24 ANIMAL NUTRITION
Heat stress in layers is under control thanks to Biovet’s Alquerfeed product line Alquerfeed Layers and Alquerfeed Ovoponedoras prevent eggshell quality problems due to heat stress
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n warm seasons, the basic thermoregulation mechanisms are insufficient and heat stress causes problems in the birds. Initially, lethargic birds are observed, with stretched wings, increased water consumption, decreased feed intake and low productive performance. Thermoregulation of birds and the consequent loss of calcium Birds lose heat by evaporation through panting, but, along with heat loss, there is also excessive loss of blood CO2, which leads to metabolic alkalosis. In order to restore the CO2 blood levels,
LIVESTOCK & POULTRY ME
birds mobilize it from the bones as calcium carbonate (CaCO3). This causes a general decalcification of the animal, which is aggravated by the elimination of calcium as CaO through the urine. The loss of this mineral has a direct impact on the quality of the eggshell since calcium is an essential element for its formation. Consequences of heat stress in laying hens Due to the low availability of calcium for the shell formation, the percentage of broken eggs increases and a high percentage of eggs without shell may appear. Another consequence of the loss
of calcium is the cage layer fatigue syndrome characterized by the inability of the hens to stand up due to the fragility of the bones after the mobilization of calcium carbonate to the blood. For the same reason, fractures of the femoral head are also observed. To make matters worse, when heat stress lasts a long time or birds are exposed to extremely high temperatures, mortality increases due to cardiorespiratory failure. Effective solutions to specific problems Biovet, S.A. has developed solutions for laying hens affected by heat stress. In order to avoid the
JULY-SEPTEMBER 2020
