Document Type : Research Articles
Authors
1
PhD Student, Department of Livestock and Poultry Sciences, Faculty of Agricultural Technology (Aburaihan), University of Tehran, Pakdasht, Tehran, Iran
2
Department of Animal Science, Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran.
Abstract
Introduction: The Japanese quail is a species known for its short production period and high productivity. Due to their small size and low feed requirements, they are considered a cost-effective option for egg production compared to other poultry species. Additionally, quail eggs are recognized for their superior nutritional value compared to regular chicken eggs. However, there is a need for effective methods to enhance productivity, especially in stressful situations. Previous research has indicated that the use of certain dietary supplements can address this issue and improve the productive traits of birds. Therefore, there is considerable scientific interest in studying the effects of natural compounds such as black seed and L-carnitine on the productive performance of laying Japanese quails, both under normal conditions and during heat stress. Investigating these factors can provide valuable insights into the development of strategies to effectively manage and optimize egg production in laying Japanese quails. This, in turn, would contribute to the sustainability and profitability of the poultry industry. In this study, we aimed to examine the effects of black seed, L-carnitine, and vitamin E on the productive performance, carcass characteristics, blood biochemical parameters, and immune responses of Japanese laying quails.
Materials and Methods: A total of 500 Japanese laying quails were included in this study. They were divided into two temperature conditions: normal temperature and high temperature (36 degrees Celsius for 6 hours per day). Additionally, there were five experimental treatments: control diet (without any additives), black seed (1.5% black seed diet), L-carnitine (250 ppm + control diet), 1.5% black seed + 250 ppm L-carnitine diet, and Vitamin E diet (200 ppm + control diet). This resulted in a 5x2 factorial experiment with a total of 10 treatments, 5 replications, and 10 quails per replication. The study consisted of three phases: an adaptation period to the experimental diets lasting two weeks, exposure to the designated temperature conditions for five weeks, and a three-week recovery period. During these phases, various parameters were measured and recorded, including productive performance, carcass characteristics, and blood biochemical and immune indicators (such as triglyceride, cholesterol, LDL, HDL concentrations, heterophil, and lymphocyte percentages) under both heat stress and recovery periods in Japanese laying quails. Data analysis was performed using the Generalized Linear Model (GLM) method with the assistance of SAS software. Mean comparisons were conducted using Tukey's multiple range tests.
Results and Discussion: The results of this study revealed several important findings. During the initial two weeks of the experiment, the consumption of feed containing black seed + L-carnitine led to the highest feed intake, while diets containing black seed, black seed + L-carnitine, and vitamin E demonstrated the highest egg mass compared to the control group (P<0.05). During the heat stress period, high temperatures caused a decrease in feed intake, egg weight, egg production, and egg mass. However, the consumption of feed containing black seed + L-carnitine resulted in increased feed intake, and diets containing black seed, black seed + L-carnitine, and vitamin E showed increased egg production and mass compared to the control group. Furthermore, vitamin E exhibited a better conversion coefficient (P<0.05). During the recovery period, high temperatures led to a decrease in feed intake but an increase in bird body weight. The control group exhibited the lowest feed intake and body weight, whereas diets containing black seed, black seed + L-carnitine, and vitamin E demonstrated the highest egg production and egg mass compared to the control group. Birds fed diets with black seed and vitamin E exhibited a better conversion coefficient (P<0.05). Regarding carcass yield and relative liver weight, the effect of environmental temperature and experimental treatments during both heat stress and recovery periods was not significant. However, the consumption of black seed, L-carnitine, and vitamin E was found to increase carcass yield and relative heart weight. Additionally, high temperatures increased the relative liver weight (P<0.05). Moreover, birds fed control and black seed diets at normal and high temperatures exhibited higher blood cholesterol levels compared to other experimental treatments. In normal temperature conditions and diets containing vitamin E and L-carnitine, a higher percentage of lymphocytes was observed in the blood. In high temperature conditions and diets containing L-carnitine and vitamin E, the heterophil to lymphocyte ratio was also higher (P<0.05).
Conclusion: Finally, the findings of this study highlight the beneficial effects of incorporating black seed, L-carnitine, and vitamin E into the diet of Japanese laying quails, both under normal and high-temperature conditions. These dietary interventions have shown positive impacts on the performance of the quails. Consequently, these results can serve as valuable guidance for quail breeders and producers in selecting suitable feed regimens to manage heat stress in Japanese quail layers, thereby enhancing performance efficiency, carcass characteristics, and blood lipid and immune parameters.
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