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1997 Swine Research Review

Article-1997 Swine Research Review

Detecting Food-Borne Parasites Research in the USDA Immunology and Disease Resistance Laboratory addresses food safety and swine health challenges. State-of-the-art molecular techniques have been investigated for dealing with parasite infections of swine.Scientists in this laboratory are developing methods for parasite diagnosis. They are probing the neonatal swine immune system and devising alternate

Detecting Food-Borne Parasites Research in the USDA Immunology and Disease Resistance Laboratory addresses food safety and swine health challenges. State-of-the-art molecular techniques have been investigated for dealing with parasite infections of swine.

Scientists in this laboratory are developing methods for parasite diagnosis. They are probing the neonatal swine immune system and devising alternate strategies to stimulate protective immune responses against food-borne parasitic diseases. The research goal is to find better ways of identifying and reducing food-borne parasite infections in swine, and therefore, providing a safer pork product for human consumption.

The researchers developed a DNA-based method for the differentiation of species of Trichinella. These parasites reside in the muscle tissue of infected hosts. No known drug therapy is available to eliminate the parasites from the host's muscles.

This group of parasites has the capability of infecting nearly any animal that ingests previously infected meat products.

Dante Zarlenga, USDA researcher, developed a method to differentiate the eight different types of Trichinella presently known to exist. These include the well-known domestic Trichinella (Trichinella spiralis) type found previously in infected pigs. Also included are the freeze-resistant Trichinella types found in Arctic regions.

This test is based upon differences in DNA content among parasites of this group. Testing can be performed on DNA generated from as little as a single parasite.

This work has formed the basis of several epidemiological studies looking at the prominent Trichinella types in North American wildlife, as well as the arctic regions of Canada. Results show the domestic Trichinella spiralis is likely not the dominant species that exists in wild animals.

This work also indicates Trichinella from wild animals obtained from arctic regions of Canada, as well as some northern regions of the U.S., cannot be killed by freezing as previously recommended for Trichinella spiralis.

Zarlenga and his colleagues have also developed a genetically engineered serology test for swine cysticercosis. Taenia solium, a cestode parasite that causes cysticercosis, is important because it can lead to serious, and sometimes fatal, medical consequences due to the development of neurological disorders associated with the parasite infection.

Concerns over increasing transmission and prevalence of this disease in the U.S. have heightened due to the dramatic increase in trade with Central America where the incidence of this infection is high. Increases in immigration to the U.S. by infected individuals from endemic parts of the world are also a concern.

The serodiagnostic test is based upon a genetically engineered parasite protein that has proven useful in identifying infected pigs prior to their meat products reaching the consumer.

When fully developed, this test will assist inspectors in providing safer meat products to American consumers. Patents are pending on this development.

This same recombinant antigen is being tested as a potential vaccine to prevent the transmission of the parasite by immunizing animals and/or humans at highest risk.

Results have indicated greater than 92% protection in a mouse model system. Preliminary work using a rat model, which more closely resembles the human/swine paradigm, has demonstrated at least 75% protection.

Research is now underway to test the protective characteristics of this antigen in swine.

If a vaccine for swine cysticercosis were proven effective, it could be used in targeted populations to prevent contamination of the food supply with this parasite.

Researchers: Joan K. Lunney, Dante S. Zarlenga, Agriculture Research Service, United States Dept. of Agriculture, Beltsville, MD. Phone Zarlenga at (301) 504-8754.

Hot Water Rinse Destroys Bacteria On Carcasses A project recently completed at Iowa State University (ISU) is an example of ongoing interest in the microbiological safety of foods. The research evaluated the use of hot water rinses to destroy bacteria on hog carcasses.

Microbial contamination of animal carcasses is a result of necessary meat processing procedures. The contamination can be minimized by good manufacturing processes, but the total elimination of food-borne pathogenic microorganisms is almost impossible.

A variety of methods have been developed to reduce the levels of contaminating bacteria on carcasses. Most of the current methods focus on washing and sanitizing.

The internal muscle tissue of healthy animals is essentially sterile. Most contamination is on the external surface of the carcass. The skin and hair constitute one of the primary sources of bacterial contamination during processing.

Fortunately, most of the contamination during processing is not disease-causing organisms. However, bacteria of public health significance such as salmonella, campylobacter and listeria can occasionally occur. It is worth noting that Escherichia coli O157:H7 has not been isolated from live hogs, and does not appear to be associated with pork meat.

The research project recently completed at ISU was entitled "Hot Water Rinses as a Bacteriological Intervention Strategy on Swine." The objectives were to determine the minimum application criteria (temperature, volume, and exposure time) of hot water rinsing to significantly reduce the population of salmonella on the skin and meat of swine carcasses.

The project proceeded in two phases. A laboratory experimentation phase was followed by a series of experiments in the abattoir in the meats laboratory at Iowa State University.

