Determination of metabolizable energy of various diets using Leghorn, dwarf, and regular broiler breeder hens.

Single Comb White Leghorns (SCWL), regular broiler breeders (BB), and dwarf BB between 45 and 52 weeks of age were used to investigate the effect of strain on nitrogen-corrected metabolizable energy (MEn) of various diets. Data are reported on a 90% dry matter basis. In Trial 1, a 20.0% crude protein diet had MEn of 2,736 kcal/kg determined with regular BB, significantly less than 2,805 determined with SCWL (P less than or equal to .05). The MEn determined with dwarf BB was 2,778 kcal/kg. Similar strain differences occurred with 14.3% crude protein diet calculated to be isocaloric using NAS (NRC) 1977 feed composition tables. In Trial 2, MEn of a high energy diet was 2,906 kcal/kg determined with regular BB, less than dwarf BB or SCWL which were 2,947 and 2,976 respectively (P less than or equal to .01). In Trial 3, ad libitum vs. 75% feed restriction had no effect on MEn determined with regular BB (P greater than .05). These results indicate that regular BB hens derive less metabolizable energy from the diet than do SCWL birds.