Mating activity of ganders during breeding period in relation to sex hormone and age of females

English. During reproduction of geese variation in fertility is observed. One of the reasons may be the decrease of the sexual activity of males. In free-living birds behavioural and hormonal within-pair compatibility influence on reproductive success. The age of geese connected with mating experience may affect the activity and hormones level in ganders. The aim of the study was to analyze the mating activity (MA) of ganders in relation to plasma concentration of testosterone (T) and age of geese. The observations were carried out from flocks formation (November) to the end of eggs production (June), on two/three year old ganders (n=15) and one- (group-1) or two/three year old geese (group-2) (1 ♂: 4 ♀). The MA was noted as a frequency of courtship, attempts of - and successful copulation. The concentration of T in plasma, number of laid eggs and fertility were evaluated. Mating activity was observed one month before the sexual maturity of geese (December). For group-1 the highest MA was noted in February (1.8 times/6 h) while for group-2 in March (1.3 times/6 h). During period February-April differences in MA were not significant for group-1 while for group-2 at January-February and April-May. Plasma T concentration was higher in January (0.81 ng/ml) and February (0.61 ng/ml) for group-1 and -2, respectively. During reproduction MA was higher for ganders in group-1 compared to group-2. Fertility was higher at the period February-March compared to April-June as well as for group-1 but only in March and June. There were no significant correlation between concentration of T, fertility and MA. It can be suggested that during breeding period age of geese modulates mating activity of ganders but with minor influence on T concentration and fertility. Total mating frequency is not a good indicator for the estimation of reproduction results in domestic ganders.

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Supplement 1