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Corn and DDGS Diet Switching Do Not Affect Pig Performance

Pork producers looking to optimize feed ingredients are including distiller's dried grains with solubles (DDGS) for grow-finish pigs when costs are in line.

To better understand the implications of suddenly including economically priced DDGS in pig diets, researchers at the University of Minnesota conducted a trial to determine the effects of switching between corn-soybean meal and corn-soybean meal-DDGS diets on pig performance and carcass quality of finishing pigs.

The 216 pigs housed in 24 pens were placed on one of four dietary treatments — the corn-soybean control diet (D0), a corn-soybean meal diet containing 20% DDGS fed throughout the study (D20), D20 and D0 diets alternated bi-weekly (D20SW), and a 40% DDGS diet alternated bi-weekly with the D0 diet (D40SW). Pigs were fed corn-soybean meal diets until they went on test at 110 lb.

There were five, two-week feeding periods. Pigs assigned to the D20SW and D40SW treatments started and ended the trial on DDGS-containing diets.

Dietary treatments had no effect on average daily gain (Table 1). Except for feed efficiency, growth performance was similar for pigs fed the control diet continuously, the 20% DDGS diet continuously or the 20% DDGS and control diets in an alternating pattern.

Researchers point out that for some reason, pigs fed the 20% DDGS diet were continuously less efficient than pigs fed the DDGS diet alternated with the control diet.

They also noted that the pigs switched on and off a 40% DDGS diet were lighter at the end of the 70-day study (Table 1), and these pigs yielded lighter carcasses than pigs in other treatment groups because they ate less feed.

Dressing percentage and carcass fat-free lean percentage were not affected by dietary treatments.

The results of this study showed no adverse effects of frequently alternating between inclusion and removal of 20% DDGS from diets for finishing pigs in terms of performance or carcass characteristics.

The researchers plan to conduct a related trial to determine if lighter pigs will respond in the same manner.

Researchers: Lee Johnston and Adrienne Hilbrands, University of Minnesota, West Central Research and Outreach Center; and Jerry Shurson, University of Minnesota-St. Paul. Contact Johnston by phone (320) 589-1711, fax (320) 589-4870 or e-mail [email protected].

Experimental Vaccine Is Effective Against PRRS

A modified-live-virus (MLV) vaccine, propagated in an innovative porcine alveolar macrophage cell line, designated ZMAC, was effective in protecting pigs from porcine reproductive and respiratory syndrome (PRRS) virus.

Use of the ZMAC-grown, MLV vaccine prevented the weight loss observed in non-immunized animals within seven days after exposure to a highly virulent strain of PRRS virus.

“Remarkably, analyses of the virus load in serum and lung samples from PRRS virus-immunized and challenged animals revealed that the vaccine virus grown in ZMAC cells was significantly more effective at reducing the extent of viremia (the presence of virus in the blood) at seven days post-challenge, and also at eliminating virulent virus from their lungs by 10 days post-challenge,” says Federico A. Zuckermann, professor of immunology at the University of Illinois College of Veterinary Medicine.

The researcher says the degree of protection afforded by this vaccine “against a genetically divergent and highly virulent PRRS virus has important implications for the prospect of developing an effective vaccine against this pathogen.

“Namely, the results of this study suggest that the effectiveness of a PRRS MLV vaccine can be improved, and that it is not, as it is commonly believed, only determined by its genetic similarity to the challenge virus, but is also influenced by how it is produced.

“The results of this study provide great hope that an effective MLV vaccine against PRRS virus can be developed,” says Zuckermann.

The goals of this project, funded by the National Pork Board, were to use an innovative porcine cell line to produce a PRRS MLV vaccine, and to compare this virus' efficacy to that of vaccine made traditionally in the simian MARC-145 cell line, the only other type of cell line known to support the growth of PRRS virus.

To evaluate the vaccine potential of the ZMAC-grown virus, a standard immunization test was conducted. Six, 8-week-old pigs were injected with the Prime Pac commercial vaccine (Schering-Plough Animal Health) propagated in either ZMAC or MARC-145 cells, while two groups of three animals were not immunized and served as controls.

Four weeks later, all vaccinated pigs and one of the PRRS naïve groups were challenged with an “atypical PRRS abortion storm” virus.

The result was that the Prime Pac vaccine grown in either cell line proved equally effective at preventing weight loss by pigs exposed to virulent virus seven days earlier. (See Figure 1, where weight changes of non-immunized and vaccinated pigs at seven days after challenge with atypical PRRS virus are depicted.)

The vaccine virus grown in ZMAC cells, however, was much more effective than the one generated in MARC-145 cells at reducing the extent of infection and also at eliminating virus from the lungs at 7 or 10 days post-challenge.

Researcher: Federico Zuckermann, University of Illinois. Contact Zuckermann by phone (217) 333-7767, fax (217) 244-7421 or e-mail [email protected].

Taking Stock

Checkoff's approval rating is sought in USDA survey.

