Energy metabolizability and nutrient digestibility in the Black-billed Magpie Pica pica

Energy metabolizability (ME) and nutrient digestibility were investigated i n a captive colony of nine adult Black-billed Magpies Pica pica over a 12-d ay period. The mean digestibility coefficients ranged from 0.84 for protein to 0.94 for fat and were generally close to those of other birds. Mean dai ly protein intake was 10.5 g/bird which was relatively high compared with t he values reported for other species. Raptor studies have also reported hig h protein intakes which not only reflects the diet composition but may sugg est that meat-eating birds have a high protein requirement. The magpies exh ibited an energy metabolizability of 324.3 kJ ME/100 g wet mass intake whic h corresponded well with the value of 328.8 kJ ME/100 g calculated using th e standard poultry equation. The measured ME intakes of the magpies were al l higher than the values predicted using published allometric equations. Th e data from the magpies were combined with those of other studies on raptor ial birds to derive an equation to predict daily ME requirement: ME (kJ) = 15.16M(0.65). We propose that this equation predicts the daily ME requireme nts of birds of 100-1500 g.