Dietary phosphorus requirement of holstein steers during early growing period

Abstract

Ninety-six Holstein steer calves (120.7 +/- 5.3 kg) were used to evaluate the influence of dietary phosphorus level (0.27, 0.31, 0.35 and 0.39\%, DMB) on growth-performance during the initial 105 d on feed. Dicalcium phosphate was the source of supplemental phosphorus. All diets were formulated to contain 0.85\% calcium (DMB). Dietary phosphorus level did not affect (P >.10) DMI or body size measurements. However, increasing dietary phosphorus level increased ADG (linear component, P <.05), gain efficiency (quadratic component, P <.05) and dietary NE (quadratic component, P <.05). It is concluded that during the initial growing period ADG, gain efficiency and dietary NE are optimal at a dietary phosphorus level of 0.35\%, 15\% lower than current NRC recommendations.