The expenses of purchasing a calf and the feed needed to finish it are the two largest variable costs facing the cattle feeding sector. Using less feed to finish a calf would substantially improve profitability in beef production, and may diminish environmental implications. Feed costs are high due to 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.
| Key Points |
|---|
| The feed to gain ratio (F:G) is a key measure of efficiency. Also known as the feed conversion ratio (FCR) |
| Because of the variability of water content, feed is measured by dry matter (DM). |
| Steers fed higher grain diets grow faster, finish sooner, and produce heavier and fatter carcasses. |
| Processing methods such as steam flaking has been shown to improve feed efficiency versus dry rolling. |
| Growth promotants are among the many sophisticated tools used by feedlots and other producers to raise more beef, more rapidly, using less feed per kg of beef produced, while maintaining high standards of animal health, carcass quality and food safety. Growth promotants include ionophores, growth implants, and beta-agonists. |
| Ionophores are antimicrobials (which are categorized as ‘Low Importance’ in human medicine and are not used to treat bacterial infections in humans) delivered through cattle feed that improve nutrient availability to the animal. They can improve feed efficiency and weight gain, reduce methane production, reduce the incidence of bloat and acidosis, and prevent diseases like coccidiosis. |
| Growth promoting implants are small pellets, containing natural or synthetic compounds that promotes a response similar to the animal’s natural hormones, applied under the skin in the middle part of the backside of the animal’s ear. They generally encourage protein deposition and discourage fat deposition which improves both weight gain and feed conversion. |
Feed to Gain Ratio
The feed to gain ratio (F:G) is a key measure of efficiency. Also known as the feed conversion ratio (FCR), F:G is a measure of an animal’s efficiency in converting feed nutrients into increased body mass. Lowering the F:G ratio will reduce the cost to finish cattle. Efficiency may also be expressed as gain to feed or G:F in which case a higher number is more desirable. Greater G:F means that the animal is putting more weight on for each kg or lb of feed consumed.
Because of the variability in water content of the different feedstuffs, the animal’s feed intake or consumption expressed on dry matter (DM) basis or free of moisture. This is because the DM portion of a feedstuff is what actually provides nutrients to meet the animal’s requirements for maintenance and growth. This allows more accurate comparison of different diets or feedstuffs.
Imagine two steer calves placed on feed. Both steers are gaining an average of 3.5 pounds per day (1.59 kg/day). Over time, we measure that Steer A consumes an average of 21 lbs (9.53 kg) DM per day, which equates to a 6:1 feed to gain ratio. Steer B consumes 28 lb/day (12.70 kg/day), a F:G of 8:1, and therefore is less feed efficient than Steer A. Based on a ration cost of $187/tonne* (or 0.085 cents per pound), Steer A costs $1.79 to feed per day. Steer B costs $2.38 per day. If both steers reach their finish weight in 200 days, the less feed efficient animal (Steer B) would cost the producer $119 more to finish than an animal with better feed efficiency (Steer A). (*Note: this example may not reflect current feed costs.)
This example illustrates the importance of improving and maximizing feed efficiency in cattle on feed, which can make or break profitability in the feeding sector.
Progress of Feed Efficiency Research
Assuming current feed costs, a further 1% improvement in feed to gain would save the feedlot sector $11.1 million annually.
Numerous research projects over the years have successfully led to substantial improvements in growth rate, days on feed, carcass weight and feed to gain.
Since the 1950’s, feed to gain has improved markedly due to research and development of new practices and technologies. Over the past 30 years, feed to gain has improved by 30%. Notable improvements were accomplished due to research on diet formulation and feed management, factors affecting grain and forage quality, grain processing, and growth promotants.
Diet Management
Substituting forage with grains in finishing rations can lead to substantial improvement in feed efficiency. Steers fed higher grain diets grow faster, finish sooner, and produce heavier and fatter carcasses. Research also suggests that the type and quality of grains and the balance of essential nutrients, like vitamins, proteins, and trace minerals, significantly impact feed efficiency. Balanced rations increase average daily gain and can decrease feed cost per pound of gain. In order to prevent rumen acidosis and liver abscesses, it is necessary to appropriately adjust cattle from forage-based feed to high-energy grain-based rations. It is important to note that depending on where you are in the country, the economics of feeding cattle forage vs grain and what is efficient and economic growth may be different. Very high grain prices may justify higher forage inclusion rates and reduced rates of gain while still remaining profitable. Ration balancing software programs such as CowBytes can also be used to look at cost comparisons of different rations based on your local input costs.
