Effect of continuous stocking of breeding ewes at different sward
surface heights during the late summer-autumn on herbage intake and
productivity
A.U. Panggabean, S.T. Morris, W.J. Parker, S.N. McCutcheon
Department of Animal Science, Massey University, Palmerston North,
New Zealand
Proceedings of the New Zealand Society of Animal Production. 1995,
55: 141-144
The Stockpol model was designed for decision support on New
Zealand sheep and beef cattle farms. It indicates the biological feasibility of
a livestockj system and provides the opportunity for users to test alternative
livestock policies. An evaluation of the Stockpol model was made using 44
data sets from farmlet trials at Gore, Ballantrae and Whatawhata Research
Centres and data from Massey Universityís Riverside farm in the Wairarapa.
These data covered a range of sheep and beef finishing systems. The main
test compared the measured pasture growth rate with that required by
Stockpol ;to predict the monthly pasture cover recorded in the data.
Measured and required pasture growth rates differed significantly (<0.01) in
July, August and September. The model was conservative and required an
average of 5.1 kgDM/ha/day more growth over these months than was
measured. In other months differences were small and non significant.
When animal demand was adjusted to mimic pasture cover, adjustments of
minus 22% from July to September were required. Overall it was considered
that Stockpol can be used with confidence for analysing options for farmer
decision making. Areas for further improvement of Stockpol have been
defined as the pasture growth model in early spring. Aspects of the animal
demand in early spring also need to be tested more vigorously. The
evaluation emphasised the importance of consistent input data for use in
models. For example, the pasture measurement technique was different at
each of the four sites studied. This may explain some of the variation
between predicted and measured data.
Keywords: NZSAPAB;
decision support; livestock policy; feed supply; pasture cover; feed
demand
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Last Updated 25-01-1997
