length patterns. The goal is to prevent early light stimulation while ensuring the birds reach physiological maturity (typically 16-18 weeks) when natural day length is either stable or decreasing, allowing for controlled artificial stimulation. Autumn-hatched pullets (March–April placement) Pullets placed in autumn present significant advantages for open-sided rearing in South Africa. As these birds progress through the rearing phase (weeks 0-17), natural day length decreases from approximately 12 hours toward the winter minimum of about 10 hours. This natural decline supports the step-down lighting programme without risk of premature stimulation. Advantages: • Natural day length decreases during the critical 8–17-week period. • Easy to maintain a constant or declining photoperiod using artificial lighting. • Birds reach maturity (16-18 weeks) during shorter days, allowing controlled stimulation by artificial lighting. • Transfer to laying houses can coincide with increasing spring day length. Figure 1: South African natural light day lengths (extracted from https://www.timeanddate.com) www.agribonus.co.za Spring/Summer 2026 BONUS 71