EGG YOLK CHOLESTEROL AND PRODUCTIVE PERFORMANCE OF LAYING HENS INFLUENCED BY DIETARY CRUDE FIBER LEVELS UNDER DRINKING NATURAL SALINE WATER

Abstract

This study was conducted to investigate the influenced of four levels of dietary crude fibers (CF) on egg yolk cholesterol, productive and physiological performance of laying hens under drinking natural saline water (2000 ppm total dissolved solids). A total number of 120 White Leghorn layers from 44 to 56 weeks of age randomly divided into four equal groups (30 hens of each). Four levels of CF (3, 4, 5 and 6 %) as substitution of alfalfa meal. The treatments were tested for 12 weeks. The results showed that under condition of drinking natural saline water (2000 ppm total dissolved solids), feeding laying hens control diet which contained 3 % crude fiber had (P<0.05) highest egg number, egg mass and feed consumption (g/day) (17.97, 30.99 g and 67.80 g, respectively) compared with other three groups which recorded no significant differences among each other's.Hens fed the highest-fiber diet (6 %) laid eggs with greatest shell, albumin and yolk weights % (4.53, 58.00 and 36.19, respectively) compared with other experimental groups. Feeding hens diet contained higher crude fiber level above 3 % had higher (P<0.05) values of albumen height (mm) and shape index values with no significant differences in yolk index (%) and Haugh units. There were a gradual (P<0.05) decrease in digestion coefficients of DM, OM, CP, ash, CF, NFE and EE with increasing crude fiber levels in hens diets; while, there were no significant differences in digestibility of fiber fractions (NDF, ADF and hemicelluloses). Water intake (ml/ bird/day) and water/feed intake increased (P<0.05) with increasing crude fiber levels. So, hens fed 6 % CF consume more water being 236.00 ml/bird/day and 3.45 ml/g feed intake. Inclusion of graded levels of CF in laying hen diets tended to decrease (P<0.05) concentrations of total lipids, triglycerides, phospholipids, cholesterol, total cholesterol, and low-density lipoproteins (LDL) in egg yolk. Hens fed diet contained 6 % CF decreased the egg yolk concentrations of the same respective parameters by 25.10, 22.22, 26.61, 22.38, 19.51 and 23.33 %, respectively compared to the control group. There were a significant decrease in serum total lipids (g/dl), cholesterols (mg/dl), triglyceride (mg/dl) and HDL values with increasing CF levels; however, AST and ALT activity was within a normal physiological range. Gizzard (%), edible giblets (%), digestive tract weight and digestive tract length had significantly increased with increasing dietary CF level; while, there were non-significant increases in carcass, liver and heart (%). The best value for economic efficiency and relative economic efficiency (117 %) had been recorded by hens fed diet contained 6 % CF as compared with the control (3 % CF). It was concluded that, we can used crude fiber by up to 6 % in laying hens diets (44 to 56 weeks of age) reared under drinking natural saline to achieve acceptable productive and physiological performance and reduce the egg yolk cholesterol.