Searching for a glossary of dairy cow fertility terms? Look no further...

Young people trying to break into the farming industry could be forgiven for feeling a little jealous of those who were born into it. After all, farming children are given a practical education from birth that continues into adulthood and beyond. For those who began life outside the world of agriculture, it can seem an intimidating industry to enter.

Dairy farming and cow fertility comes with its own language of terms and phrases that have the potential to embarrass and confuse those not familiar. For industry newcomers, we’ve created a concise glossary to highlight some of the most common dairy fertility terms to get up to speed with.


When one or more calves are born dead or survive for less than a day when born between 152 and 270 days after successful service.

Artificial insemination (AI)

The service of a cow by inserting frozen bull semen into a cow’s uterus. This allows the selection of high-quality genetics and avoids the risks of keeping a mature bull on the farm.


Technology that utilises biology to reap benefits for the herd. Often this involves creating or modifying DNA to select optimum genetic traits.


The birth of one or more calves more than 270 days following an effective service.

Calving rate

This is the total number of services received by a group of cows which result in calving as a percentage of the total number of services.

Cull cow

A cow that is removed from the herd.

Dairy nutritionist

Expert animal health consultants who advise on the nutritional needs of cows. They help recommend the best diets for maximising the fertility of each cow.


The mother of a calf.

Date of conception

The date of the effective service.

Date of service

The date of the first natural mating or artificial insemination.

Earliest service date

The date that a cow will be served in oestrus.


Effective service

A service that results in pregnancy.


The developing calf from the date when it was conceived to the 42nd day of the cow’s pregnancy.

Embryo loss

When a developing calf does not survive during the first 42 days of pregnancy.


The developing calf from day 43 to birth.

Foetal loss

When a foetus dies between 43 and 151 days of pregnancy.

Fresh cow

A cow that has recently given birth.


The genetic constitution of an animal.

Gestation period

The amount of days between conception and birth.

Genetically modified organism (GMO)

When a copy of a gene is made from one organism and then used in another organism. This helps improve plants or other organism by allowing the selection of specific beneficial genes.

GMO feed

A feed that has had ingredients altered or modified by genetic engineering.


A mature female cow that is yet to give birth.

In-calf heifer

A heifer that has been confirmed to be in calf.

Inter-service interval

The amount of days between the last service of a cow to the next, during the same lactation.

Maiden heifer

A heifer that has not had a service.


The physiological state whereby a cow will voluntarily stand to be mounted.

Oestrus cycle

The regular advent of oestrus / coming into heat, this comes with a change in the genitals and reproductive hormones.

Oestrus cycle length

Duration of time from the start of the oestrus cycle to the beginning of the next. The start of the first oestrus is counted as Day 0.

Premature calving

This term refers to the birth of one or more calves between 152 and 270 days after an effective service. The calf must survive for 24 hours or more.


Replacement rate

The number of cows or heifers that are required to replace the cows that have left the herd during a period (usually 12 months) as a percentage of the total average herd size.

Served heifer

A heifer that has been served, or has transferred an embryo, but is yet to be confirmed to be in calf.


One or more natural or artificial inseminations during a period of oestrus.

Stillborn calf

A calf that has been birthed dead or found dead after an unobserved calving.

Over to you...

Dairy farming terminology may seem like another language at first. But it quickly becomes second nature as you grow into the job. Using a dairy cow fertility glossary like this one can help you get to grips with the jargon and speed your journey towards dairy farming success.  A little study goes a long way.