A feeding and balance trial was conducted for 15 weeks on 25 lambs (aged 3–5 months) divided into five groups of 5 animals each on a basal ration consisting of oats, groundnut cake, barley, common salt, green grass and wheat straw. The five groups were fed a mineral supplement as follows:
Group I. Basal ration plus ‘Supermindiff’ mineral mixture (control group).
Group II. Basal ration plus calcined superphosphate.
Group III. Basal ration plus superphosphate.
Group IV. Basal ration plus superphosphate plus oral cobalt chloride (3 mg Co/10 kg body weight).
Group V. Basal ration plus superphosphate plus parenteral vitamin B12 (50 μg/week/ animal).
Calcination of fertilizer-grade superphosphate at 600°C for 2 h reduced the fluorine content from 23350ppm to 1600 ppm. The results show that high fluorine or superphosphate significantly reduced growth rate and retention of calcium and phosphorus and significantly increased blood inorganic phosphorus. Calcination of superphosphate in Group II gave comparable results to the control group (Group I). The oral Co or parenteral vitamin B12 supplementation (Groups IV and V) did not ameliorate the adverse effects of high fluorine in superphosphate.
It is concluded that calcination of superphosphate at 600°C for 2 h yields a suitable defluorinated product which can be used as a phosphorus supplement in the feeding of animals. Fertilizer-grade superphosphate is unsuitable due to its high fluorine content, the adverse effects of which are not mitigated by oral Co or parenteral vitamin B12 supplementation.