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Lipid content, fatty acid composition and histochemistry of normal and fatty liver in broiler chicks

Chicken liver is organ where majority of fatty synthese take place. Approximately 25-30% of intensively fed Hubbard broilers at the end of fattening period have organoleptically altered light yelowish liver with high amount od fat. These changes are not the consequence of bacterial or viral infection. Based on the presumption of fatty degeneration such liver is considerate of lower quality for human consumption. In this study it was investigated wheather the changes really represent fatty degeneration or just more intensive biosynthesis of the fat and the deposition of the fat in hepatocytes. Therefore histopathological changes in the liver and histochemical localisation of the enzymes which participate in fat biosynthesis in hepatic parenchyme were examined. Lipid content in organoleptically altered liver was significantly higher (p<0.001) than in normal liver. Histology revealed diffuse fat infiltration of hepatic parenchyme without degenerative changes in nuclei of liver cells. Histochemical acitivities of glucose-6-phosphate dehydrogenase (G-6-PDH),  -glycerophosphate dehidrogenase ( GDPH), glutamate dehydrogenase (GLDH), lactate dehydrogenase (LDH), succinat dehydrogenase (SDH), diphosphopyridin-nucleotide diaphorase (DPND) and triphosphopyridine nucleotide diaphorase (TPND) in the fat and normal liver tissue did not exhibit significant difference. It can be concluded that the degenerative changes were not present in fat infiltrated liver. Only physiological fat infiltration represents normal hepatic function during high carbohydrate fattening diet. Besides enzymatic activities as markers of functional status of liver, neutral lipids and phospholipids of normal and organoleptically altered (fatty) liver were investigated, as well as their fatty acid composition. The portion of neutral lipids in total lipids of fatty liver was higher (p<0.001) and phospholipids lower (P<0.001) than in normal liver. The fatty acid composition of neutral lipids and phospholipids indicated that fatty liver has more unsaturated and less saturated fatty acids compared to normal liver. The content of oleic acid (18:1) was significantly higher in fatty liver (p<0.05), while myristic (14:0) and linoleic acid (18:2) content was lower (p<0.05). It can be concluded that the fatty acid composition of organoleptically altered liver could be even better for human consumption compared to normal liver. The obtained findings in fatty liver of chicken are similar to those described earlier for fattening geese, which liver is used as delicacy food.

liver; lipid content; fatty acids composition; histochemistry; broiler chicks

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