Alongside providing nourishment, it contains antibodies that act as messengers from the mother’s immune system, reflecting the diseases she has been exposed to before the calf is born. These antibodies help the calf recognise ‘foreign invaders’, allowing it to respond to disease-causing bacteria quickly - either preventing illness altogether or significantly reducing its severity. 

Calves that don’t receive enough good-quality colostrum soon enough after birth - whether due to weak suckling, poor mothering, or poor-quality colostrum (for example, cows leaking milk before calving) - start life at a clear disadvantage. These calves are more likely to get sick and often have reduced growth rates. 

It’s hard to overstate how important early colostrum intake is. At birth, a calf’s gut can absorb antibodies from the colostrum efficiently, but this ability drops rapidly. By six hours, absorption is halved, and by 24 hours, it has stopped. This creates a risk for calves that are slow to feed or are only picked up once a day, as even high-quality colostrum given later won’t provide the same level of protection.