The liveweight, carcasses and meat quality of intact and castrated male lambs reared under a pasture-fed Australian production system

Shawn R. McGrath; M. Bruce Allworth; James Stephens; Michelle L. E. Henry; Benjamin W. B. Holman

doi:10.1071/AN24155

RESEARCH ARTICLE (Open Access)

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The liveweight, carcasses and meat quality of intact and castrated male lambs reared under a pasture-fed Australian production system

Shawn R. McGrath

^A ^B , M. Bruce Allworth ^A ^B , James Stephens ^C , Michelle L. E. Henry ^D and Benjamin W. B. Holman

^E ^*

+ Author Affiliations

- Author Affiliations

^A Fred Morley Centre, School of Agricultural, Environmental and Veterinary Sciences, Charles Sturt University, Wagga Wagga, NSW 2678, Australia.

^B Gulbali Institute of Agriculture, Water and Environment, Charles Sturt University, Wagga Wagga, NSW 2678, Australia.

^C University Farm, Charles Sturt University, Wagga Wagga, NSW 2678, Australia.

^D Gundagai Meat Processors, South Gundagai, NSW 2722, Australia.

^E Wagga Wagga Agricultural Institute, NSW Department of Primary Industries and Regional Development, Wagga Wagga, NSW 2678, Australia.

^* Correspondence to: benjamin.holman@dpi.nsw.gov.au

Handling Editor: Andy Greer

Animal Production Science 64, AN24155 https://doi.org/10.1071/AN24155

Submitted: 10 May 2024 Accepted: 9 October 2024 Published: 31 October 2024

© 2024 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

Intact male (ram) lambs are often discounted by meat processors because of their perceived defective meat quality.

Aims

This study quantified the effects of castration on the liveweight, growth, carcass parameters and the meat quality of male lambs.

Methods

Liveweight, growth and carcass data were collected from 133 ram and 132 castrated (wether) lambs reared under a pasture-fed production system. A total of 50 lambs were subsequently selected, balanced by final curfew liveweight and castration status, to investigate additional carcass, meat quality, consumer sensory panel scores and colour stability parameters.

Key results

It was found that total average daily gains for ram lambs were highest (242.9 ± 5.2 g/day; P = 0.002), resulting from their higher pre-weaning growth rate of 327.7 ± 9.7 g/day (P < 0.001). Wethers were fattier, having higher estimated intramuscular fat (3.9 vs 3.3 ± 0.1%, respectively) and subcutaneous fat depth (14.7 vs 13.5 ± 0.4 mm, respectively) than ram lambs. Purge loss (P < 0.030) and ultimate pH (P < 0.035) were higher for the meat of wether lambs, but only after 32 days of wet ageing. Consumers scored the meat of wether lambs as significantly more tender (61.0 vs 54.6 ± 2.3%; P = 0.005) and of greater overall liking (65.1 vs 61.1 ± 2.0%; P = 0.044) than that of ram lambs. These, and a comparison of shear force, near infrared spectroscopy for intramuscular fat content and retail colour with consumer thresholds, suggest a general satisfaction with ram and wether lamb meat quality.

Conclusions

Collectively, there seems to be few tangible performance and meat quality advantages to the castration of male lambs.

Implications

Prime lamb producers must consider flock management and market preference when deciding on best practice.

Keywords: animal performance, carcass properties, consumer sensory panel, intact ram lambs, lean tissue yield, meat shelf-life, wet ageing period, wethers.

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