The first phase simulated processing conditions in the laboratory, and used salmonellae as a test bacterium.

Since the abattoir in the meats laboratory is a federally inspected facility, it was not possible to use salmonella in the second phase. A group of "marker" bacteria (which have similar responses to treatments as salmonella) were monitored to evaluate the effectiveness of the process.

The results of the laboratory phase of the project showed that hot water rinses in the range of 130 degrees F to 150 degrees F for up to 15 seconds significantly reduced the populations of salmonella and the indicator bacteria (Enterobacteriaceae).

This data suggests hot water rinses could be used successfully in a hog processing facility.

The second phase was conducted in the Meats Laboratory.

The forelegs of market-weight hogs were intentionally contaminated and then subjected to a hot water rinse. A 150 degrees F, 10-second rinse reduced the populations of the marker bacteria by greater than 90% compared to the non-processed control carcasses.

This represents a significant improvement in the microbiological quality of the carcasses, and suggests a significant reduction in the potential risk associated with pork.

The researchers at ISU say the exciting part of this process is that it is a "low-tech" process. It is reasonable and affordable. Even very small processors, such as locker plants, would be able to implement the process.

While everyone is concerned with the very large processors because of the volume of product they produce, smaller processors are important to their local geographic areas and to the people that they serve. For this reason, part of the research program at ISU focuses on technology which can be implemented by all processors, irrespective of their size. This project is an example of that research approach, which hopefully will help the swine industry at all levels to provide the safest possible product to the consumers.

Researchers: Luisa Eggenberger-Solorzano and James S. Dickson, Iowa State University. Phone Dickson at (515) 294-4733, or email: [email protected]

Growth Rates Differ In Young Barrows, Gilts Recent research at the University of Kentucky (UK) shows barrows and gilts grow differently as early in life as 3-4 weeks of age.

Researchers summarized 58 starter ration experiments conducted at the university between 1987 and 1996 to determine if barrows and gilts grew at different rates during the postweaning period. The pigs had been weaned at 3-4 weeks of age and most of the experiments ran four weeks in duration.

Barrows and gilts were mixed in pens (generally 4-8/pen), so only initial and final weights and growth rates were obtainable from the records. Both sexes were treated identically prior to the experiments, except barrows were castrated at 10 to 14 days of age.

The data set involved 7,146 pigs (3,621 barrows and 3,525 gilts). Although initial age was essentially the same (25.7 days) for both sexes, barrows were slightly heavier at the start of the experiments than gilts (15.64 vs. 15.48 lb).

Overall, gilts grew about 4.7% faster than barrows (.782 vs. .747 lb./day), and they averaged about 1 lb. more in weight at the end of the experiments (36.5 vs. 35.7 lb.). Both of these differences were highly significant from a statistical standpoint.

The gilts gained faster than barrows in 43 experiments, and gained slower than barrows in only 14 experiments. Gilts outgained barrows by 10% or more in 12 of the 58 experiments, and out-gained barrows by 5% or more in 27 of the experiments.

Barrows did not out-gain gilts by 10% or more in any of the experiments, and out-gained gilts by 5% in only one of the 58 experiments.

For many years, it has been assumed that barrows and gilts do not differ in their growth rate, feed intake, or efficiency of feed utilization until they reach 75-100 lb. At that time, the estrogenic hormones in gilts kick in and differences begin to show up.

Gilts will grow slower than barrows, but they are more efficient in converting feed to weight gain. They deposit less fat, and they are leaner at market weights.

The results of this UK research clearly indicates gilts outgain barrows during the postweaning period, though the difference is not very great. Whether the gilts simply consume more feed or are more efficient in converting feed to weight gain is not known. Whether this difference in performance merits penning the two sexes separately during the postweaning period remains to be determined.

Researchers: Gary Cromwell, Richard Coffey, Gary Parker, Merlin Lindemann, Jim Randolph and Jim Monegue, University of Kentucky. Phone Cromwell at (606) 257-7534.

Shock Waves Tenderize Pork The USDA-ARS Meat Science Research Lab, Beltsville, MD, recently conducted studies to compare a new pork tenderizing process to postmortem aging.

The Hydrodyne Process (HP) uses a small amount of explosive to generate a shock wave in water. The shock wave passes through the muscle, causing small tears that disrupt the cellular structure of the muscle and tenderizing the meat.

Boneless pork loins were removed from carcasses 24 hours post-slaughter and cut into sections. The rib end and loin end were randomly vacuum-packaged and assigned to either HP treatment or control treatment.

Study 1 consisted of 24 control and 24 HP samples treated one day postmortem and then evaluated for tenderness.

Study 2 consisted of 12 control and 12 HP samples treated one day postmortem. The samples were evaluated for tenderness, vacuum packaged and refrigerated for 40 days of aging, after which tenderness was again measured.

