Review: A historical perspective of specific milk-replacer feeding programs in the United States and effects on eventual performance of Holstein dairy calves

Early weaning Holstein dairy calf programs used low milk-replacer feeding rates and fat levels to limit feed costs, foster calf-starter intake, and facilitate rumen development. Milk replacers in those programs contained about 22% CP on an as-fed basis, from 8 to 15% fat, and were fed to wean calves at about 1 mo of age. Later milk replacers migrated to contain about 20% CP and fat, the proverbial 20/20 “industry standard.” As milk-replacer fat and milk-replacer feeding levels increased, this inversely affected calf-starter intake. The 2001 Dairy NRC Young Calf Model emerged at about the same time as a series of research trials at Cornell University and the University of Illinois began an accelerated feeding of milk replacers. These studies illustrated that increasing amount fed of milk replacers with higher protein concentration increased body protein deposition and growth rate without excessive fattening until milk-replacer fat percentage increased to 20% or more. Increasing average daily feeding rates beyond about 0.6 to 0.7 kg/d of DMI before weaning of higher protein (> 25 to 26%) milk replacers with 15% or more fat led to reduction of calf-starter intake so that daily gain during and after full weaning decreased considerably. Male and female calves in these studies seemed unable to adjust their starter intake quickly enough on high milk-replacer feeding rates to avoid major performance decreases during and after weaning. Although potential benefits of accelerated milk-replacer feeding programs were originally postulated as reducing age at first calving, recent analyses of about 10 studies indicated primary benefits may be increased first, and possibly later, lactation milk yield.