Investigation of the relationship between milk tissue hormones and some galactopoietic hormones in holstein and simental cattle

In this study, the physiological changes of leptin, adiponectin and ghrelin hormones that are effective on regulating energy metabolism; and galactopoietic hormones that are also effective in regulating metabolic activities such as growth hormone (BH), insulin, insulin-like growth factor-I (IGF-I), cortisol, Thyroid Stimulant Hormone (TSH) and Thyroxine (T4) were investigated and their correlation with milk yield were determined in low, medium and high milk yield of Holstein and Simmental cows. For this purpose, Holstein (n = 30) and Simmental breed cows (n = 30) with low, medium and high milk yield were used. Holstein and Simmental cows were divided into 6 groups with 10 animals in each group and prepartum body condition scores were determined. Blood samples were taken from all animals on the same day. Blood serum levels of growth hormone, insulin, IGF-I, cortisol, TSH, T4, leptin, adiponectin and ghrelin were determined.Growth hormone levels were determined to be increased in Holstein with low milk yield, as well as in Simental with low and high milk yield (P<0.05). Plasma cortisol levels were determined to be increased in Holstein with low and high milk yield statistically (P<0.05) when it was numerically increased in low milk yield Simental. Plasma T4 levels were decreased at high milk yield level in Holstein cows (p <0.05) and increased as milk yield level decreased (p <0.05). Ghrelin levels were statistically decreased (p <0.05) in low and high milk yield Simental cows, as Holstein cows were increased numerically. There was a positive correlation between plasma leptin levels, insulin and GH levels, and plasma adiponectin levels and leptin and insulin (p <0.01) in low, medium and high milk yield cows without breeding. As a result, in the present study, in cases where the energy requirement in lactation increases without serious dimensions, growth hormone, cortisol and ghrelin hormone levels were increased; decreased plasma T4 level was decreased; and insulin, IGF-I, TSH, leptin and adiponectin levels did not change, physiologically. In addition, there is interaction between leptin, adiponectin and ghrelin hormones and galactopoietic hormones.