Pork loin chops (1 in. thick) were cooked on open-hearth broilers to an internal temperature of 162 degrees F and objective shear force tenderness was determined using .5-in. core samples.

Shear force of HP-treated pork was significantly lower than controls at one day postmortem in study 1. Hydrodyne-treated chops also exhibited 2.4% less weight loss during cooking.

In study 2, Hydrodyne-treated pork was more tender than control samples at one day postmortem, but was similar to controls after 40 days postmortem.

Postmortem aging improved tenderness in the control samples, but not in the HP-treated samples.

The HP process instantaneously improved pork tenderness, and this improvement was of the same magnitude the control samples after 40 days of postmortem aging.

Results suggest tenderizing pork with the Hydrodyne process presents a potentially novel opportunity in the way the pork industry can assure consistently tender meat.

Researchers: M.B. Solomon, J.S. Eastridge, and J.B. Long, USDA-ARS, Meat Science Research Lab, Beltsville, MD and Hydrodyne, Inc., San Juan, PR. Phone Solomon at (301) 504-8400.

Quality Checked After Shock Tenderization Ohio State University researchers studied the effect of the Hydrodyne Meat Tenderization Process on a variety of pork quality attributes.

Paired, boneless pork loins were obtained from 76 market hogs to evaluate the tenderness, meat quality characteristics, sensory attributes and microbial content of pork loins after exposure to the Hydrodyne Process (HP).

The process uses a small amount of explosive to generate a shock wave in water. If the shock is large enough, a tenderizing effect is brought about by the destruction of muscle structure.

Following slaughter, paired loins from each pig were de-boned, trimmed of external fat, vacuum packaged in an oxygen-impermeable bag and frozen.

Frozen loins were transported to the USDA Beltsville Agricultural Experiment Station where the HP was conducted.

One loin from each pig was assigned to either a control or HP treatment protocol. All loins were thawed prior to administration of the HP.

After the HP treatment, all loins were re-frozen and transported to Ohio State University. The loins were thawed and samples collected for further testing. Muscle quality tests included:

* Subjective, visual assessment of color, marbling and firmness.

* Objective, Minolta reflectance and color scores.

* Drip loss estimation of uncooked samples.

* Total lipid extraction.

Two loin samples from each control and HP-treated loin were cut to a standard thickness of 1 in. One loin sample from each treatment (control or HP) was assigned to one of two designated cooking times (11 or 16 min.) to determine the effect of internal temperature on Warner-Bratzler shear force values.

Loin samples were weighed prior to and following cooking to determine cooking loss. Warner-Bratzler shear force values were recorded on cooked loin samples to determine the effect of treatment and cooking time on the tenderness of the loin samples.

A trained sensory panel evaluated cooked loin samples for pork flavor, off-flavor, initial tenderness, sustained tenderness, juiciness, cohesiveness and the number of chews necessary to consume the meat sample.

No significant differences were observed between the HP- and control-treated loins for visual assessments by color score or machine-measured light reflectance (Minolta) and color, indicating the HP, did not affect the overall appearance of pork loins.

Tests showed HP-treated loins had reflectance values less red than control loins. Loins treated with the HP protocol also had significantly lower marbling scores and intramuscular fat content than control loins from the same pig. This finding is not easily explained from a biological or procedural standpoint, and is an area that needs further investigation.

The results of this study indicate no negative effects on commonly measured muscle quality traits including color, firmness and water-holding capacity when treated by the HP protocol. The observed drip loss values were extremely low for both control (0.81%) and HP (0.73%) loins, which is probably the result of the freezing and thawing that took place as a result of the need to transport the loins between sites for treatment and collection of data.

Sensory evaluation scores on a subset of 16 randomly selected and paired loins showed significant differences between HP and control treatments for juiciness. The HP loins had lower juiciness scores than the controls.

In contrast to the 17% improvement in shear force found in the whole sample, randomly selected loins utilized in the taste panel tests showed no difference in shear force between the HP and control loins. This results in no detectable improvement in sensory evaluations of initial or sustained tenderness.

Sensory tests were also unable to detect differences in cohesiveness or number of chews necessary to consume a sample.

The impact of HP on tenderness was consistent across cooking times.

Differences in pork flavor and off-flavor approached significance, with the HP-treated loins having slightly less off-flavor and higher pork flavor scores than the control loin samples.

The sensory evaluation findings support the conclusion that the HP protocol had no major effect on sensory characteristics other than juiciness. Because the 16 loins used in the sensory evaluation showed no differences in shear force, the ability of sensory panels to detect treatment differences could not be tested.

It should be noted the sensory tests were conducted on 16 of 76 animals and with this small sample size, the statistical power to test differences among treatments is not large. To fully test sensory attributes, further sensory panel evaluation and analysis need to be conducted with HP-treated pork.

