As the dairy industry improved in technology during the twentieth century, animals were affected by a higher exposure to artificial light at night and this kind of light is comparable with a solar day light. This change in farm management brought damaging consequences to the animals, for example, a reduced production of melatonin in the pineal gland [1]. Melatonin is a hormone with a higher secretion in darkness and lower secretion during exposure to light [2]. It plays a role in the regulation of the circadian rhythm of several biological functions like heart rate and sleep-wake cycle, modulates reproduction, the neuroendocrine system, pregnancy and parturition times, CL function and it is considered an effective antioxidant [2,3]. In mammals, melatonin is produced by pinealocytes, retina and the gastrointestinal tract (GI). The major source of melatonin emanates from the pineal gland, and functions as an endocrine hormone [4].