Improving Egg Shell Quality using Hy-D® (25-OH-D₃)

Nutrition plays an important role in the development of the eggshell and poor eggshell quality can be related to deficiencies in calcium, vitamin D3, trace minerals, protein,  imbalance of phosporous, and environmental impacts. The complex relationship between vitamin D3, calcium and phosphorous directly impacts the eggshell formation.

Vitamin D3 is biologically inactive and must be converted to its active form via two hydroxylation processes one by the liver and the other by the kidneys. The conversion of Vitamin D3 is explained in figure 1. Increasing the circulating levels of 25-OH-D₃ in the blood puts less pressure on the liver and ensures adequate levels are always available for calcium homeostasis. The second hydroxylation process in the kidneys converts the active form 25-OH-D₃ into the hormonal form 1, 25-OH₂-D₃, this is critical for the active transport of calcium and phosphorus for bone and eggshell formation.

Calcium is regulated by the parathyroid hormone (PTH), this upregulates to conversion of 25-OH-D₃ into 1, 25-OH₂-D₃ which signals the increased absorption of calcium from the small intestine or mobilisation of calcium from the bones. When blood calcium levels are high there is a reduction in absorption of calcium and increased renal excretion via the kidneys. Calcium homeostasis is essential for proper bone development particularly in the pullet phase.

Laying birds rely on the calcium reservoir within the medullary bone for eggshell production, during egg production 35-40% of the calcium is drawn from the bone reserves therefore the development of the cortical and medullary bone prior to the laying phase is vital for eggshell quality and the longevity of the hen. If the formation of these bones is not supported in the developmental phases, birds are at an increased risk of avian osteoporosis and keel bone fractures.

(Chen et al., 2020) showed that feeding Hy-D® as an alternative to vitamin D3 during the pullet phase can increase bone growth rate and cortical tissue volume; this provides more mineral deposition which can be utilised throughout the laying period thus leading to increased eggshell thickness and strength. By supporting bone development in the pullet phase and throughout the laying phase with Hy-D® supplementation producers can directly increase the number of eggs produced, on average 2.5% more eggs are produced during a 60-week laying cycle. With pressure to increase the length of the laying cycle there is further necessity to invest in pullet bone health and development to ensure the hen has adequate reserves to continue laying good quality eggs 60 weeks and beyond.

Hy-D® supports the skeletal development, reduces the pressure on the liver, lowers the risk of bone fractures and layer fatigue, increases egg production through better calcium homeostasis and increases the number of saleable eggs.