Effects of dietary phytosterol concentration on performance , egg quality and cholesterol content in laying hens Einfluss einer hohen

Introduction Phytosterols are widely known to have cholesterol-lowering properties due to their structural and functional similarity to cholesterol in vertebrate animals (MOREAU et al., 2002; OSTLUND, 2002). Phytosterols are minor unsaponifiable components of edible vegetable oil products, such as margarine, which are the most important dietary sources of phytosterols for humans (BAKER et al., 1999). The most common natural phytosterols are the 4-desmethylsterols, namely β-sitosterol, campesterol and stigmasterol, which occur as free isoforms but may also be esterified to free fatty acids, sugar moieties or phenolic acids. Phytosterol intake from normal food sources are approximately 200 mg per day in an average human diet (MORTON et al., 1995), with consumption being somewhat higher for vegetarians than non-vegetarians. Data collected over the past decade suggest that phytosterols significantly lower total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) in serum after being incorporated into various food products (LAW, 2000; KATAN et al., 2003). Following initial use as pharmaceutical treatments in the past, phytosterols are now supplemented into a variety of human food and have been shown to be effective and safe for humans (KRITCHEVSKY and CHEN, 2005; POLLAK, 1953). The physiological effects of phytosterols have been studied extensively in recent years, although public health recommendations regarding phytosterol intake remain controversial (ELKIN and LORENZ, 2009). Nonetheless, phytosterols became popular as animal dietary supplements to lower cholesterol levels in plasma or animal products (eggs or muscle) (OSTLUND, 2004). Because few conventional subchronic and chronic safety studies using phytosterols as supplements in poultry feed have been published, a 12-week feeding study in laying hens was conducted to examine whether high dietary phytosterol concentrations affect the performance of hens, including impacts on laying performance, egg quality, and cholesterol concentration in serum, liver and egg yolk as part of a comprehensive programme for safety evaluation. A series of concentrations, including a very high dose, of phytosterol provided a unique opportunity to evaluate dietary risks and safety.