The importance of Muscovy ducks in industrial poultry production is growing; however, little is known about the physiology of their reproductive cycles. This study investigated the influence of male biostimulation on female ducks before the commencement of the laying phase. A total of 15 female Muscovites were kept in contact with a male duck until the point of laying, while 15 other females were kept without any contact with a male conspecific. Before reaching egg-laying maturity, the cloacae of 29 adult ducks were subjected to daily clinical assessments. The evaluations yielded four unique categories of outcomes, determined by assessing factors such as the degree of redness and protrusion of the mucous membrane, moisture level, and swelling of the cloacal sphincter muscle. In terms of biostimulation, the findings demonstrated that, on average, ducks in contact with males laid the first egg 16 days earlier than isolated ducks. Furthermore, there was no significant difference observed in the mean initial egg weight between both groups (p = 0.841). The changes in the cloacal morphology indicated significant morphological changes 25–26 days before laying. Efforts to improve Muscovy production and develop biotechnological techniques to modify the reproductive cycle will benefit from these advancements.