The Effect of Pre-Laying Mineral Nutrition on the Development, Performance and Mineral Metabolism of Pullets ,

Abstract

FOURTEEN to sixteen days before the onset of egg production, (Hurwitz, 1964), the pullet undergoes profound changes in its mineral metabolism. This stage coincides with the development of the primary and secondary sex organs and is characterized by increased plasma calcium, increase in calcium retention and formation of medullary bone (Simkiss, 1961).Such an intense mineral metabolism is preceded by a period of about two months of low intensity mineral metabolism during which the calcium and phosphorus requirements are extremely low (Berg et al., 1964). During the pre-laying period the calcium and phosphate retention reach 800 and 400–500 mg./day, respectively (Taylor and Moore, 1958). It thus must follow that the mineral requirements during the pre-laying period are increased.It has been shown that during the early production period, the young hen is in a negative calcium balance (Morgan and Mitchell, 1938) which cannot be alleviated by high dietary calcium…