The USDA Agricultural Marketing Service is conducting a “request for referendum” survey on the Pork Promotion, Research and Consumer Information Act, more commonly known as the pork checkoff. The survey has been a topic of discussion since Feb. 28, 2001, when the USDA announced a settlement agreement, which effectively required a “distinct separation” between the National Pork Board and the National Pork Producers Council.

That agreement also specified that a survey of all eligible pork producers and pork importers would be conducted sometime after June 2003, asking if a referendum on the mandatory checkoff program should be held.

The survey period is Dec. 8, 2008 through Jan. 2, 2009. Participants must be at least 18 years old and must have documentation that they were actively engaged in pork production or the importation of pigs, hogs or pork products between Jan. 1, 2007 and Dec. 31, 2007.

For a referendum of the checkoff to be staged, 15% of pork producers and pork importers must go to their USDA county Farm Service Agency (FSA) office, fill out form LS-54-1, sign and submit (or postmark) it before midnight on Jan. 2, 2009. Forms may be requested from FSA offices in person, by fax, by mail or by downloading them from the Web site: www.ams.usda.gov/LSMarketingPrograms.

The USDA says there are about 69,446 eligible pork producers and importers, so 10,417 votes favoring a referendum on the pork checkoff must be cast.

A Civic Duty

As a journalist covering the U.S. pork industry, it is my civic duty to provide the details for this “call for referendum” survey. It's no secret, however, that I am an ardent supporter of the pork checkoff. Although we try hard to offer balanced reporting of all pork checkoff-funded programs and activities in our regular editorial pages, this “opinion page” allows me the opportunity to openly express my support of this self-funded, self-help program for the U.S. pork industry.

The survey process also affords each of you the challenge to stop and think about your checkoff investment, how it has served you and, more importantly, how it will serve you in the future.

Consider some of the challenges and opportunities that lie ahead:

  • Animal rights activists will keep the pressure on. The passage of California's Proposition 2 banning individual sow gestation stalls has empowered them. Solid research that will stand scrutiny from both sides of this issue must be funded to ensure your hogs and pigs can be raised and housed in the best possible environment.

  • The value of exports to the U.S. pork industry is unquestionable. The need to reinforce the value and quality of U.S. pork to our global customers is ongoing.

  • Research is the mainstay of any progressive industry. Whether focused on porcine circovirus, PRRS, the conversion of feedstuffs to meat protein, or employee training, research will lead the way toward more efficient, sustainable pork production.

These and other issues are included in the plan of work and the National Pork Board's budget for 2009. This is your money and it is vital that everyone understands the process of prioritizing checkoff funding and how the checkoff rate is set.

The latter issue is periodically brought before the Pork Act delegate body for consideration during National Pork Industry Forum held each March. Whether the checkoff rate should be increased or decreased is always open for debate.

Voice Your Opinions

Much has changed in the U.S. pork industry since the mandatory pork checkoff was enacted in 1985. The cost to produce a pound of pork has steadily increased, as we all know, particularly feed costs. Energy costs, too, continue to climb. More research in these and other critical areas is needed to guide all pork producers to a higher, more efficient plain. A unified, pooled effort will move us in the right direction, faster, than any one person or firm can do on their own.

Agree or disagree — it is imperative that your voices be heard. Whether you cast a ballot in the USDA survey or place a call to your state delegate to Pork Forum, it is your responsibility to air your views on where the checkoff rate should be set and how that investment should be allocated.

Chances are you were motivated to vote in the November elections. Now is the time to channel that proactive energy into your pork industry to ensure your pork checkoff investment targets your highest priorities.

Whether the pork checkoff impacts your business, there is no doubt. How you participate in the industry's platforms is left to everyone — individually and collectively. Regardless of your stand, be sure your voice is heard.

Wireless Pregnancy Detector Introduced

Virtual scan ultrasound system for sows is lightweight and cordless.

ECM has developed a new ultrasound device to meet the specific needs of pork producers and swine veterinarians. The Virtual Scan (V-Scan) provides an alternative to the various screen-less Doppler mode A devices, as well as other ultrasound competitors. The V-Scan is lightweight (1 lb.) and comes equipped with an internal five-hour battery and 5-MHz sector probe. The pregnancy detection device is easy to operate and boasts 100% accuracy. Compact and cordless, the V-Scan can be used in any tight, narrow, hard-to-reach stall. The detector is ergonomically designed to fit comfortably in the palm of the hand, and the screen is well positioned to be visible for quick reading. Pregnancy checking can be performed as early as 21 days following insemination, permitting re-insemination of an open sow without wasting an additional heat cycle. The V-Scan cleans easily with a damp towel. ECM and COTRAN Corp. (U.S. sales) will exhibit the V-Scan at the World Pork Expo on June 8-10, 2009 in Des Moines, IA. For more information, e-mail [email protected] or go to www.agroscan.com.

No Behavioral Side Effects With Ethanol By-Product Use

New research at Iowa State University (ISU) tested whether the use of ethanol by-products in swine diets to reduce air emissions would have an impact on pig behavior.

