Effect of the age of ganders on reproductive behavior and fertility in a competitive mating structure

Abstract

This paper presents the study on determination of gander-goose mating activity in relation to age and the position of gander in social hierarchic rank. Moreover, levels of fertility (F) and testosterone (T) in different gander age groups were analyzed. The study was carried out on one-year-old geese (N = 64) and one- or two-year-old ganders (N = 16; 1♂: 4♀). Observations of mating activity (MA) were conducted during the 3-h period of the daylight (10 h), 2-3 times per week (102 h/group/34 days). The recording was done with a digital recorder connected to cameras. Agonistic behavioral interactions between ganders were noted to determine a social hierarchic rank. The MA was described by frequency of courtship displays, copulation attempts, successful copulation (SCop), and interaction disrupted (DMI) with agonistic behavior. Fertility was evaluated after the artificial incubation (1×/week) in a commercial hatchery. The frequency of SCop, DMI, and T concentration were higher (P<0.05) for two- than one-year-old ganders. Moreover, F was higher by 11.2% for group of geese kept with two-year-old ganders. There was an effect of the gander's rank in social hierarchy on the frequency of MA. For dominant ganders, frequency of courtship displays (1.0/times/3 h) and copulation attempts (0.8/times/3 h) were lower (P<0.05), but SCop (1.5/times/3 h) was higher (P<0.05) than for subordinate ones. Thus, in domestic goose flocks reproductive success was associated with age of ganders used in competitive mating system. This is probably a multifactor effect of interaction between sexual/social experience, T-dependent mating motivation, and efficiency of MA. It is recommended to keep one-year-old geese with older ganders (after sexual reactivation) for optimal fertility results with sex ratio adjusted to gander-gander antagonistic interaction dynamic.