Abstract:

This experiment was conducted to study the relationship among gene expression of malate dehydrogenase and lipoprotein lipase in muscle and contents of intramuscular fat and composition of fatty acids in F₁ hybrids with boar × Laiwu pigs, and to investigate the sedimentary mechanism of intramuscular fat. F₁ hybrids with boar × Laiwu pigs(called YL F₁) and pigs with Landrace × Yorkshire (40 pigs for each, 20 for male, 20 for female) were used. The dorsal-waist longissimus muscle were collected when the body weight reached 20, 35, 50, 70 and 90 kg. The developmental changes of MDH and LPL genes expression was detected by fluorescent quantitative RT-PCR method, and the relationship between the change and the content of intramuscular fat and composition of fatty acids was analyzed. The results indicated that with the increase of body weight, the MDH gene expression in muscle in F₁ hybrids with boar × Laiwu pigs and pigs with Landrace × Yorkshire pigs increased from 20 to 70 kg, and decreased from 70 to 90 kg. The LPL gene expression in muscle in F₁ hybrids with boar × Laiwu pigs and pigs with Landrace × Yorkshire pigs increased with the increase of body weight. Correlation analysis showed that in F₁ hybrids with boar × Laiwu pigs, the expression of MDH and LPL mRNA had significant positive correlationship with content of intramuscular fat(P<0.05), but had no correlation with rate of polyunsaturated fatty acid to saturated fatty acid (P>0.05). In Landrace × Yorkshire pigs, the expression of MDH and LPL mRNA had no correlationship and had significant positive correlationship with content of intramuscular fat, respectively(P>0.05 and P<0.05), and had significant negative correlationship with rate of polyunsaturated fatty acid to saturated fatty acid (P<0.01 and P<0.05). The rate of polyunsaturated fatty acid to saturated fatty acid had significant negative correlationship with the content of intramuscular fat in two pig populations(P<0.05). The results suggest that with the increase of body weight, the expression of both MDH and LPL genes in muscle of pigs have apparent developmental characteristic. We can adjust the content of PUFA in muscle by controlling the content of PUFA in diet of pigs, which can affect the expression of MDH and LPL genes, and adjust the content of intramuscular fat.