Applied Nutrition for Optimal Gut Health and Pig Performance

Dr Chad Hagen (Hagen Swine Consulting) offers suggestions how to improve feed conversion and make the difference between profitability and loss as margins in pork production become ever narrower. The paper was presented at Alpharma's Swine Enteric Health Symposium 2008.
calendar icon 27 January 2009
clock icon 12 minute read


The US feed commodity market has experienced a rollercoaster ride in price fluctuations the past 18 months. Corn price has gone from an average of about $3.30 per bushel in 2007 to more than $6.50 in the summer of 2008 to current levels of about $4.00per bushel. During that same period, the price of 46.5 per cent soybean meal has gone from about $220 per ton to as much as $400 per ton, and is now trading around $270 per ton. Similarly, feed cost for a pig from 50 to 260 lb body weight and a 2.80 feed conversion has swung from about $44 per pig to a high of around $72 per pig, back down to a current expense of about $60 per pig.

Whereas average daily gain (ADG) used to be the driver of profitability when commodity prices were significantly lower, feed efficiency (F/G) is king today. Using today’s commodity input prices, every 0.10 improvement in feed efficiency returns from $0.20 to $0.25 per pig. Any and all management and nutritional practices that improve F/G must be carefully considered and thoughtfully implemented.

Pig Body Composition Changes as a Pig Matures

Reviewing a graph plotting the change in ADG, average daily feed intake (ADFI), and F/G over the growing-finishing period of a pig’s life is helpful in understanding the relationship between the three parameters.

Figure 1 shows that ADG increases during a pig’s life until the period from about 160 to 200 lb body weight, after which ADG declines. Feed intake continues to increase throughout the pig’s life. As a direct consequence, F/G continues to worsen throughout, and deteriorates rapidly as the pig approaches market weight.

Another driver of the poor F/G that pigs experience in the latter stages of their growth curve is the change that occurs in the components of the ADG. Early in the nursery and grower, muscle is the predominant component of the ADG. The major component of muscle is water (around 84 per cent), resulting in a fairly efficient feed conversion in the early growth phase. However, during the later stages of the growth curve as pigs approach market weight, fat is the major component of the ADG. Conversion of feed nutrients to fat gain is relatively inefficient.

Figure 1. Relationship between ADG, ADFI and F/G as pigs mature

Select the Correct Genetic Lines

There are major differences within and between genetic lines in their ability to efficiently convert feed to pork. Historically, producers have looked to the terminal sire to carry the genetic load for growth rate, carcass characteristics and feed efficiency.

As feed input costs have risen dramatically, producers should be motivated to attempt to improve feed conversion through their maternal lines as well. On-farm evaluation has revealed differences of more than 0.20 in F/G between different maternal F1 lines. This equates to more than $3.00 per market hog produced.

Selecting genetic lines that excel in F/G is important but it is not enough. Estimated breeding value (EBV) management is another important step in maximizing return over genetics. Ten points EBV can be worth over $3.00 per market hog produced. As one ejaculate can produce over 300 pigs, it is critical that boar culling decisions are made on the basis of EBV, and not how difficult a boar is to collect! Production systems with their own internal boar stud need to have a “Production Decision Maker” – not the stud manager – managing the EBVs. Production systems that use purchased semen must hold the semen provider accountable for EBV management.

Follow The Feed Budget

Many feed companies and consultants will supply feed budgets each time a new batch of pigs is delivered. Feed budgets are designed to match the dietary nutrients being supplied in the feed with the pig’s metabolic requirement for growth during a specific period of time (usually 2-3 weeks per diet).

Matching the supply of nutrients with growth requirements minimizes overfeeding expensive diets, and maximizes pig growth potential by reducing the time pigs are underfed nutrients as they progress through the different phases.

Feed budgets are driven by the number of pigs in the barn and must be adjusted for mortality throughout the feeding period. When mortality is significant, as in the case of a circovirus or PRRSV outbreak, failure to adjust the budget for mortality results in the surviving pigs being “off-sequence” on all their diets. If not adjusted, the pigs may never get to the last (and cheapest) diet. Using today’s commodity prices and a six-phase feed budget with a 2.80 F/G, overfeeding the first five diets by 10 per cent and adjusting the last diet will cost an extra $0.61/pig. Overfeeding the first five diets by just 5 per cent and adjusting the last diet will cost an extra $0.30/pig.

