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Alternative Product Aids Nursery Health With future restrictions on antibiotics used to promote growth in farm animals a real possibility, a number of non-antibiotic substitutes are being developed to boost performance in the weaned pig. Bio-Mos (Alltech, Inc.), a mannan oligosaccharide derived from the cell wall of yeast, may provide the same positive health and performance benefits as antibiotic

Alternative Product Aids Nursery Health

With future restrictions on antibiotics used to promote growth in farm animals a real possibility, a number of non-antibiotic substitutes are being developed to boost performance in the weaned pig.

Bio-Mos (Alltech, Inc.), a mannan oligosaccharide derived from the cell wall of yeast, may provide the same positive health and performance benefits as antibiotic growth promoters, according to the University of Illinois.

The theory is that mannan may remove pathogenic gut organisms that block nursery pig growth and often lead to diarrhea. When these organisms are removed, the pig enjoys efficient feed utilization and enhanced growth. Bio-Mos is also touted to improve health by reducing or removing the underlying cause of diarrhea.

University of Illinois researchers conducted a comprehensive review of all Bio-Mos research shown to have an effect on nursery pig performance. A total of 27 experiments, involving 51 comparisons with levels of Bio-Mos from 2 to 8 lb./ton, were evaluated.

The overall response was clear — the inclusion of Bio-Mos in the diet can provide a significant improvement in growth performance. Average daily gain improved by an average of 4.01%.

Researchers also reviewed the impact of weaning age, length of experiment and concentration of the product. Bio-Mos appeared to be most effective when pigs were weaned at 17-18 days of age and fed for 24-28 days after weaning. Concentration levels of 2, 4 and 6 lb./ton were compared, but the results were inconclusive as to a recommended dose level.

Researchers concluded that Bio-Mos can improve the growth rate and feed efficiency of newly weaned pigs.

Researchers: James Pettigrew and Jennifer Miguel, University of Illinois. Phone Pettigrew at (217) 244-6927; or email

Dietary Supplement Has Marginal Benefits

Feeding betaine to finishing pigs is of marginal benefit. Its greatest benefit may be when low-energy diets are fed.

Betaine is a naturally occurring compound found in plants and animals. It has been available as a dietary supplement for a number of years as Betafin (FinnFeeds International).

The University of Kentucky conducted nine experiments on betaine, including 43 replications of four to nine pigs per pen, 938 pigs in all, from 103 to 249 lb. (Table 1). (This requires Adobe Acrobat Reader, download at:

Overall, the supplement had very little effect on growth rate, feed intake or feed efficiency. Ultrasonically scanned backfat tended to be less, carcass lean was somewhat improved and lean gain increased slightly.

Three experiments evaluated betaine in corn-soy diets vs. diets with reduced energy. The low-energy diets were corn-soy diets supplemented with 20% wheat middlings. Betafin was added to half of the diets at 0.125%, which supplied 1.14 g. of betaine/kg. (1 kg. = 2.2 lb.) of diet.

Betaine showed the most benefit in the low-energy diets, improving gain 4% and feed:gain 3.7%. Carcass lean gain was improved in pigs fed low-energy diets by 3.1%, compared with 1.2% in the standard corn-soy ration.

Five other trials looked at efficacy of betaine in low-protein, amino acid-supplemented diets. Pigs on these diets were slightly fatter than those fed intact protein diets. Adding betaine partially alleviated some of the increased fatness.

A final experiment was conducted to determine if betaine could improve performance in crowded conditions. Pigs were housed five, seven or nine pigs per pen at 10.7, 7.6 and 5.9 sq. ft./per pig, respectively, from 72 to 255 lb. Crowding reduced feed intake and growth rate by 8%. But betaine had no effect on performance.

Researchers: Gary Cromwell, Merlin Lindemann, Richard Coffey, Gary Parker, Allen Pettey, Jim Monegue, Jim Randolph and Kevin Laurent, University of Kentucky. Phone Cromwell at (859) 257-7534; fax (859) 323-1027; or e-mail

Dehulling Boosts Corn's Nutritional Value, Decreases Manure Output

Researchers at North Carolina State University and the University of Illinois are investigating ways to reduce the amount of manure pigs excrete.

