Obifertil is a bolus of trace elements composed mainly of beta-carotene, vitamin A, selenium, iodine, and zinc. It allows the cow to be prepared before breeding.

A deficiency of beta-carotene causes discrete heat, delayed maturation of the follicles and an increase in ovarian cysts. There are also embryonic mortalities or early abortions. Beta-carotene is essential for the cow to synthesize vitamin A.

Vitamin A is involved in multiple metabolisms: 
- Reproduction: Vitamin A is essential for many stages of reproduction - cutaneous 
- Cutaneous: Vitamin A deficiency causes disruption of skin barriers 
- Immunity: deficient animals are at increased risk of breast infections 
- Growth: Vitamin A promotes proteosynthesis and ossein synthesis 
- View: Vitamin A-deficient cows can give birth to blind calves.

Iodine and selenium play an important role in cow breeding: iodine and selenium deficiency in cows can result in dead calves or calves with potentially fatal respiratory distress.