Where in the digestive system of brown layers is phosphorus primarily absorbed, and how does dietary phytase enzyme localize its activity?

In the avian digestive tract, inorganic phosphorus is absorbed primarily across the mucosal brush border of the duodenum and upper jejunum via active transport. However, up to 70% of plant-derived phosphorus in layer feed is bound as phytic acid (phytate), which hens cannot digest. Exogenous phytase enzymes added to the feed localize their hydrolytic activity in the highly acidic environments of the upper digestive tract—specifically the crop, proventriculus, and gizzard. Here, the low pH solubilizes the phytate complex, allowing the enzyme to cleave orthophosphate groups before the digesta reaches the duodenum. This maximizes phosphorus availability and reduces excretion. Nutritional biochemists can study enzyme kinetics in the Poultry Encyclopedia, purchase high-stability phytase on Poultry Plaza, track soy and maize rates on Poultry Rates, and trade premium feed blends on Murghi Mandi.