When should gilts be inseminated after detection of estrous?

The correct timing for inseminating gilts after the detection of estrous is approximately 12 hours later. This recommendation is based on the understanding of the estrous cycle in swine, specifically the timing of ovulation.

After the onset of estrus, ovulation typically occurs around 36 to 42 hours later. Sperm can survive in the reproductive tract for about 24 hours. Therefore, to maximize the likelihood of successful fertilization, inseminating about 12 hours after the detection of estrus allows the sperm to be present when ovulation occurs. This timing improves the chances of achieving a successful pregnancy as it coordinates the presence of viable sperm with the release of eggs.

In contrast, timing the insemination much earlier, such as at 6 hours after the onset of estrus, may not align with ovulation, potentially resulting in diminished fertility. Similarly, waiting longer than 12 hours, such as 24 or 48 hours, increases the risk that the sperm may no longer be viable by the time ovulation occurs, leading to a decrease in conception rates. Thus, the 12-hour mark is considered the optimal time for insemination after detecting estrus.