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Summer-growing components of a pasture system in a subtropical environment. 2. Relations between pasture and animal production

Published online by Cambridge University Press:  27 March 2009

G. J. Murtagh ,
A. G. Kaiser  and
D. O. Huett
G. J. Murtagh
Affiliation:
Agricultural Research Centre, Wollongbar, N.S.W. 2480, Australia
A. G. Kaiser
Affiliation:
Agricultural Research Centre, Wollongbar, N.S.W. 2480, Australia
D. O. Huett
Affiliation:
Agricultural Research Centre, Wollongbar, N.S.W. 2480, Australia
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Summary

Relations were developed between the carrying capacity or production of fat-corrected milk (FCM)/ha and various measures of pasture growth for six pasture treatments grown in a subtropical environment. The pasture and animal production variables were obtained from pastures grazed on a weekly rotation using stocking densities which were varied so that a target weight of leaf material remained on the pasture at the conclusion of each grazing.

Within a treatment, there was a curvilinear relation between the rate of leaf growth and carrying capacity, with the greatest efficiency of conversion at the lowest leaf growth rates. This relation generally varied between pasture treatments because of differences in grazing intensity. There was little variation in the production of FCM per cow between grazing periods within a treatment, reflecting the experimental technique of matching the stocking density to the amount of forage. Consequently FCM/ha largely mirrored the stocking density with some adjustment for differences in production per cow caused by differences in grazing intensity between treatments. Production of FCM/ha was affected more by a unit change in residue leaf yield than by a unit change in leaf yield before grazing.

Using the rate of leaf removal (intake plus grazing losses) per cow as an inverse index of grazing intensity, it was apparent that the use of variable stocking densities to obtain specified residue yields after grazing did not necessarily equalize the grazing intensity because the rate of leaf removal per cow varied according to the before-grazing leaf yield. Also soiling by dung caused differences in the acceptability of forage for grazing, resulting in differences in grazing intensity between pastures with the same yield and stocking density.

Type
Research Article
Information
The Journal of Agricultural Science , Volume 94 , Issue 3 , June 1980 , pp. 665 - 674
Copyright
Copyright © Cambridge University Press 1980

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