The economic optimum mob size at lambing for triplet-bearing Maternal and Merino ewes across southern Australia

John M. Young; Paul R. Kenyon; Lyndon J. Kubeil; Andrew N. Thompson; Jason Trompf; Amy Lockwood

doi:10.1071/AN24334

RESEARCH ARTICLE (Open Access)

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The economic optimum mob size at lambing for triplet-bearing Maternal and Merino ewes across southern Australia

John M. Young

^A ^* , Paul R. Kenyon ^B , Lyndon J. Kubeil ^C , Andrew N. Thompson

^D , Jason Trompf ^E and Amy Lockwood

^D ^F

+ Author Affiliations

- Author Affiliations

^A College of Environmental and Life Sciences, Murdoch University, Murdoch, WA 6150, Australia.

^B School of Agriculture and Environment, Massey University, Tennent Drive, Palmerston North 4410, New Zealand.

^C Department of Economic Development, Jobs, Transport and Resources, Benalla, Vic 3672, Australia.

^D Centre for Animal Production and Health, Murdoch University, Murdoch, WA 6150, Australia.

^E J.T. Agri-Source, Mill Park, Vic 3082, Australia.

^F Present address: neXtgen Agri International Limited, 61 Ngaio Street, St Martins, Christchurch 8022, New Zealand.

^* Correspondence to: j.young@murdoch.edu.au, john@farmingsystems.com.au

Handling Editor: Andy Greer

Animal Production Science 65, AN24334 https://doi.org/10.1071/AN24334

Submitted: 11 October 2024 Accepted: 23 December 2024 Published: 16 January 2025

© 2025 The Author(s) (or their employer(s)). Published by CSIRO Publishing. This is an open access article distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND)

Abstract

Context

Lambing triplet-bearing ewes in smaller mobs significantly increases lamb survival.

Aims

This paper reports economic analysis to assess the optimum mob size for triplet-bearing ewes during lambing.

Methods

The analyses considered scenarios for Merino and non-Merino (Maternal) flocks where producers subdivided lambing paddocks using permanent fencing or where ewes were re-allocated within existing paddocks on the basis of pregnancy status.

Key results

The optimum mob sizes for triplet-bearing ewes during lambing were affected by ewe breed, stocking rate, lamb price and the target return-on-investment if subdividing paddocks. The optimum mob size for triplet-bearing Maternal and Merino ewes was between 27% and 40% of the optimum for twin-bearing ewes and this was similar for scenarios where paddocks were subdivided, or where ewes were re-allocated within existing paddocks. At the standard lamb price of AUD$7/kg carcass weight, the economic return from adjusting the relative mob size of triplet-bearing ewes was AUD$2.05 per multiple-bearing or AUD$14.20 per triplet-bearing Maternal ewe and AUD$0.54 per multiple-bearing ewe or AUD$5.70 per triplet-bearing Merino ewe.

Conclusions

Overall, these analyses demonstrated that reducing mob size at lambing can be a profitable strategy for improving survival of triplet-born lambs, depending on the current size of lambing mobs.

Implications

As reported previously for single- and twin-bearing ewes, it is difficult to provide generic recommendations to producers for the optimum mob size of triplet-bearing ewes at lambing because optimum mob size was dependent on several enterprise-specific factors.

Keywords: lamb survival, lambing paddock, marking rate, multiple-bearing, non-Merino, permanent fencing, reallocation, subdivision.

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