Calves reared for veal are usually transported from the dairy farm to the rearing unit during the first 2 weeks of life. The vigour of calves after arrival at the rearing unit is dependent on:

• Their vitality before leaving the dairy farm (colostrum quality and quantity, timing and hygiene)
• Duration and nature of the transfer (climatic stresses, deprivation of milk and water, handling, noise)
• Changes in environmental conditions (mixing calves, high infection risk, change in housing system, climate, feeding level and composition etc.)

Calves are especially vulnerable to infections and diseases. All the above factors may reduce the calf’s ability to fight new disease challenges.

The period of 2 to 3 weeks after arrival at the rearing unit is considered the most critical phase in veal production. The priority during this period is not only to optimize growth but more importantly to control and minimize the occurrence of health disorders.  (J.Schrama et al, J.Dairy Sci.1992)
 
After arrival at the veal unit, the appetite of these calves may be low. The importance of feeding a high energy, quality milk replacer is paramount in maintaining the calf’s thermoneutrality and optimizing growth and the immune system. These young calves tend not to be in a steady state of energy metabolism. If low levels of feed are offered and the calf’s energy requirement for maintenance is not met, then the calf will be partially dependent upon the mobilization of body energy reserves to meet energy requirements. This will reflect in low or negative growth rates. (Postema 1985)

Heat production is an important criteria in calf survival at this young age. Heat production decreases with time during this 2-week period and is affected by feeding level and ambient temperature. i.e. At low feeding levels, animals are less cold tolerant. (Schrama, 1993)

Nutrition

Restricted feeding can impair the immune system. (Kelly, 1980)
Calves fed a higher amount of milk replacer (600g vs 400g/d) and ad-libitum access to calf starter had the greatest gains and the least mortality. (Williams et al, 1981)
Low level of nutrition results in impaired immune response in young calves. Griebel et al, 1987; Pollock et al. 1993,1994.

Stress can affect the apparent digestibility of energy and thus utilization of feed ME. (Schrama, 1993).
If feed is restricted, digested dietary protein is used as an energy source. (Mcdonald et al, 1981) This will negatively affect protein gains and will increase the production of urea and energy loss via urine. This is not an efficient use of feed supplied.

Conclusion

Energy shortage (by low feeding levels or inappropriate ration) in newly purchased calves is undesirable since it may be a predisposing factor for health disorders.

Newly purchased calves should be fed an adequate level of a high quality balanced milk replacer to overcome stress challenges and provide for optimum growth.

Andre Roy MSc.
Sally Charlton BSc. (Hons)
 April 2003