Rare earths as a feed additive for poultry

Abstract

Rare earths (RE) is the common name for the metallic elements of the lanthanide series, together with yttrium and scandium, which make up 0.016% of the earth's crust. This review summarizes the results of experiments conducted in China in which RE were added to poultry diets. Additions of 30–1000mg/kg RE to layer diets resulted in increases in egg production of 3–15% and improved feed conversion efficiency of 2–22%. The hatchability of eggs increased by 5–15%. Improvements of 4–14% in body weight gain were observed in broilers fed 20–400 mg/kg, together with 3–6% better feed conversion efficiency and increases of 3–5% in eviscerated yield. Similar benefits have also been reported when feeding RE to ducks, although not statistically validated, and to meat-type pigeons. No adverse effects of feeding RE have been reported. It is concluded that rare earths have a role as feed additives in the poultry industry, particularly in conditions where the genetic potential for production traits is not achieved. Key information from some of the papers cited in the paper is summarized in an appendix.

Keywords:

• Additive
• China
• egg production
• feed
• meat
• poultry
• rare earths
• trace elements