Effect of sex on meat quality of Spanish lamb breeds (Lacha and Rasa Aragonesa)

The influence of sex on the meat quality of Lacha (L) and Rasa Aragonesa (R A) lambs was studied. Male and female L lambs were given ewes' milk and wer e slaughtered at 25 and 24 days of age corresponding to 11.4 and 10.9 kg li ve weight (LW), respectively. Male and female XA lambs were weaned at 58 da ys (16.0 kg LW) and then given concentrate and barley straw until slaughter at 89 and 91 days of age, corresponding to 24.5 and 23.1 kg LW, respective ly. The parameters measured on the carcasses were: hot carcass weight, cold carcass weight, conformation, colour, firmness and thickness of dorsal fat and colour of muscle rectus abdominis. Parameters measured on longissimus dorsi muscle were: ultimate pH (pH(u)), instrumental colour (L*, a*, b*), m yoglobin concentration, ash, crude protein, fat, moisture and water-holding capacity (WHC). Iodine value and fatty acid composition were studied in th e intramuscular (IM), intermuscular (IN) and subcutaneous (SC) fat depots. Females of both breeds had higher amount of IM fat (P < 0.001 and P < 0.05 for L and RA breeds, respectively) and firmer SC fat than males (P < 0.05). There were no differences between sexes in pH(u), myoglobin concentration, WHC and the L*, a* and b* colour parameters. No significant differences be tween sexes were observed in the total saturated fatty acids, total unsatur ated fatty acids and in the iodine value in the three fat depots studied in both breeds. However, the females of the breed had significantly higher pr oportions of fatty acids with 15 carbon atoms (pentadecanoic (C-15:0)) and with 16 carbon atoms (palmitic (C-16:0) and palmitoleic (C-16:1)) than the males in the three depots. The females of Rasa Aragonesa breed had a higher proportion of palmitoleic acid (C-16:1) in the IM depot (P < 0.001) and of palmitic acid (C-16:0) in the SC depot (P < 0.05) than the males. The abse nce of significant differences in the unsaturated fatty acid content betwee n males and females showed that at the low slaughter weight, sex had no eff ect on the nature and composition of fat.