Growth Promotants and the Environment

This article written by Dr. Reynold Bergen, BCRC Science Director, originally appeared in the October 2021 issue of Canadian Cattlemen magazine and is reprinted on the BCRC Blog with permission of the publisher.
growth promotants improve feed efficiency of beef cattle and also have environmental benefits
Growth promotants dramatically improve the growth rates and feed efficiency of beef cattle. Trenbolone acetate (TBA) behaves like testosterone and is used in several feedlot implants (Component, Revalor, and Synovex). Melengestrol acetate (MGA) behaves like progesterone, a pregnancy hormone. Some feedlots feed MGA to suppress estrous cycles and riding activity in heifers until a few days before slaughter. Ractopamine (Actogain, Optaflexx) is a feed additive that improves weight gain, feed efficiency and leanness in the last 28-42 days before slaughter.

Growth promotants also have environmental benefits; reducing the number of days (and amount of feed) needed to finish cattle means fewer days producing greenhouse gases and manure, and less water, feed and fossil fuel inputs per pound of beef.

Animals metabolize and excrete these growth promotants over time – that’s why growth promotant residues in beef are too low to pose any risk to consumers. But do these excreted residues and metabolites pose a risk to the environment? How long do they persist in soil and manure, and is there a risk they could enter surface or groundwater?

A Beef Cluster study led by Frank Larney and co-workers at Agriculture and Agri-Food Canada’s Lethbridge Research & Development Centre and the University of Saskatchewan’s Toxicology Centre is examining these questions. Their first study was published earlier this year (Ractopamine and Other Growth-Promoting Compounds in Beef Cattle Operations: Fate and Transport in Feedlot Pens and Adjacent Environments; Environmental Science & Technology. DOI: 10.1021/acs.est.0c06450). Continue reading

Ractopamine angst

Russia’s decision to ban imports of meat that may have been produced using ractopamine has led to increased questions about livestock growth promotants. Ractopamine is a beta-agonist used by many cattle feedlots near the end of the feeding period to increase growth rate, feed efficiency, and carcass leanness.

Like vaccines and other veterinary products, all growth promotants Continue reading

Explaining Growth Promotants Used in Feedlot Cattle

Feed efficiency in cattle can make or break profitability in the feeding sector, and has environmental implications. The costs of buying a calf and the feed needed to finish it are the two largest variable expenses facing the beef cattle feeding sector. Feed costs are higher than ever because of poor growing conditions in major grain producing countries, because of the use of feed grains in ethanol production, and because of increasing competition of land for crop production versus urban development.



Growth promotants are among the many sophisticated tools used by feedlots and other producers to raise more beef, more rapidly, using less feed, while maintaining high standards of animal health, carcass quality and food safety. Growth promotants include ionophores, growth implants, and beta-agonists. A number of products within each category are approved for use by Health Canada’s Veterinary Drug Directorate. Continue reading