Adjust Feeders Daily

Daily feeder adjustment is a necessary and profitable requirement in pork production. Daily adjustment is necessary as feed flow changes daily based on the micron size of the feed, the moisture of the feed and the humidity in the building.

“If you can see feed on the floor in front of the feeder, it represents at least 10 per cent feed wastage.” Everyone has probably heard this expression in the past, but what does it mean in terms of opportunity dollars lost in today’s commodity market? Assume a system achieving a 2.80 F/G from 50 to 260 lb body weight, but with visible amounts of feed on the floor in front of the majority of the feeders. Eliminating all feed wastage by careful daily feeder adjustment would be equivalent to improving the system’s F/G from its current 2.80 to 2.52! Using today’s commodity prices, an extra $6.10/pig could be added to the bottom line.

Totally eliminating all feed waste may be extremely optimistic. Cutting feed wastage in half in this system would be equivalent to improving F/G from its current 2.80 to 2.66 and adding an extra $3.05per pig to the bottom line. No other management practice has so much bottom line profit potential.

Monitor Corn Micron Size

Whether producers are purchasing complete feed or have their own feed production facilities, corn micron size should be measured regularly. Particle size of corn will increase over time as hammer-mill hammers and screens wear and roller mill adjustment drifts. Smaller particles increase the total surface area of the feed allowing maximum exposure and success of digestive enzymes. Nutrient absorption is maximized, and F/G is minimized as a result.

A target goal for corn micron size in grow-finish swine diets should be between 300 to 400 microns. It may be difficult to consistently get below 600 microns with a roller mill. As micron size is reduced, feed flowability may be reduced and feed bin bridging may increase. The best approach is to work down gradually from the current micron size in increments of 50 microns, making sure that feed flow problems and ulcer rates are not increasing. Installing AP Sure-Flocones (Automated Production Systems) in every bin is one alternative to the banging on bins that will most surely occur as micron size is reduced.

On average, each 100 micron reduction in particle size results in an improvement in feed conversion of approximately 0.05. Using today’s commodity prices, opportunity costs are about $1.00/pig for every 100 micron size increase over 400 microns. That equates to $3.00/pig lost potential by feeding a diet composed of 700 micron corn.

Is There Value In Feeding Pelleted Diets?

There are several documented advantages to feeding pelleted diets. These include a reduction in feed waste, possible destruction of pathogenic organisms within the feedstuffs, modification of the starch, protein, and fibre of the feedstuffs, and improved palatability.

Dated research from Kansas State University and Iowa State University shows a combined average improvement in ADG of four per cent and in F/G of 6.75 per cent during the grow-finish period. However, another KSU study showed that the benefits of pelleting to F/G were diminished as the amount of fines in the final product increased, and were lost as the amount of fines approached 20 per cent.

Results from several commercial trials comparing performance of pigs fed pellets versus pigs fed mash diets do not support the large feed conversion improvements observed in the KSU and ISU studies. In these commercial trials, improvements due to pelleting were approximately 1.5 per cent for ADG and just three per cent for F/G. The modest performance improvements within the commercial trials were likely due to the marginal pellet quality. Marginal pellet quality is a reality when feed is pelleted in large commercial mills.

Another pitfall with pelleted feed is increased mortality due to ulcers. It is common in commercial systems to observe increases in finishing mortality rate of two per cent or more due to feeding pellets. The magnitude of this elevated mortality is affected by the genotype and the overall health and biosecurity of the system. Using current feed and production costs, F/G must improve a minimum of three per cent and mortality must not increase more than one per cent for pelleting to be a cost-effective option.

Use Alternative Ingredients

Although regional niche markets exist for alternative ingredients like field peas, canola or barley, the reality is that “a rising tide will raise all ships.” All commodity prices respond and follow the price of corn and soybean meal. Producers must realize that it is very difficult for a mill to constantly swap-out ingredients. Ingredient bin space is usually limited and often the market has changed by the time the ingredient swap is completed.

