The biggest expense when producing pork is feeding pigs. In fact, feed makes up roughly 70-80% of the variable total costs to produce pork. Since 2020, the cost of feed has been rising steadily, and pork producers feel the financial pinch of lower margins.

“Over the last two years, we’ve had historically high prices for pigs, and if producers ten years ago heard these prices, they’d be ecstatic,” said Dr. Hans Stein, professor of Animal Sciences at the University of Illinois, Urbana-Champaign. “But the reality is producers have still lost money because feed costs have been increasing more than the profit from the higher pork prices. Corn prices have been very high and soybean meal prices have increased. Overall, everything has increased and therefore, it just has not been possible to make profit-producing pigs the last two years.”

Finding efficiencies in feed that complement the herd’s development can save resources and reduce a producer’s bottom line. Beyond traditional feed, additives can provide efficiencies in digestion, helping producers use less feed to get the same amount of weight gain. Additives can be advantageous during certain stages, such as post-weaning or farrowing, and can prevent disease by creating a strong immune system and intestinal health.

What nutrients do pigs need?

Swine are monogastric animals, meaning they have simple stomachs like humans. They are omnivores, capable of consuming both animal and plant matter in their diets. Pigs are fed diets that are specifically formulated by nutritionists to meet the nutrient requirements of pigs depending on the stage of production.  For example, sows are fed a diet different from that fed to newly weaned pigs. Diets that don’t meet nutrient requirements result in poorer performance, while diets above nutrient requirements increase feed cost and wasted nutrients via excretion. Hog diets are designed to provide the following six classifications of nutrients.

Carbohydrates are one of swine’s main energy sources and are typically derived by feeding grains. In the U.S., corn is the most commonly used carbohydrate source because of its cost and availability. Carbohydrates are often increased on the day of farrowing to provide sows with additional energy to support the energy demands of lactation and in finishing stages to optimize growth.

Fats and oils contain approximately 2.5 times the amount of energy as grains and are highly digestible. Supplemental fats are often added to a swine’s diet to improve the palatability of feed, decrease feed dust (which can cause illness and hinder growth), provide fatty acids and increase energy density. Fat sources include vegetable oils, such as corn, soybean or canola oil and animal fat from the rendering industry.

Proteins and amino acids are essential for growth and development. Soybean products are the most widely used protein source, such as soybean meal, fermented soybean meal, soy protein concentrate, enzyme-treated soybean meal and soy protein isolate. The amino acids present in soybean products complement those in corn to optimize lean muscle growth in pigs.

Minerals are included in swine diets because they support a variety of metabolic and biological processes.  Some, such as zinc, copper and selenium, are needed in trace amounts. While others such as, Phosphorus and calcium are needed in greater amounts since they are essential for proper skeletal growth; 96-99% of all calcium and 60-80% of all phosphorus are found in the skeletal system.

Vitamins support physiological functions such as growth, reproduction, development and maintenance. Some vitamins are produced by the pigs, while some are fed supplementally to prevent deficiencies. Vitamins that are most commonly included in swine diets are A, D, E, K, B12, thiamine, riboflavin, pyridoxine, folic acid, niacin, pantothenic acid, biotin and choline.

Water is the most consumed nutrient throughout a swine’s lifetime. It accounts for as much as 80% of a piglet’s body weight and approximately 50% of a finished pig. Fresh, clean water is available for pigs at all times.  Water flow is closely monitored to provide sufficient supply but reduce waste.

What are feed additives?

Feed additives are supplemental products used in swine diets to enhance animal health and performance. Additives may be used to improve gut health, growth, feed efficiency or to fight disease. “Not all additives are equal,” said Dr. Hans Stein. “Some are more efficient right after weaning rather than later on in growing and finishing, and some are effective through the whole cycle. Use will change throughout a pig’s life cycle and nutritionists can help determine when the right time to add is.”

The following feed additives are among the most common, but there are a plethora of additives that can be explored by a herd’s nutritionist.

Probiotics are used to strengthen the gut microbiome, which has layered benefits in swine. A healthy gut will decrease the amount of feed a pig consumes, Dr. Stein estimates between 3-4%. Additionally, probiotics are believed to prevent disease, as swine’s internal system is stronger and more likely to fend off diseases. Therefore, probiotics are a tool producers may use to reduce the need for antibiotics in swine production, combating antimicrobial resistance. Using probiotics to create a strong gut is especially relevant to piglets, which are prone to digestive disorders.

