the available energy values of fats for broiler chickens at 42 days of age

an experiment was conducted to determine the effect of different inclusion rates and degree of saturation of fat sources on true metabolizable energy corrected to zero nitrogen retention ( tmen) values in broiler chickens at 42 days of age. animal fat and cotton seed oil were blended in the proportions of: 0.25:0.75 , 0.50:0.50 , 0.75:0.25. the three blends together with the animal fat and cotton seed oil were each added at 0, 3, 6 and 9 percent to a basal diet. fats were analyzed for most chemical parameters (fatty acid profile, gross energy, dry matter, peroxid value, acid value, sophonification index, iodin index, unsophonification index). the experimental diets were evaluated for tmen according to sibbald method. 136 male broiler chicks were selected at 42 days of age and randomely distributed in 68 cages. each treatment had 4 replicates of 2 birds each. there wasn't any significant deviation from linearity in the response of dietary tmen to added fat. synergism , as demonstrated by a higher determined than calculated tmen values, was detected with fat blends. for all fats, the best regression equation can be achieved from the 3 following parameters: true dry matter digestibility, oleic acid level and gross energy.