Poultry need high quality feed because it passes quickly through their digestive system (Rendered). When the feed is balanced for energy and essential nutrients, the amount consumed will determine growth rate. Much of the energy is obtained from the grain and the balance from animal fat. The only required essential fatty acid is linoleic. Animal fats need to be stabilized by adding antioxidants. Animal fats provide essential fatty acids, reduce abrasiveness of feeds, increase nutrient density and therefore energy intake, and increases the energy value of feed above caloric value. An experiment would be to see if broiler chicks preferentially selected feed with added animal fats over normal feed.
Rosebrough, McMutry and Vasilatos-Younken (1999) looked at the relationships between fat and protein in the diet of broilers and found that increasing dietary protein compared to increasing dietary fat increased their body weight. A diet containing 600 kcal of fat decreased lipogenesis and malic enzyme activity in birds fed 190 g CP/kg protein but not birds fed 124g CP/kg - this required 1200 kcal of fat to suppress lipogenesis or malic enzyme activity. An experiment could be carried out offering the chicks diets high in protein and diets high in fat and seeing if there was a difference in which one they preferred. The levels of fat and protein could be varied and the relationship determined, i.e. how much fat is required to make the diet the preferred diet of the chicks.
Celik and Ozturkcan (2003) found that supplementation of the diet of broiler chicks with L-carnitine, ascorbic acid or L-carnitine plus ascorbic acid was beneficial compared to animals receiving unsupplemented diets under high temperatures. However, supplemental L-carnitine or L-carnitine plus ascorbic acid reduced body weight under normothermal conditions. Feed conversion efficiency was significantly improved with supplemental ascorbic acid, and this effec...