Usual fertility values

Service rate is defined as the percentage of cows detected in oestrusAlso known as heat, is the physiological and behavioral phenomena which precedes and accompanies ovulation in female mammals. out of the ones available to be inseminated.

A simple way to estimate this value is by calculating the average interval between inseminations or breeding interval (BI) and divide the length of the reproductive cycle (21d) by this number. For instance, a herd in which the BI=45 days, approximately have oestrusAlso known as heat, is the physiological and behavioral phenomena which precedes and accompanies ovulation in female mammals. efficiency equal to 21/45=47%. Normally oestrusAlso known as heat, is the physiological and behavioral phenomena which precedes and accompanies ovulation in female mammals. detection efficiency needs to be maintained above 60% to keep an adequate calvingGiving birth to a calf. interval in the herd.

The conception is defined as the number of cows that conceive out of the ones that are detected in oestrusAlso known as heat, is the physiological and behavioral phenomena which precedes and accompanies ovulation in female mammals. and inseminated. Some specialists tend to use the term “pregnant-per-inseminated” for this same reproductive parameter.

Briefly, one simply needs to count how many cows conceived out of the ones inseminated within 21 days for instance. Normally, conception rates in dairy herds are around 30 to 40%.

It is a combination of the last two parameters. In other words, it is the percentage of cows getting pregnant out of the ones available to be inseminated. Another option is to simply multiply the oestrusAlso known as heat, is the physiological and behavioral phenomena which precedes and accompanies ovulation in female mammals. detection rate by conception rate and you have as an outcome pregnancy rate.

Dairy and beef herds working in a breeding season schedule, concentrating the inseminations in 3 or 4 months of the year tend to use other parameters.

For example, in order to have a balanced breeding season, farmers need to ensure that most of the cows are pregnant before the middle of the breeding season, otherwise too many cows will calve too late in the following year and the breeding season scheme can’t be continued. Thus, an index normally used is the percentage of cows pregnant before the middle of the breeding season, which needs to be above 70% for both beef and dairy herds.

CalvingGiving birth to a calf.-to-conception is another reproductive parameter used by many dairy and beef operations. Ideally, calvingGiving birth to a calf. to conception should be between 80 to 100 days in order to obtain 1 calf per cow per year (up to 115 days in large intensive dairy farms with HYDCs*).

*HYDC = High Yielding Dairy Cow

The first AI conception rate is defined as the proportion of cows that become pregnant after a first artificial insemination divided by the total number of cows that where inseminated. A success rate of over 50% is adequate (35 to 40% in HYDCs*), but this may vary depending on a number of issues including the calvingGiving birth to a calf.-to-1st service interval (also known as voluntary waiting period).

*HYDC = High Yielding Dairy Cow

Animals are culled because of disease, infertility and in order to improve the genetic merit of the herd. A cullingProcess of removing an animal from the breeding stock, on most occasions sending it to be slaughtered. rate due to infertility of 25 to 30% is common.