RESUMO
In seasonally anestrous goat does, ovulations can be induced by combining a treatment regimen including progestagen, eCG and prostaglandins. Nonetheless, ovulations occur only once and then does return to a seasonally anestrous state. This study was performed to determine whether the presence of a sexually active buck can stimulate a second ovulation after induced luteolysis using prostaglandins following the first ovulation. Three groups of seasonally anestrous does were treated to induce ovulations using an intra-vaginally inserted sponge containing a progestin combined with eCG and prostaglandin administrations. Goats that had ovulations were treated with a prostaglandin 11 days after progestin sponge removal. After the prostaglandin injection, does continued to be isolated from bucks (nâ¯=â¯8), were penned with a control buck (nâ¯=â¯9), or were penned with a sexually active buck (nâ¯=â¯10). The proportion of goats having ovulations after imposing the ovulation-induction protocol was greater than 80% and did not differ among treatment groups (Pâ¯>⯠0.05). The proportion of does having ovulations after injecting prostaglandins was greater when does were penned with a sexually active buck (8/10) than does penned with a control buck (0/9) or that were isolated from bucks (0/8; Pâ¯<â¯0.05). It is concluded that in seasonally anestrous goat does induced to have ovulations using a hormonal treatment regimen, the presence of a sexually active buck can induce a second ovulation when there is an induced luteolysis.
Assuntos
Gonadotropina Coriônica/farmacologia , Acetato de Fluorogestona/farmacologia , Cabras/fisiologia , Ovulação/fisiologia , Prostaglandinas/farmacologia , Estações do Ano , Animais , Gonadotropina Coriônica/administração & dosagem , Feminino , Acetato de Fluorogestona/administração & dosagem , Masculino , Ovulação/efeitos dos fármacos , Indução da Ovulação/veterinária , Fotoperíodo , Prostaglandinas/administração & dosagem , Comportamento Sexual AnimalRESUMO
In ewes, the ovulatory response of females exposed to familiar rams is lower than the response of those exposed to novel ones. In goats, males rendered sexually active by exposure to long days are more efficient to induce ovulation in seasonal anestrous females than untreated males. Two experiments were conducted to determine 1) whether male goats remain familiar to females after 45days of separation; and 2) whether photostimulated males are able to stimulate the sexual activity of females, independently of their familiarity with them. In Experiment 1, three groups of goats (n=10 goats per group) were put in contact with males (n=2 per group) during 10days in November (familiarization period). These males were called familiar males. After 15, 30 and 45days of separation from the males, females of each group were exposed to familiar or novel males during 10min. In each test, goats in contact with novel males displayed more distress bleats, escapes, head butts, and sniffing than those in contact with familiar males (P<0.05). In Experiment 2, we used sexually inactive (n=4 control males), and sexually active males (n=4 photostimulated males). In February, two groups of goats (n=50 each) were put in contact with control or photostimulated males (n=2 each) during 10days ("familiar" control or photostimulated male, respectively). After 45days of separation from the males, both groups of females were further divided into two groups (n=25 goats per group). In April, two groups were re-exposed to "familiar" control or "familiar" photostimulated males (n=2 per group), whereas the other two groups were exposed to "novel" control or "novel" photostimulated males (n=2 per group). The photostimulated males displayed a higher level of sexual behavior than the controls. The proportion of goats that ovulated and displayed estrus was higher when exposed to the photostimulated males than when exposed to control ones (≥80% vs. 0%; P<0.05). These proportions did not differ between groups exposed to familiar or novel photostimulated males (P>0.05). We concluded that after 45days of separation, males are still familiar to females. The photostimulated males are able to induce the sexual activity of seasonally anestrous goats independently of their familiarity with them.