Effect of the inclusion time of dietary saturated and unsaturated fats before slaughter on the accumulation and composition of abdominal fat in female broiler chickens.

The aim of this experiment was to assess the effects of four different feeding programs designed to include tallow, a saturated fat at 0, 8, 12, and 28 d prior to slaughter on female broiler performance and the deposition, fatty acid profile, and melting point of abdominal fat. The following treatment groups were established according to dietary inclusion--from 21 to 49 d of age--of: sunflower oil (SUN), sunflower oil followed by tallow during the last 8 d (SUN + 8TALL), sunflower oil followed by tallow during the last 12 d (SUN + 12TALL), and tallow (TALL). The diets were designed to be isoenergetic and isonitrogenous. Abdominal fat deposition increased linearly with increasing number of days in which birds were fed the tallow-enriched diet. However, linear and quadratic response patterns were found between days before slaughter in which the birds were fed the tallow-enriched diet and abdominal fat melting points. This result suggested an exponential response in which 85% of the maximum level was already attained when the dietary fat type changed from an unsaturated to a saturated condition during the last 8 d of the feeding period. The use of an unsaturated fat source during the first stages of growth, and the substitution of a saturated fat for a few days before slaughter, may offer the advantage of lower abdominal fat deposition and an acceptable fat fluidity compared with the use of a saturated fat source during the whole growing and finishing period.