METABOLIZABLE ENERGY REQUIREMENTS FOR MAINTENANCE AND GROWTH OF SUCKLING CALVES GIVEN MILK REPLACER

A total of 38 energy balance trials were done for calves fed a liquid milk replacer, calf starter and second cut mixed hay. Milk replacer supplied 81% of the total dietary energy. Live weight of calves averaged 54.1 (S.D 6.2) kg and daily gain 0.37 (${\pm}0.23$)kg. The metabolizability of gross energy averaged 0.822. A regression was calculated relating energy retention (ER, $kJ/kg^{0.75}$) to the intake of metabolizable energy (IME, $kJ/kg^{0.75}$): ER = 0.72 (${\pm}0.12$) IME - 330, r = 0.702, P < 0.01, $S.E.{\pm}18.0$. Metabolizable energy for maintenance (MEm) was calculated to be $458kJ/kg^{0.75}$ when ER = 0. The amount of IME over MEm for an individual animal (Meg, $kJ/kg^{0.75}$) was regressed on averaged daily gain (ADG, kg): Meg = 413 (${\pm}91$) ADG + 0.2, r = 0.650, P < 0.01, $S.E.{\pm}21$. The amount of ME requirement for suckling calves was estimated using values obtained above.