Microbial tests showed no differences between control and HP treatments for coliform bacteria or Aerobic Plate Count. No detectable levels of E. coli were observed in any samples.

The overall importance of this research for the swine industry is the fact that the HP, a process that requires little space, time or energy, appears to improve tenderness of the pork loin. In addition, it accomplishes this without having a major detrimental effect on muscle quality traits, sensory characteristics or the safety and wholesomeness of pork.

The use of the HP may be a tool that can be effectively utilized by the pork industry to improve overall tenderness of pork products, but should not be considered a shortcut to improving tenderness problems associated with major genes, genetic types, nutrition programs or management styles that contribute to tough pork.

Researchers: Steve Moeller, D. Wulf, D. Meeker, Ohio State University Animal Science Dept., M. Ndife, N. Sundararajan, Ohio State University Food Technology Dept. and M. Solomon, USDA-ARS, Beltsville, MD. Phone Moeller at (614) 688-3686.

Bacterial Causes Of Mastitis Identified University of Tennessee (UT) researchers are using DNA fingerprinting techniques to determine which strains of bacteria are responsible for mastitis in sows. Identifying mastitis causes will then help determine where the problem organisms originate within facilities and herds, explains Alan Mathew and Kris Ann Jaggers at the UT Agricultural Experiment Station.

Streptococci, Staphylococci, and E. coli have all been implicated in mastitis cases. These organisms have also been identified as causing similar diseases in dairy cows.

The UT investigators found the most common bacteria in cases of swine mastitis belonged to a group of organisms known as Corynebacteria. According to the researchers, Corynebacteria can cause mastitis in dairy cows, where it is more of an indication of poor sanitation rather than contagious transfer associated with other pathogens.

This information could help explain why mastitis occurs in some swine facilities and identify prevention strategies.

If dairy practices are any indication, keeping sow udders clean and dry during the final days of gestation may help reduce the incidence of mastitis caused by Corynebacteria.

The researchers will continue to analyze bacterial DNA patterns from various sources to help pinpoint reservoirs of mastitis pathogens in swine facilities.

Reports indicate mastitis affects up to 40% of lactating sows. Producers often don't notice the problem unless the entire udder is infected. Usually only a few teats are infected and the overall health of the udder seems normal. Thus, while the majority of pigs in a litter may receive adequate colostrum and immunity, a few pigs confined to the mastitic teats may not. Although few in number, these pigs may become the source of more widespread problems at weaning. These pigs may succumb to minor pathogen challenges and begin shedding large numbers of virulent organisms that then infect the entire nursery group.

Researchers: Alan Mathew and Kris Ann Jaggers, University of Tennessee. Phone Mathew at (423) 974-7286.

Subjecting Swine To Multiple Stresses Pigs deal with a variety of stressful experiences as they grow. University of Illinois (UI) researchers wanted to understand how different stressors presented to pigs simultaneously would influence growth performance.

The researchers subjected pigs to an arrangement of treatments involving three stressors. Their results confirmed previous studies which show when presented alone, high ambient temperature, reduced space allowance, and regrouping depress growth (ADG), feed intake (ADFI) and feed conversion efficiency (G:F).

The important finding of this research was that when these stressors were presented together, as is often the case in typical swine production systems, the effects were additive. The data from this research indicates the removal of a single stressor can have a substantial, beneficial effect on the growth performance of pigs, even when a number of other uncontrollable stressors persist.

The data also suggest it may be possible to predict the effects of multiple simultaneous stressors on growth performance of pigs if the effects of the individual stressors are known.

Eight treatment combinations were used on the 256 Yorkshire x Hampshire, or purebred Duroc pigs in this experiment. The pigs weighed around 76 lb. at the beginning of the experiment which was carried out over a four-week period.

The temperature treatments included ambient temperature ( a constant 75.2 degrees F) or high-cycling temperature ranging from 82.4 degrees F to 93.2 degrees F. Treatments included stocking density of 6 sq. ft./pig or 2.7 sq. ft./pig. Social group treatments included a static group, or pigs regrouped during the first and third weeks of the 4-week experiment.

Pigs were provided ad lib access to a corn-soybean meal-based diet formulated to exceed NRC (1988) nutrient requirements for grower pigs (17% CP, .9% lysine, and 3296 Kcal ME/kg). Eight pigs were assigned to each pen, and following a 1-week acclimation period at 6 sq. ft./pig and 75.2 degrees F, stressors were imposed.

Pigs were subjected to zero to three stressors at once, depending on the treatment group. The type of stressor and the level of stress were chosen in order to ensure a detrimental effect on performance, but to still be within limits of what may be observed in typical production systems.

The treatments were as follows: no stressors (control), one stressor (either high diurnal temperature, regrouping or reduced space allocation), two stressors (high diurnal temperature and regrouping; high diurnal temperature and reduced space allocation; and regrouping and reduced space allocation), or three stressors (high diurnal temperature and regrouping and reduced space allocation).

