Feed is the largest expense in raising dairy heifers, and one aspect of controlling feed costs is managing shrink. Michael Brouk, extension specialist at Kansas State University, defines shrink as the amount of feed delivered or grown on a farm that is never consumed. Brouk estimates that shrink may account for 5 to 30 percent of feed purchased.
As small as they are birds may seem like an insignificant source of shrink, but consider the following example. Starlings can consume up to half of their bodyweight in grain each day. If a farm has 20,000 starlings and 80 percent of them steal feed, they may be eating 1,000 pounds of grain per day.
Birds not only eat feed, they also contaminate it with feces, which may reduce intake or spread disease. Starlings eat an estimated 0.0625 pounds per bird each day, and they usually only eat concentrate. This is not only more expensive than forage, but if concentrates are eaten from the feed bunk, the remaining feed is no longer the intended ration. Facility design can limit birds’ access to bunks, and habitat and population management can help when access cannot be eliminated. Reducing feed availability during the day can help, as that is when birds feed most actively. Also, lowering water levels to at least 6 inches below the top of the waterer and maintaining water depth of at least 6 inches in the trough can discourage birds.