Iron requirements of broiler chickens as affected by supplemental phytase.

Iron is routinely supplemented in broiler feeds to prevent possible dietary deficiencies. We carried out an experiment with the objective of evaluating the Fe requirements of broilers fed with the exogenous enzyme phytase. From the eighth day, a total of 1,280 male broilers were distributed in a combination of diets supplemented with phytase or not and 5 graded increases in dietary Fe. Diets were formulated with corn and soybean meal, laboratory-grade calcium carbonate, and phosphoric acid. Phytase was added in excess (4,452 ± 487 FYT/kg analyzed) to facilitate complete degradation of dietary phytate. Laboratory-grade ferrous sulfate heptahydrate was increasingly added to the feeds to provide Fe. Iron in the experimental diets was present at 53.3 ± 1.41, 65.5 ± 0.59, 77.2 ± 1.97, 87.6 ± 1.72, 97.7 ± 1.33 mg/kg. Supplementing diets with phytase resulted in enhanced live performance, along with increased digestibility of ileal energy and Fe. Linear increases in Fe retention and excretion, hepatic Fe contents, and serum ferritin were observed with the progressive increase in dietary Fe. The supplementation of a total of 97.7 mg/kg of Fe in diets was found to have no significant impact on live performance traits. However, the Fe-related blood parameters reached their maximum levels at a dietary Fe level of 91.9 mg/kg. Phytase supplementation provided a significant increase in the digestibility of Fe and other nutrients evaluated.