Resumo

HORCADA-IBANEZ, Alberto et al. Effect of slaughter weight on fat composition in lacha lambs. Agrociencia [online]. 2010, vol.44, n.6, pp.643-654. ISSN 2521-9766.

Due to the fact that domestic consumers prefer low fat meat, the lamb production system in Spain is based on slaughtering low weight animals (12 to 24 kg). Lambs in other European countries are slaughtered at higher weights because consumers prefer more intense flavored and fatter meat. Based on evidence that slaughter weight affects fat characteristics, the effect of slaughtering weight on the fatty acid profile of omental (OM), mesenteric (MES), kidney knob (KK), subcutaneous (SC), intermuscular (IN) and intramuscular (IM) fat in Lacha breed lambs was studied. Forty-two male Lacha lambs were raised and slaughtered at 12 (L12), 24 (L24) and 36 kg (L36) live weight. L12 lambs were fed only on mother's milk until slaughter, one month old. L24 and L36 lambs were fed ad libitum on commercial feed and barley straw from weaning (around 16 kg live weight) until slaughter. Adipose tissue samples were taken at the slaughterhouse, vacuum-packed, frozen and stored. Fatty acid methyl esters were analyzed by capillary gas chromatography, and the relative amounts were recorded. The results were analyzed using ANOVA and Tukey's test (p<0.05). Concentrations of C12:0 and C14:0 decreased after weaning due to the fact that the lambs no longer ingested mother's milk. In all fat depots, L24 showed the highest saturated fatty acid concentration, mainly due to the higher C18:0 content. An increase in C18:1n-9cis in heavier lambs (L24 to L36) was observed, associated to fat reserve accumulation processes. The analysis of these data suggests an increase in desaturation enzymes activity among higher-weight lambs, when ruminal activity was initiated. The most suitable n-6/n-3 and polyunsaturated/saturated ratio in muscle fat for preventing cardiovascular disease were observed in L24 lambs.

Palavras-chave : fat deposit; fatty acids; lambs.