Because corn makes up a major portion of swine feed, the researchers focused on the impact corn has on manure production. Previous research had shown approximately 40% of fresh grower pig feces (dry weight basis) was made up of corn hulls, also known as the corn pericarp. Researchers surmised that removing the indigestible fiber making up the corn pericarp before feeding could mean less manure produced.

A series of nutrition experiments compared the nutritional value of conventional corn to degermed, dehulled corn obtained from a dry milling plant.

Eight canulated barrows were used in the first experiment to test ileal digestibility. Degermed, dehulled corn dry matter was 83% digestible in the ileum, compared to conventional corn's 78% digestibility. The ileal digestibility of crude protein improved from 83% to 89%, and the lysine digestibility improved from 78% to 86% with the degermed, dehulled corn.

A second experiment looked at total tract digestibility in 12 barrows. Digestibility of dry matter improved from 89% to 96% and crude protein use improved from 78% to 94% with the degermed, dehulled corn. The impact of this improvement meant fecal dry matter excretion decreased 67% and fecal crude protein excretion was reduced 29%.

A third experiment evaluated growth performance with 96 nursery pigs. Nutritional values for degermed, dehulled corn were based on data from the previous experiments. Although daily gain was not affected, feed efficiency improved in the diets containing degermed, dehulled corn from 1.54 lb. of feed/lb. of gain to 1.48.

The degermed, dehulled corn tested in these experiments was manufactured using conventional dry milling techniques. The results of the process to remove the pericarp and germ from the endosperm meant the degermed, dehulled corn had 4% neutral detergent fiber (NDF) and 0.09% phosphorus. The germ contained 17% NDF and 0.97% phosphorus, and the pericarp had 33% NDF and 0.29% phosphorus.

To evaluate the nutritional value of each of these fractions and of extruded corn (an alternative means to improve the digestibility of corn), these ingredients were used as energy sources in complete diets. They provided exactly 5.5% crude protein to the complete feed. The remaining 6.5% protein was provided by soybean meal. These diets were evaluated for ileal digestibility.

Compared to unprocessed corn, indigestible dry matter decreased by 30% when degermed, dehulled corn was used, and 19% when extruded corn was used. In contrast, researchers say the use of germ and pericarp in the diet increased indigestible dry matter 18% and 61%, respectively. Indigestible phosphorus was reduced 15% with degermed, dehulled corn.

The results of these experiments suggest the nutritional value of corn products can be improved substantially by removing fiber, achieved by removing hulls and germ, or by altering fiber through extrusion. Additional benefits of feeding degermed, dehulled corn could be less dry matter, crude protein and phosphorus excreted in swine manure.

Researchers: Theo A. van Kempen, Eric van Heugten, Adam J. Moeser, and Kelly Zering, North Carolina State University. Kent D. Rausch and Mike E. Tumbleson, University of Illinois. Contact van Kempen at (919) 515-4016, or e-mail:

Phytase-Based Rations Aid Nutrient Balance

Feeding any combination of low phytic acid (LPA) corn, LPA soybean meal and phytase can greatly enhance phosphorus digestibility, while dramatically decreasing phosphorus (P) excretion.

Feeding LPA corn and LPA soybean meal also significantly reduces excretion levels of potassium (K) and enhances its digestibility.

Results of the study by Purdue University scientists are presented in Table 1.

Forty-eight, 100-lb. barrows were assigned to one of eight dietary treatments covering all diet combinations of LPA corn, LPA soybean meal, normal corn and normal soybean meal, with and without supplemental phytase.

Phytase was added to diets at 226 phytase units (PU)/lb. of feed. Diets were formulated to provide 0.38% total phosphorus with the phytase enzyme replacing corn starch in the control diet.

Feces and feed samples were analyzed for dry matter (DM), nitrogen (N), P and K contents. Urine was analyzed for N, P and K. Total DM digested and excreted did not differ among groups.

Nitrogen and ammonium N contents of feces and urine also weren't altered by dietary treatment regimens.

However, there was a noticeable reduction in fecal P excretion: 11% less for pigs fed LPA corn vs. normal corn, 2.87 vs. 3.22 g./day; and 17% less for pigs fed LPA soybean meal vs. normal soybean meal, 2.74 vs. 3.34 g./day (Table 1). (This requires Adobe Acrobat Reader, download at:

There was also 18% less fecal P excretion for pigs fed phytase vs. non-phytase diets, 2.74 vs. 3.35 g./day.

