Voluntary intake and digestibility of straw and hay supplemented with silages or lucerne by yearling cattle

M. Basery and R. C. Campling

Abstract

Three experiments were conducted with yearling cattle to measure the voluntary Intake of diets composed of two long forages and especially to examine the use of grass, maize and Lucerne silages as well as Lucerne forage as supplements to diets consisting of barley straw and hay. Giving supplements of 1.14, 2.27 and 3.40 kg DM grass silage to cattle receiving barley straw ad lib. increased total forage Intake to a similar extent because straw intake decreased proportionately. Supplement of 3.20 kg DM Lucerne and grass silage to barley straw diets increased total forage intake to the same extent and straw intake fell by 0.53 kg DM per kg DM silage. Similarly, supplements of lucerne silage to diets of maize silage increased total intake and reduced intake of maize silage by 0.67 kg DM per kg supplement. The voluntary intake of a mature rye grass hay was not altered by supplementing it with 67% fresh lucerne. The results confirmed the hypothesis that the intake of mixtures of long forages were proportional to the maximal intake of the individual components when offered as the sole feed. although there were evidence of small deviations from this general finding. The substitution of one forage by another is discussed as are the associative effects on voluntary intake and digestibility which was observed.

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