Feed disappearance and pig body weight were measured at 1-week intervals so ADG, ADFI and gain:feed (G:F) could be calculated.

The stress of high temperature, high stocking density and regrouping depressed 4-week average daily gain (ADG) by 12%, 16% and 10%, and average daily feed intake (ADFI) by 7%, 6% and 5%, respectively.

Out of a possible 60 stressor interactions for ADG. ADFI and G:F, there were no significant three-way interactions, and only six two-way interactions, suggesting the effects of the individual stressors were additive. This means the stressors' effects on performance were similar regardless of whether they were imposed singly or in combination.

When pigs were subjected to all three stressors simultaneously, ADG, ADFI and G:F were depressed by 31%, 15% and 18%, respectively.

As the number of stressors increased from 0 to 3, ADG, ADFI and G:F decreased linearly.

The researchers say multiple, concurrent stressors affect growth performance of pigs in a predictable, additive fashion, and indicate avoidance or removal of a given stressor would give pigs an advantage, even when other uncontrollable stressors persist.

Researchers: Young Hyun, Mike Ellis, G. Riskowski and Rodney W. Johnson, University of Illinois. Phone Johnson at (217) 333-2118.

Biochemical Markers Of Sickness Reduced feed intake and lowered lean muscle growth often means sick pigs. The emerging view among researchers is that these consequences in sick pigs happen because of the increased production of certain cytokines. Cytokines are substances secreted by cells of the immune system that help pigs fight offsickness. University of Illinois scientists used 72 pigs weighing 26 lb. to find out how a specific disease challenge affects cytokine production and body protein accretion.

The pigs were given an injection of E.coli lipopolysaccharide (LPS) to induce sickness, and blood samples were taken at specific intervals after injection. Several blood parameters were measured, including the cytokines interleukin-6 and tumor necrosis factor-alpha. The results showed disease challenge resulted in a dramatic increase in cytokine production, which was followed by an increase in muscle protein breakdown indicated by an increase in plasma urea nitrogen.

The researchers were trying to mimic what would happen if pigs got sick in a typical production environment. The next step with the research is to figure out if it is necessary to feed animals differently when they are experiencing an immune challenge.

"In the future we might be able to use a simple test that would indicate the sickness level of a pig," says Douglas M. Webel, University of Illinois animal scientist. "If the producer could determine the disease level in his herd,then it might be possible to design specific feeding programs to maximize efficiencies in that particular situation."

Researchers: Douglas M. Webel, Brian N. Finck, Rodney W. Johnson, and David H. Baker, University of Illinois. Phone Webel at (217) 333-4366.

Weaning Changes Intestinal Coating Mucins, protective compounds in the small intestine of young pigs, protect the animal from invasion by intestinal pathogens like E. coli and salmonella.

University of Tennessee (UT) researchers detected significant changes in mucins following weaning. They suspect the change from a milk-based diet and/or other factors associated with weaning may be partly responsible for the changes in mucin structure. This means lower resistance to intestinal pathogens.

There are indications that the types and proportion of carbohydrates in the diet may play an important role in maintaining this protective coating.

Researchers are currently testing dietary compounds for their ability to maintain the integrity of intestinal mucins. They hope to use this information to formulate starter diets that provide maximum protection for the intestinal tissues and, thus, reduce the incidence of postweaning intestinal disorders.

Researchers: Alan Mathew and Marina Pestova, Rose Clift, University of Tennessee. Phone (423) 974-7286.

Gestation Feeding Impacts Offsprings' Carcass Results Kansas State University (KSU) animal scientists are investigating ways to alter pig growth potential by increasing nutrient levels fed to sows during early gestation.

The objective of a recent experiment was to determine if feeding sows more feed or more carbohydrates during gestation led to improved carcass characteristics in offspring.

A total of 321 sows were used in the experiment. Sows received either increased feed (8 lb./day of complete feed) or added corn (4 lb./day of complete feed plus 4 lb./day of ground corn) from day 30 to day 50 of gestation.

This experiment was conducted on a 3,000 sow, farrow-to-wean operation in southwest Minnesota. On day 30 of gestation, sows were assigned randomly to groups of five, then fed one of three treatments.

All sows were fed by drop feeders, but those receiving added corn received their extra 4 lb. as a top-dress.

All sows were fed 4 lb./day of complete feed before day 30 and after day 50 of gestation. Sows fed increased levels during gestation treatment periods had fewer pigs born live than control sows. This decrease was not observed for sows fed ground corn.

There were no differences in number of mummified or stillborn pigs per litter (Table 1). No differences appeared in either pig birth weight or birth weight variation.

Pigs were mixed within sex at weaning and moved to offsite nurseries. Pigs were moved to finishing buildings at 10 weeks of age.

