Expression of sexual activity within a herd can be increased by introducing another animal for the purpose of heat detection. This can be a bull whose penis has been laterally deviated or surgically removed. A testosterone-treated female also can be used. Timing of insemination Cows should be bred at a time which will allow a population of highly viable sperm to be present at the site of fertilization when the unfertilized egg arrives. Thus, it is important for dairymen to estimate the time of ovulation for each cow that is to be bred.
Ovulation is related to standing heat.
Standing behavior is the only reliable symptom dairymen have to determine time of ovulation. Since ovulation occurs approximately 10 to 12 hours after the end of standing heat, breeding should occur during the period between the middle of standing heat and 6 hours after the end of standing heat. Sperm cells remain viable in the female reproductive tract for 18 to 24 hours. Although not yet proven, it is thought that sperm may require 6 hours to become adapted to the female reproduction tract before they are capable of fertilization. Improper semen handling or poor artificial insemination technique can dramatically reduce the number of sperm cells available for fertilization and thus reduce conception rate.