Grain Processing
Digestibility of grains like corn, barley, wheat and oats is improved when grains are processed. Processing methods such as dry rolling, temper rolling, and steam flaking have been shown to improve feed efficiency. The processing method needed to maximize grain digestion will vary depending on the grain type. For example, to maximize corn digestion, reduce fecal loss, end improve feed efficiency a more intensive processing (i.e. steam flaking) will be needed. However, for barley similar improvements can be done by proper dry or steam rolling. By cracking the outer shell of the grain during processing, rumen microbes are better able to utilize grain starch and minerals. Processing also allows grain to be mixed with supplements and affects palatability and passage rates. However, processing grains too finely leads to acidosis. Fine tuning grain processing contributes to an improved F:G.
Growth Promotants
Analysis indicates that production costs would be 10% higher if producers did not use implants, ionophores or beta agonists.
Growth promotants are among the many sophisticated tools used by feedlots and other cattle operations to produce more beef, faster, using less feed, while maintaining high standards of animal health, carcass quality and food safety. Growth promotants include ionophores, in-feed estrous suppressants (for heifers), growth implants, and beta-adrenergic ligands. A number of products within each category are approved for use by Health Canada’s Veterinary Drug Directorate and the Canadian Food Inspection Agencies Compendium of Medicating Ingredients Brochure.
One study2 found that overall average daily gain was 21% higher and feed efficiency was 23% better for grain-finished cattle given both implants and ionophores compared to control cattle. Economists John Lawrence and Maro Ibarburu at Iowa State University reported that feedlot average daily gain increased when ionophores, implants, and beta-agonists were used by 3%, 16% and 16% respectively. Feed efficiency improved 4% with ionophores, 10% with implants, and 14% with use of beta-agonists.
Ionophores
As with all refined technology, appropriate and optimal use of growth promotant products can improve animal performance and value, while improper use result in no benefit, reduced carcass value, and/or lost money.
Ionophores are antimicrobials delivered through cattle feed that improve nutrient availability to the animal and prevent diseases like coccidiosis. There are different types of ionophores but the most used in Canada is monensin.
Monensin improves feed efficiency by acting on rumen microbes. Ruminal microbes breakdown complex fiber and starch in forage and grain into simple molecules (short-chain fatty acids, i.e. acetate, propionate and butyrate) that can be absorbed into the bloodstream to provide energy to the animal. By doing this, ruminal microbes also acquire energy for their growth/reproduction, and as they leave the rumen and reach the small intestines, they become a source of protein to the animal. Monensin improves feed efficiency and weight gain by selectively inhibiting the growth of a group of ruminal bacteria (gran+). Consequently, there is an increase in propionate and a decrease in acetate and butyrate production in the rumen during the breakdown feeds. When acetate and butyrate are formed it promotes the production of methane gas in the rumen, but when propionate is formed it promotes a reduction in methane. Methane contains energy, but it cannot be absorbed by the animal, so it is belched out and wasted. By promoting more propionate production and less methane production, monensin reduces energy losses during feed digestion, making more feed energy available to the animal.
Ionophores are often erroneously included in discussions about the concern of antimicrobial use in livestock and the potential link to antimicrobial resistance in humans. These antimicrobials are categorized as “Low Importance“ in human medicine, meaning they are not used to treat bacterial infections in humans, and therefore reducing or eliminating their use would have detrimental impacts on cattle production with little or no benefit for human health. When advocate groups spread statistics like “over 80 percent of all antibiotics used in the United States are used in food animals, and the vast majority of this use is for animals that are not sick,” they not only ignore the much higher populations and body weights of livestock compared to Americans, they include ionophores in the calculation.
Hormonal growth implants
Other growth promotants impact how nutrients are used by the animal after the nutrients have been absorbed into the bloodstream. Growth implants, delivered through a pellet under the skin in the back of the animal’s ear, enhance the reproductive hormones that occur naturally in the animal. In steers, implants replace some of the hormones that were removed when the animal was castrated.
Implants generally encourage protein deposition and discourage fat deposition. This improves both weight gain and feed conversion. Fat deposition requires more than twice as much feed energy as protein deposition does. In addition to this, muscle tissue contains around 70% water, while fat contains less than 25% water. This means that for every ten pounds of muscle gained, about three pounds comes from dry feed and seven pounds comes from water. This ratio is reversed for fat growth (roughly seven pounds from dry feed and three pounds from water). Very aggressive implant regimes may negatively impact carcass quality (maturity, marbling score, tenderness, and possibly lean color), especially if used on the wrong types of cattle.
