While genetics clearly play a key role in cow production measures, epigenetics (the environmental impacts on how genes are expressed) is coming into the light when looking to maximize calf potential. Several benefits have been seen in high quality nutrition and growth in the early period of life, including udder development and immune function. Whilst not being the only contributing factor, higher pre-weaning growth rates have been linked to increased milk production in first lactation.
The largest economical factor in heifer rearing is age at first calving. Aside from epigenetics, meeting growth rate targets in the first 6 months make age at first calving targets more achievable. Age at first calving of 22-24 months has been shown to result in higher lifetime yields and increase survivability to subsequent lactations (Faber et al 2005). Feeding an intensive pre-weaning diet has been linked to a 27 day reduction in age at first calving in a 2009 study (Raeth-Knight et al 2009).
Calves fed on higher planes of nutrition have been seen to have improved immune responses to disease (Ballou et al 2012). This seems logical as calves require energy for maintenance, warmth, growth and immune function. Calves receiving inadequate energy levels will have a reduced capacity to mount an immune response.
What is an intensive diet?
Intensive or accelerated pre-weaning diets typically offer dry solid intakes of over 1kg per day to achieve pre-weaning growth rates of over 0.8kg per day. Accelerated diets are more suited to automated feeders or three times per day feeding, that being said, with suitable milk powder* twice a day feeding of around 3.5L per feed can be achieved without negative effects of bloat or nutritional scour.
How to ‘switch on’ epigenetics?
Optimise Colostrum management – a 2005 study found calves fed 4L of colostrum had higher growth rates and produced more milk (>1000kg) in their first 2 lactations
Feed a high quality pre-weaning diet designed to meet growth rate targets >0.8kg/day
High volume milk feeding requires consideration, as not all milk powders are suitable for large volume feeds
Reduce disease challenges with an optimal environment – see our previous article on What makes a good rearing system
Maintain growth rates during and post weaning with a strategic weaning plan
Weaning calves on high volume milk diets can be more difficult than those fed on a moderate or restrictive diet – planning is essential.
*suitable milk powders should provide high levels of milk protein with an osmolality similar to whole milk.
If you’re ready to find out more about assessing milk powders and Youngstock Nutrition check out our online courses.
Faber, S.N., Faber, N.E., McCauley, T.C. and Ax, R.L., 2005. Effects of Colostrum Ingestion on Lactational Performance, The Professional Animal Scientist 21:420 – 425.
Raeth-Knight, M., H. Chester-Jones, S. Hayes, J. Linn, R. Larson, D. Ziegler, B. Ziegler, and N. Broadwater. 2009. Impact of conventional or intensive milk replacer programs on Holstein heifer performance through six months of age and during first lactation. J. Dairy Sci. 92:799–809.
Ballou, M.A. 2012. Immune responses of Holstein and Jersey calves during the preweaning and immediate postweaned periods when fed varying planes of milk replacer. J Dairy Sci