Nayak, Dr.Sunil
The chicken egg is a cheap source of high quality protein, is readily available and popular among consumers. Iodine supplementation in layer diets could increase the levels of iodine in hen eggs and can lead to prevention of iodine deficiency in humans. Therefore, the objectives of this study were to investigate the effect of supplementation of layer diet with different levels of iodine on performance, iodine content of eggs, egg quality traits and cost of production. A total of 135 layers of 55 weeks of age were randomly distributed to 5 dietary treatments with 3 replicates and 9 layers in each. T1 was basal layer diet without iodine enrichment (Control), in which iodine content (I2) was as per NRC recommendation (0.45 mg/kg). Layer diets T2, T3, T4 and T5 were same as T1 except that in these diets iodine was supplemented as calcium iodate Ca (IO3)2 @ 5, 10, 15 and 20 mg/kg, respectively. Therefore, dietary iodine (I2) content in diets T2, T3, T4 and T5 were 3.25, 6.50, 9.75and 13.00 mg/kg, respectively. All the diets were formulated as per NRC recommendation (1994)). The experimental diets were formulated as per NRC (1994) specification. The laying hens were fed the respective experimental diets ad libitum during experimental period of ten weeks. The cumulative performance of laying birds fed on different levels iodine from 55 to 65 weeks period in terms of feed intake, cumulative feed intake, hen day production, average egg weight, feed conversion ratio per dozen eggs and per kg eggs and cost of production was determined and study indicated that inclusion of higher levels of iodine (9.75 and 13.0 ppm) reduced their performance (weight gain, feed intake, percent hen day production and egg weight) significantly (P<0.05). However, it was significant (P<0.05) only when inclusion level of I2 was above 6.50 ppm. Hens receiving 3.25ppm to 6.50ppm I2 (T2 and T3) produced better egg quality traits (shape index, albumen index, yolk index and HU), while hens receiving higher levels of iodine (9.75 and 13.0 ppm) showed better egg shell thickness. Significantly (P<0.05) higher dry matter utilization as well as retention of nutrients (CP, EE, CF and NFE) where seen in hens receiving 3.25 and 6.50 ppm of iodine. But increase in the level of I2 above 6.50ppm adversely affected on these parameters and decreased dry matter intake and nutrient utilization significantly. Increasing iodine levels in diet of hens from 0.45 to 13.0 mg/ kg significantly (P<0.05) increased egg iodine concentration, therefore highest concentration of egg iodine was observed for the group fed diet supplemented with 13.0ppm followed by those fed 9.25, 6.50 3.25 and 0.45 mg iodine /kg diet. The levels 3.25 and 6.50 mg iodine / kg diet increased egg iodine concentration without any adverse effect on egg production. Boiling reduces 10-15% iodine content of egg. Therefore, the consumers are ensured to receive the optimal levels of iodine from boiled iodine-enriched eggs. Among different diets, minimum and significantly lower cost Kg feed per dozen or Kg eggs was noticed in hens allotted T3 diet (6.50 mg I2 / kg). However, hens receiving 3.25 and 9.25 mg I2 / kg diet produced statistically (P<0.05) similar cost Kg feed per dozen or Kg eggs as control groups (T1). Further, cost Kg feed per dozen or Kg eggs was significantly increased due to inclusion of higher level of iodine (13.0ppm). Taking all the production factors of the laying hens from this study it was concluded that an iodine content of 3.25 mg/kg to 6.50 mg/kg in the diet of laying hens are better for production of iodine enriched eggs without any adverse effect on egg production and egg quality.
Nanaji Deshmukh Veterinary Science University, Jabalpur (M.P.)
Animal Nutrition
scientific research
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