Dairy Australia program manager Dr Kathryn Davis said animal scientists had known for some time that dairy heifers reared on conventional restricted milk feeding programs did not achieve their full genetic potential for growth. 

“Recent studies overseas have shown improvements in calf health, growth rates and feed conversion efficiency when calves are fed greater volumes of milk or milk replacer during the pre-weaning period.”

To better understand the benefits and risks of feeding fortified milk on health and growth of dairy heifers, Dairy Australia funded a study on four farms in western Victoria where a total of 213 group housed, dairy breed calves were randomly allocated into two diets.

One diet was of fortified milk comprising two litres of whole milk supplemented with 150 grams of high quality 25/20 milk replacer fed twice daily.

The other diet was a control diet of two litres of whole milk fed twice daily.

“Although there was significant variation between farms, calves on the fortified milk were almost five kilograms heavier and two centimetres taller by the end of the trial period,” Dr Davis said.

Due to the low incidence of calf disease observed in the trial, no significant differences in calf health were observed between the treatment groups.

Another trial conducted in winter/spring calving herds may be required to show the full benefits of accelerated calf nutrition under the study conditions, Dairy Australia said.

The estimated average total cost, excluding the cost of waste milk, to rear a calf to eight weeks of age in the control group was $33.97 while the cost to rear a calf to eight weeks of age in the fortified group was $93.27.

Dr Davis said that despite the increased cost of rearing calves on fortified milk, its potential benefits could extend beyond calfhood because an increased growth rate from birth to 12 weeks had a positive impact on mammary gland development.