Upon reaching market weight (260 lb.), pigs were sorted and marketed by treatment and sex for a total of six different marketing groups (i.e. a load of barrows or gilts from each individual treatment).

Experimental pigs were processed at the slaughter plant as the first pigs of the day to decrease potential variation in Fat-O-Meater measurements. Individual carcass measurements were obtained on 2,358 pigs (See results in Table 2).

Analysis of hot carcass weight revealed offspring (barrows and gilts) from sows fed increased diet were the heaviest. Offspring from sows receiving additional corn weighed in the intermediate range.

Barrows showed no differences in 10th-rib fat depth. However, gilts from sows fed added corn or increased feed had less 10th-rib fat depth at slaughter.

Researchers speculate changes in growth potential during gestation may result from the ability to alter the number of muscle fibers in the developing fetus.

The development of muscle at this stage involves the formation of primary and secondary muscle fibers. As the primary fibers develop, they are supported by the proliferation of secondary fibers.

Research from Europe observed that increasing gestation feed intake from day 25 to day 80 resulted in offspring that grew faster and more efficiently than controls.

The decrease in number born live with the increased feed intake, but not with added corn, is a concern, KSU scientists say. Research from Europe has shown no effect of high feed intake on number born live, but in that study, feed intake was increased then decreased over several days.

KSU researchers say the results suggest increased nutrient intake during critical periods in gestation can influence growth and carcass composition of the offspring.

They indicate additional research is needed to determine the mode of action. Their next step will be to determine the timing and amount of increased feed intake that will affect carcass characteristics of the offspring.Re searchers: R. E. Musser, Robert D. Goodband, Steve S. Dritz, Mike D. Tokach, Jim L. Nelssen, J. S. Bauman, and M. Heintz, Kansas State University. Phone Goodband at (913) 532-1228.

Added Fat For Sows Boosts Litter Gain Supplemental dietary fat increases milk fat in multiparous sows and improves litter gain, according to North Carolina State University (NCSU) research results.

The NCSU experiment utilized 24 gilts and 24 sows to study the effects of 10% supplemental dietary fat and the use of lutalyse on milk composition and litter performance.

The eight treatments included all possible combinations of parity (1 vs. greater than 3), diet (0 or 10% choice white grease), and farrowing (natural vs. lutalyse on day 112) variables.

The researchers felt milk fat would be depressed in dams induced to farrow early, and in primiparous gilts due to a mammary gland that is not fully functional at the time of parturition. Supplemental dietary fat may help overcome this milk fat depression.

Dietary treatments were initiated on day 90 of gestation and continued through day 21 of lactation. The sows were limit fed 4.4 lb./day during gestation. Feed was available ad libitum after farrowing. Table 3 provides information on diet composition.

Prostaglandin was given on day 112 to induce farrowing in the sows assigned to the induced farrowing treatment. These sows farrowed 24 to 36 hours later.

Milk was collected from the right front teat beginning at the birth of the first pig (0 hours) and subsequently at 3, 6, 9, 12, 24, 48, 72 and 168 hours post-farrowing.

The milk samples were analyzed for total protein, lactose, fat and insulin-like growth factor-I (IGF-I).

Sows were weighed on days 90 and 109 of gestation, and again post-farrowing and at weaning.

Piglets were weighed at birth, day 7, 14 and at weaning. Piglet average daily gain was 20% greater in dams fed fat over all three weeks of lactation (Figure 1). Milk fat and lactose concentrations progressively increased over time, while protein concentrations decreased.

Dietary fat elevated milk fat concentrations at 48 and 72 hours post-farrowing by 21.6 and 22.6%, respectively (Figure 2).

Multiparous sows show a more consistent increase in milk fat concentration when fat is added to their diet. Milk IGF-I concentration declines over time for all treatments. Sows fed no additional dietary fat tended to have lower IGF-I levels than sows fed a diet with 10% added fat.

Induction of farrowing also seems to depress milk IGF-I levels. IGF-I levels in an animal fed 10% added dietary fat and induced to farrow compare favorably to those allowed to farrow naturally, but consuming a diet with no added fat.

Sow weights were not affected by treatments. Supplemental dietary fat increases milk fat in multiparous sows more than primiparous sows regardless of farrowing treatment, and improves litter gain throughout lactation regardless of parity or farrowing treatment.

The amount and composition of colostrum and milk a dam provides has a direct relationship with the growth and survival rates of her litter (Table 4). In addition to nutrients, milk is also an important source of "growth factors" such as IGF-I that may stimulate development of the piglet intestine.

Supplemental dietary fat has been shown to improve the reproductive efficiency of swine by reducing post-natal mortality.

It may also increase the energy reserves in the piglet at birth, as well as increasing the caloric density of the dam's colostrum and milk.

A large, follow-up study furthering this research is currently being completed at NCSU.

