Abstract
This experiment was designed to evaluate the effect of various dietary vitamin $B_6$ levels on conversion from linoleic acid to arachidonic acid in various tissues in growing chicks. Growing chicks were fed the purified diet containing 7% safflower oil with different levels of vitamin $B_6$ (0, 4, 8, 40, 80 mg per kg diet) for 14 days. Feed intake and weight gain in chicks fed the vitamin $B_6$-free diet were markedly depressed. Esterified and free cholesterol concentrations in serum were significantly higher, while the serum triglyceride concentration was significantly lover in chicks fed the vitamin $B_6$-free diet compared to that fed diets with vitamin $B_6$. The liver triglyceride content was also lower in chicks fed the vitamin $B_6$-free diet. The liver and serum cholesterol ester fractions in chicks fed the vitamin $B_6$-free diet showed higher rate of $C_{18:2n6}$ and lower rates of $C_{18:3n6}$, $C_{20:3n6}$ and $C_{20:4n6}$ as compared with vitamin $B_6$ fed groups. In serum phospholipid fraction of chicks fed the vitamin $B_6$-free diet, rates of $C_{20:3n6}$ and $C_{20:4n6}$ were markedly lower. As dietary vitamin $B_6$ level was increased, the rate of $C_{20:4n6}$ was slightly increased, although it was statistically not significant. The fatty acid compositions of adipose tissue showed almost the same pattern as those in liver and serum. This result suggests that the desaturation of $C_{18:2n6}$ to $C_{18:3n6}$, elongation to $C_{20:3n6}$ or both steps might be impaired by vitamin $B_6$ deficiency in growing chicks.