Ali Asghar Saki *1, Hossein Karimi Lasaki, Khalil Zaboli, Maziar Mohiti Asli, Zeinab Bardel, Erfan Darmanloo
Abstract: (191 Views)
Introduction and Objective: In recent years, population growth and the increasing demand for food resources have made the production of animal protein and the development of the poultry industry an inevitable necessity. Although the non-therapeutic use of growth-promoting antibiotics improves production performance, serious concerns have been raised about the development of bacterial resistance and the transfer of drug residues to humans and the environment. The gradual elimination of these antibiotics from animal diets has led to a decrease in performance; however, researchers are seeking natural alternatives such as plant essential oils, organic acids, probiotics, and enzymes. Medicinal plants, due to their antimicrobial compounds, can improve digestion and absorption, feed intake, and poultry health, while reducing human concerns. Various studies have also shown that plant additives in poultry diets have positive effects on growth and the intestinal microbial population. Accordingly, the aim of the present study was to investigate the effects of different dietary protein levels, along with the use of a plant additive (O. x. plant), on growth performance and intestinal microbial flora in Japanese quail chicks.
Material and Methods: In this study, 640 Japanese quails were used in a completely randomized design and factorial experiment. The experiment consisted of 8 treatments with 4 replications and 20 birds per replication. The experimental treatments included: 1-21% protein without additives 2-21% protein + 100 mg/kg of additives 3-22% protein level without additives 4-22% protein + 100 mg/kg of additives 5-23% protein without additives 6-23% protein + 100 mg/kg of additives 7-24% protein level without additives 8-24% protein + 100 mg/kg of additives. The diets were formulated according to the NRC (1994) recommendations. The herbal additive used was a combination of microencapsulated essential oils of savory, oregano, thyme, red pepper, and garlic, added at a rate of 100 grams per ton of feed, following the instructions of the Daneshbonyan Tehnologiya Novin Company. The quails were purchased at one day of age and fed a standard diet until day 12. The experiment began on day 12, when the chicks were ready to receive nutritional treatments after passing the initial sensitive stage in terms of growth and digestive system stability. To examine carcass traits and intestinal microbial flora, two birds from each replicate were selected and slaughtered at the end of the experiment. Carcass measurements included the weight of the carcass without viscera, relative weights of the breast, liver, gizzard, pancreas, and thigh. Body weight was recorded at the beginning and end of each week, and feed intake was also measured weekly. After slaughter and opening the abdominal cavity, approximately two centimeters of the contents from the middle part of the ileum were collected and transferred to microtubes for microbial analysis. EMB agar was used for Escherichia coli enumeration, and MRS agar was used for Lactobacillus enumeration.
This experiment was conducted using a completely randomized design with a 4×2 factorial arrangement, including two levels of additives (with and without herbal additives) and four levels of protein (21, 22, 23, and 24%). Means were compared using the Tukey-Kramer test at a 0.05 significance level, and data were analyzed with SAS version 9.4.
Results: Different levels of protein and herbal additives, either independently or in combination, did not show a significant effect on feed intake during the entire period or in different weeks (P>0.05). The feed conversion ratio also did not differ significantly throughout the period; however, weekly analysis indicated that in the first week, the treatment containing 21% protein without additives had the highest feed conversion ratio, while the treatment with 22% protein without additives had the lowest conversion ratio (P<0.05). The interaction effects of protein and herbal additives created a significant difference between treatments, such that the treatment with 23% protein without additives had the lowest feed conversion ratio (P<0.05). In the third and fourth weeks of the experiment, different levels of protein and herbal additives did not show a significant effect on the feed conversion ratio (P>0.05). In the first week, the treatment with a protein level of 22% showed the highest daily weight gain (P<0.05). In the second week, there was no statistically significant difference among the different levels of protein and additives in terms of daily weight gain (P>0.05). However, the treatment containing 21% protein without additives had the lowest weight gain compared to other treatments (P<0.05). In the third and fourth weeks, the experimental treatments did not show a significant effect on daily weight gain (P>0.05). In the study of the interaction effects of different levels of protein and herbal additives, the treatment containing 22% protein without herbal additives showed the highest body weight, while the treatment containing 21% protein without herbal additives showed the lowest body weight (P<0.05). In the fourth week, as well as during the entire experimental period, there was no statistically significant difference in body weight at the end of each week or in average daily weight gain among the different treatments (P>0.05). The use of different levels of protein and herbal additives, and their interaction effects, did not have a significant impact on the carcass characteristics of quails (P>0.05). However, the use of herbal supplements significantly increased gizzard weight (P<0.05). Different protein levels had no significant effect on the numbers of Lactobacillus and Escherichia coli (P>0.05). The use of herbal supplements significantly increased the number of Lactobacillus and significantly decreased the number of Escherichia coli (P<0.05).
