The effect of phosphogypsum as the mineral feed additive on fluorine content in eggs and tissues of laying hens

In the present study, laying hens were fed with mixtures supplemented with mineral feed additives, containing waste phosphogypsum, as the source of calcium and sulfur. Waste phosphogypsum containing 0.4% fluorine from a wet-process phosphoric acid plant was used. During 16 weeks of the test, the following production indicators were analyzed: egg quality, fluorine content in eggs, muscles, livers and bones in the control group of hens fed with feed containing no phosphogypsum, the test groups containing 1% phosphogypsum and 3% of phosphogypsum. The average fluorine in the egg content was: 0.71, 0.86 and 0.94 mg F/kg and in eggshells 12.52, 16.87 and 38.86 mg F/kg, respectively, for groups I, II and III. In the muscles of hens, fluorine concentration was in the range of 1.47–3.70, in livers 4.14–7.94 and in long bones 149.3–463.8 mg F/kg. In group III the lowest rate of egg laying and egg mass was observed, along with a decrease in the quality of eggshells and an increase of feed consumption. The investigation showed the possibility of phosphogypsum application as the mineral feed additive, but simultaneously showed the possibility of uptake of insoluble fluorine compounds by hens.