Untersuchungen zum Einsatz Seltener Erden als Leistungsförderer beim Schwein

Studies on the effect of rare earth elements as growth promoter in
pigs In China, rare earth elements were used in agriculture already
for some decades. Rare earth elements are 17 elements which include
scandium, yttrium, lanthanum and the 14 lanthanides. They were used
as fertilizer in plant production and as growth promoters in animal
production. Spectacular improvement of the fattening parameter
daily body weight gain and feed conversion ratio of pigs were
reported in the Chinese literature. In previous experiments of our
working group the growth promoting effect of the rare earth
elements has been proven for pigs under western feeding and housing
conditions. In this thesis two feeding experiments with fattening
pigs and a field trial with weaned piglets are described. In the
first experiment a total of 48 pigs (German Landrace x Piétrain)
were allotted to four dietary groups, 12 pigs in each group. The
animals received a mixture of rare earth elements in a
concentration of 0 or 300 ppm rsp. or pure lanthanum chloride and
cerium chloride in a concentration of 100 ppm LaCl3 and 200 ppm
CeCl3 or 200 ppm LaCl3 and 100 ppm CeCl3. Because of a disease this
first study had to end ahead of schedule. In the second trial the
design of the trial was the same as in the first one. During the 12
weeks of this experiment the pigs received feed, supplemented with
the above described concentration of rare earth elements. The daily
body weight gain in the REE group during the study period was 4 to
5 % better than in the control group, where there was no influence
on the feed conversion rate. The accumulation of the lanthanides in
the muscle and the liver was very low as shown in the experiments
before. The analysis were made by ICP-mass spectrometry. In the
serum, the levels of triiodothyronine and thyroxine were lower in
the groups receiving the rare earth elements than in the control
group. Thyroxine in the groups with 300 ppm REE mixture and with
100 ppm LaCl3 and 200 ppm CeCl3 was significantly lower than in the
control group. In a field trial with piglets of the race Swiss
Edelschwein the growth promoting effect of rare earth elements was
proved by two experiments. The animals were fed with a commercial
feed supplemented with a mixture of rare earth elements in a
concentration of 0 rsp. 200 ppm. In the first trial for 16 days
body weight gain and feed conversion ratio of the group with 200
ppm REE mixture improved by 3 % rsp. 9 % as compared to the
controls. The second field trial lasted for 30 days and here, the
group supplemented with 200 ppm REE mixture gained by 10 % more
weight than the control group. The feed conversion ratio improved
by 2 %. These results showed for the first time, that rare earth
elements are able to improve the performance of the piglets under
field conditions.