Bonus Tydskrif AUTUMN 2024

Factors affecting eggshell quality in laying hens Eggshell quality is key to the profitability of farming. Special attention must be paid to the egg quality, as changes in eggshell quality are often the first sign of factors affecting the laying hens. The colour, texture, shape, size, and strength of an eggshell tell a story about the chicken and what has affected her during the 24 - 26 hours it takes for an egg to be formed. This article will give a brief overview of some common factors that can affect the eggshell quality of hens. 1. Stress Chickens can be particularly vulnerable to environmental stress. The eggshell is formed by the activity of the cells located in the hen’s reproductive tract, particularly the oviduct and uterus. When hens are affected by stress, the cells’ secretions can become acidic and damage or destroy the cells themselves. This in turn affects the eggshell quality and can manifest in different eggshell problems depending on the cause of stress. Stress caused by relocation or disturbances during calcification can cause excess calcium coatings on the eggshell (see Figure 1). Moving birds during peak laying times can frequently impact the quality of the egg. Stress can also interrupt normal calcification and cause two eggs to come into contact with one another in the shell gland. This can cause a white band to form (see Figure 2) on the first egg from an extra layer of calcium that is deposited while the egg is retained in the egg pouch. Heat stress caused by high environmental temperatures (above 25°C) often contributes to increased eggshell problems, particularly in summer months. High temperatures will cause chickens to reduce their feed intake and increase panting to keep themselves cool. Panting reduces the carbon dioxide (CO2) in the blood, thus increasing the pH and alkalinity of the blood in a condition called respiratory alkalosis. Retha Gericke - Technical Advisor Poultry Figure 1: Calcium deposits on egg shell Figure 2: White-banded egg Figure 3: Soft-shelled egg Eggshell quality is key to the profitability of farming. Special attention must be paid to egg quality, as changes in eggshell quality are often the first sign of factors affecting the laying hens. The colour, texture, shape, size, and strength of an eggshell tell a story about the chicken and what has affected her during the 24 to 26 hours it takes for an egg to be formed. Stress Heat stress caused by high environmental temperatures (above 25°C) often contributes to increased eggshell problems, particularly in summer months. High temperatures will cause chickens to reduce their feed intake and increase panting to keep themselves cool. Panting reduces the carbon dioxide (CO 2 ) in the blood, thus increasing the pH and alkalinity of the blood in a condition called respiratory alkalosis. Chickens can be particularly vulnerable to environmental stress. The eggshell is formed by the activity of the cells located in the hen’s reproductive tract, particularly the oviduct and uterus. When hens are affected by stress, the cells’ secretions can become acidic and damage or destroy the cells themselves. This in turn affects eggshell quality and can manifest in different eggshell problems, depending on the cause of stress. Factors affecting eggshell quality laying hens By Retha Gericke, technical advisor poultry, De Heus Stress caus d by relocation o disturbances during alcific tion can caus ex ess calcium coatings on the eggshell (Photo 1). Moving birds dur ng pe k laying times can frequently impact the quality of the egg. Stress can also interr pt normal calcifi ation and cause t o eggs to come into contact with one another i the shell gland. This can caus a white band to form (Photo 2) on the first egg from an extra layer of calcium that is deposited while the egg is retained in the egg pouch. 1. Calcium deposits on the egg shell. 2. A white-bande egg. 3. A soft-shelled gg. This article provides a brief overview of some common factors that can affect the eggshell quality of hens. Autumn / Herfs 2024 BONUS www.agribonus.co.za 24