Characteristics of the plasma melatonin rhythm are not modified by steroids during the estrous cycle in Ile-de-France ewes

International audienc

The characteristics of the melatonin secretory rhythm are not modified by the stage of pregnancy in ewes

International audienc

Characteristics of the plasma melatonin rhythm are not modified by steroids during the estrous cycle in Ile-de-France ewes

International audienc

The characteristics of the melatonin secretory rhythm are not modified by the stage of pregnancy in ewes

International audienc

The large variability in melatonin blood levels in ewes is under strong genetic influence

International audienc

The large variability in melatonin blood levels in ewes is under strong genetic influence

International audienc

Enhancement of the male effect on reproductive performance in female Mediterranean goats with long day and/or melatonin treatment

The aim of this study was to determine whether the male effect on reproductive performance in female Mediterranean goats could be enhanced if used in combination with long day and/or melatonin treatments. Thirty-two does were exposed to long days (16 h of light/day) for 95 days. At the end of this period, 16 received one melatonin implant (group LD-M) and 16 did not (group LD). Simultaneously, 16 does under natural photoperiod were implanted with melatonin (group M) or given no treatment (group C. n = 16). On April 14th, after 49 days of isolation from males, all does were exposed to bucks fitted with marking harnesses. Oestrous activity, as detected by visual observation, was recorded daily. Transrectal ultrasonography was used to record ovulation, and ovarian activity confirmed by determining plasma progesterone concentration. Oestrous activity, ovulation and fertility were greater in all treatment groups compared with group C (P 0.05). Productivity (mean number of kids per female) of the LD-M and M groups was significantly greater than in group C (1.50 +/- 0.01 and 1.37 +/- 0.01 vs. 0.69 +/- 0.01 kids, respectively) (P < 0.05). Combining melatonin treatment with natural or artificial long days adds to the impact of the male effect