Some variation exists in the protein and fat composition of milk from beef cattle. Some data indicate that fat percentage ranges from 2.5 to 6.5% and that of protein from 3.0 to 4.0%. The range for protein percentage appears to be narrower than that of fat. The variation in fat percentage may be due to genetics in beef cattle. For example, some breeds’ strengths are in carcass composition, and typically these breeds do not excel in milk production. Also, some beef breeds are considered dual-purpose breeds, meaning they were designed for both beef and milk production. One would conjecture that dual-purpose breeds would have a greater fat percentage, but the data do not always bear that out. Data on the relationship between milk fat and marbling (IMF) in the carcass are hard to find in the literature. However, dairy breeds (Jersey, Holstein) tend to marble at a higher rate than beef breeds. Fat percentage in milk from Holsteins has a pretty narrow range (3.3 to 3.9%), and that from Jersey is greater but still pretty narrow (4.3 to 5.0%). Most breeds of beef cows would have fat composition within these ranges.