72 72 TILL 30 WEEKS: END OF PREPARATION PERIOD LOHMANN › MANAGEMENT GUIDE › NUTRITION › PREPARATION PERIOD PRE-LAY DIET At this point, we must decide what type of diet to provide to the hens: 1 A pre-lay diet, with intermediate levels of calcium (2–2.5%) and amino acids. 2 A lay diet with higher levels of calcium (3.6–3.9%) and amino acids. It is evident that hens show a specific appetite for calcium (learned preference) which is generally determined by the levels of ionic calcium in the blood. On the other hand, calcium is not very palatable. This fact has been related to the low feed intake in diets with high calcium content. In any case, experience tells that both strategies are valid, although birds fed with feeds containing calcium levels between 3.7–3.9% show an improvement in bone and eggshell quality in the long term (De Juan et al., 2023), which has economic, welfare, and health implications. Whether we use pre-lay or an early lay diet after the developer diet, it is recommended to maintain a certain level of insoluble fibre to sustain the hen’s feed intake capacity during this period, when the demand for nutrients is high due to the imminent start of the production. RECOMMENDED NUTRIENT LEVELS PREPARATION PERIOD CORRECT USE OF PRE-LAY DIET From a nutritional point of view, pre-lay feed is a compromise phase-feed that contains an intermediate level of calcium allowing a smooth transition between a developer diet (low in calcium) and layer diets (high in calcium) helping to support feed intake and improving uniformity. A maximum of 500 g per hen is recommended before production reaches the first egg. During this period, a blend of coarse (3–4 mm ø) and fine (1–2 mm) calcium carbonate particles is advisable. A typical ratio would be 50% coarse and 50% fine. It's also an advisable strategy to add 1.5–2.5 g/hen/day coarse calcium particles 1:30–2:00 h before lights off as it supports eggshell formation during the dark hours. Recommended inclusion levels of oystershell / coarse and fine limestone in relation to the hen's age Particle size 0–13 weeks from 13 weeks to Pre-Lay End of preparation period (till week 30) 31–55 weeks 56–70 weeks 71 weeks – end Fine (ø 0–2 mm)* 100% 75% 50% 50% 35% 25% 15% Coarse (ø 3–4 mm)* 25% 50% 50% 65% 75% 85% * Fine Limestone: average 1 mm ** Coarse Limestone / Oystershell: less than 15% of particles < 3 mm and less than 10% > 5 mm
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