Ingestion of soil fluorine: Its impact on the fluorine metabolism and status of grazing young sheep

Abstract

When young sheep ingested soil fluorine (F) at moderate to high rates (69-184 mg F day-1 for 63 days) the apparent absorption of F ranged from 44 to 53%, while apparent retention of F ranged from 28 to 42%. The respective values for ingestion of sodium fluoride (NaF) at 69 mg F day-1 were 69% and 39-45%. Increasing F intakes had little effect on kidney and liver F concentrations, but markedly increased the bone F concentrations in the sheep fed NaF or soil with high levels of F. Further, serum F concentration and the rate of F accumulation in bone were related to soil F intake. The rate of F accumulation in bone was curvilinearly related to serum F concentration, and serum F concentration had to be > 0.25 mg litre-1 before a significant accumulation of F occurred in bone. Serum F concentration could be a useful index to assess the soil F intakes and F status of grazing sheep. An examination of the sheep during and at the end of the study showed no clinical signs of fluorosis, such as mottled teeth or bone abnormalities.

Total and soluble fluorine concentrations in relation to properties of soils in New Zealand

“…The F t concentration range of 212–617 µg g −1 soil is similar to that of 217–454 µg g −1 soil previously obtained for another set of New Zealand pasture topsoils (0–75 mm depth) (Loganathan et al ., 2001). At normal soil ingestion rates, soils with these F concentrations are unlikely to cause F toxicity to grazing animals (Grace et al ., 2003). The F water and F KCl concentrations were approximately equal for each soil and they were nearly two orders of magnitude less than the F t concentrations (Table 4).…”

“…Large rates of ingestion of soil with elevated F concentration have potential to cause chronic fluorosis in grazing animals (Cronin et al ., 2000; McLaughlin et al ., 2001). However, a soil‐F ingestion study on grazing young sheep showed that chronic fluorosis is unlikely to occur in most New Zealand pastoral conditions at current soil F concentrations (Grace et al ., 2003), but remains a concern if soil F continues to accumulate. If the solubility of F in soil is excessive it can also affect plant growth (Stevens et al ., 1997).…”

Pasture Soils Contaminated with Fertilizer-Derived Cadmium and Fluorine: Livestock Effects

“…In this trial, young sheep (14 mon old) were fed daily with lucerne (7 mg F/kg dry matter) or lucerne plus soil (184 mg F/kg dry matter) daily for 63 d. The blood F concentration Grace et al (2003). in sheep fed with soil increased signifi cantly within 23 d and then remained constant up to 55 d (Fig. 14).…”

Ingestion of soil fluorine: Its impact on the fluorine metabolism of dairy cows

“…The soil used in this study was a Yellow-grey earth (Pallic Soil) (Hewitt 1993), collected from a depth of 0-5 cm, at two sites, 10-20 and 200 m from a fertiliser bin next to an air strip on a Manawatu sheep farm in New Zealand. The soil from this site was previously used for a sheep F ingestion study, and has been described by Grace et al (2003). The soil samples had F concentrations of 1452 and 336 mg F kg -1 air dried soil at the 10-20 and 200 m sites, respectively.…”

“…The animals were slaughtered at day 64 and the right metacarpus removed, defleshed, weighed, dried at 100°C for 24 h, and DM determined. The methods of sampling have been described by Grace et al (2003).…”