Effect of L-carnitine and soybean oil on growth performance and body composition of early-weaned pigs.

Two experiments were conducted to evaluate the effect of dietary L-carnitine on growth performance and body composition of early-weaned pigs. In Exp. 1, 120 weanling pigs (initially 5.6 kg and 19 +/- 2 d of age) were allotted in a 3 x 2 factorial with four pigs per pen and five replications (pens) per treatment. Main effects from d 0 to 14 after weaning included dietary L-carnitine (0, 500, or 1,000 ppm) and soybean oil (0 to 10%). From d 14 to 35 after weaning, levels were reduced to 0, 250, or 500 ppm L-carnitine and 0 or 5% soybean oil. No L-carnitine x soybean oil interactions were observed (P > .10). From d 0 to 14, L-carnitine and soybean oil had no effect (P > .10) on pig performance. From d 14 to 35 and d 0 to 35, gain:feed ratio (G/F) improved (linear, P < .05) with increasing dietary L-carnitine; however, ADG and ADFI were not affected. Soybean oil improved ADG and G/F (P < .05) from d 14 to 35 and ADG from d 0 to 35. In Exp. 2, 180 weanling pigs (initially 6.0 kg and 22 +/- 2 d of age) were allotted in a 2 x 3 factorial. Pigs were fed either 0 or 1,000 ppm L-carnitine from d 0 to 14 after weaning and then pigs fed each of these diets were fed diets containing 0, 250, or 500 ppm L-carnitine from d 14 to 35. No interactions occurred between feeding L-carnitine from d 0 to 14 and performance observed from d 14 to 35. From d 0 to 14 after weaning, L-carnitine increased ADG (P < .08) and ADFI (P < .02). From d 14 to 35, ADFI decreased (linear, P < .05) and G/F increased (quadratic, P < .05) as dietary L-carnitine increased. Cumulative (d 0 to 35) ADFI decreased (linear, P < .05) and G/F increased (linear, P < .05) with increasing L-carnitine. On d 35, 14 pigs from each of four selected treatments (0 or 1,000 ppm L-carnitine from d 0 to 14 followed by either 0 or 500 ppm from d 14 to 35) were slaughtered, and carcass composition was recorded. Carcass moisture and CP percentages were not influenced (P > .10) by dietary L-carnitine. However, pigs fed 1,000 ppm L-carnitine from d 0 to 14 had less (P < .05) carcass lipid and daily lipid accretion on d 35 whether they were fed L-carnitine from d 14 to 35 or not. These results suggest that dietary L-carnitine improves G/F and reduces carcass lipid accretion in early-weaned pigs.