Dietary Carnitine and Lysine Affect Channel Catfish Lipid and Protein Composition

The effects of carnitine (L‐carnitine) at 0.1% were tested at three levels of dietary lysine (L‐lysine‐HCl), 1.1, 1.4 or 1.7%, with fingerling channel caffish. Semipurified diets containing 30% protein and 3.44 kcal digestible energy/g were fed for 8 wk in flow‐through water at 26.5 ± 0.5 C. Carnitine did not significantly (P > 0.71) affect channel catflsh weight gain over this time interval. Weight gain was less when 1.1% dietary lysine was fed without supplemented carnitine than when diets contained 1.4 or 1.7% lysine. Carnitine reduced muscle lipid (P < 0.0003) and liver lipid (P < 0.0001) significantly. Percentage visceral fat was reduced with added dietary carnitine (P < 0.0001) but not with dietary lysine although there was a combined effect of carnitine and lysine (P < 0.0008). Channel catfish wholebody lipid content was reduced by supplemented dietary carnitine, lysine, or both. Protein content of channel catfish wholebody increased with added carnitine, lysine, and their interaction (P < 0.19, P < 0.003 and P < 0.001). Under these conditions, dietary carnitine improves caffish tissue characteristics by reducing fat content and increasing protein content.