Document Type : Research Articles
Department of Animal Sciences, Faculty of Agriculture, University of Tabriz, Tabriz, Iran
Department of Poultry Sciences, college of Agricultural and environmental science, University of Georgia, Athens.
Introduction: Vitamin D3 is one of the important vitamins in calcium metabolism, which increases the active transport of calcium and phosphorus in the intestinal epithelium. However, the mechanism by which vitamin D3 increases the absorption of calcium and phosphorus is not fully understood. The active form of vitamin D3 or 1,25-hydroxycalciferol is transported to the nucleus of the intestinal cells. In the presence of 1, 25-hydroxycalciferol, a specific RNA is secreted from the cell nucleus, which is translated into a specific protein by the ribosomes, thereby increasing the uptake of calcium and phosphorus. The primary role of 1, 25-hydroxyvitamin D3 in vertebrates in regulating calcium homeostasis is the direct action of 1,25-hydroxyvitamin D3 on the gut, kidneys and bones by inhibiting the production of parathyroid hormone in the parathyroid glades. Vitamin C prevents stress by preventing the release of corticosteroid hormones, which can be effective for bird function, egg production and reducing mortality. In the liver, vitamin D3 is converted into 25-hydroxycalciferol, which is later converted into calciferol hydroxylase (activated by vitamin C) in the kidneys by the enzyme 25-hydroxy molecule. This metabolite increases the absorption of calcium and phosphorus from the intestinal wall and renal tubules. The aim of this experiment is therefore the effect of vitamin D3 and vitamin C on performance, egg quality and hatchability in broilers breeder hen at the end of the production period.
Materials and Methods: A total of 240 broiler breeder hens and 24 cockers (Ross 308) were distributed in a 2×2 factorial arrangement including two levels of vitamin D (3500 & 5500 IU) and two levels of vitamin C (0 & 150 mg/kg) with 6 replicate pens of 10 hens and one cock each. The experiment lasted for 12 weeks (from the age of 49 to 61 weeks), and during the trial, the performance traits production and hatchability were recorded. Every 28 days 4 eggs were evaluated for internal and external quality.
Results and Discussion: The results of the study showed that the main effect of vitamin D3 had a significant impact on egg weight, with higher concentrations resulting in a reduction in egg weight. However, there was no significant effect on other performance parameters. The main effect of higher concentrations of vitamin D3 was an increase in the number of hatching eggs, shell percentage, shell thickness, specific gravity of the eggs, a decrease in the percentage of egg breakage. However, this effect was not significant for other parameters. Increasing the level of 1,25 hydroxycalciferol significantly increased plasma calcium levels, which led to increased renal 1-alpha-hydroxylase activity, envelope secretion, reduced oocyte rupture, resulting in increased hatch fertility. The main effect of vitamin C significantly increased production percentage and reduced feed conversion and feed consumption per egg. However, there was no significant effect on other parameters. Addition of vitamin C significantly increased external characteristics of the eggs, including shell proportion, shell thickness, shell ash and phosphorus, number of hatching eggs, but reduced the number of broken eggs. However, there was no significant effect on internal parameters, except for yolk color. The use of vitamin C activates the enzyme 25-hydroxycholecalciferol hydroxylase to produce 1,25 hydroxycalciferol, which increases calcium absorption from the intestinal wall and reduces the number of ruptured eggs. Regarding the interaction of different levels of vitamin D3 and vitamin C, the results showed that higher levels of vitamin D3 and vitamin C increased production percentage, egg mass, number of hatching eggs, shell thickness, phosphorus and FCR. Intake in the egg removed significantly increased, but the number of broken eggs decreased.
Conclusion: In general, according to the results of the present experiment, it can be concluded that the use of vitamin C in an amount of 150 mg / kg with 5500 IU of vitamin D3 can increase the production percentage, increase the mass of eggs and improve the feed conversion ratio. It can also increase shell thickness and the number of chickens produced weekly and over the period, decrease the number of broken eggs, increase the number of hatching eggs, reduce feed intake per egg and feed intake per chicken at the end of the broiler breeder production period.