Rearing Calves 

Good rearing of calves is the key to a successful dairying operation. The lifetime production of a cow is determined by how well it is reared as a calf. 

The key to rearing good calves is to get the basics right at the very beginning. Calves that are poorly grown up to weaning never recover and will result in poorly grown heifers. 

Colostrum 

Colostrum contains immunogloblins at levels 60 times that of whole milk and is 20% higher in energy than whole milk. The immunoglobulins provide protection against infections such as navel ill and neonatal scours. 

Calves (including bobby calves) require 2 to 4 litres of colostrum within the first 10 hours after birth. 50% of calves will naturally get this amount of colostrum in the required time. Calves suckling well will get this amount in the first 6 hours but slow suckers will still be slow suckers 24 hours after birth. The best way to ensure that calves get good quantities of colostrum is to remove them from the cow within 6 hours of birth and feed colostrum or tube them with 2 litres of colostrum. 

Milk and Milk Powder 

The following choices are available for rearing calves in energy order: 

Stored Colostrum 

This is the very best of calf foods, being higher in energy and protein, and immunoglobulins than the other alternatives. Selling colostrum for manufacturing is like selling the family jewels. It is important that antibiotic-containing milk is not added to stored colostrum because this affects the keeping quality of the colostrum. 

Whole Milk 
Next best for energy, and the natural calf-rearing food. 

Commercial Milk Replacers (CMR’s) 
These are a mixture of dairy based products including skim milk powder, whey, casein and buttermilk. They typically contain 18% fat as opposed to whole milk powder at 28%, and 10% less energy than whole milk. 

Soya CMR’s 
The ingredients vary, but most contain whey (protein and lactose), soya (protein), and vegetable oil (fat). The soya needs trypsin inhibitors added and the starch removed (which is not digestible by the calves). 

The digestibility of these products varies. Poorly digestible products allow more lactose and protein to pass through the abomasum quicker allowing the potential for more bacterial multiplication. Colostrum and whole milk form a good curd which is easily digestible. CMR’s vary and can be checked by submitting a sample to your nearest VetEnt clinic for testing. 

Soya products do not form a clot. Some have been used successfully overseas but work best in controlled environments. They should be fed at 40°C to increase gut motility, increase gastric juices, and protein digestibility. Some experienced calf rearing consultants believe these products should only be used to finish off the rearing process in New Zealand conditions. 

Meal and Roughage 
Good quality meal should always be available. Most meals contain 18 – 20% protein, and should contain a coccidiostat. A successful regime is to have calves eating at least 0.5kg of meal at 8 weeks of age, then to increase to 1 – 1.2kg at weaning until the calf is at least 12 weeks of age or 100Kg. Similarly good quality roughage should be available from birth. Best is meadow hay. This is to assist the development of the rumen so the rumen is fully functioning at the time of weaning. 

Water 
Calves from birth should have access to good quality water. 

Housing 
Good quality housing is essential and there are a few fundamental requirements: 

• The shed should be sprayed out with a suitable bactericide / virucide such as Vetsan before the new season’s litter is added, then after it is added. 
• The open side of the calf house should not be exposed to the prevailing winds. 
• The ventilation should be across the calf house not along the length. 
• The calves should have plenty of area – suggested 1.2 m2 per calf with a maximum of 20 per pen. 
• The pens should be filled from one end so that there is no cross contamination of groups. 
• There should be a good quantity of good quality litter to a depth of at least 10cm. If the litter becomes wet or soiled it should be replaced or have more litter added. 
• Calves should be housed for at least the first 3 weeks, and once they go out into the paddock have access to shelter. 
• Areas under the feeding area should be well drained, and any water leaks controlled. 

When calves are brought into the calf shed for the first time their navels must be treated with a good quality iodine based spray. The navel should be checked regularly to make sure that it is drying up and there is no sign of infection. 

Post-weaning 
Weaning is a very stressful time for calves and the transition should be smooth with the continuation of meal feeding for the first month after weaning. 

Scouring calves 

• Once the calves are off meal that has had coccidiostat added there is a danger that they may get Coccidiosis. This will require treatment. 
• Yersiniosis can be a problem associated with the stress of weaning. 
• Control worms by watching for signs of worms and using a regular treatment programme. 

Nitrate Poisoning 

This can happen at any time but usually at the time when grass is very rapidly growing – over the summer in the good times and the autumn, and often with new grass. Symptoms include cattle found dead, staggery, or down. The mucus membranes (inside the mouth and under the eyelids) appear brown or muddy. If treatment is started quickly, cattle can be saved; there is a very good antidote. As a preventative, grass samples can be taken to check the nitrate levels. 

Performance Monitoring and Target Weights 

If farmers are able to weigh their own animals this is a very good management tool. Target weights can be set according to the breed, and the animals monitored.