Effects of L-carnitine in layer diets containing different fat sources and energy levels on hen performance and egg quality

The study was conducted to determine the effects of feeding diets containing two levels of metabolisable energy (normal or low) and three sources of fat (palm-, sunflower- or fish-oil) with or without L-carnitine (0 or 500 mg/kg diet) on the performance and egg quality parameters of Brown egg-type laying hens. The hens receiving the low energy diet had significantly higher body weights and feed intakes (FI) than the birds on the normal energy diet, but their feed conversion ratio (FCR) was poorer. L-carnitine in the diet containing sunflower oil (SO) increased FI significantly, resulting in a poorer FCR. However, the FI and FCR were higher when the fish oil (FO) was added to diets without L-carnitine compared to the other diets. The palm oil (PO) supplemented diet without L-carnitine significantly decreased the specific gravity of the eggs. L-carnitine inclusion into the diet containing PO significantly increased the Haugh unit and albumen index of the eggs, while the inclusion of FO in the low energy diet increased the Haugh unit and albumen index significantly. However, when PO was included these parameters decreased significantly. The addition of L-carnitine to the normal energy diet reduced the pH of the egg yolk, while it increased egg yolk pH when added to the low energy diet. The inclusion of FO in the low energy diet resulted in a significant increase in yolk pH. Albumen pH was significantly decreased by dietary L-carnitine supplementation, but increased when the diet low in energy contained FO, as well as the normal energy diet containing SO. The inclusion of FO to both the normal and low energy diets, except the low energy diet with L-carnitine, improved the breaking strength of the eggshells. Similarly, SO and PO inclusion to low energy diets with L-carnitine increased eggshell breaking strength. The supplementation of PO and L-carnitine to