Growth implants combined with ionophore feed additives are effective in feedlot programs. Research has shown that the growth implants produce improvements of 15 to 25% in average daily gains and 5 to 10% in feed efficiency; while the ionophore feed additives, in combination with the growth implants, will reduce the amount of feed required for a given amount of gain by an additional 7 to 8%.
Growth promotant safety has been reviewed by many experts and agencies, including Health Canada, the World Health Organization and the Food and Agriculture Organization of the United Nations. All have concluded that hormones can be used safely in beef production. The levels found in food products, such as beef, are too low to be of risk to human health.
To put these levels into perspective, consider the levels of estrogens that occur naturally in all plants and animals, including humans. This table shows that a person would have to eat 3 million hamburgers every day from cattle administered growth hormones before he or she would be exposed to as much estrogen as average women produces daily.
Testosterone-containing implants are similar; there is a safety factor of several thousand-fold based on the assumption that people consume the equivalent of 6 to 7 servings of beef per day.
Beta adrenergic agonists
Beta-adrenergic ligands are the newest class of growth promotants, commercially available since 2004. These feed additives are not antimicrobials, and do not mimic or supplement reproductive hormones. Asthma medications are also beta-adrenergic ligands.
‘Beta adrenergic ligands are substances that binds to a beta-adrenergic receptors on the muscle cell surface. These ligands can be agonists and antagonists of the different beta-adrenergic receptors present in the cell’s surface. These beta-ligands in general re-directs nutrients for more muscle tissue growth and increase the efficiency of energy utilization by the animal. In the animal’s body there is always protein synthesis and breakdown happening. These products promote muscle protein synthesis and decrease the breakdown, consequently promoting muscle hypertrophy.
All beta-ligands approved for beef cattle (e.g. ractopamine and lubabegron) increase protein deposition (muscle growth), growth rate, feed efficiency, and carcass leanness. These products also have shown to consistently increased dressing percentage by about 0.5% unit (e.g. 60.0 to 60.5%). Beta-ligands are fed at the end of the feeding period, when muscle growth is slowing, fat deposition is speeding up, and feed efficiency is dropping off.
It is important to highlight that the latest beta-adrenergic receptor ligand approved for feeding in Canada (lubabegron) in 2022 was approved with an environmental claim for reducing ammonia gas emissions (~13%) and not for improving feed efficiency.
As with aggressive implants, beta-ligands must be managed appropriately, on the right class of cattle in order to avoid negative consequences on carcass quality. The benefit of feeding beta-ligands can be lost if the product is fed for too long, or if the delay between product withdrawal and slaughter is too long.
Concerns about the use of beta-ligands in livestock are popular in the media. Some importing nations have a zero tolerance policy for certain kinds of beta-ligands, which also make their use an issue in some trade negotiations. In fact, a person would have to eat more than 180 servings of beef per day, or 30 servings of liver per day, from cattle administered beta-agonists in order to get the effect of one “hit” of asthma medication.
Determining Finished Weight
Determining when an animal has reached its finished weight is an important aspect to feed efficiency. Once an animal’s rate of gain slows, most of the feed consumed is converted to waste fat rather than useable meat, and therefore is not cost effective. Producers can weigh and track individual animals or pens in order to track gains and determine when finished weight is reached.
Genetics
In addition to management practices that optimize feedlot feed efficiency, selecting cattle that are genetically feed efficient is important. Much research has been done to make genetic improvements in feed efficiency by measuring Residual Feed Intake (RFI). Advances in producing terminal animals through crossbreeding also maximize gains, grading and dressed yield.
- References
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1. F. Whiting. 1957. The effect of concentrate to hay ratio and other ration factors on the feedlot performance of beef cattle. Canadian Journal of Animal Science, 37, pp 50-57
2. L. Faucitano, P. Y. Chouinard, J. Fortin, I. B. Mandell, C. Lafrenière, C. L. Girard and R. Berthiaume. 2008. Comparison of alternative beef production systems based on forage finishing or grain-forage diets with or without growth promotants: 2. Meat quality, fatty acid composition, and overall palatability. Journal of Animal Science, 86, pp 1678-1689
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Acknowledgements
Thanks to
- Dr. Jock Buchanan-Smith, retired University of Guelph professor and researcher of beef cattle nutrition and management,
- Dr. Katie Wood assistant professor University of Guelph, and
- Dr. Gabriel Ribeiro, Saskatchewan Beef Industry Chair, University of Saskatchewan,
for contributing their time and expertise to writing this page.
This content was last reviewed February 2025.