Response to the buck effect in goats primed with CIDRs, previously used CIDRs, or previously used autoclaved CIDRs during the non-breeding season

The sudden introduction of males induces ovulation in anestrous goats. However, unless goats are primed with progestagens, in most cases ovulation is followed by short cycle, decreasing the conception rate. CIDR devices may be used for more than one treatment, but as progesterone content decrease, estrous and conception rates are negatively affected. It has been reported in cattle that progesterone concentrations increase after autoclaving the devices. The aim of the present study was to determine the plasma progesterone levels, and the estrous and pregnancy rates of anestrous goats previously primed with a new CIDR, a previously used CIDR or a previously used and autoclaved CIDR and exposed to the male effect. During April-May, a total of 126 adult dairy goats were treated for 5 days with a new CIDR (NC, n=40), a previously used and disinfected CIDR (DUC, n=44), and a previously used and autoclaved CIDR (UAC, n=42). Recycled devices were previously used for 14 days. At CIDR withdrawal, does were joined to sexually experienced adult marking males. Goats in estrus were recorded during 10 days, and pregnancy was determined by ultrasound 50 days after CIDR withdrawal. Blood progesterone concentrations were measured throughout the treatment. Goats treated with a new CIDR had greater progesterone concentrations than DUC (P<0.05), but similar than UAC goats (P>0.05). Progesterone concentrations tended to be significantly greater in group UAC than in group DUC (P=0.06). The area under the curve of progesterone was greater in groups NC (25.4±2.6 ng day mL−1) and UAC (18.1±2.6 ng day mL−1) than in DUC (11.0±2.6 ng day mL−1, P<0.05). Estrous (97.5, 100 and 100%) and pregnancy rates (62.5, 79.5 and 69%) were not different between groups (NC, DUC and UAC respectively). In conclusion, autoclaving used CIDRs, after a previous use of 14 days, tended to increase progesterone concentrations in treated goats. Estrus and fertility in goats exposed to the buck effect was not affected by the use of primings with new CIDRs, previously used CIDRs or previously used autoclaved CIDRs.