Theme 11: Biological Constraints to Animal Production from Grasslands
Description
The wiregrass/bluegrass (Aristida/Bothriochloa) native pasture community in Eucalypt woodlands is a major cattle producing resource in Queensland. The effects of poplar box tree (Eucalyptus populnea) competition (at 5 m2/ha tree basal area) and grazing pressure on pastures and on growth of Brahman-cross steers were measured in a grazing experiment. Treatments were 2 tree competition levels (live trees or clearing) by 3 grazing pressures (low - 25%, medium - 50% and high - 75% utilisation of annual pasture growth). Pasture yield and pasture foliage cover increased for 3 years from the reduction in tree competition by clearing and by low grazing pressure with increasing annual rainfall. Clearing increased pasture yield by 33% in the first summer growing season and by 94% in the third year. After 3 years, foliage cover after clearing was 51% compared with 39% in pastures with live trees. Pasture yield and cover were reduced by 34% and 33% respectively by high grazing pressure compared with the low rate. Reducing tree competition by clearing produced a 39% increase in annual average daily steer weight gain (0.32 kg/day) over the third year, by eliminating weight loss in winter. Annual steer growth was highest at the low and medium grazing pressures, with most rapid growth in summer when pastures were green and growing. Highest liveweight in the third year occurred with clearing and low grazing pressure (gaining 131 kg/hd). There was greatest liveweight loss (14 kg/hd) between autumn and spring at high grazing pressure.
Citation
Hall, T. J. and Douglas, J. R., "Tree Competition Reduces Cattle Growth Rates in Eucalypt Woodlands of Queensland" (2021). IGC Proceedings (1993-2023). 4.
https://uknowledge.uky.edu/igc/19/11/4
Included in
Tree Competition Reduces Cattle Growth Rates in Eucalypt Woodlands of Queensland
The wiregrass/bluegrass (Aristida/Bothriochloa) native pasture community in Eucalypt woodlands is a major cattle producing resource in Queensland. The effects of poplar box tree (Eucalyptus populnea) competition (at 5 m2/ha tree basal area) and grazing pressure on pastures and on growth of Brahman-cross steers were measured in a grazing experiment. Treatments were 2 tree competition levels (live trees or clearing) by 3 grazing pressures (low - 25%, medium - 50% and high - 75% utilisation of annual pasture growth). Pasture yield and pasture foliage cover increased for 3 years from the reduction in tree competition by clearing and by low grazing pressure with increasing annual rainfall. Clearing increased pasture yield by 33% in the first summer growing season and by 94% in the third year. After 3 years, foliage cover after clearing was 51% compared with 39% in pastures with live trees. Pasture yield and cover were reduced by 34% and 33% respectively by high grazing pressure compared with the low rate. Reducing tree competition by clearing produced a 39% increase in annual average daily steer weight gain (0.32 kg/day) over the third year, by eliminating weight loss in winter. Annual steer growth was highest at the low and medium grazing pressures, with most rapid growth in summer when pastures were green and growing. Highest liveweight in the third year occurred with clearing and low grazing pressure (gaining 131 kg/hd). There was greatest liveweight loss (14 kg/hd) between autumn and spring at high grazing pressure.
