Treatments with eCG and courtship behaviour in rams during the breeding and the non-breeding seasons

Abstract

Equine chorionic gonadotrophin (eCG or PMSG) is a hormone with FSH/LH effect that has been widely used in ewes and cows to induce follicle development. However, the possible positive effects of its administration to males have been rarely studied. ECG stimulates testosterone secretion and increases rams’ ability to stimulate ovulation in anoestrous ewes (the ‘ram effect’), but it is still not known if this effect is at least partially explained by an enhancement of a ram’s sexual behaviour. Thus, the aim was to determine if the administration of eCG induces an increase in testosterone concentration, and thus improves sexual behaviour of Saint Croix rams during both the breeding and the non-breeding seasons. Two doses of 1000 IU of eCG were administered separated by 4 days to 10 rams during the breeding and five rams during the non-breeding seasons, with the same number of animals as untreated controls. Administration of eCG increased testosterone concentration during the breeding (P = 0.008) and the non-breeding (P = 0.0009) seasons. The number of ano-genital sniffings, lateral approaches, as well as total courtship behaviours were greater in treated than untreated rams during the breeding season. Treated rams also tended to mount and mate more during the breeding season. During the non-breeding season, treated rams tended to display more ano-genital sniffs, lateral approaches and total courtship behaviours than untreated rams 6 days after the first dose. Overall, eCG increased testosterone concentrations the breeding and the non-breeding seasons, and was associated with a greater display of sexual behaviours during the former.

Effect of rams’ social hierarchy upon scrotal circumference, semen quality, and copulation performance under arid land conditions

“…A key player triggering such a response could be the serum testosterone concentration (Keller and Levy, 2012;Recabarren et al, 2017), as this hormone is highly correlated with scrotal circumference as well as ejaculatory volume in bulls (Sajjad et al, 2007). Testosterone is also correlated with aggression (Muller and Wrangham, 2004), male social dominance (Koren et al, 2002;Muller and Wrangham, 2004), and courtship (Ungerfeld et al, 2019).…”

Use of Short-Term CIDR-Based Protocols for Oestrus Synchronisation in Goats at Tropical and Subtropical Latitudes

“…Accordingly, ref. [ 49 ], who treated anoestrus ewes with a previously used CIDR for 22 days, obtained poor oestrus response and fertility. Based on the literature, it can therefore be inferred that the treatment of cyclic and anoestrus females with short-term CIDRs previously used for a period not longer than 14 days should result in a high oestrus response and acceptable fertility.…”

“…The effect of not combining short-term CIDR with eCG on oestrus response and fertility has been observed with the 9-day CIDR protocol [ 49 ]. In this study, the oestrus response of Saanen goats and their kidding rates after controlled natural mating (hand mating), with and without eCG were 100% vs. 70%, p = NS and 100% vs. 69.8%, p ≤ 0.05, respectively.…”

Systematic review of hormonal strategies to improve fertility in rams

“…According to the results, the use of eCG within and outside the breeding season affects T concentrations and sexual behaviour but not semen quality and scrotal circumference. In rams and bucks, it has been used since 2008, when doses of 100 to 400 IU of eCG were evaluated in prepubertal lambs ( Ungerfeld and Bielli, 2008 ), with no effect on semen quality and sexual behaviour; However, at does higher than 400 IU, up to 1000 IU, or when two doses of 1000 IU are given to rams 3 days before mating with ewes, it can induce an increase in T secretion in rams during the period of sexual rest ( Ungerfeld et al, 2018 ; Ungerfeld et al, 2019 ), but without altering semen quality ( Beracochea et al, 2020 ). In this sense, eCG has been used to increase libido and make the use of the male effect more efficient in rams ( Ungerfeld et al, 2014 , 2019 ).…”