Effects of feeding l-carnitine to gilts through day 70 of gestation on litter traits and the expression of insulin-like growth factor system components and l-carnitine concentration in foetal tissues

We investigated the influence of supplemental l -carnitine on foetal blood metabolites, litter characteristics, l -carnitine concentration in skeletal muscle and insulin-like growth factor (IGF) axis components in foetal hepatic and skeletal muscle tissues at day 40, 55 and 70 of gestating gilts. A total of 59 gilts (body weight = 137.7 kg) received a constant feed allowance of 1.75 kg/day and a top-dress containing either 0 or 50 ppm of l -carnitine starting on the first day of breeding through the allotted gestation length. Foetuses from the gilts fed diets with l -carnitine tended to be heavier (p = 0.06) and the circulating IGF-II tended to be lower (p = 0.09) at day 70, compared with the foetuses from the control gilts. Insulin-like growth factor-I messenger RNA (mRNA) was lower (p = 0.05) in hepatic tissue in the foetuses collected from gilts fed l -carnitine. Free and total carnitine concentration increased (p < 0.05) in the skeletal muscle from the foetuses collected from gilts fed supplemental l -carnitine. This study showed that l -carnitine had beneficial effects on the average foetal weight at day 70 of gestation, associated with changes in the foetal IGF system.