1- Tehran University
Abstract: (9 Views)
Introduction: Sheep farming has long played an indispensable role in providing valuable resources such as meat, wool, milk, and hides, and remains a cornerstone of the livestock industry. This animal, with its adaptability to various climatic conditions, has become an integral part of rural and nomadic life. Among the genetic factors that affect the growth and production traits of sheep, the leptin gene has garnered special attention. Leptin, a key regulator in this context, plays a crucial role in regulating metabolism and physiological systems. Leptin, a product of the obese (ob) gene with a molecular weight of 16 kilodaltons, is secreted by adipose tissue. This hormone, by acting on appetite centers in the hypothalamus, not only regulates food intake but also contributes to maintaining energy balance, fertility, and immune function. The structure of the leptin gene includes three exons and two introns, of which two exons are translated into protein. Genetic variations or polymorphisms within this gene can lead to significant differences in growth and production traits.
Materials and Methods: In this study, aimed at examining the role of the leptin gene in sheep growth, 169 nine-month-old Lori-Bakhtiari sheep (63 males and 106 females) and 130 Zel sheep (30 males and 100 females) were investigated. Blood sampling was performed, and biometric traits were precisely measured. Growth-related data, including birth weight, weaning weight, and six- and nine-month weights, were collected from breeding stations and recorded for detailed analysis. DNA extraction was conducted using 250 microliters of blood and an optimized saline method. The quality and quantity of extracted DNA were assessed through spectrophotometry and 1% agarose gel electrophoresis to ensure accuracy and reliability. Following polymerase chain reaction (PCR), genetic patterns were determined, and precise sequencing was performed. To evaluate the effect of genotypes on measured traits, two animal models were employed. In Lori-Bakhtiari sheep, the age factor was excluded from the model due to the uniform age of the animals. Fixed factors examined included birth type (singleton or multiple), birth month, maternal age, and each animal’s genotype. Additionally, the effect of each animal was considered a random factor, and inbreeding coefficient was treated as an independent variable in the statistical model. Birth weight, weaning weight, and the age of animals at the three-month weighing were considered covariates to enhance model accuracy. Statistical analysis of data was conducted using SAS 9.12 software to verify the normal distribution of data and apply necessary adjustments where required.
Results and Discussion: Genetic analysis conducted on sheep samples indicated that the DNA samples were suitable for further research stages. Following the PCR process and the use of the SCCP marker, seven distinct banding patterns were identified, highlighting genetic diversity among the samples. Sequence analysis revealed five different genotypes, with no polymorphisms detected at positions 107 and 316 of the leptin gene in Zel and Lori-Bakhtiari sheep. However, nucleotide mutations were identified at positions 271, 387, and 433, leading to changes in associated amino acids. These alterations may impact the three-dimensional structure of the leptin protein and consequently influence its functionality. In the Zel breed, only a nucleotide mutation at position 387 was observed, indicating lower genetic diversity compared to Lori-Bakhtiari sheep. Statistical analysis also demonstrated significant effects of sex, birth month, and the leptin gene on various traits. Specifically, sex had a notable impact on traits such as body length, height, tail length (P < 0.05), chest and neck circumference (P < 0.01), abdominal girth, thigh circumference, tail circumference, mid-length, left and right rump length, mid and lower rump width, and rump cleft length (P < 0.05). Male sheep exhibited higher values in many of these traits compared to females, which can be attributed to physiological and hormonal factors. Birth month also influenced birth weight and daily weight gain (P < 0.01). Lambs born in different months exhibited growth variations due to environmental factors such as temperature, humidity, and feed availability. For example, lambs born in favorable climatic conditions demonstrated better weight gain. The leptin gene significantly affected daily weight gain, Kleiber ratio, body length, height, abdominal girth, neck circumference, and chest circumference (P < 0.05). These results underscore the critical role of this gene in growth-related processes and energy metabolism in sheep. Animals with specific leptin genotypes showed superior growth performance, making them potential candidates for selective breeding programs.
Conclusion: The findings of this study demonstrated that genetic mutations in the leptin gene can influence the structure and function of the protein, thereby affecting growth and production traits in sheep. The highest genetic diversity was observed in the Lori-Bakhtiari breed. In this breed, genotype 1 exhibited the lowest values, while genotype 3 showed the highest values in the studied traits, indicating a positive impact of certain genotypes on growth characteristics. In the Zel breed, genotypes 1, 2, and 3 were identified, with significant correlations among them in traits such as daily weight gain, Kleiber ratio, tail length, body length, height, chest circumference, abdominal girth, and neck circumference. These results highlight that even in breeds with lower genetic diversity, identifying superior genotypes can contribute to the enhancement of key economic traits. Overall, this study underscores that precise identification and analysis of genetic mutations in the leptin gene can serve as a powerful tool for improving breeding programs and boosting efficiency in the livestock industry. The use of genetic markers associated with growth traits facilitates targeted selection of superior animals, leading to increased high-quality meat production, improved feed efficiency, and enhanced productive traits. Further research is recommended to explore the effects of leptin gene mutations on additional economically relevant traits in sheep, ensuring optimal utilization of the acquired data in breeding strategies and livestock management.
