نوع مقاله : مقاله پژوهشی
نویسندگان
گروه علوم دامی، دانشکده کشاورزی، دانشگاه شهرکرد، شهرکرد، ایران
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
The effect of different sources and levels of zinc on the performance and retention of zinc, copper and manganese in laying hens
Introduction:
Mineral supplements are an important component of the diet of laying hens to improve biochemical processes, embryonic development, and bone structure (Leeson, 2005). Micronutrients are involved in the structure of hundreds of proteins and hormones as intermediates in metabolism (Tom Dieck et al., 2003). Nowadays, micronutrients are added to the diet in inorganic form at levels much higher than those recommended by the National Research Council (NRC) (Leeson, 2005; Bao et al., 2007).Research shows that the addition of micronutrients of organic origin increases the bioavailability of the elements and improves performance due to their insoluble nature and organic complexation (Mézes et al., 2012). Consequently, formulating laying hen diets with trace elements from organic sources due to their higher bioavailability is considered a strategy to reduce the excretion of minerals in the animal’s feces. However, these sources are significantly more expensive, making them difficult to access for general use and increasing the cost of the feed. Hydroxychloride structure Trace mineral elements have several advantages due to their special crystalline structure (Hawthorne & Sokolova, 2002).
Materials and Methods: This experiment was conducted with 240 laying hens of the Hy-Line strain (W-36) from 40 to 50 weeks of age for 10 weeks in a completely randomized design with 8 treatments in 5 replications and 6 birds per experimental unit. The experimental treatments included: Treatment 1- negative control (without zinc supplementation), treatments 2, 3 and 4, respectively, included the negative control diet with 80, 120 and 160 mg/kg zinc sulfate with a purity of 34%, and treatments 5, 6 and 7, respectively, included the negative control diet with 50, 75 and 100 mg/kg zinc hydroxychloride with the chemical formula Cl2.H20 (Zn5 (OH8) with a purity of 55%, and treatment 8 included the negative control diet with 124 mg/kg zinc-methionine complex with a purity of 22%. The chickens were transferred to 40 metal cages (6 birds per cage) in a completely random manner within the weight range of 1590 ± 25 g. The composition of the basal diet was adjusted based on the guidelines for the (W-36) strain and the age of 40 to 50 weeks according to Table 1. The temperature range of the house was 24 ± 2 °C and the lighting schedule was set to 16 hours of light and 8 hours of darkness throughout the day according to the recommendations of the breeding guidelines.
During the experiment, egg mass produced, laying rate, percentage of defective eggs, and survival rate were measured calculated, and reported for the duration of the experiment.
Serum levels of zinc, copper and manganese concentration of soluble zinc, copper and manganese were measured using an atomic absorption spectrophotometer (Dozier et al., 2003).
Bioavailability (retention of zinc, copper and manganese) To measure the levels of zinc, copper and manganese in the breast muscle, liver and tibia, one chicken was randomly selected from each replicate and slaughtered at the end of the experiment.
The results were analyzed in a completely randomized design. For this purpose, the GLM procedure of SAS software version 9.4 (2015) was used, and Duncan's test at a significance level of 0.05 was used to compare the means.
Results and Discussion: The results of Table 2 show zinc storage in the pectoral muscle showed that with increasing levels of zinc supplementation in the diet, its storage increases linearly. These changes are affected by the bioavailability of its sources and levels. As is also known in the tibia, the storage of zinc is strongly affected by the levels and type of its source. Therefore, the zinc storage index in the tibia is a better criterion for measuring its bioavailability in the body. It was found that with increasing zinc in the diet, the storage level of copper in the pectoral muscle decreased and showed a negative correlation, so that with increasing levels of 160 mg/kg of the sulfate form and 100 mg/kg of the hydroxy form, we see a significant decrease in copper storage in the tissue. The results of this study are in agreement with the findings that state that the level of zinc in the pectoral and tibia muscles depends on the type of source and its levels in the diet, so that with increasing it in the diet, its storage in the tissue increases. This increase in the organic form is due to the specific absorption mechanism of the element chelated with the organic peptide (Afshar Bakeshlo et al., 2024; Hu et al., 2022).
The results of Table 3 show that the survival rate in the flock was not affected by the source and level of zinc in the diet (P<0.05). As is clear from Table 3, egg mass was not affected by the treatments and it seems that the bird tried to compensate for the zinc deficiency by reducing the egg-laying rate in the negative control treatment. Also, the increase in egg mass, due to the biological limitations of the bird, is more affected by the amount of energy and protein in the diet than by the zinc element. In confirmation of these findings, it has been reported that different sources and levels of zinc, copper and manganese do not affect the production rate and egg weight in laying hens (Chen et al., 2022; Domel et al., 2024).
Conclusion: The use of sources with higher bioavailability and longer retention in the bird's body is proposed as a new strategy for enriching animal products. Increasing the amount of zinc with conventional inorganic forms, such as zinc sulfate, can reduce copper absorption and lead to negative biological consequences. On the other hand, the use of an organic source, despite retention, is associated with increased production costs and difficulty in supply. Therefore, it is recommended to use a level of 75 mg/kg of zinc hydroxychloride to improve the zinc storage index in eggs, while also enhancing the biological response of the hens.
کلیدواژهها [English]
)
ارسال نظر در مورد این مقاله