A note on the effect of rare earth elements on the performance and thyroid hormone status of rearing piglets

D Förster,W Rambeck,H Hoppen,A Berk,G Flachowsky

doi:10.22358/jafs/66471/2008

Abstract

Rare earth elements (REE) have been used for decades in China to promote growth in plant production and farm animals. Studies are presently also being conducted under Western animal production. conditions, however dose-response studies are relatively rare. In this study a total of 80 piglets were-fed a diet supplemented with 0, 100, 200, 400 or 800 mg of citrate-bound rare earth elements, consisting of, %: lanthanum 30, cerium 55, praseodymium 5 and neodymium 10. The trial lasted 35 days, the initial mean body weight of the piglets was 7.2 kg. Apart from growth and feeding parameters, blood serum was analysed for T-3 and T-4 by radioimmunoassay (RIA). Feed intake decreased insignificantly with higher REE-levels. The daily weight gain of piglets amounted to 283 (control), 301 (100 mg), 254 (200 mg), 258 (400 mg) and 271 g (800 mg). Thyroid hormone levels increased with REE-supplementation. More dose-response studies will be necessary to prove the effects of REE on growth parameters and their intermediate effects

Highlights

The term rare earth elements (REE) encompasses the elements scandium, yttrium, lanthanum and the 14 chemical elements following lanthanum called lanthanides
REE have been used in China for decades in plant production and farm animal feeding to promote growth
Even under Western animal production conditions it has been reported that rare earth elements in the diet can improve animal growth performance significantly, as recently summarized by Redling (2006)

Summary

Introduction

The term rare earth elements (REE) encompasses the elements scandium, yttrium, lanthanum and the 14 chemical elements following lanthanum (order numbers 58-71) called lanthanides. REE have been used in China for decades in plant production and farm animal feeding to promote growth. Even under Western animal production conditions it has been reported that rare earth elements in the diet can improve animal growth performance significantly, as recently summarized by Redling (2006). Most of the experiments with piglets and pigs were carried out with dosages of between 100 and 300 mg REE mixtures per kg feed (Redling, 2006). Higher growth rates were mostly accompanied by decreased thyroid hormone levels (Schuller et al, 2002; Knebel, 2004). The aim of the present study was to investigate the effect of higher REE-dosages on feed intake, daily weight gain, feed efficiency and thyroid hormone concentration in piglets

Objectives

Methods

Results