Milk Replacer for lambs with Probiotics Lamb Milk Replacer with probiotics for lambs is great for gut health and digestion. It?s easy to mix and includes the protein needed for growth and development. All-milk protein supports growth and development. Powered by Opti-Gut? to support gut health and digestion. Easy to mix for fast prep and optimal consumption. The Science Behind Opti-Gut: Opti-Gut is a blend of natural ingredients, including both contents of the yeast cell and probiotic bacteria. Together, these ingredients help control harmful bacteria and support the population of good bacteria in the digestive tract.