Infertility: The temporal inability of the female either to produce a viable ovum ready to be fertilized or to keep embryos till normal parturition.

Anestrum: The female is not observed in estrus either because she has not come into estrus (not cycling) or because estrus was not detected (cycling).

Abortion: 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.

Repeat breeder: the female animal is called as repeat breeder when it has failed to conceive even after three or more services, has normal estrus cycle length, no abnormality in the vaginal discharge, and no palpable abnormality in the reproductive tract.

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.

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

Calving: 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 results in calving as a percentage of the total number of services.

Calving interval is the number of days between two consecutive calvings. Calving interval covers both return to cyclicity and conception
Conception: Conception is the act of becoming pregnant through fertilization and implantation of the fertilized egg onto the lining of the uterus.

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 maximizing the fertility of each cow.

Date of conception: The date of the effective service.

Date of service: The date of the first natural mating or artificial insemination.

Days open is the interval between calving and the last insemination date.

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

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

Fetus: The developing calf from day 43 to birth.

Fetal loss: When a fetus dies between 43 and 151 days of pregnancy.

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

Estrous cycle: The regular advent of estrus / coming into heat, comes with a change in the genitals and reproductive hormones.

Estrous cycle length: Duration of time from the start of the estrus cycle to the beginning of the next. The start of the first estrus is counted as Day 0.

Gestation period: The number of days between conception and birth.

Heat detection rate (HDR): The percentage of eligible females that are seen or detected in heat. In a perfect system, this would be 100%.

Heifer: A mature female cow that is yet to give birth.

Non-return rate is a binary measure of whether a new mating or insemination event occurs after the first insemination within a time period.

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.

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

Pregnancy Rate (PR): This can also be known as Reproductive Efficiency. It is an American KPI that is rapidly being adopted in the UK. It’s the product of HDR/SR and CR. For example, in a herd, if 50 animals are eligible in one 21-day period: 40 are inseminated (40/50 = 80% SR); 20 of those cows become pregnant (20/40 = 50% CR).