Abstract

Investigations on the effects of Rare earth Element Citrates on growth promoting parameters in pigs and on ruminal fermentation in an artificial rumen (RUSITEC) For decades Rare Earth Elements, such as lanthanum, cerium, and praseodymium have been used in Chinese agriculture and farming for yield increase and growth promoting effects. Many Chinese studies showed partly enormous growth promoting effects whereas the most spectacular is seen in poultry and pig production. Several feeding trials with Rare Earth Elements were already carried out in our working group. So far mineral salt chlorides were used in previous studies. In the present study we tested for the first time the effects of Rare Earth Elements Citrate in grower pigs as well as in an in vitro trial in ruminants. A feeding study with 28 piglets (German Landrace x Piétrain) was carried out. They were separated in 4 dietary groups, each containing 7 animals. These animals received a regular diet, supplemented with a mixture of Rare Earth Elements Citrate in concentrations of 0, 50, 100, and 200 mg/kg feed for a 6 week period. A positive effect of the Rare Earth Elements Citrate on fattening performance parameters was determined. In the trial period the daily body weight gain of the two high supplemented groups increased between 8.6 % to 22.6 % compared to the control group. The low dosage group showed no difference. An increase in the feed conversion rate from 2 % to 6 % was shown in all Rare Earth Elements supplemented groups. This indicates that within the pig feeding highly increased growth-promoting effects were determined when supplemented with Rare Earth Elements Citrate compared with the studies in which the chloride form was used. The study on possible effects of Rare Earth Elements in ruminal fermentation was carried out with the Rumen Simulation Technique (RUSITEC), an artificial rumen. The effect of Rare Earth Elements in different dosages was compared to a negative control (without supplement) and a positive control (Tetracycline). Each trial lasted for a period of 10 days. The influence on the parameters pH-value, NH3, redox potential, fatty acid pattern, and gas production was analysed. Since the ruminal fermentation was not influenced, the conclusion can be drawn, that in this respect microorganisms are not affected by Rare Earth Elements.