As with dairy production, poultry products are marketed with the assistance of provincial marketing agencies. These agencies were established by the 1960s. Previous to the 1960s the poultry industry went through many cycles of growth and collapse which resulted from uncontrolled surplus and shortages of product. Provincial regulatory agencies alone did not have the power to regulate production. Different regions of Canada have a comparative advantage (including cheaper abundant supplies of feed) over other areas for the production of poultry products. Without provincial trade barriers, poultry produced in any area of Canada could be shipped between province and marketed at a lower price driving other producers out of business and reducing the stability of the market. For this reason, the federal government became involved in the regulation of interprovincial trade in the 1970s, by granting power to the Canadian Broiler Council to control movement of product between provinces and in and out of Canada. Today, poultry products including chicken, turkeys and eggs are marketed through provincial marketing agencies which are regulated by national agencies. It is the responsibility of these national agencies to dictate the quantity of product to be produced by each province based on it's population. In addition to regulating the quantity of meat produced in Canada, there are also a program for the inspection and grading of eggs. Grading stations are responsible for the storage, washing, drying, candling, grading, packing, storage and delivery of eggs. During this time eggs are kept in cool and humid coolers to maintain their quality. Eggs are washed to remove manure or shell contaminates. A sanitizing detergent may be added to the water to reduce bacterial numbers. After washing, eggs must be dried to prevent bacterial populations from multiplying on the shell surface. After drying, eggs may be sprayed with a light coat of oil to seal their shell and prevent moisture loss. Eggs will be graded based on their weight, shell quality and interior quality. All eggs must meet standards set and enforced by Agriculture Canada. The internal characteristics of the egg will also be graded, considering albumin (egg white) and yolk quality, and presence of blood and meat spots. After inspection, eggs will be given one of four grades (A1, A,B,C). Grades A and A1 meet the requirements for table eggs, while B and C grade eggs are suitable for processed egg products. Eggs which do not meet strict requirements are removed.