Relative priorities for feed between ewes and ewe hoggets in winter and spring: a modelling analysis

D.G. McCall

Whatawhata Hill Country Research Centre, Ministry of Agriculture and Fisheries, Hamilton

Proceedings of the New Zealand Society of Animal Production. 1984, 44: 121-124

A simulation model was used to generate functions to evaluate winter and spring feed priorities for replacement hoggets and ewes on North Island hill country. The functions relate ewe, hogget and lamb live weights at the end of the respective seasons to seasonal stocking rate and live weight and pasture cover at the start of the season. The site simulated was Ballantrae Hill Country Research Station.

At high stocking rates, switching priorities from hoggets in winter (relative stocking rate, 1 hogget/ewe) to ewes in spring (2.4 hoggets/ewe) provided no benefit to ewe and hogget live weight at weaning, compared to other selected winter/spring strategies (eg. 1.2/2.05 or 1.4/1.8 hoggets/ewe). However, lamb weaning weight was greater under the former strategy. The same pattern held for lower stocking rates. Imposition of system constraints reduced the apparent advantages displayed in the general functions. Rationing feed to hoggets in spring was important to success at high hogget stocking rates.

Keywords: NZSAPAB; Simulation; model; production functions; ewes; lambs; hoggets; live weight; pasture cover; feed priorities; winter-spring

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Last Updated 03-05-1997