Materials and Methods: In this study, aimed at examining the role of the leptin gene in sheep growth, 169 nine-month-old Lori-Bakhtiari sheep (63 males and 106 females) and 130 Zel sheep (30 males and 100 females) were investigated. Blood sampling was performed, and biometric traits were precisely measured. Growth-related data, including birth weight, weaning weight, and six- and nine-month weights, were collected from breeding stations and recorded for detailed analysis. DNA extraction was conducted using 250 microliters of blood and an optimized saline method. The quality and quantity of extracted DNA were assessed through spectrophotometry and 1% agarose gel electrophoresis to ensure accuracy and reliability. Following polymerase chain reaction (PCR), genetic patterns were determined, and precise sequencing was performed. To evaluate the effect of genotypes on measured traits, two animal models were employed. In Lori-Bakhtiari sheep, the age factor was excluded from the model due to the uniform age of the animals. Fixed factors examined included birth type (singleton or multiple), birth month, maternal age, and each animal’s genotype. Additionally, the effect of each animal was considered a random factor, and inbreeding coefficient was treated as an independent variable in the statistical model. Birth weight, weaning weight, and the age of animals at the three-month weighing were considered covariates to enhance model accuracy. Statistical analysis of data was conducted using SAS 9.12 software to verify the normal distribution of data and apply necessary adjustments where required.
Results and Discussion: Genetic analysis conducted on sheep samples indicated that the DNA samples were suitable for further research stages. Following the PCR process and the use of the SCCP marker, seven distinct banding patterns were identified, highlighting genetic diversity among the samples. Sequence analysis revealed five different genotypes, with no polymorphisms detected at positions 107 and 316 of the leptin gene in Zel and Lori-Bakhtiari sheep. However, nucleotide mutations were identified at positions 271, 387, and 433, leading to changes in associated amino acids. These alterations may impact the three-dimensional structure of the leptin protein and consequently influence its functionality. In the Zel breed, only a nucleotide mutation at position 387 was observed, indicating lower genetic diversity compared to Lori-Bakhtiari sheep. Statistical analysis also demonstrated significant effects of sex, birth month, and the leptin gene on various traits. Specifically, sex had a notable impact on traits such as body length, height, tail length (P < 0.05), chest and neck circumference (P < 0.01), abdominal girth, thigh circumference, tail circumference, mid-length, left and right rump length, mid and lower rump width, and rump cleft length (P < 0.05). Male sheep exhibited higher values in many of these traits compared to females, which can be attributed to physiological and hormonal factors. Birth month also influenced birth weight and daily weight gain (P < 0.01). Lambs born in different months exhibited growth variations due to environmental factors such as temperature, humidity, and feed availability. For example, lambs born in favorable climatic conditions demonstrated better weight gain. The leptin gene significantly affected daily weight gain, Kleiber ratio, body length, height, abdominal girth, neck circumference, and chest circumference (P < 0.05). These results underscore the critical role of this gene in growth-related processes and energy metabolism in sheep. Animals with specific leptin genotypes showed superior growth performance, making them potential candidates for selective breeding programs.
Conclusion: The findings of this study demonstrated that genetic mutations in the leptin gene can influence the structure and function of the protein, thereby affecting growth and production traits in sheep. The highest genetic diversity was observed in the Lori-Bakhtiari breed. In this breed, genotype 1 exhibited the lowest values, while genotype 3 showed the highest values in the studied traits, indicating a positive impact of certain genotypes on growth characteristics. In the Zel breed, genotypes 1, 2, and 3 were identified, with significant correlations among them in traits such as daily weight gain, Kleiber ratio, tail length, body length, height, chest circumference, abdominal girth, and neck circumference. These results highlight that even in breeds with lower genetic diversity, identifying superior genotypes can contribute to the enhancement of key economic traits. Overall, this study underscores that precise identification and analysis of genetic mutations in the leptin gene can serve as a powerful tool for improving breeding programs and boosting efficiency in the livestock industry. The use of genetic markers associated with growth traits facilitates targeted selection of superior animals, leading to increased high-quality meat production, improved feed efficiency, and enhanced productive traits. Further research is recommended to explore the effects of leptin gene mutations on additional economically relevant traits in sheep, ensuring optimal utilization of the acquired data in breeding strategies and livestock management.
Type of Study: Research |
Subject:
ژنتیک و اصلاح نژاد دام
Received: 2025/01/28 | Accepted: 2025/07/14
Received: 2025/01/28 | Accepted: 2025/07/14
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