BROILER BREEDER AGE AND DIETARY-FAT INFLUENCE THE YOLK FATTY-ACID PROFILES OF FRESH EGGS AND NEWLY-HATCHED CHICKS

The purpose of the present study was to investigate the combined effec ts of breeder age (36-, 51-, or 64-wk) and different dietary fat sourc es (3% added corn oil, poultry fat, or lard) on Lipids in fresh egg yo lks and yolks of newly hatched chicks. Isocaloric breeder diets were a ltered by the inclusion of different types of dietary fat such that th e poultry fat and lard diets had the highest levels of saturated fatty acids when compared to the corn oil diet. Fresh egg yolks obtained fr om 36-wk-old breeders exhibited higher levels of palmitoleic acid when compared to the levels observed in fresh egg yolks of 51- or 64-wk-ol d breeders. Furthermore, these levels decreased significantly by 21 d of incubation only in eggs from 36-wk-old hens. At 36 wk of breeder ag e, the levels of oleic and arachidonic acid were higher in yolks from hatched chicks than in previous fresh egg values, regardless of type o f added dietary fat; whereas the level of linoleic acid was higher onl y in yolks from hatched chicks compared to those of fresh eggs from 36 -wk-old hens fed 3% added corn oil. These data suggest that breeder ag e influences the utilization of yolk lipid by developing embryos, and that the type of fat provided in the diet may have an additional influ ence.