Four treatments were studied: distiller’s dried grains with soluble (DDGS), dehulled, degermed corn (DDC), corn germ meal (CGM) and a conventional corn-based diet (CORN). All diets were formulated to National Research Council recommendations.

Forty-eight (PIC) pigs, averaging 40 lb., were allocated to eight rooms (6 pigs/pen). Each pen included a two-hole feeder and a hanging nipple waterer.

Starter and two grower phase diets are shown in Table 1. Pigs received the starter test diet at 40 lb., the first grower diet at 60 lb., and the second grower diet at 90 lb.

The first finisher diet was fed at 128 lb., the second at 172 lb., and the final finishing phase diet began at 222 lb. (Table 2). Pigs averaged 273 lb. at the end of the trial.

Pigs were observed for two behaviors (eating, drinking), two postures (active, inactive) or unknown (when posture or behavior could not be determined).

Pigs were checked twice daily at 7 a.m. and at 3 p.m. for general health appearance, feed and water. Video footage was collected for 24 hours following each dietary phase change.

None of the dietary regimens produced changes in behavior or posture. (Table 3).

On average, the grow-finish pigs spent 7.2% of their time eating, 0.9% drinking, 4.4% active and 87.2% of the time inactive.

“It is encouraging to note that even by manipulating the level of hemicellulose content in the diet of the growing-finishing pig, there were no changes in the pigs’ behavioral repertoire, in particular in the amount of time engaged in maintenance-related behaviors,” the research team explained.

And while pigs adapted quickly to all of the dietary phases, due to the small number of pens used, this work should be repeated to determine if this adaptation holds true in a commercial setting.

The research was supported by the National Pork Board and ISU Department of Animal Science Startup Funds.

Researchers: A.K. Johnson, A.J. Holliday, L.J. Sadler and K.J. Stalder, Iowa State University; and Wendy Powers, Michigan State University. Contact Johnson by phone (515) 294-2098, fax (515) 294-4471 or e-mail [email protected] .

Enhanced DDGS Offer Improved Swine Diets

Enhanced distiller's dried grains with solubles (E-DDGS) provides greater energy concentration in swine diets, improving the nutritional value of DDGS for pigs, according to a study at the University of Illinois.

The end result is not only improved feed efficiency, but in many cases, increased growth rates, leading to increased profits.

DDGS has a high fiber content. A process known to separate fiber from DDGS — called the elusieve process — removes about 10% of the material, mostly fiber, yielding E-DDGS with 2.3% less total dietary fiber than conventional DDGS (28.7% vs. 26.4% fiber).

The E-DDGS has higher crude protein (CP) and higher fat concentration (Table 1).

The goal of this experiment was to determine digestible energy (DE) and metabolizable energy (ME) in two sources of DDGS, and in E-DDGS produced from each of the DDGS sources.

The trial consisted of 30, 51-lb. growing pigs and 30, 161-lb. finishing pigs placed in metabolism cages and assigned a randomized diet.

The two groups of pigs received five different diets: standard corn and soybean meal and four additional diets formulated by replacing 40% of the base diet with 40% of each source of DDGS and E-DDGS.

Pigs were fed experimental diets for 14 days. Urine and feces were collected during the final five days.

Diets containing E-DDGS produced 6-7% greater DE and ME than those containing DDGS (Table 2). Researchers said the result was expected due to the fiber removal from DDGS, resulting in an ingredient higher in fat and protein content.

About 94% of the DE and ME in the original DDGS was captured in the E-DDGS. The DE and ME values were not different between growing and finishing pigs.

In conclusion, the co-product E-DDGS is nutritionally more appropriate for pigs than DDGS because of the lower fiber concentration and higher energy density.

Researchers: J.A. Soares, H.H. Stein, R. Srinivasan, V. Singh and J.E. Pettigrew, University of Illinois. Contact Pettigrew by phone (217) 244-6927, fax (217) 333-7861 or e-mail [email protected].

Genetics

Organic Selenium Enhances Boar Fertility

The resounding acceptance of artificial insemination (AI) by commercial pork producers necessitates the need to manage boars for maximum fertility and semen production.

Several research groups have investigated the effects of supplemental selenium on reproductive characteristics of boars, and there is strong evidence to support the inclusion of this mineral in the daily ration.

Researchers at Ohio State University reported improvements in sperm production, sperm morphology and fertility for boars fed diets supplemented with the traditional, inorganic source of selenium (sodium selenite) at levels of 0.5 ppm. Because of environmental concerns, however, the Food and Drug Administration (FDA) allows a maximum of 0.3 ppm supplemental selenium in swine diets.

It has been suggested that selenium from sodium selenite may not be as biologically effective as the selenium indigenous in grains, which is incorporated in an organic form called selenomethionine. Sel-Plex (Alltech, Inc.) is an organic source of selenium that consists primarily of selenomethionine.

A working hypothesis is that because of greater bioavailability, an organic selenium source may be superior to an inorganic source when supplemented at the 0.3 ppm level in an effort to improve boar semen quality and fertility.

