| Abstrakt: |
One hundred and eighty Isa Brown layers, 40 weeks old, were used to study the role of dietary yeast supplementation on productive performance and cholesterol levels in laying hens. All hens were equally classified into four groups. The 1 st group, hens were fed the basal diet without any supplementation (control), while those in the 2nd, 3rd and 4th groups were fed the basal diet supplemented with yeast at levels of 0.2, 0.4, and 0.6%, respectively. Feed consumption, feed conversion, egg production and eggshell traits, serum total lipids, cholesterol, triglycerides concentrations as well as yolk and liver contents of cholesterol were measured. The obtained findings indicated that feed consumption for hens of yeast- supplemented groups was significantly lowered compared with control. The lowest amount of feed consumption was recorded for 0.6% yeast-treatment group. On the other hand, each of egg production, egg weight and feed conversion were not significantly influenced. The means of eggshell (weight, thickness, and breaking strength) for hens supplemented with 0.6% yeast were significantly improved compared with the other yeast-treated and control groups. Dietary yeast supplementation significantly reduced egg yolk and liver tissues cholesterol content comparing with control group. However, the lowest (P≤0.05) values were recorded for hens supplemented with yeast at 0.6%. Similarly, serum total lipids, and cholesterol as well as triglycerides levels were significantly lowered in yeasttreated groups than the control group From the previous results, it could be recommended to use 0.6 % yeast in laying hen diets especially at late age to improve eggshell quality and produce low-cholesterol eggs. [ABSTRACT FROM AUTHOR] |
