Duration of dietary linseed feeding affects the intramuscular fat, muscle mass and fatty acid composition in pig muscle

摘要

The aim of the study was to investigate the effect of duration of dietary linseed feeding on subcutaneous fat, intramuscular fat depot and muscle mass of growing-finishing barrows. Two isoenergetic and isonitrogenous diets were formulated, and one of which was the basal diet and another one was the linseed diet including linseed at the level of 10%. Twenty-four LandracexYorkshire barrows weighing 35pl3.7 kg were randomly assigned to four treatments with six replications per treatment. Pigs in treatment 1 (T1) fed the control diet throughout the experimental period, while pigs in T2, T3, and T4 fed the control diet except for 30, 60, and 90 d prior to slaughter when the linseed diet were fed. The experiment was conducted for 90 d. Carcass quality and meat quality data were collected and analyzed. The longissimus muscle mass, posas minor mass and each muscle mass in the hind leg were weighted. Additionally, fatty acid composition (%) of the diet, the longissimus dorsi muscle and the backfat were analyzed by gas chromatography method. No significant difference (P >0.05) was observed for average backfat thickness, lean meat percentage, loin muscle area, whereas the intramuscular fat content increased linearly (P <0.01) as prolonged the time of feeding linseed diet. As prolonged the time of feeding linseed diet, the longissimus dorsi muscle mass, quadriceps femoris muscle mass and semitendinosus muscle mass increased linearly (P <0.01). Duration of feeding linseed diet linearly increased (P <0.01) the C18:3n-3, C20:5n-3 and C22:5n-3 concentrations in the longissimus muscle and backfat. There was significant quadratic relation between the intramuscular fat content and the n-3 polyunsaturated fatty acids (PUFA) enrichment (R po =0.87, P <0.01), or C18:3n-3 enrichment (R po =0.91, P <0.01) in the longissimus dorsi muscle. Likewise, the longissimus dorsi muscle mass was also quadratically related to the n-3 PUFA enrichment (R po =0.89, P <0.01), or C18:3n-3 enrichment (R po =0.86, P <0.01) in the longissimus dorsi muscle. These results indicated that duration of feeding linseed diet may stimulate intramuscular fat accumulation, and promote the hypertrophy of the longissimus dorsi muscle, quadriceps femoris muscle mass and semitendinosus muscle by increasing the n-3 PUFA enrichment, especially C18:3n-3 enrichment in the longissimus dorsi muscle.