Why has the 20:20 Milk Replacer Been the Industry Standard

For many years milk replacers containing 20 per cent protein and 20 per cent fat fed at a rate of 1 lb. of powder per day have been commonly accepted as the best diet for dairy calves, but why? asks RE James, Extension Dairy Scientist at Virginia Cooperative Extension.
calendar icon 28 July 2012
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The powder was diluted with water to yield one gallon of liquid with about 12 per cent solids.

Why? At the time these recommendations were developed, the goal in raising dairy calves was to provide limited nutrients from milk powder to encourage calves to eat dry calf starter and thereby promote early weaning and low daily rearing costs for the preweaned calf.

However, given that the dairy cow produces far more than one gallon per day from the beginning of her lactation and that on a solids basis it contains more than 25 per cent protein and nearly 30 per cent fat it’s obvious that this practice creates some serious challenges for the preweaned calf.

One pound of milk or milk replacer solids is barely enough nutrition to support 200g of gain per day when the temperature is 60oF. As the temperature drops to 46oF, there isn’t enough energy to support any gain and the calf will begin mobilizing body fat. The consequences of limit feeding calves are higher mortality and disease as demonstrated by a Minnesota study where 52 per cent of calves fed this diet were treated for disease during the winter and approximately 13 per cent during the summer.

In this same study, calves fed pasteurized cow’s milk had corresponding treatment rates of 20 per cent and four per cent.

Extensive research conducted at multiple universities—as well as feed company research—indicates a positive relationship between the composition of the liquid diet fed to calves and their growth, health, and performance once they reach the milking herd. Feeding recommendations are heavily dependent upon environmental conditions, but indicate that feeding at least 1.5 to 2.5 lb. of milk or milk replacer solids per day which contains 25 per cent protein supports optimal growth and later performance.

Desired fat content of the dry matter portion of the diet can vary from a low of 10 per cent (summer) to as much as 30 per cent during the coldest weather. These diets have commonly been referred to as “intensive” or “accelerated” programmes when “biologically normal” is probably more appropriate.

The greatest risk in feeding limited amounts (1 lb. powder or one gallon liquid) of a 20:20 milk replacer occurs during the first two weeks of life when calf starter intake is minimal regardless of the liquid feeding programme.

Preweaned calves should double their birth weight by the time the reach 60 days of age. This requires an average daily gain of only 1.5 lb. per day for Holsteins and about 1 lb. per day for Jerseys.

“Biologically normal” feeding programmes will cost more per day. The return is in a lower cost per unit of gain, improved health and less treatment for respiratory disease and scours and higher production during the first lactation.

Cornell studies found that each lb. of average daily gain during the preweaning period was worth more than 1,000 lb. of milk in the first lactation. Cutting feed cost by limit feeding calves a 20:20 milk replacer is a short sighted management decision which sacrifices future health and productivity of the animal.

July 2012

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