With the wide variety of milk replacer products on the market, the complexity of their ingredients, and the fact that additives such as vitamins, probiotics and medications can easily be supplied through milk replacer leaves many producers feeling like they need an animal nutrition degree to determine what to feed their calves. Consequently, much work has been completed to analyze and evaluate milk replacers from complex chemical and microbiological standpoints.

While price is often a consideration for producers in the market for milk replacers, ingredients from the following categories are also important factors in selecting the best milk replacer for long-term results.

Protein
The recommendation for milk re-placer protein level is 20 to 28 percent. Higher protein levels usually coincide with higher milk replacer feeding rates designed to increase calf growth. Proteins are typically the most expensive milk replacer ingredients, with many different protein sources formulated into milk replacers.

It is important to remember that there are a variety of sources for the protein in milk replacer, and these vary in their bioavailability to the calf. Milk Proteins are typically more digestible than non-milk proteins and provide a desirable amino acid profile for calf growth. Protein amounts, source (where the protein came from), and antinutritional factors should be considered when evaluating protein in milk replacer.

Energy
The primary sources of energy in milk replacers are fats and carbohydrates. Fat is the most concentrated energy source in milk, providing 2.25 times the energy that a carbohydrate offers. Calf milk replacers are typically formulated with 15 to 24% fat. High fat milk replacers provide more energy and are often used in colder climates which necessitate higher energy requirements, while lower fat formulas are sometimes used in hot climates and in formulations designed for intensive milk replacer feedings that support higher rates of gain. Fat provides necessary fatty acids for calf development and should be highly digestible and contain an antioxidant.

Producers should remember that the most optimal milk replacer offers ideal protein-to-energy ratios.

Vitamins and minerals
Vitamins play an important role in metabolism and are involved in enzyme systems. The young calf has limited storage of vitamins, making it dependent on dietary sources of these essential nutrients. Milk replacer should contain adequate contents of vitamins A, D, and E. Minerals are important for the structural development of the calf. They are an important part of body fluids, playing a critical role in maintaining acid-base balance and nerve transmission.

A note about plasma
There have been at least 30 research trials conducted to evaluate the effects of animal plasma on the growth and performance of baby calves. In these trials, plasma always performed as well as or better than all-milk protein milk replacers.

The choice of milk replacer should be made only after careful consideration of the requirements for the specific calf operation. While there are general guides for a quick milk replacer evaluation, the value of a consultation with a qualified nutritionist can not be diminished.