Conclusion: In general, the results of this study showed that regulating dietary protein levels plays an important role in improving the growth and weight gain of quails. In contrast, herbal supplements had a greater impact on the quality of the intestinal microbial flora and did not cause significant changes in internal organs. Therefore, the simultaneous use of appropriate protein levels along with plant additives can be an effective approach to improving bird performance—an approach that contributes to more sustainable and healthier production by enhancing growth efficiency and supporting digestive health.
Material and Methods: In this study, 640 Japanese quails were used in a completely randomized design and factorial experiment. The experiment consisted of 8 treatments with 4 replications and 20 birds per replication. The experimental treatments included: 1-21% protein without additives 2-21% protein + 100 mg/kg of additives 3-22% protein level without additives 4-22% protein + 100 mg/kg of additives 5-23% protein without additives 6-23% protein + 100 mg/kg of additives 7-24% protein level without additives 8-24% protein + 100 mg/kg of additives. The diets were formulated according to the NRC (1994) recommendations. The herbal additive used was a combination of microencapsulated essential oils of savory, oregano, thyme, red pepper, and garlic, added at a rate of 100 grams per ton of feed, following the instructions of the Daneshbonyan Tehnologiya Novin Company. The quails were purchased at one day of age and fed a standard diet until day 12. The experiment began on day 12, when the chicks were ready to receive nutritional treatments after passing the initial sensitive stage in terms of growth and digestive system stability. To examine carcass traits and intestinal microbial flora, two birds from each replicate were selected and slaughtered at the end of the experiment. Carcass measurements included the weight of the carcass without viscera, relative weights of the breast, liver, gizzard, pancreas, and thigh. Body weight was recorded at the beginning and end of each week, and feed intake was also measured weekly. After slaughter and opening the abdominal cavity, approximately two centimeters of the contents from the middle part of the ileum were collected and transferred to microtubes for microbial analysis. EMB agar was used for Escherichia coli enumeration, and MRS agar was used for Lactobacillus enumeration.
This experiment was conducted using a completely randomized design with a 4×2 factorial arrangement, including two levels of additives (with and without herbal additives) and four levels of protein (21, 22, 23, and 24%). Means were compared using the Tukey-Kramer test at a 0.05 significance level, and data were analyzed with SAS version 9.4.
Results: Different levels of protein and herbal additives, either independently or in combination, did not show a significant effect on feed intake during the entire period or in different weeks (P>0.05). The feed conversion ratio also did not differ significantly throughout the period; however, weekly analysis indicated that in the first week, the treatment containing 21% protein without additives had the highest feed conversion ratio, while the treatment with 22% protein without additives had the lowest conversion ratio (P<0.05). The interaction effects of protein and herbal additives created a significant difference between treatments, such that the treatment with 23% protein without additives had the lowest feed conversion ratio (P<0.05). In the third and fourth weeks of the experiment, different levels of protein and herbal additives did not show a significant effect on the feed conversion ratio (P>0.05). In the first week, the treatment with a protein level of 22% showed the highest daily weight gain (P<0.05). In the second week, there was no statistically significant difference among the different levels of protein and additives in terms of daily weight gain (P>0.05). However, the treatment containing 21% protein without additives had the lowest weight gain compared to other treatments (P<0.05). In the third and fourth weeks, the experimental treatments did not show a significant effect on daily weight gain (P>0.05). In the study of the interaction effects of different levels of protein and herbal additives, the treatment containing 22% protein without herbal additives showed the highest body weight, while the treatment containing 21% protein without herbal additives showed the lowest body weight (P<0.05). In the fourth week, as well as during the entire experimental period, there was no statistically significant difference in body weight at the end of each week or in average daily weight gain among the different treatments (P>0.05). The use of different levels of protein and herbal additives, and their interaction effects, did not have a significant impact on the carcass characteristics of quails (P>0.05). However, the use of herbal supplements significantly increased gizzard weight (P<0.05). Different protein levels had no significant effect on the numbers of Lactobacillus and Escherichia coli (P>0.05). The use of herbal supplements significantly increased the number of Lactobacillus and significantly decreased the number of Escherichia coli (P<0.05).
Conclusion: In general, the results of this study showed that regulating dietary protein levels plays an important role in improving the growth and weight gain of quails. In contrast, herbal supplements had a greater impact on the quality of the intestinal microbial flora and did not cause significant changes in internal organs. Therefore, the simultaneous use of appropriate protein levels along with plant additives can be an effective approach to improving bird performance—an approach that contributes to more sustainable and healthier production by enhancing growth efficiency and supporting digestive health.
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