Beef cattle consume primarily human, non-edible material – forage and high fiber byproducts. These feedstuffs cannot or are poorly digested by monogastric animals of which humans are one. Thus, ruminant animals, of which cattle are dominant species, are necessary to convert these abundant carbohydrates into human edible food – beef. In addition to digestion of carbohydrates, ruminants also digest the protein, vitamins, and minerals in these feedstuffs. But cattle are fed some human edible grains, primarily corn.
The question that arises is whether beef is a net nutrient contributor to the human nutrient supply. When it comes to protein, ruminants not only digest the plant protein and convert it into a human edible form, they increase the biological value of the protein, which means that beef protein meets the amino acid needs of humans better than the original plant protein. Beef has a biological value for humans 2 to 3 times that of the feedstuffs consumed in the beef supply chain. Looking at individual sectors of the beef supply, the cow-calf and stocker sectors have the greatest conversion ratio of human edible protein consumed by the cattle to human edible protein produced in beef because these sectors of the supply chain feed very little grain. Corn is the largest contributor of human edible nutrients consumed in the beef supply chain, which is why the feedlot sector has a low conversion of human edible protein.
Besides protein, beef is also a good source of many vitamins and minerals such as iron, zinc, selenium, phosphorus, vitamin B6, vitamin B12, riboflavin, niacin, and choline. Typically, absorption of vitamins and mineral from beef is greater than plant foods in addition to beef having a greater concentration of nutrients. Iron, zinc, vitamin B6, riboflavin, and niacin are absorbed 1.5 to 3 times better from beef than plant foods. Additionally, vitamin B12 cannot be produced by plants or animals, only microorganisms, and thus animal foods are the only source of vitamin B12 in the human diet.
A recent analysis evaluated the net contribution of the beef supply for these nutrients to the human diet. The beef supply chain has a net positive contribution of iron, phosphorus, riboflavin, niacin, and choline to the human diet (Figure 1). A large portion of the positive contribution is from organ meats, of which the US population does not consume much, but other cultures readily consume. Organ meats are a significant part of beef exports and the value of a beef carcass. Thus, organ meats are not only important for economic sustainability of the beef industry, but also social sustainability through reducing food security.
