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.