In addition, the assumption is that pig performance does not change when incorporating “opportunity” ingredients. This may not be true if the alternative ingredient quality is sub-par, or if the alternative ingredient has been assigned incorrect nutrient values.

With that said, dried distillers grains with solubles (DDGS) is extremely abundant and can provide substantial feed cost savings. As previously stated, one of the biggest challenges in extracting the maximum return from DDGS is assigning the proper nutrient values to DDGS, which will vary by source. It is common to see relative value differences in excess of $40.00 per ton DDGS between plants even though product pricing from plant to plant is similar. Producers must understand which plants produce the highest value DDGS and then assign the proper nutrient loadings (metabolisable energy, net energy, digestible amino acids and digestible phosphorus) to the product they are using.

It is also important to understand changes in relative value within a given plant over time. For instance, many plants have begun to centrifuge the oil off the solubles, which decreases the relative energy value of the product.

Another challenge to address with DDGS is mycotoxins. The process of producing DDGS results in concentrating the mycotoxins by a factor of three. Studies have shown that a high percentage of DDGS does contain mycotoxins. Utilization of an effective toxin binder is a critical insurance policy in sow diets containing DDGS.

Levels of DDGS of up to 10 per cent in lactation, 30 per cent in gestation and 30 per cent in finishing diets can be incorporated successfully. Feed cost savings of from $4.00 to $5.00 per head can be achieved when DDGS is utilized properly and aggressively.

Maximize Use of Phytase

Much of the natural phosphorus in feed grains is unavailable to pigs because the phosphorus is in the form of phytic acid, which pigs cannot digest.

Phytase is an enzyme that when incorporated into the feed can break the bonds between the phosphorus molecule and the phytic acid allowing pigs to absorb the phosphorus. Phytase has been available for several years, but has increased in value as dicalcium and monocalcium phosphate prices have skyrocketed.

Most producers are using phytase, but many are not using it properly or aggressively enough. Incorporating phytase in a diet containing DDGS may make it possible to remove all supplemental phosphorus from finishing pig diets, and most supplemental phosphorus from sow diets.

Selecting the phytase source that gives the most economical phosphorus release and utilizing the correct nutrient loading values are the keys to maximizing phytase value. Utilizing phytase correctly can reduce feed costs by as much as $1.00 per head in today’s market.

Incorporate Growth Promotants

During this period of record high commodity prices, some pork producers have pulled growth promotants out of feed to reduce cash outlay. That is a mistake. Antibiotic growth promotants that improve feed conversion have never had more value. Antibiotic growth promotants will usually improve feed conversion by two to five per cent during the grow-finish phase.

In more than 80 trials with more than 8,000 pigs, BMD® (Alpharma Animal Health, Bridgewater, NJ) has been shown to improve ADG by four per cent and improve F/G by more than three per cent. Using today’s commodity prices, a three per cent improvement in F/G would deliver an extra $1.44 per pig to the bottom line above the input cost of the BMD.

Withdraw Feed Prior to Slaughter

After working hard to minimize F/G during the finishing period, why send a pig to market with six pounds of expensive feed in its stomach that will end up on the slaughter floor?

Withdrawing feed prior to slaughter reduces feed cost and transport deads, and improves pork quality. On close-out loads it is simple to manage: just shut off the feed so that pigs have 12 to 18 hours without feed prior to slaughter.

Transport time must be considered. Top-off loads are not as simple. Sort barns and barn designs that allow a gate to be placed in front of the feeder while still allowing access to water serve the purpose. Some producers with conventional barns are shutting off feed on the whole barn prior to taking top loads and getting by without problems. Before implementing this practice on a large scale, producers should try the practice on a few barns and make sure that ulcers and haemorrhagic bowel problems do not spontaneously occur.


Efficient conversion of feed to pork is an indirect indicator of gut health. Understanding how pig growth and feed intake change as the pig matures and incorporating the suggestions in this manuscript may improve F/G and make the difference between profitability and loss as margins in pork production become increasingly narrower.

January 2009
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