The objective of this study was to evaluate the in-vitro fertilizing capability of sperm cells from boars fed selenium from either organic or inorganic sources.

From weaning through the completion of the experiment, Yorkshire × Landrace boars were fed the following diets:

  • Basal diets that met or exceeded the nutrient recommendations for boars (NRC, 1998) with the exception of selenium;

  • Basal diets supplemented with 0.3 ppm selenium from an organic source (Sel-Plex), or

  • Basal diets supplemented with 0.3 ppm selenium from an inorganic source (sodium selenite).

At sexual maturity, boars were trained to mount an artificial sow for semen collection. Ejaculates were collected and semen was diluted and stored at 65°F (18°C) in Androhep-Lite (3 billion sperm cells in 85 mL of semen and extender). Using in-vitro fertilization (IVF) procedures, sperm fertilizing capability was determined on Days 2 and 8, post collection (Day 1 = day of semen collection).

Fertilization rates were significantly greater for the Day 2 post-collection semen from boars fed the diet supplemented with organic selenium (Figure 1). Moreover, on Day 8 post-semen collection, fertilization rates tended to be greater for boars fed a diet supplemented with Sel-Plex compared with boars fed the control diet or the diet supplemented with sodium selenite.

Therefore, the use of an organic source of selenium in boar diets may result in greater conception and farrowing rates in swine operations employing AI. While the cost/benefit relationship of this research has not been addressed, it is assumed that a technology that increases conception and farrowing rates would enhance reproductive efficiency in the breeding herd, and thus increase profitability.

Additionally, research has shown that swine fed diets supplemented with organic selenium excrete less selenium into the environment than swine fed diets supplemented with inorganic selenium.

Researchers: Mark J. Estienne, Susan M. Speight, James W. Knight and Allen F. Harper, Virginia Tech, Blacksburg, VA. Contact Estienne via e-mail at: [email protected].

Marker-Assisted Selection Could Boost Sow Performance

The length of a sow's productive life (SPL) in a breeding herd is impacted by reproductive performance, locomotion and structural soundness.

SPL is usually defined as either the number of days that a sow remains in the breeding herd or the number of litters that a sow produces. Length of sow productive life or longevity is evaluated by removal, culling and replacement rates, percentage of gilts in the herd, average parity of females in inventory and average parity at removal.

Because reproductive traits carry low to moderate heritability, marker-assisted selection (MAS) may be an effective tool to reduce the culling rate of sows and improve SPL.

In this study, 119 single nucleotide polymorphisms (SNPs) from 95 genes were examined in a commercial sow population with recorded reproductive traits for six parities. SNPs are changes in a single, specific coding unit of the genetic code.

The SNPs association analyses revealed a number of potentially interesting genes associated with total number born, number born alive and with gestation length in several parities. These associated genes could be considered for marker-assisted selection to improve SPL in commercial sow herds.

According to the PigChamp 2007 benchmarking report (http://www.pigchamp.com/summary_archives.html) in the last 10 years, the average culling rate of breeding females was 49.7% and sow mortality rate averaged 9.2%. The two most prominent reasons for culling are reproductive problems and locomotion disorders. Both appear to affect a higher percentage of sows in early parities.

Reproductive traits are low to moderately heritable and have low repeatability across parities. Traditional phenotypic selection, based on reproduction records, is less effective. Marker-assisted selection (MAS) is one method to improve lowly heritable traits.

The identification of genetic markers significantly associated with high sow longevity would allow breeders to select gilts at early ages — prior to the entry of the herd — that would have the best opportunity for increased sow longevity. Genetic suppliers could use the markers to improve selection methods and possibly “fix” the important genes in the population.

The objective of this research was to identify genetic markers or SNPs associated with sow productive traits. A commercial herd involving 2,066 gilts supplied by Newsham Choice Genetics was included in the project.

Six reproductive traits were recorded: total number born (TNB), number born alive (NBA), stillborn number (SBN), mummy number (MN), gestation length (GL) and non-productive days (NPD). The study included six different parities that were comprised of gradually reduced numbers of sows. DNA was isolated and large-scale genotyping was performed.

Twenty-three genes showed significant associations with at least three reproductive traits. For Parity 1, six genes were significantly associated with both TNB and NBA, while four genes were highly significantly associated with SBN. Two genes were highly significantly associated with MN and NPD, respectively.

In later parities, the six genes had significant association with TNB and NBA. Four genes were significantly associated with GL in several parities.

Researchers also recognized four genes were simultaneously associated with reproductive performance, fatness and locomotion traits, implying that these genes have more than one genetic effect on sow longevity-related traits. The study verified that there are genes causing variation in sow productive life; therefore, the use of marker-assisted selection could improve sow longevity.

The National Pork Board, Newsham Genetics, Hatch funding and the State of Iowa and the College of Agriculture funded this research effort.

Researchers: Bin Fan, Suneel K. Onteru, Marja Nikkilä, Kenneth J. Stalder and Max F. Rothschild, Iowa State University. Contact Stalder by phone: (515)-294-4683 or e-mail: [email protected] or Rothschild by phone: (515)-294-6202 or e-mail: [email protected].

