Intramuscular lipid and fatty acid profile of sheep comprising four sex-types and seven slaughter weights produced following commercial procedure

The intramuscular lipid and fatty acid profiles of the m. longissimus dorsi from 84 sheep comprising four sex-types (enire ram, vasectomised ram, wether and ewe) and seven slaughter weights (32, 36, 40, 44, 48 and 52 kg) were measured. Animals were reared following the commercial practice. Specifically, they were fed pasture and a concentrate diet, and age at slaughter ranged from 180 to 390 days. Differences between entire and vasectomised rams, and between wethers and ewes in intramuscular lipid content were not significant (P > 0.05). However, entire and vasectomised rams were significantly lower (P < 0.05) in intramuscular lipid content than ewes and wethers. Sex related differences in 14:0 (myristic acid), t18:1, c18:1, t18:2 and c18:2 proportions were not significant (P > 0.05). Ewes and wethers were similar in 16:0 (palmitic acid) and 18:0 (stearic acid) proportions, but ewes contained significantly higher 16:0 and lower 18:0 proportions than entire and vasectomised rams (P < 0.01). Entire and vasectomised rams recorded the highest c18:3 proportions, wethers were intermediate whilst ewes contained the lowest proportion (P < 0.01). Although neither saturated fatty acid (SFA) nor monounsaturated fatty acid (MUFA) proportions varied with sex-type, vasectomised rams contained significantly higher polyunsaturated fatty acid (PUFA) proportion that the other sex-types (P < 0.05). Whilst intramuscular lipid content, and 18:0 and c18:1 proportions were linearly correlated with slaughter weight (P < 0.001), 14:0 and c18:3 proportions decreased quadratically with increasing slaughter weight (P < 0.001). The vasectomised ram and the entire ram were similar in fatty acid profile, except the significantly higher PUFA proportion recorded by the vasectomised ram.