“When pigs are in the post-weaning stage, their diet is shifted dramatically from liquid milk to solid feed and they are moved to a different area,” said Dr. Yanhong Liu, director of swine research at the CLEAR Center at UC Davis. “Both of these things create very high stress, so we have to provide highly digestible, nutritious feed to help them get through this stage. Additives can be included to bolster the diet and strengthen the gut. When they have a stronger gut, they are able to fight off infections that cause post-weaning diarrhea.”

Improving feed efficiency through nontraditional ingredients or feed additives can further sustainability goals by incrementally decreasing the feed needed for each pig. While kilograms needed per pig may only decrease by 0.5-2%, this is impactful when applied across a producer’s entire herd.

“There is a lot we do with feed to better sustainability in pork production,” said Dr. Liu. “We’re using byproducts to reduce waste, we’re continuing research on feed additives to determine their potential values and we’re turning to probiotics to strengthen the gut. The gut is important because it prevents us from needing to use antibiotics to treat enteric diseases. This reduces our antibiotic use, and therefore reduces antimicrobial resistance, furthering the One Health goal for animals, people and the planet to thrive.”

Enzymes are often included in swine diets to accelerate the breakdown of nutrient components, releasing nutrients quicker for digestion and absorption. Enzymes are used to break down carbohydrates and proteins.

Carbohydrase is the name of a group of enzymes that break carbohydrates down to sugar, which is used for energy. Adding carbohydrases to diets for growing pigs or sows may improve the nutritional value of the feed and increase the inclusion rate of nutrients in the diet.

Proteases are the enzymes that break down proteins. Adding protease allows swine to utilize less digestible dietary proteins.

Phytase is an enzyme that increases the availability of phosphorus in pig diets. Phytase lowers the amount of supplemental phosphorus required in the diet by liberating the phosphorus present in the grain. This improves dietary phosphorus utilization so less phosphorus is excreted in the manure.

“While there are a number of additives that are routinely used and have been for decades, phytase is the most commonly used,” said Dr. DeRouchey. “It’s really the exception to the rule not to have the phytase enzyme in swine feed because it helps so much with phosphorous digestion. It helps us lower input cost and helps us get a balanced diet that meets requirements without any excess, so less phosphorous is excreted in manure.”

Plant-based supplements/extracts such as essential oils, herbs and spices are used for their antioxidant effects and to boost the immune system. These compounds are called phytochemicals. Research is ongoing on the benefits of phytochemicals, with a belief that they can enhance feed flavor. This, in turn, could lead to an increase in feed intake if ingredients are less palatable for swine.

Acidifiers are used to lower pH in pig stomachs to increase efficiency in digesting protein, especially in newly weaned pigs.

Zinc and copper are minerals required at trace levels. However, the addition of zinc and copper slightly above the required levels has beneficial effects on growth performance. Pharmacological dose of zinc oxide can also be used to reduce post-weaning diarrhea.

Factoring in price

Because swine are monogastric, their diet can be composed using a variety of ingredients and are adjusted based on ingredient cost. Due to the rising costs of corn and soybeans in recent years, it is becoming harder to make a profit on each pig. Swapping high-cost feed ingredients with less costly ingredients and including additives can combat high feed costs while still meeting the pig’s nutrient requirement.  Nutritionists work with producers to determine if feed additives would be beneficial to generate cost savings.

As prices for soybeans rise, alternative sources of protein can be substituted into swine diets. These include plant-based meals (canola meal, peas, sunflower meal, peanut meal), animal co-products (meat and bone meal, fish meal, etc.), grain co-products (dried distillers, corn gluten meal, wheat middling’s) and synthetic amino acids.

Feed ingredients and processing further sustainability goals

Feed additives increase swine’s digestive efficiency, decreasing supplies needed to feed a herd. Fully-grown hogs can eat anything, but they are actually picky eaters, so using additives to increase the palatability of feed enables producers to feed them cost-effective ingredients or mask additives that might not taste good.

Byproducts from other industries can be fed to swine to reduce feed costs. For example, corn used to produce ethanol results in unused corn byproducts that can be fed to pigs. Byproducts from manufactured foods such as cereal or baked goods may also be included in swine feed.

The way swine are fed is another area to save incremental costs. Grinding feed ingredients into meals or pelleting the complete feed can increase feed efficiencies of 3-5% per pig. The feed pan should only be 40-50% full, so waste is reduced as pigs drag feed out of the pan and into the pit. In-barn practices are used to control these factors and reduce feed waste.

The CLEAR Center receives support from the Pork Checkoff, through the National Pork Board.