Frozen Boar Semen Use Shows Promise

The use of frozen boar semen technologies to preserve genetics, reduce risk when introducing new genetics into the breeding herd, allow international distribution of genetics and provide a reserve of semen to cover emergency needs has been a goal of the pork industry for many years.

A study conducted at the University of Illinois, in collaboration with the USDA and Purdue University, was designed to help establish the parameters for successful use of frozen boar semen. The fertility effects of 1, 2 or 4 billion thawed, motile boar sperm were studied using single or double inseminations in gilts.

Semen from six selected sires was collected and shipped by PIC to the USDA National Animal Germplasm Program laboratory at Fort Collins, CO, for freezing in ½ cc. straws. Frozen semen was shipped in liquid nitrogen tanks to the University of Illinois Swine Research Center for use in the fertility trials. The experiment was conducted in five replicates using terminal line PIC gilts.

At 180 days of age, prepubertal gilts were treated with PG600, followed by Matrix (Intervet, Inc.), to synchronize estrus. All gilts that expressed estrus following Matrix withdrawal were assigned to a treatment. Gilts were allotted to treatment with each boar represented across treatments.

Multiple straws of frozen boar semen were thawed into Minitube thawing extenders to create 80 cc. doses containing 1, 2 or 4 billion motile sperm/dose. Semen was used within one hour of thawing.

Estrous detection and real-time ultrasound were each performed at 12-hour intervals to determine onset of estrus and to verify fertility and time of ovulation. Gilts were inseminated once at 32 hours or twice at 24 and 32 hours after the onset of estrus using conventional artificial insemination (AI) catheters.

Data were collected for interval from AI to ovulation, pregnancy and number of fetuses at Day 24-35. The data were analyzed for the effect of dose, number of inseminations, replicate, boar, and interval from insemination to ovulation, where appropriate.

There was no effect of either dose or number of inseminations on pregnancy rate, number of healthy fetuses or embryo survival (Table 1). There was an effect of interval from insemination to ovulation on number of fetuses and embryo survival, but not on pregnancy rate.

Optimal insemination occurred within eight hours before ovulation. Boars significantly influenced number of fetuses and embryo survival, but not pregnancy rate.

Results suggest that limited numbers of thawed, frozen sperm can be used to establish acceptable pregnancy rates and litter sizes in gilts. There was little evidence that using double insemination at 24 and 32 hours after onset of estrus or using higher numbers of sperm was advantageous. This indicates that acceptable fertility can be achieved using a single insemination with 1-2 billion thawed, motile sperm. It was also evident that the boar impacted litter size and that selection for fertility and motility after freezing may be a necessary measure. Lastly, the interval from insemination to ovulation is an important limitation to fertility when using frozen boar sperm. Insemination within eight hours of ovulation has the greatest potential for fertility.

Researchers: K. Spencer, S. Breen, J. Taibl, B. Yantis and R. Knox, University of Illinois; P. Purdy, H. Blackburn, S. Spiller and C. Welsh, National Animal Germplasm Program, ARS, USDA, Fort Collins, CO; and T. Stewart, Purdue University. Contact Knox by phone (217) 244-5177) or e-mail: [email protected].

Table 1. Impact of Number of Thawed, Motile Frozen Boar Sperm and Number of Inseminations on Pregnancy Rate and Number of Fetuses at Day 30 of Gestation

Dose (billions of motile sperm) Number of inseminations Inseminated gilts Pregnancy rate (%) Number of normal fetuses Embryo survival (%)
1 1 16 87.6 11.6 67.0
1 2 18 67.6 11.1 65.3
2 1 17 76.0 10.6 66.8
2 2 15 85.7 11.4 67.9
4 1 17 67.6 10.0 61.3
4 2 18 81.9 10.1 67.7

Adding Amino Acids Cuts Protein Costs, Boosts Net Energy

Supplementing a low-protein diet with synthetic amino acids can provide a cost-effective way to avoid adding excess crude protein (CP).

Two experiments with grow-finish pigs confirmed that performance could be maintained when either high- or low-crude protein diets are fed as long as amino acids are balanced and the diets are formulated to provide similar net energy.

The introduction of crystalline amino acids has allowed a reduction in the crude protein (CP) in swine diets. Low-CP diets supplemented with essential amino acids can decrease nitrogen excretion in the manure and may reduce diet costs.

This study compared the performance of grow-finish pigs fed either high- or low-CP diets supplemented with crystalline amino acids.

High-CP diets were formulated to meet the lysine and other amino acid requirements of the pig (Table 1). Low-CP diets were formulated to provide the same amount of lysine, but the CP was reduced from 20% to 16% in the grower and from 16% to 12% in the finisher diet.

Diets were formulated to provide equal net energy. Sodium bicarbonate was added to the low-CP diets to maintain the electrolyte balance of the diet.

