HERFS/AUTUMN BONUS TYDSKRIF 2026

Photo-stimulating a non-uniform flock will not result in a rapid or synchronised onset of lay. The flock will often not have a defined production-peak, but rather an extended point of lay, and a ‘flattened’ and lower production-peak will be seen. When physiologically immature hens are stimulated, this can lead to hormonal imbalances within the hen which affect egg production. The development of the ovaries can be disrupted, leading to disrupted follicular hierarchy, irregular ovulation patterns, increased incidence of internal laying, cystic ovaries, and pauses between laying. Figure 6 shows two sets of follicular hierarchies, where follicles are denoted with the letter F in combination with a number; the lower the number, the higher up in the hierarchy the follicle. The arrow indicates where the last follicle was released. Figure A shows an irregular follicular hierarchy, hampered sexual development, health and or limited feed intake, whereas Figure B shows the normal desired follicular hierarchy of a sexually mature, healthy hen. Figure A would represent the lighter hens that were not stimulated correctly, that may have been bullied away from the feeders and did not meet their intake and nutrient requirements. These hens would be more prone to increased pause periods as follicles do not mature as rapidly as they should, and will be less productive layers. Egg production and quality A lack of uniformity has negative consequences on egg production and quality, and many of these issues stem from the effect of uniformity on sexual maturity, as previously discussed. Poor uniformity will result in a greater variation in egg size within the flock. Hormonal imbalances in immature hens that are stimulated can result in double yolks and “fairy eggs” (Figure 7). This happens as hens are designed to produce an egg and will do so even when going through hormonal imbalances, and an interruption or imbalance in hormones will not affect all hormones equally. For example, when levels of FSH and LH are low, ovum development and the release of a mature ovum will be hampered; however, progesterone and oestrogen will still be present. When an immature ovum moves down the oviduct, albumin formation and shell formation will still take place, resulting in a small egg. Eggshell thickness and colour may also be compromised in underweight hens that struggle to meet their nutritional requirements due to hampered intake and the cage hierarchy. Compromised shell quality, in turn, can result in an increased crack percentage. Non-uniform flocks may also have a decreased persistence of lay compared to more uniform flocks, as well as a flattened peak in production, as previously discussed. Management factors and achieving uniformity The easiest flock to manage is a uniform flock. Feed is used more efficiently with troughs emptying at an even speed, and nutrient uptake meets the requirements of each hen. Figure 5: Henday production with the red graph depicting a delayed flattened peak Figure 6: Variations in follicular hierarchy and development Figure 7: Double yolk from 22-week-old pullet (left) & “fairy” eggs (right) Herfs/Autumn 2026 BONUS www.agribonus.co.za 130