J. M. Young

Whole-farm profit and the optimum maternal liveweight profile of Merino ewe flocks lambing in winter and spring are influenced by the effects of ewe nutrition on the progeny's survival and lifetime wool production

Profitability of sheep production systems in southern Australia is optimised at a stocking rate that provides adequate nutrition for breeding ewes and enables efficient utilisation of grown pasture and supplements. In this paper we used bio-economic modelling to develop optimum liveweight1 profiles for spring-lambing Merino ewes in different environments. The modelling included the impacts of the ewe liveweight profile on the production of the ewe and the survival and lifetime wool production of her progeny. Fifteen ewe liveweight profiles were analysed for each region to determine the profitability of varying ewe liveweight at joining, varying rate of loss of liveweight after joining and the rate of gain in liveweight from the minimum to lambing. The analyses support the hypotheses that whole-farm profitability is sensitive to the liveweight profile of Merino ewe flocks and that there is a liveweight profile that maximises whole-farm profit. The variation between the most and least profitable ewe liveweight profile was

Bioeconomic modelling to identify the relative importance of a range of critical control points for prime lamb production systems in south-west Victoria

69 0002 per farm (

Successful adoption of new guidelines for the nutritional management of ewes is dependent on the development of appropriate tools and information

14.30/ewe) for south-west Victoria,

The critical control points for increasing reproductive performance can be used to inform research priorities

51 000 per farm (

The value of genetic fatness in Merino ewes differs with production system and environment

8.70/ewe) for Great Southern Western Australia and

The economic benefits of providing shelter to reduce the mortality of twin lambs in south-western Victoria

33 300 per farm (

Economic value of pregnancy scanning and optimum nutritional management of dry, single - and twin-bearing Merino ewes

9.70/ewe) for southern New South Wales. The changes in profit were due to differences in costs of feeding to achieve the ewe liveweight profile and its influence on the production of both the ewes and their progeny. Failure to include the impacts of liveweight profile on progeny survival and lifetime wool production incorrectly identifies the optimum ewe liveweight profile and provided inaccurate estimates of profitability. The optimum liveweight profiles for ewes lambing in spring were similar for all three regions and insensitive to changing commodity prices, pasture productivity and management. The optimum profile was to join ewes at ~90% of the standard reference weight of the genotype, lose a small amount of weight after joining and regain weight in late pregnancy to return to the joining weight by lambing. Regaining the liveweight lost in early pregnancy by lambing is the most important target to achieve. The cost per farm of missing this liveweight target by 1 kg was

The potential value of genetic differences in liveweight loss during summer and autumn in Merinos ewes differs with production environment

13 000 (

A comparison of the profitability of farming systems using wool and wool/meat sheep genotypes in south-west Victoria

2.60/ewe) for south-west Victoria,

Potential economic benefits from improving ewe nutrition to optimise lifetime wool production and quality in South-west Victoria

8900 (