Less-expensive alternatives for milk proteins in calf milk replacer have long been sought. In many cases these proteins have been found to have lower nutritional value for the calf and a typical recommendation is that only products containing all-milk proteins be fed to calves less than three weeks of age. Alternative proteins have been seen as a cost-effective option for older calves, with the expectation that performance may be somewhat less than that possible with an all-milk protein milk replacer. New processing methods and new protein sources (plasma) may be challenging that conventional wisdom.

At the recent joint meeting of the American Dairy Science Association and the American Society of Animal Science, researchers from the University of Minnesota (Ziegler et al.) presented data on utilizing alternative protein sources. They evaluated 4 milk replacers with different protein sources; alternative proteins replaced 50% of total protein in the feeds tested. Treatments were: all-milk protein; wheat and plasma; soy protein concentrate and plasma; or wheat, soy protein concentrate, and plasma. All milk replacers were non-medicated, formulated at 20% protein, 20% fat and fed at 1.25 pounds of powder per day (12.5% solids) in 2 feedings for 35 days. Milk replacer was reduced by half beginning at day 36 and calves were fully weaned at day 42. Calf starter was available beginning from day 1, and measurements continued through 56 days.

No differences were detected in grain intake, average daily gain, body weight, or hip height. Feed efficiency during the milk feeding period was greater for calves fed protein from wheat and plasma compared to the other alternative proteins, but it was similar to the all-milk protein replacer. Feed efficiency after weaning was lower for calves fed all-milk protein compared to those fed soy protein concentrate and plasma or wheat, soy, and plasma.

When feed efficiency was calculated over the entire trial, no differences between treatments were found. Fecal scores and scour days were higher for all-milk calves, which the researchers attributed to the use of plasma protein in all of the alternative milk replacers. Previous research has shown that plasma proteins have functional benefits to the immune system beyond their use as a source of amino acids. Treatment costs for illnesses were not affected by milk replacer protein source.