Interest in the production of maize silage in Ireland has increased in the last few years. The objective of this experiment was to evaluate the performance of steers when fed maize or grass silage based diets ad libitum and supplemented with varying levels of concentrates.

Sixty continental cross steers were blocked on the basis of live weight (av. initial weight = 617 kg) and breed (Charolais, Limousin and Simmental) and were allocated to one of the following six dietary treatments with 10 animals per treatment: A) maize silage-1 (sown under polythene) plus 2 kg concentrates (22% CP); B) 50:50 mixture of maize silage-2 (grown without the use of polythene):grass silage plus 4 kg concentrates (16% CP); C) maize silage-2 plus 4 kg concentrates (16% CP); D) maize silage-3 (as for silage-2 but with additive applied to control aerobic deterioration) plus 4 kg concentrates (16% CP); E) grass silage plus 4 kg concentrates (16% CP); F) grass silage plus 6 kg concentrates (14% CP). The steers were fed for 105 days during which live weight gains and group intakes were measured. After slaughter carcass gains were calculated (using an initial kill-out of 53%), kidney knob and channel fat weights were measured and carcass conformation and fat scores were taken.