Average daily feed intake was lower when the pigs consumed the high-CP diet, while average daily gain was similar between treatments, resulting in an improved feed:gain ratio with the high-CP diet (Table 2).

The low- and high-CP diets resulted in similar pig performance during the finishing phase (Table 2).

In summary, CP levels can be decreased by 4% in grower and finisher diets without impacting pig performance, provided that diets are formulated to be equivalent in available amino acid, net energy and dietary electrolyte balance.

Researchers: J.F. Patience, A.D. Beaulieu and I.U. Haq, all of the Prairie Swine Centre (PSC). Contact PSC's Ken Engele by phone (306) 373-9922, fax (306) 955-2501 or e-mail [email protected].

Manure Management

Hydrogen Sulfide Detector Warns of Dangerous Gas Levels

A research team at Iowa State University (ISU) has developed a wireless hydrogen sulfide (H2S) detector that successfully detects the potentially fatal gas released from manure in deep-pit barns during slurry agitation and pumping events. This project was funded by the National Pork Board.

Lethal concentrations of H2S can develop rapidly and vary spatially in a swine barn during manure agitation and removal.

It is estimated the lost market value of 20 or more hogs to H2S poisoning during slurry agitation would pay for the new detection system in one year.

Personnel should never enter a swine barn during slurry agitation. The Occupational Safety and Health Administration's (OSHA) limit for immediate threat to life is 100 ppm of H2S. Field studies have shown that H2S concentrations can exceed this level quickly during slurry agitation with concentrations recorded as high as 1,300 ppm.

Researchers at ISU have the following objectives for this project to reduce the risk of human or animal fatalities from H2S gas:

  1. Develop and test a wireless hydrogen sulfide detection system for use during hog manure agitation and removal;

  2. Better establish building ventilation management strategies to increase human safety and maintain animal health during the manure agitation and removal process; and

  3. Add to the knowledge base about the development of hazardous conditions due to H2S from manure.

Initially, six commercially available H2S sensors were tested in ISU's Agricultural Waste Management Laboratory.

The prototype consists of a sensor/transmitter and a handheld receiver. The sensor/transmitter is equipped with the H2S sensor, a wireless communication system and battery power. The unit is placed inside the swine barn before agitation begins. The receiver remains outside so the operator can safely monitor H2S gas levels inside the barn. Both an audible and visual alarm are activated when a predetermined H2S concentration is detected.

The prototype matched performance of a research grade H2S analyzer.

To better understand H2S burst formation and distribution in swine facilities, the prototype system was used to detect concentrations at various locations in a swine finishing facility. While using surface agitation with splashing (agitation that disturbs the slurry surface), measurements were collected simultaneously from the pit below the slats and just above the slats in the same location. The use of stir fans equalized H2S concentrations above and below the slotted floor. By using stir fans, the operator can obtain a representative sample of room gas levels using a single point detection system.

H2S gas levels from above and below the slats in the same location can be collected during subsurface agitation (no disturbance of the slurry surface). While H2S concentrations were detected below the slats, no measurable H2S concentrations were detected above the slats. These results suggest that subsurface agitation should be used whenever possible to minimize H2S burst releases.

In a third test, H2S gas data was collected simultaneously from different areas within the barn just above the slats. In less than 10 minutes after vigorous surface agitation, the H2S gas concentration had exceeded the maximum range of the gas detector (500 ppm), demonstrating the dangers of H2S gas emissions during slurry agitation.

Researchers: Ross Muhlbauer, Randy Swestka, Robert Burns, Hongwei Xin, Steve Hoff and Hong Li, all of Iowa State University. Contact Burns by phone (515) 294-4203, fax (515) 294-4250 or e-mail [email protected].

Electrostatic Collection System Reduces Barn Dust

Test results in a hog finishing barn demonstrate that the Electrostatic Space Discharge System (ESDS) maintained a significant level of dust reduction compared to the control group.

The ESDS reduced 63% of total particle sizes (expressed as “total spatial particulates” or TSP) of dust and 47% of smaller particles less than 10 microns in size (PM-10). The 10-micron and smaller dust particles are the size inhaled by workers in hog barns.

Dust is a mixture of very small particles and liquid droplets that can cause or worsen health conditions in people and pigs. The PM-10 and smaller particles are of most concern because they can settle in the bronchia and lungs.

The ESDS reduces dust by negatively charging particles and causing them to attach to walls and equipment in the barn. This reduces the dust concentration in the room air as well as the air exhausted through the ventilation fans.

The ESDS has been shown to reduce dust levels in poultry buildings with great success — but little is known about the advantages in swine confinement facilities, the main goal of this research project.

To evaluate ESDS, a 1,000-head, two-room finishing barn was tested. Each room contained 24 pens, 12 per side. One room was equipped with an ESDS unit and the other served as a control.

The ventilation in each room included four pit fans and six wall fans. The ventilation controller was set to run through six stages. Fresh air entered the room through quad ceiling inlets for stages 1-3, and entered through wall inlets near the ceiling during stages 4-6.

