The Incidence of Head Retraction in Newly-Hatched Chicks and the Manganese Contents of the Eggs of Some Inbred Lines of Brown Leghorn Fowls

Abstract

ABSTRACT IN THE flock of Brown Leghorn fowls maintained at the Poultry Research Centre it had been noted that some newly hatched chicks suffered from head retraction which could be so severe that the back of the head touched the spine. If the affected chicks were segregated to prevent them being trampled to death, or had collars affixed to keep the heads in the normal position, they usually recovered in about a day. Similar symptoms were reported by Caskey, Norris and Heuser (1944) when diets inadequately supplied with manganese were fed to breeding hens. The incidence of head retraction in newly-hatched chicks and the manganese contents of the eggs from the inbred lines of fowls maintained here have therefore been determined. METHODS The inbred lines at the Poultry Research Centre are maintained under intensive conditions in pens with concrete floors. Wood-shavings litter is changed frequently and the environment is kept as . . .