Managing the Replacement Heifer Calf to Weaning

Calves. They become heifers. They become cows. After all, that’s the point… to raise healthy, productive animals that become part of the dairy herd. From a financial perspective, it’s important that we invest enough in our heifers for them to grow at the proper rate and enter the milking herd at the right size and age. The future profitability of the dairy herd is dependent on the success of the heifer rearing program.

Management of the dry cow is designed to prepare her for the next lactation. Strategies should also consider the potential effects on the calf prior to and after calving. The dry cow diet needs to supply adequate levels of vitamins A, D3 and E along with trace elements to optimise her immunity and quality of colostrum.

‘The immune status of the dry cow has an important influence on calf health. The question whether the cow has been vaccinated, exposed to infectious disease, has produced protective antibodies or has transported these into the mammary gland determines the colostral quality and calf health. (Mallard, 1998).’

Inadequate dry cow nutrition may increase serum cortisol the stress hormone and consequently calves may be born with reduced metabolic rate, lower vigour and a lower chance of survival.

Newborn calves do not have meaningful levels of immunoglobulins, high levels of IgG are present in quality colostrum and receiving an adequate amount in a timely period is essential for the development of the calf’s immunity and protection against disease. Ideally the calf should receive 4 litres within 1 hour of birth, approximately 12%-15% of body weight in total by 12 hours of birth. By 6 hours after birth the absorptive capacity is reduced by 50%.

A failure of passive transfer (FPT) can result in non-immune shedders contaminating the environment with pathogens.

The two most common diseases to affect heifers are respiratory diseases and scours. Respiratory disease can be controlled through a timely vaccination program and good environment. Scours can be controlled through quality colostrum feeding and a clean environment. When treating calves for scour do not withdraw the milk, this may starve the bugs causing the scour but the calf is also being starved, it needs its full nutrition requirement to fight the infection. A quality electrolyte should be fed.

Calves must be provided with additional water in addition to what is consumed as the liquid diet. Empty body tissue in young calves ranges from 65% to 75% of total body weight, therefore it is the component deposited in greatest amounts during growing. It is also critical for development of the bacterial population in the rumen and starter intake. Concentrates should be available from day 3 onwards and intake monitored, calves can be weaned once they are consuming 1kg per day.

The 5 C’s provide an effective formula for managing the young dairy calf.

• Colostrum
• Cleanliness
• Comfort
• Calories
• Consistency

While the agents that cause disease are always there and are important in a disease outbreak, maximising the five C’s the calf can be disease free even if they become infected.

Calf health and survival and age at calving;

• Heifers treated for pneumonia -2.5 times more likely to die.
• Heifers treated for diarrhea – 2.5 times more likely to be sold.
• Heifers treated for diarrhea – 2.9 times more likely to calve > 30 months.

Waltner-Towes et al 1986.

Author: Pat O’Byrne (B.Ag.Sc.), Nutritionist, Nutribio/CAHL