Different mature ewe sizes require different stocking rates and lamb slaughter weights to maximise whole-farm profit

Kennedy, K.L., Ferguson, M.B., Martin, G.B., Thompson, A.N.ORCID: 0000-0001-7121-7459 and Pannell, D.J. (2011) Different mature ewe sizes require different stocking rates and lamb slaughter weights to maximise whole-farm profit. Proceedings of the Association for the Advancement of Animal Breeding and Genetics, 19 . pp. 339-342.

Abstract

To understand the tradeoff between maintaining a larger ewe and the higher income received from producing larger and faster-growing lambs, we used bio-economic simulation modelling to explore the relationship between ewe mature size, lamb slaughter weight and stocking rate. For the majority of factors tested, ewe feed costs did not reduce gross margin, with the exception of the 80 kg ewe at 14 ewes/ha. Conversely, the 50 kg ewe had higher lamb finishing costs and lower lamb income due to the reduce lamb growth potential, which counteracted the lower ewe feeding costs. Unless enterprises are near the upper limits of stocking rate and mature size tested here, the selection for growth rate in Merinos should continue. To maximise gross margin at each level of mature size, management factors (stocking rate and lamb slaughter weight) were different for each mature size, which influenced income and expense sources differently. When setting breeding objectives and formulating selection indexes the complex interactions between genetic and management factors should be considered.

Item Type:	Journal Article
Murdoch Affiliation(s):	School of Veterinary and Biomedical Sciences
Publisher:	Association for the Advancement of Animal Breeding and Genetics
Notes:	Paper presented at the AAABG 19th Conference, Perth, Western Australia, 19 - 21 July 2011
URI:	http://researchrepository.murdoch.edu.au/id/eprint/24746

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