ARTICLE 74 FEED & ADDITIVE MAGAZINE June 2024 The preparations towards the onset of lay in a laying hen are marked by significant metabolic and hormonal changes, environmental changes and changes in the nutritional requirements. The metabolic and hormonal changes are essential for the development of the reproductive system, particularly the ovaries and the oviduct, as they play the major role in egg production. During the first weeks in the rearing farm, it is important to support the transformation from a small, fully dependent, day-old chick into a good quality pullet. During the final phase of rearing and at the start of the laying period, we need to support the transformation from a pullet into a productive and robust laying hen. By carefully monitoring the flock, and recording and analysing the data the flock provides to you, it will be easier to establish an appropriate feeding program for the hens, which will be able to support them through the various stages of growth and production. When the reproductive organs start to develop, the laying hen requires more energy and water, resulting in a higher intake of these nutrients by the laying hen. Besides, the nutrients which were previously solely used for growth and maintenance will also be needed to produce the egg and the eggshell. In order to tackle this sudden increase in nutritional requirements, the laying hens (and other birds) have established unique physiological characteristics. Next to the hens’ ability to increase her feed intake significantly within just a few weeks, they also develop unique bone characteristics, the so called medullary bone. The medullary bone is functioning as a calcium reservoir, and as soon as the hens’ preparations for egg production have started, the laying hen is able to mobilize calcium for eggshell formation from the medullary bone. This specialization has a major impact on the hen’s total calcium metabolism. Photo stimulation triggers a hormonal change by the release of the gonadotropin-releasing hormone (GnRH) from the hypothalamus, which does not only stimulate the follicle-stimulating hormone (FSH), but also the luteinizing hormone (LH) from the pituitary gland. These GnRH and LH hormones are crucial for the development and release of the follicles, which form the basis for egg production. The follicles are producing the hormone called estrogen, better known as the “female hormone”. Estrogen stimulates the oviduct development and the formation of egg yolk. Overall, the transition from the rearing to the production phase is accompanied with stress. Not just related to the hormonal and metabolic changes that are increasing the stress in the laying hens, or the immune responses related to the vaccinations, but also related THE PERFECT START FOR YOUR FLOCK OF LAYING HENS: GUIDANCE TO OPTIMIZE GUT HEALTH Estella Leentfaar Nutritionist and Product Manager Hendrix Genetics Layers
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