When pigs were fed both LPA corn and LPA soybean meal, there was an additive benefit of a 28% reduction in P excretion vs. normal corn and soybean meal, 2.51 vs. 3.47 g./day. When pigs were fed LPA corn, LPA soybean meal, phytase vs. normal corn and normal soybean meal and without phytase, there was a 43% drop in fecal P excretion, 2.13 vs. 3.76 g./day.

In addition, P digestibility improved by 21% for pigs fed diets with LPA corn vs. normal corn, 48.3% vs. 39.9%. Digestibility improved by 16% for pigs fed LPA soybean meal vs. normal soybean meal, 47.3% vs. 40.9%. It also improved 22% for pigs fed phytase vs. non-phytase diets, 48.5% vs. 39.7%, and 78% for pigs fed LPA corn, LPA soybean meal and phytase vs. controls, 60.8% vs. 33.9%.

Pigs fed LPA corn retained 46.5% of P vs. 38.3% of P retained for pigs fed normal corn. In LPA soybean meal-fed pigs, P retention was 45.3% vs. 39.5% for normal soybean meal. And P retention in phytase-fed pigs was 46.6% vs. 38.2% for non-phytase-fed pigs.

Fecal K excretion was reduced for pigs fed LPA corn vs. normal corn, 0.73 vs. 1.01 g./day, and for pigs fed LPA soybeans, 0.8 g./day vs. normal soybeans, 0.95 g./day. Digestibility of K was also increased for pigs fed LPA corn over normal corn, 94.8% vs. 92.7%. K retention for pigs fed LPA corn vs. normal corn was also higher, 73.1% vs. 70.9%.

Researchers: B.E. Hill, S.L. Hankins, S.A. Trapp, A.L. Sutton and B.T. Richert. Phone Sutton at (765) 494-8012 or e-mail ; phone Richert at (765) 494-4837, or e-mail

Phytase Can Replace Trace Mineral Premix

Louisiana State University (LSU) Agricultural Center researchers recently discovered microbial phytase supplementation could replace added trace mineral premixes in nursery pig diets.

The primary reason phytase is added to swine diets is to help increase phosphorus availability and to reduce the amount of phosphorus excreted in feces.

The researchers say adding phytase to corn-soybean meal diets can increase the availability of calcium, phosphorus, energy and amino acids. In addition, phytase has been shown to increase the availability of some trace minerals, including copper, manganese, iron and zinc.

Researchers speculate the effect of phytase on trace minerals may mean trace minerals could be removed from diets when phytase is added.

The LSU research was conducted with 208 crossbred barrows and gilts, weaned at 21 days of age and fed four different diets.

Pigs were fed a conventional nursery diet with trace mineral premix (control diet), conventional nursery diet without trace mineral premix (- Mineral), control with microbial phytase (+ Phytase), or control with phytase but without trace mineral premix (-Minerals, + Phytase). See Table 1. (This requires Adobe Acrobat Reader, download at:

Average daily gain (ADG), average daily feed intake (ADFI) and gain:feed were measured at the end of Phase 1 (7 days), Phase 2 (14 days) and Phase 3 (13 days).

Researchers found pigs fed the conventional nursery diet without the trace mineral premix had decreased growth performance. However, pigs fed the same diet, but with supplementation of phytase, had growth performance equal to that of the pigs fed the control diet. Pigs fed the diet without the trace minerals returned to normal growth after they were fed the control diet for two weeks.

Table 1 shows the effects of the experimental diets on growth performance during the nursery phase.

Skin lesions developed on 26 of the 52 pigs fed the conventional nursery diet without the trace mineral premix. No lesions were found on any of the pigs fed the diets with the trace mineral premix or with the addition of phytase. The skin lesions were healed on all pigs after five weeks of being fed the control diet.

Researchers: Jason Shelton, L. Lee Southern, and Tom Bidner. Contact L. Lee Southern at (225) 578-3449, or e-mail

Evaluating Grow-Finish Phosphorus Requirements

Kansas State University (KSU) scientists have been evaluating phosphorus requirements of grow-finish pigs raised in typical, commercial environments.

The researchers found phosphorus requirements similar to National Research Council (NRC) suggestions when expressed on a dietary percentage basis. However, because pigs in typical commercial environments tend to have decreased feed intake vs. pigs in typical university research settings, the grams-per-day requirements in the KSU results were less than NRC suggestions.

