The goal of dairy producer are to optimize both milk yields and conception rates in the herd .Typically scientific research is conducted on specific area of the study , such as reproductive physiology or nutrition .The dairy cow is a complex organism comprised of all these integrated systems that we often times isolate into disciplines. From the obtained results we can conclude that leptin is a key metabolic signal synthesized and secreted by fat cells that communicates information about body energy reserves, nutritional state, and metabolic shifts to the reproductive axis. This is indicated by increase in leptin levels in farm cows of good body reserves and resume their postpartum cyclicity than others of delayed postpartum estrus. The correlation between cortisol and postpartum ovarian cyclicity is important to be studied. Our results suggested that serum cortisol concentrations not correlated with resumption of postpartum cyclicity and its concentrations increased during under nutrition. Cholesterol concentrations were higher in animals showing good reproductive performance suggesting that the cholesterol may be involved in steroid synthesis in the ovary and luteal function and strongly influenced the interval from calving to conception. Serum concentrations of triacylglycerols were lower in animals with positive energy balance suggesting the storage of fat in fat depots rather than lipid mobilization as showed in animals of negative energy balance. Animals of high body condition scoring (5-7) showed good reproductive performance and resume their postpartum cyclicity. They had high levels of leptin and cholesterol with low triacylglycerols levels. In the current study , certain hormones (leptin , cortisol) and metabolites (cholesterol and triacylglycerols) were examined during winter and summer seasons and revealed the non significant changes in serum leptin, cortisol, cholesterol and triacylglycerols concentrations between the two seasons. Finally, it is recommended to use balanced ration containing essential nutritional parameters to resume postpartum cyclicity.