Sudden introduction of bucks during the late luteal phase of isolated female goats induces a biphasic change in progesterone concentrations

Ungerfeld, ROrihuela, A

The aim was to determine the progesterone profile after the introduction of bucks during the advanced luteal phase of does. Fourteen does received vaginal sponges impregnated with 40 mg fluorogestone acetate for 12 days, and a luteolytic dose of a prostaglandin analogue (75 μg of D-cloprostenol) 2 days before sponge removal. Fifteen days after sponge withdrawal one buck was introduced in one of the pens (BE group; n = 6), while the female goats in the other pen remained as controls (CON group; n = 8). The buck was replaced every 24 h, alternating their presence until the end of the experiment. Serum progesterone levels were used to monitor ovarian activity. Progesterone concentration from day 14 to 20 varied with time (P < 0.0001), and there was an interaction between treatment and day (P = 0.02). While progesterone concentration increased from day 15 to day 16 in BE does (P = 0.01), there were no changes in CON does on those days (P = 0.2). On the other hand, progesterone concentrations decreased in BE does from day 18 to day 19 (P = 0.02), without changes in CON does (P = 0.6). Finally, there was a sharp decrease from day 19 to day 20 in both BE (P = 0.0009) and CON (P < 0.0001) does. Overall, our results demonstrated that the introduction of bucks during the late luteal phase of isolated does can induce changes in the progesterone pattern, showing an early increase followed by a pronounced withdrawn.(AU)

1. male effect
2. estrous cycle
3. socio-sexual signals
4. pheromones
5. luteolysis