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

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.