Effects on composition, oxidative stability and fatty acid profile of meat of chickens fed diets containing animal fat or flax seed oil and supplemented with pumpkin seeds

Introduction: The relationship between baby's diet and disease prevention has promoted interest in improving the nutritional quality of animal food products through nutritional strategies. Particular attention has been paid to the fat composition, especially in the content of polyunsaturated fatty acids (PUFAs) that elicit several nutritional benefits on consumer health. However, the increase in the degree of FAs unsaturation of these products without adequate antioxidant protection, reduces the oxidative stability resulting in a decrease of shelf life and quality (González-Esquerra and Leeson 2001). In monogastric animals, the amount of PUFAs in tissues can be increased by increasing dietary levels of PUFAs (Woods and Fearon 2009). Chicken is the meat most appreciated among children and it is considered a healthy product by consumers because of its nutritional characteristics. Pumpkin (Cucurbita pepo) seeds (PS) are a good source of natural antioxidants and are generally considered to be agro-industrial wastes. With the purpose of increasing the nutritional quality of the chicken meat, the objective of this study was to investigate the effects of two dietary fats (lard and flax seed oil) and PS supplementation on FAs profile and oxidative stability of meat, assuming that flax seed oil in the diet could result in an increase of oxidation in fresh meat, while PS could protect broiler meat from this effect. Materials & Methods: Ninety-six 64 d-old broilers were randomly distributed into four groups of 24 broilers each (eight per cage, three cages per treatment) and fed a lard diet (LF), a LF diet supplemented with 50 g PS/kg, a flax seed oil diet (FSO) and a FSO diet supplemented with 50 g PS/kg for 49 d. Broilers were then slaughtered according to current standards (EC Regulation 2009) in a poultry slaughterhouse and the breast muscle was removed from carcasses and divided into two parts: one part was used to measure pH and colour, and to assess thiobarbituric acid reactive substances (TBARS) at three storage times (1, 3 and 9 days after slaughter) under refrigeration, the other part was frozen at - 20C° and freeze-dried to determine FAs profile. Results and Discussion: The pH value of the meat measured at 24 h after slaughter was significantly higher (P<0.05) in the broilers fed the LF diet than in those fed the FSO diet. Both dietary fat and PS inclusion influenced TBARS content of meat at day 3 of storage without interaction: in the LF groups, the TBARS concentrations were significantly lower (P<0.05) than those of the FSO groups, and groups supplemented with PS showed a significant decrease (P<0.05) of TBARS values compared with groups without PS. The use of flax seed oil instead of lard as a lipid source in broiler feed favourably modulates the FAs profile of meat, by increasing both linoleic and ?-linolenic acid content and reducing the n-6/n-3 PUFAs ratio, atherogenic and thrombogenic indexes. In conclusion, flax seed oil and pumpkin seed supplementation could contribute to improve chicken meat quality and shelf life by the modulation of the oxidative stability and FAs composition.