Ventilation air flow ranged from 8 to 22% less than fan manufacturers' published data, probably due to the dirtiness of the fans.

The ESDS consists of an electrical multiple wire design, which maximizes the ions created by the 30,000 volts in the ESDS.

Air samples in each room were collected using MiniVol portable air samplers suspended 6 ft. above the slotted floor. The system samples air at 1.3 gal./minute, collecting in three different particulate categories: total spatial particulates (TSP), particles less than 10 microns (PM-10) and particles under 2.5 microns (PM-2.5). Particle size separation is achieved through impaction and collection on 2-in. filters.

Dust samples were collected over 24-hour periods. The collection process was repeated three times at about six-week intervals: first for 29- to 48-lb. pigs, then for 150- to 169-lb. pigs and finally for 240- to 260-lb. pigs. Each filter was weighed before and after sampling to get the mass of the dust particles on the filter.

In all three dust removal particle size test groups shown in Figures 1-3, the ESDS room reflected a significant advantage in total dust removal over the control room.

The greatest amount of TSP removal occurred in all three finisher weight groups (Figure 3).

Also, the first group of finishing pigs weighing 29-48 lb. showed a greater percentage reduction of dust particles.

Concentrations of dust removed were less in general for the middle weight group (150-169 lb.) because outside temperatures were warmer, increasing fan operation and decreasing dust concentration because of greater air exchange.

The application of the ESDS technology needs further study to determine the impact on other hog barn issues, such as odor, pathogens and gases, researchers note.

Dust will continue to be an issue in swine barns. Efficient and effective ways of removal will be key to maintaining a healthy working environment for the workers and for swine.

Researchers: R.E. Nicolai and B.J. Hofer, both of South Dakota State University. Contact Nicolai by phone (605) 688-5663, fax (605) 688-6764 or e-mail [email protected].

Gas-Phase Biofilters Reduce Odor, Emissions

Alternative media are being tested for use in gas-phase biofilters in an effort to minimize pressure drop, lower operating costs and reduce the biofilter footprint. Improved biofilters will also be more resistant to rodents and extend the useful life through reduced maintenance costs.

Gas-phase biofilters are a proven method for reducing odor and other gaseous emissions from swine facilities. However, widespread adoption of biofiltration has stalled due to four issues:

  • The relatively large footprint needed to manage the media pressure drop;

  • The concerns about the biofilter media harboring rats;

  • The potential problem of long-term biofilter media compaction; and

  • The concerns about potential nitrate leaching from the biofilter media into the soil.

This project at the University of Minnesota, funded by Pork Checkoff, was designed to identify and evaluate alternative biofilter media that would solve some of these issues.

Six media were evaluated in Phase 1: bag mulch, lava rock, cedar chips, pine bark nuggets, western pine bark and wood shreds. Media sieve analysis (filtration process), porosity and unit pressure drop vs. unit airflow relations were determined.

Phase 1 testing was conducted in a biofilter media testing unit with six columns, including individually controlled airflow rates and moisture control (pictured above).

Phase 1 testing involved the air-cleaning performance and pressure drop characteristics of each media evaluated on the basis of hydrogen sulfide (H2S), and ammonia (NH3) removal.

In Phase 2, three media — wood shreds, pine bark nuggets and lava rock — were placed in similar columns and evaluated for pressure drop and reductions of H2S and NH3.

In Phase 3, pine bark nuggets were used in all six columns and H2S, NH3 and odor removal were analyzed.

Overall, pine bark nuggets and lava rock scored the highest by recording the lowest unit pressure drops vs. unit airflow rates.

Results from Phase 1 indicate that all six media supported microbial growth if seeded, and were effective, reducing H2S concentrations between 21-75% and NH3 concentrations between 43-80%.

All three media in Phase 2 performed well in the study.

Some biofilter media in Phase 3 had lower percent H2S, NH3 and odor removal than others.

Researcher: Kevin A. Janni, University of Minnesota. Contact Janni by phone (612) 625-3108, fax (612) 624-3005 or e-mail [email protected].

Crop Residues + Swine Manure Enhance Methane Generation

Co-digesting swine manure with crop residues shows great promise in boosting methane generation in anaerobic digesters.

The problem with using swine manure only for anaerobic digestion is its low carbon/nitrogen (C:N) ratio (6:1 to 8:1, normal range), while good digestion re-quires a C:N ratio between 16:1 and 25:1.

University of Minnesota agricultural engineer Jun Zhu says the use of crop residues can be an effective way to enhance methane production, and at the same time reduce the volume of crop residue materials for disposal.

In his research, the addition of the crop residues at all C:N ratios increased the total daily gas volume produced (Figure 1). Wheat straw didn't achieve the same increase in gas production compared to corn stalks and oat straw during the first two weeks of production, but surpassed corn stalks later for the C:N ratio of 25.

Corn stalks and oat straw performed equally well in increasing gas production when compared to the control group (Figure 1).

