Dairy Manufacturers, Inc.

Articles

"Evaluating Milk Replacers for Calves"
Mike Watkins, Ph.D.
Dairy Manufacturers, Inc.

“The most expensive milk replacer a calf raiser can buy is a poor-quality one.” This is especially true when it comes to feeding calves during the first three weeks of life. The following points should be helpful when evaluating different milk replacers.

Protein

Protein quality and quantity greatly influences the feeding value of milk replacers and therefore calf performance. The protein content of milk replacers generally ranges from 20%-28%. The protein found in milk replacers is from either all-milk proteins or from non-milk proteins plus some milk proteins. Milk proteins (dried non-fat skimmed milk, dried whey, dried whey protein concentrate, dried milk protein concentrate, etc.), compared to non-milk proteins, have a higher feeding value, are more digestible, have a complete amino acid pattern, and are more palatable. Non-milk proteins (soy flour, soy concentrate, soy isolate, dried whole egg, dried fish solubles, dried brewers yeast, potato protein, and the like) have a lower feeding value due to such factors as indigestible fiber, anti-nutritional factors, an incomplete amino acid pattern, and possibly containing high levels of sodium or other compounds used in their production.

The most popular milk replacers are all-milk and contain about 20% to 22% protein. New recommendations are for feeding a 28% protein milk replacer. Calves gain faster and the gain is more muscle when fed higher-protein milk replacers properly balanced with the energy content, and their performance is nearer that of calves fed whole milk. Calves younger than three weeks old should be fed only all-milk milk replacers. Milk replacers containing non-milk proteins have lower feeding values and tend to be less costly depending on the amount and kind of non-proteins used. These kinds of milk replacers should be fed only to calves over three weeks of age, when the rumen becomes sufficiently functional to digest lower-quality ingredients.

Energy

The guaranteed fat level is the primary indicator of the energy content of a milk replacer… the higher the fat level, the higher the energy content. Dried whole milk contains from 26% to 30% fat while most milk replacers contain from 10%-25% fat. Dry fats from vegetable oil (hydrogenated soy oil) or animal fat (lard or tallow) are the major fat sources used in milk replacers. The fats should be stabilized and void of any rancidity. Higher fat levels should be balanced with the protein content to maintain efficient nutrient utilization for lean gain rather than excess body fat. Feeding rate is often a bigger factor in limiting energy consumption, especially during the winter months.

Milk sugar, lactose, is the other significant energy source in milk replacers. Lactose may represent as much as 50% of the dry matter. Fat, pound per pound, contains about 2.25 times the energy of lactose. Calves can utilize glucose and galactose (the two monosaccharides which compose lactose) for energy, but milk replacers containing fructose (corn syrup), sucrose (table sugar), maltose (corn sweetener), and starches should be avoided. Young calves cannot digest starch because amylase, the starch-digesting enzyme, is not present. Starch and fiber from soy flour and cereal grains yield energy in the form of volatile fatty acids once rumen function is sufficient.

Fiber

Fiber dilutes the energy content and decreases the digestibility of milk replacers. Crude fiber guarantees less than 0.15% generally indicates an all-milk milk replacer while guarantees greater than 0.15% indicates the milk replacer contains some non-milk protein (e.g., soy flour). Plant protein isolates are high in protein and low in fiber; therefore, it is always important to read the ingredient statement regardless of the fiber guarantee to know just what proteins are in the milk replacer being considered. Milk replacers with 0.15% or less crude fiber may still contain some plant proteins. The decreased digestibility due to using non-milk proteins is partially compensated for by feeding a product containing at least 2.0% more protein for each 1.0% of crude fiber. As noted earlier, high- fiber milk replacers are usually “economy” products because cheaper ingredients are used, and the cost is reflected in the price. And, price usually reflects quality.

High-quality milk replacers are made from highly digestible proteins and high-quality fats supplemented with water-soluble vitamins and water-soluble or readily suspendable minerals at levels that meet or exceed National Research Council recommendations for young calves. A 20-20 all-milk milk replacer meets the needs of many calf raisers; however, more and more calf raisers are finding that feeding a 28-15 all-milk cost more up front but pays off when more heifers enter the milking herd earlier and produce more milk.