The diet of the preweaned calf is the single most expensive diet on the farm. The traditional wet calf feeding program was based on limiting milk consumption to facilitate starter intake in attempting to achieve an appropriately developed rumen system to minimize stress through the weaning process. An alternative approach to wet calf feeding is what is referred to as a natural growth or accelerated growth calf rearing program. In this approach, larger quantities of liquid feeds are fed during the preweaning period, allowing for a greater expression of the calf’s growth potential. Both feeding programs require proper colostrum feeding management.
In feeding larger quantities of liquid feed, rumen development will be delayed because it depends on solid feed fermentation generating volatile fatty acids (ie, butyrate and propionate). In this system, weaning is often delayed, taking advantage of greater growth rate and improved health. The delay in sufficient solid feed consumption (relative to traditional programs) requires a gradual rather than abrupt weaning process to ensure sufficient rumen development to make a successful transition to solid feed. An important aspect of this approach to calf feeding is to ensure sufficient feeding practices after weaning to ensure continued growth efficiency and minimize postweaning growth depression.
After weaning, forage is not offered until heifers are >3 months old. Dietary protein concentrations during the pre- and postweaning periods are increased (relative to traditional programs) to assure adequate lean gain and to avoid excessive fattening. Rates of gain can be as high as 1 kg/day, with heifers entering the milking herd at 22–23 months old. Close monitoring is necessary to assure that heifers have adequate frame development and do not become excessively fat. The accelerated growth program has been advocated based on calf health as well as increased milk production at first lactation, although not all studies support this contention. To realize a return on investment requires improved animal health, reduced age at first calving, and increased milk production. Most financial studies generally do not show a positive return compared to traditional calf feeding programs that achieve similar age at first calving.