The estimates of lower phosphorus requirements could reduce diet cost by $.20/pig for most producers and may reduce the amount of land needed to apply manure where application rates are based on phosphorus content.

Three research trials were conducted at a commercial research facility in southwestern Minnesota. Each pen contained one, four-hole, dry self-feeder and one cup waterer. Pigs had ad libitum access to feed and water. Pen weights and feed disappearance were measured approximately every 14 days to calculate average daily gain (ADG), average daily feed intake (ADFI) and feed:gain.

Pigs were fed a diet containing 0.40% available phosphorus in Experiments 1 and 2, and 0.27% available phosphorus in Experiment 3, prior to starting experimental diets.

All diets were formulated using NRC nutrient composition values for the respective ingredients, according to 1998 findings.

Experiment 1

The first experiment was a 98-day pilot study, which obtained an available phosphorus estimate on which to conduct additional studies. Two dietary treatments were fed to 600 gilts with an initial weight of 95.2 lb. There were 25 pigs/pen and 12 pens/treatment.

A constant calcium-to-phosphorus ratio of 1.1:1 was maintained in all diets. Pigs in each treatment were phase-fed six diets from 95 to 106 lb., 106 to 150 lb., 150 to 183 lb., 183 to 212 lb., 212 to 245 lb. and 245 to 267 lb.

The corresponding available phosphorus concentrations were: 0.30%, 0.28%, 0.27%, 0.24% and 0.19% for pigs fed the low available phosphorus regimen. Pigs in the high available phosphorus regimen were fed 0.37%, 0.33%, 0.30%, 0.28%, 0.27% and 0.26% available phosphorus.

Dietary formulations are available from researchers. The range of values used represented recommendations for commercial production in the U.S., similar to those proposed by swine breeding stock companies and nutritionists.

No differences were observed over the entire 98-day experiment for ADG or ADFI. Pigs fed the low available phosphorus regimen tended to have better feed:gain than those fed the high available phosphorus regimen. The researchers say these results suggest the available phosphorus levels in the high regimen were above those necessary for maximum growth. Results of this experiment are shown in Table 1. (This requires Adobe Acrobat Reader, download at:

The data from Experiment 1 was used to establish a range of available phosphorus concentrations to evaluate in the subsequent experiments.

Experiment 2

A second experiment involved 1,260 gilts with an initial weight of 74.5 lb., randomly allotted to one of five dietary treatments for 26 days. There were 28 pigs/pen and nine pens per treatment.

A constant calcium-to-phosphorus ratio of 1.1:1 was maintained in all diets by varying the amounts of monocalcium phosphate and limestone to attain the desired levels.

Pigs were fed corn-soybean meal-based diets containing 6% added fat and formulated to 1.25% total lysine. Experimental treatments consisted of five levels of available phosphorus: 0.18%, 0.22%, 0.25%, 0.29% or 0.32%.

One pig from each pen was randomly selected and euthanized at the conclusion of Experiment 2. The right 5th, 6th, and 7th ribs and the right rear leg were collected for bone analysis to measure the effects of the varying phosphorus levels on bone strength.

Increasing available phosphorus tended to increase ADG and feed:gain from the first to the 14th day of the experiment.

The greatest improvement on both ADG and feed:gain was observed as available phosphorus increased from 0.18% to 0.22% (see Table 2). This corresponded with available phosphorus intakes of 2.70 and 3.21 g./day. From Day 14 to 26, and during the overall study, no differences were observed in ADG, ADFI or feed:gain.

Experiment 3

A total of 1,260 gilts, with an initial weight of 195.1 lb., were randomly assigned to one of five dietary treatments in a 28-day experiment. There were 28 pigs/pen, nine pens per treatment. Pigs were fed diets containing 0.05%, 0.10%, 0.14%, 0.19% or 0.23% available phosphorus.

A constant calcium-to-phosphorus ratio of 1.1:1 was maintained for all diets, while varying the amounts of monocalcium phosphate and limestone to attain the desired levels of calcium and phosphorus in the diets.

Two pigs from each pen were randomly selected, tattooed and shipped to a commercial meat packing facility for slaughter at the conclusion of the experiment. The lower third of the front right leg was removed for bone analysis after processing.