When the C:N ratio was increased from 16:1 to 20:1, there was a clear increase in gas volume produced for all of the materials tested (Figure 1). However, continuing to increase the C:N ratio to 25:1 didn't produce the same increase in gas production seen in the increase in the C:N ratio to 20:1.

Figure 2 shows the methane (CH4) content in the gas from reactors using different crop residues and C:N ratios. Not much difference was observed in methane production between wheat straw and the control. However, the difference was quite significant for the other two crop products tested. Oat straw showed quick success, achieving a 44.4% digestion rate on Day 1 for a C:N ratio of 20:1, and a 58.8% digestion rate and C:N ratio of 16:1 by Day 3.

Corn stalks also reached 45% methane content on Day 5 for C:N ratios of 16:1 and 20:1.

The increase in C:N ratio doesn't seem to correlate with an increase in methane production for wheat straw treatment as compared to the control when the digester enters into a steady state.

But methane content mushrooms for both oat straw and corn stalks during the same period at a C:N ratio of 20:1 with 57% for oat straw, 68.2% for corn stalks and just 46.5% methane digestion rate for wheat straw.

“Since the quantity of pure methane is a product of total gas volume and the methane concentration in the off-gas, the higher the methane content and gas volume, the more methane is produced,” Zhu explains.

“Therefore, it appears that oat straw and corn stalks perform better than wheat straw when co-digested with swine manure, from the perspective of pure methane productivity,” he concludes.

Researcher: Jun Zhu, University of Minnesota Southern Research and Outreach Center at Waseca. Contact Zhu by phone (507) 837-5625, fax (507) 835-3622 or e-mail [email protected].

Feeder Design Impacts Growth Performance, Carcass Traits

Wet-dry feeders improved finishing pigs' feed intake by close to 9% and growth rate by 6-7% compared to conventional dry feeders in two recent Kansas State University research trials. And, pigs fed on wet-dry feeders were 4.5% heavier at marketing, but their carcasses were fatter and they yielded less than the pigs fed with conventional feeders.

Both experiments investigated the effects of conventional dry feeders with cup waterers (see Figure 1), compared to wet-dry feeders with a nipple in the feed pan, their sole source of water. Although pens with a wet-dry feeder also contained a cup waterer, they were shut off during the experiments.

Water was delivered to all of the pens of each feeder type, independently, and daily water consumption was measured using water meters.

The first experiment included 1,186 pigs, averaging 70.8 lb., on test. Groups were divided into 26-28 pigs/pen and allocated to one of two feeder types (22 pens/feeder type).

All pigs received the same diet sequence in four phases — Day 0-10, Day 10-28, Day 28-50 and Day 50-69.

Overall, pigs using the wet-dry feeder had greater average daily gain (ADG), average daily feed intake (ADFI) and final weight compared with pigs using the conventional dry feeder (Table 1). Feed-to-gain ratio (F:G) was essentially the same with both feeder types.

Average daily water usage for pigs on the wet-dry feeder was 1.44 gal./day. Pigs on the conventional dry feeders averaged 1.38 gal./day.

The second experiment was conducted with 1,236 pigs allotted to pens with one of the two feeder types. There were 23 pens per feeder type with 25-28 pigs/pen. Pig weights averaged 63.2 lb. at the beginning of the 104-day research trial. All pigs were fed the same feed budget.

The three largest pigs per pen were marketed on Day 84. The remaining pigs were fed a fifth dietary phase containing Paylean until they were slaughtered on Day 104. Table 3 shows the effects of feeder design on the carcass characteristics and the resulting economic return.

Overall, pigs using the wet-dry feeder had greater ADG, ADFI and final weight compared with those using the conventional dry feeder. However, pigs using the wet-dry feeder consumed more feed, had poorer feed/gain and higher feed cost/pig than pigs using the conventional feeder (Table 2).

Carcass yield, fat-free-lean index, premium per pig and live value per cwt. were higher and average backfat depth was lower for pigs using the conventional dry feeder. All of these effects combined resulted in a lower net income per pig for pigs fed with the wet-dry feeder (Table 3).

The KSU researchers felt the experiments demonstrated that growth performance is improved when pigs are offered feed and water, ad libitum, via a wet-dry feeder when compared to a conventional dry feeder and drinker bowl.

Still, the research results brought up some interesting questions for further study, such as: “Can we manage within-group variation better by feeding the lightest pigs placed in a finisher, or even gilts, with a wet-dry feeder?” asks Jon Bergstrom, KSU swine laboratory research coordinator.

He predicts that with the growing emphasis on understanding behavior, maximizing welfare and related productivity, research in this area will continue. And he wonders if feeder design and feed presentation can overcome the reduced feed intake associated with feeding some by-products.

Because carcasses of pigs fed with a wet-dry feeder yielded less and were fatter, the use of wet-dry feeders may not be justified with some carcass incentive programs, note researchers.

Researchers: Jon Bergstrom; Mike Tokach; Steve Dritz; Jim Nelssen, DVM; Joel DeRouchey and Robert Goodband, Kansas State University. Contact Bergstrom at 785-532-1277 or e-mail [email protected].