Compensatory growth in cattle grazing different vegetation types

Abstract

Fifty-four Charolais-cross weaned suckled calves were used in an experiment to investigate the effects of feeding level during the post-weaning winter on their subsequent performance, when grazing different vegetation types in summer. During winter they were given grass silage and barley at one of three levels (low, medium and high). The winter live-weight gains were 0·50, 0·75 and 0·96 (s.e. 0·019) kg/day (P < 0·001) for the low, medium and high treatments respectively. During summer they grazed either a sown ryegrass pasture (S), a hill reseed (R) or part of an unimproved hill (H).Live-weight gain during summer was inversely related to winter feeding level on all grazing treatments, the mean live-weight gains being 1·01, 0·79 and 0·65 (s.e. 0·027) kg/day (P < 0·001) for the low, medium and high winter feeding levels respectively. Summer treatment significantly affected performance, the live-weight gains being 0·88, 0·94 and 0·61 (s.e. 0·027) kg/day for the S, R and H treatments respectively. There was no interaction between winter and summer feeding treatment on live-weight gain. The organic matter intake was highest on the H treatment but the digestibility of herbage consumed was the lowest, resulting in the lowest digestible organic matter intake.Similar and high levels of performance were obtained on sown ryegrass pastures and reseeded hill land, while unimproved hill vegetation supported only moderate levels of live-weight gain. Compensatory growth occurred when a wide range of vegetation types were grazed in summer.