Increasing available phosphorus from the first to the 14th day of the experiment increased ADG and feed:gain. The greatest ADG was observed in pigs fed 0.19% available phosphorus. ADFI tended to increase, with the greatest increase occurring as available phosphorus increased from 0.05% to 0.10%. This corresponded to an increase from 0.96 to 2 g./day available phosphorus intake.

No differences were observed for ADG, ADFI or feed:gain from Day 14 to 28 and from the first day of the experiment to Day 28 (see Table 3).

Bone tests were conducted because typically, available phosphorus requirements to maximize bone strength are greater than those required to maximize growth. KSU researchers did not find any interactions between bone strength and treatments. The results of Experiment 3 suggest that some added inorganic phosphorus is necessary to maintain growth and bone strength in corn-soybean meal-based finishing diets for pigs from 195 to 240 lb. in commercial facilities.

Three-Trial Summary

This research suggests approximately 0.22% available phosphorus is adequate to maintain growth and bone strength in pigs weighing from 74 to 121 lb. in commercial facilities.

It appears that at least 0.19% available phosphorus is adequate for maintaining growth and bone strength in pigs from 74 to 121 lb. and from 195 to 240 lb. Bone bending moment and bone ash continued to increase with increasing available phosphorus.

Researchers: Chad Hastad, Steve Dritz, Mike Tokach, Jim Nelssen, Bob Goodband and Joel DeRouchey, Kansas State University. Contact Hastad at (785) 532-1270, or e-mail

Zinc Levels in PostWeaning Diets Raise Environmental Concerns

Both environmental and nutritional implications should be considered when feeding high levels of zinc to nursery pigs, according to University of Kentucky scientists. Researchers suggest the amount of zinc excreted during the nursery period may be as much as that excreted during the entire growing-finishing period.

High levels of zinc, supplemented with zinc oxide, are often included in postweaning diets of early weaned pigs. Many studies have shown 1,500-3,000 ppm zinc can increase pig performance and reduce diarrhea.

Although they don't fully understand how the high levels of zinc work, researchers speculate the positive responses in pig health are probably associated with how the resident microorganisms respond to the high levels of unabsorbed zinc in the gut. Because most of the zinc is not absorbed, large amounts of zinc end up in manure. This raises concerns about potential environmental impact, particularly around off-site nurseries where young pigs are concentrated.

Kentucky researchers sought to determine how much zinc is excreted when weanling pigs are fed high levels of zinc as zinc oxide. A study was conducted using 18 weanling, crossbred barrows weighing 16 lb. The 22-day-old pigs were penned in stainless steel metabolism crates and fed nursery-type diets for 21 days.

The diets contained 150 ppm zinc, 12 ppm copper, and 120 ppm iron. Treatments consisted of 0, 2000, or 3000 ppm additional zinc from zinc oxide for the 21-day period.

Excretion of zinc and other minerals was measured by total fecal collection. Indigo carmine marked the beginning and end of each weekly period. The pigs were killed at the end of the study, and liver samples were obtained so minerals could be analyzed.

Researchers discovered that increasing the dietary zinc level from 0 to 2,000 ppm or 3,000 ppm resulted in linear increases in zinc intake, absorption and excretion, and linear increases in copper and iron excretion over the entire period (Table 1). (This requires Adobe Acrobat Reader, download at:

A major portion of the increased amounts of absorbed zinc in pigs fed the high zinc diets was retained in the liver (Table 1). Liver copper levels decreased when the high zinc diets were fed.

Although the feeding of high levels of zinc caused marked increases in manure zinc content, high dietary levels in typical nurseries are generally only included for a relatively short period of time — 10 days to two weeks. However, as Figure 1 illustrates, the zinc excreted during the nursery period may be as much as during the entire growing-finishing period when considerably lower levels of zinc are fed.

The results of this study show that increasing dietary zinc levels clearly increases fecal zinc excretion. Based on these results, the researchers say the lowest possible level of pharmacological-level zinc should be used that will give the desired response. Producers may want to consider feeding zinc for a limited time period of two weeks or less, postweaning, for both environmental and nutritional reasons.

Researchers: Terry Meyer, Merlin Lindemann and Gary Cromwell, Dept. of Animal Sciences, University of Kentucky, Lexington. Contact Cromwell at (859) 257-7534.