There are no published feed-energy standards for growing rabbits. Even nutritional factors that affect intake and digestibility, and consequently performance, are not well documented. Two experiments were carried out, as part of a programme to develop energy feeding standards for growing rabbits. Experiment 1 investigated the effect of physical and chemical characteristics on intake and digestibility of diets. Experiment 2 investigated the effects of level of feeding on digestibility of diets varying in energy density.

A 3 x 2 factorial design was used in both experiments, with 20 Individually-fed weaned rabbits per treatment (initial weight approximately 800 g). Diets were pelleted (4 mm die diameter) and were of the same formulation in both experiments. Diets (LH, MB, HH) were formulated to contain different crude fibre levels (Table 1) by varying, the inclusion rates of grass hay - (LH, Low Hay, 273 g/kg; MB, Medium Hay, 556 g/kg and HH, High Hay, 831 g/kg). Diets were formulated to contain the same amounts of crude protein. In Experiment 1 the hay component In diets LHf, MHf and HHf was ground through a 1 mm screen whereas that in diets LHc, MHc and HHc was ground using a 6 mm screen. In Experiment 2, diets LHf, MHf and HHf were fed ad libitum or at 70% of ad libitum Intake.