In a strange but promising study published last year in the journal HortScience, Bruce Kimball and others at the National Wildlife Research Center reported that white-tailed deer were consistently turned off by food sprayed with highly concentrated hydrolyzed casein (also called HC) an easier-to-digest form of the main protein in cow’s milk.
Kimball says his deer-browsing research, usually focused on large-scale reforestation and agriculture, can be adapted to home gardens by using powdered formula made for colicky babies.
Available online or at drugstores, the formula usually lists HC concentrations of 17 percent on the label. And at about $25 for 16 ounces, it costs less than many deer repellent products, he says.
Look for Enfamil Pregestimil, Nutramigen, or Similac Alimentum.
Retail sources of HC (concentrated baby formula powders) are not as effective as pure hydrolyzed protein, but do offer browse protection when alternative sources of deer food are available nearby.
Mix 2 teaspoons of Elmer’s glue in a gallon of water and spray it on your plants, then sprinkle the powdered formula over that with a grated-cheese shaker.
see this research report: Baby Formula to Repel Deer
deer damage to hosta