Efeito macho na indução do estro em ratas Wistar (Rattus norvegicus)

The objective was to evaluate the induction of estrus in Wistar female rats in two ways: the presence of vasectomized males (MV) and the presence of male odor from the bedding (OM). The presence of intact males was used as a positive control (MF) and the absence of males and male odor as a negative control (SM). Sixty females were caged individually and assigned to one of four treatments with 15 females each. In the MV treatment, each female was exposed to an adult vasectomized male. In the OM treatment, each female was exposed to male odor, i.e., she was placed daily in direct contact with bedding from an adult male. In the MF treatment each female was directly exposed to a certified fertile male. In the SM treatment females had no contact with males or male bedding. In all groups females were exposed to treatment for five consecutive days. All the females had their vaginal smear collected for estrous cycle phase determination. A survival analysis was employed to compare treatments. Treatments tended (P=0.0971) to differ in relation to the number of days to present estrous. All the females from treatments OM and MF achieved estrous within the four-day period, reaching the following daily percentages: 40.0, 13.3, 20.0 and 26.7% and 20.0; 20.0; 20.0 and 40.0% for OM and MF, respectively. In the SM treatment, 13 females (86.7%) showed estrous in the same period with daily percentages of: 20.0, 20.0, 26.7 and 20.0%. In the MV treatment 11 females (73.3%) showed estrous along the four readings with the following daily percentages: 6.7, 26.7, 13.3 and 26.7%. It is not possible to affirm that the exposition of nuliparous female Wistar to vasectomized males or to adult male odor in bedding is effective for estrous induction.