Researchers: Jack Odle and Lori Averette, North Carolina State University. Phone Averette at (919) 515-8626).

Somatotrophin Alters Lysine Requirement Of Growing Pigs Porcine somatotropin (PST), not yet approved by the U.S. Food and Drug Administration, has a marked impact on the dietary levels of protein (amino acids) pigs will need to be fed in order to maximize performance and lean accretion rate.

University of Kentucky (UK) animal scientists say PST-treated pigs clearly required a higher lysine diet than control pigs during a recent research trial.

Research has shown PST is effective in increasing lean tissue deposition in finishing pigs. Along with the dramatic increase in carcass leanness, pigs treated with PST grow faster, consume less feed, and convert feed to weight gain more efficiently.

Because of the decrease in feed intake in pigs treated with PST, it is generally assumed the nutrient requirements are increased. While this has been demonstrated in finishing pigs, there is very little information on the effects of PST in pigs during the growing stage.

UK animal researchers fed four corn-soybean meal diets with lysine levels of .75, 1.00, 1.25 or 1.50% to 40 pigs from 50-132 lb. body weight.

Diets were formulated to have a near-ideal blend of amino acids. The .75% lysine diet was equivalent to current NRC estimates of the amino acid requirements for pigs of this weight range.

Half of the pigs received a daily injection of 2 mg. PST. In addition to measuring performance, the researchers killed the pigs at the end of the experiment and ground their entire body. This was done to determine the composition and accretion rate (gain) of whole body protein, fat, water and ash.

Administration of PST resulted in a marked increase in the lean content of the carcass, and in the whole body protein content and protein accretion rate.

PST-treated pigs had greater accretion rates of whole body protein (143 vs. 118 g./day), compared with untreated pigs. Treated pigs also had greater water (495 vs. 417 g/day) and ash (24 vs. 22 g/day), and reduced accretion rates of whole body fat (135 vs. 186 g/day).

Increasing the dietary lysine had little effect on protein accretion rate in the untreated pigs (117, 118, 119 g/day), but it markedly increased the whole-body protein gain in PST-treated pigs (114, 147, 156, 154 g/day).

According to the researchers, the PST-treated pigs clearly required a higher lysine diet than control pigs. Their whole-body protein gain did not maximize until 1.25% lysine was fed. In controls, .75% lysine (the NRC requirement) resulted in maximum protein accretion.

Researchers: Gary Cromwell, Bill Dozier, and Merlin Lindemann, University of Kentucky. Phone Cromwell at (606) 257-7534.

Reduced Phosphorus Diet Compared To Phytase Diet Oklahoma State University researchers investigated how to decrease the amount of manure phosphorus excreted by pigs in the late finishing stage. The pigs were fed corn-soybean meal diets. Researchers compared pigs receiving reduced phosphorus diets with pigs receiving supplemental phytase from 144 to 238 lb.

The experiment involved 48 Yorkshire barrows. Dietary treatments included:

Diet 1 - A control corn-soybean meal diet containing .60% calcium and .50% phosphorus (dicalcium phosphate was the supplemental phosphorus source).

Diet 2 - Same as diet 1 with no supplemental inorganic phosphorus and no added phytase (.50% calcium and .33% phosphorus).

Diet 3 - Same as diet 2 with 303 units of microbial phytase (Natuphos from BASF) per lb. of diet.

Feeding the diet devoid of inorganic phosphorus reduced gain, feed efficiency, bone-breaking strength, femur ash and femur phosphorus when compared with pigs fed the control diet.

Adding microbial phytase to the low-phosphorus diet restored performance, bone-breaking strength, femur ash and femur phosphorus to the levels observed in pigs fed the control diet.

Feed intake, metacarpal ash, femur calcium, metacarpal calcium and phosphorus were not affected by dietary treatments.

These results indicate inorganic phosphorus removal, even for relatively short feeding periods with calcium at .50% of the diet, had a dramatic effect on reducing performance and bone mineralization.

The addition of microbial phytase to a low-phosphorus finishing diet improves performance and bone status in finishing swine and suggests phytase may be an effective means of reducing phosphorus excretion in swine.

Researchers: B. Z deRodas, S. Mandali and C. V. Maxwell, Oklahoma State University. Phone Maxwell at (405)-744-6619.

An Economic Look At Ractopamine Use Ohio State University (OSU) researchers evaluated ractopamine use on a representative Ohio hog farm.

Ractopamine is a feed additive and repartitioning agent, not yet on the market in the U.S. Repartitioning agents redirect the nutrients in the diet away from the formation of adipose tissue (fat) toward muscle growth. This results in a more efficient use of feed, a major expense on the hog operation.

Research indicates ractopamine has the potential to increase feed conversion, decrease feed consumption, increase the average daily gain (ADG), and increase the total carcass leanness, say the researchers. Previous research identified a range of 3.75% to 12.3% improvement in the feed conversion.

