Table 2 Groups of cattle in different ’Physiological statuses’ and different age categories in the study (Eritrea, 2011)

Calf

Young female/ male animal <2 years old

Bull

Male animal (entire/ castrated) ≥2 years old

Heifer empty

Young female animal ≥2 years old that hasn’t calved and is not pregnant

Heifer pregnant

Young female animal ≥2 years old that is pregnant and hasn’t calved before

Lactating empty

Mature ≥3 years old, lactating cow that is not pregnant

Lactating pregnant

Mature ≥3 years old, lactating and pregnant cow

Dry pregnant

Mature >3 years old pregnant cow that is approximately 4 to 8 weeks from calving, and not lactating

Age (three categories)

<3 years old

3 to ≤5 years old

>5 years old