Determination and comparison of serum leptin and ghrelin levels in Anatolian merino and akkaraman sheep of different age groups

In this study, serum leptin, ghrelin, and insulin levels were measured in 3 months, 9 months and 24 month Merinos and Akkaraman sheep, which were fed in the same pen, with the same feeds and under the same conditions. The aim was to determine the values of leptin, ghrelin, and insulin in different breeds and age groups, as well as in fat-tailed and lean-tailed sheep, and to compare the relationships among them. The Akkaraman breed, which is a fat-tailed breed, was compared with the Anatolian Merinos breed, which has a lean tail. The research material was collected from a farm engaged in Akkaraman and Merinos sheep breeding located in the Orta district of Çankırı province. Blood samples were taken from a total of 60 sheep, with 10 from each age group. These samples consisted of Anatolian Merinos and Akkaraman sheep aged 3 months, 9 months, and 24 months. Serum leptin, ghrelin, and insulin levels were measured using separate kits with the ELISA method from the collected blood samples. Body weights of Akkaraman and Merinos sheep were measured in kg. At ages 3 months, 9 months, and 24 months, the average weights for Akkaraman sheep were 42.3 kg, 56.5 kg, and 77.68 kg respectively, while the average weights for Merinos sheep at the same ages were 35.24 kg, 54.91 kg, and 66.14 kg, indicating that Akkaraman sheep were heavier than Merinos sheep at every age. Ghrelin levels in the heavier Akkaraman breed were measured at an average of 180.99 ng/mL at 3 months, whereas the Merinos breed had a lower average of 124.30 ng/mL at 3 months, and declines were observed in both groups in subsequent age measurements. In the results, leptin values, synthesized from adipose tissue, were found to be higher in the Akkaraman breed compared to the Merinos breed. The average leptin value for Akkaraman sheep at 3 months was measured at 122.19 ng/mL, while the average for Merinos sheep at the same age was 100.91 ng/mL, with leptin values increasing in both groups in later age measurements. Insulin levels for 3 months Akkaraman sheep were measured at an average of 13.49 mIU/L, while for 3 months Merinos sheep it was 9.66 mIU/L, showing an increase in average measurements as age progressed. With the progression of age and body weight, increases in leptin and insulin levels were observed, alongside a decrease in ghrelin levels. As a result, most studies investigating the effects of ghrelin, leptin, and insulin hormones on age, body weight, and fat mass have been conducted on humans, with very few studies on animals, particularly ruminants. This study examined for the first time the relationship of three hormones with age and body weight in both fat-tailed and lean-tailed sheep.