Among all the discussion about efficiency and sustainability in food production, beef’s critics often leave out a critical point—cattle eat things we cannot. They turn grass, corn stalks, wheat straw and byproducts such as distillers’ grains and cottonseed meal into high-quality protein for human consumption.
While it also is true cattle eat products such as corn and soybean meal, which could be used in human diets, analysis indicates beef has a good story to tell regarding the ratio of human-edible nutrients invested to human-edible nutrients produced.
During the recent Academy of Veterinary Consultants conference, bovine nutritionist Tryon Wickersham, Texas A&M University, discussed his analysis of cattle as “the original up-cyclers.”
Beef’s critics often point to pigs, poultry or fish having better feed conversions than cattle, Wickersham notes. However, simply considering calories in versus calories out does not tell the full story. Non-ruminant livestock tend to consume entirely grain-based, high-protein diets, while cattle gain weight on roughage-based diets, with, of course, some protein supplements and a shift toward corn in finishing rations.
Wickersham shared his preliminary analysis, based on assumptions that underestimate the contributions of roughage and byproducts to beef production. The figures in the table on page 12, he says, are based on assumptions from a 2014 analysis of feed conversions and livestock rations (Peters et al). That analysis used assumptions that corn provides all the non-forage energy in cattle rations, while soybean meal provides all the non-forage protein.
In the table, for example, 100% corn matches with the estimate in the Peters analysis, while 70% corn assumes 30% of the non-forage ration energy would come from other sources, and 120% corn represents a diet including 20% more corn than the Peters assumption. Note that even at 120% corn, cattle come out well below pigs and broilers in consumption of human edible protein and well ahead in net protein contribution (NPC).
Wickersham plans to refine the analysis based on real-world cattle feeding scenarios where byproducts such as distillers’ grains account for a share of the protein and energy inputs in beef production.
He also plans to incorporate other sustainability factors, such as methane production, into his future analyses. This will involve some tradeoffs, he says. Forage-based production systems provide the best gains in NPC, with cattle producing protein on diets almost entirely inedible for humans. However, cattle on forage diets produce more methane than cattle on grain-based diets.
Our U.S. beef-production system strikes a good balance between methane production and protein conversions, he says, since most cattle spend much of their lives on forage, with a shorter period of finishing on grain-based rations.
While some of the figures in this analysis might perplex typical consumers who are unfamiliar with beef production systems and ruminant nutrition, a simple message could be that cattle are more efficient than most people realize, because of their ability to convert forages and byproducts into high-quality food.