The financial performance of a representative hog-grain operation was investigated after adopting ractopamine, a size neutral technology. Size neutral means the technology has the same response rate on all size operations.

The researchers had to calculate an implied indifference price and potential product price, (because the product is not on the market in the U.S.). The product price was then incorporated into the farm financial scenarios.

Using a Lotus template, the financial position of the operation was calculated and evaluated based on profitability, liquidity and solvency.

A representative farm was developed from information collected for the Ohio Longitudinal Survey. The survey divides farms into hobby/part-time and full-time, commercial operations. A full-time commercial farrow-to-finish operation is approximately 200 sows.

The representative farm also operates a 600-acre grain enterprise, producing corn, wheat and soybeans. Some of the corn is ground and mixed on-farm for use as feed in the hog operation.

The base case hog enterprise has a feed conversion rate of 3.28 lb. feed/lb. gain. The feed efficiency figures were used to represent the response of ractopamine use. A 3.75% improvement in feed conversion translates to 3.15 lb. feed/lb. gain for the minimum response rate.

The maximum improvement was 12.3%, resulting in a feed efficiency rate of 2.87 lb. feed/lb. gain.

A moderate case was also developed, using the mid-point between the two, resulting in a 6.15% improvement and a feed efficiency rate of 3.06 lb. feed/lb. gain. The scenario assumed the 200-sow operations would produce 8.5 pigs/litter and have 2.2 turns/year. The hogs marketed in the ractopamine scenarios also received a carcass merit premium.

The changes in feed efficiency, plus the carcass merit premiums were used to develop three scenarios: minimum, moderate and maximum response rate to ractopamine. These response rates were used in the Lotus template to generate an implied indifference price. The implied indifference price is calculated by dividing the change in gross revenue by the number of hogs marketed. This resulted in an implied indifference price of $4.03/hog, $4.69/hog and $6.08/hog, respectively.

The implied indifference price is interpreted as the price above which farmers are indifferent to adoption. A product price below the indifference price would cause farmers to consider adopting the technology.

>From this information, a product cost is calculated. The three indifference prices were averaged with 50% attributed to the price of the product. This resulted in a potential product cost of $2.47/hog. This was then incorporated into the three-farm scenarios as a production cost. The financial position of the base and ractopamine response rate scenarios was determined using a Lotus template. Financial performance of the operation was evaluated using profitability measures of net income and return on assets, a liquidity measure, cash flow coverage ratio, and a solvency measure of debt-to-asset ratio.

Results indicate adoption could improve a financially sound operation. Profitability generally improved.

Return on assets was 6.45% for the base plan, 6.33% for the minimum response rate, 6.45% for the moderate response rate, and 6.55% for the base scenario. This resulted in $37,800 for the minimum response rate, $39,500 for the moderate rate, and $41,400 for the maximum rate.

Operating profit margin is also used to evaluate profitability. For the base scenario, the operating profit margin was 6.17%. This did not improve until the maximum response rate was achieved.

The operating profit margins were 6.32%, 6.25% and 6.11% for the minimum response rate, moderate response rate and maximum response rates, respectively.

Two additional important measures are liquidity and solvency. The cash flow coverage ratio improved from $5.16 in the base scenario to $5.46, $5.50 and $5.59 for the minimum, moderate and maximum response rates, respectively.

The solvency measure of debt-to-asset ratio did not improve above the base scenario of 6.17%; however, it was well below the desired rate of 50% and did improve within the three scenarios.

The minimum response rate had a debt-to-asset ratio of 6.4%, while the moderate response rate was 6.3% and the maximum response rate was 6.2%.

The research suggests ractopamine could have a positive effect on an already profitable farm operation; however it is not likely to improve a farm that is not already in good financial health.

The researchers note an interesting result is related to the operating profit margin. It would appear ractopamine adoption is not a profitable venture. It is felt this result is related to decreasing the amount of on-farm feed used in market hog production. The farmer would be getting the market price for corn.

For this reason, ractopamine may have a greater impact on the feeder-finisher operations than on the farrow-to-finish operations.

Researchers: Deborah E. Rausch and Thomas L. Sporleder, Ohio State University. Phone Sporleder at (419)354-6916.

Late Inseminations Reduce Sow Fertility University of Minnesota(UM) researchers say even though multiple, artificial inseminations during estrus have been shown to be beneficial to fertility, performing the last insemination during late estrus or metestrus (the period of regression that follows estrus) reduces fertility.

Both previous research and experience with UM research herds suggest three AI services spaced 24 hours apart may be counterproductive to fertility and increase vaginal discharge. When a large volume of semen is deposited in a sow's uterus, it causes an inflammation beginning two hours after insemination. Researchers speculate the inflammation occurs in response to semen as well as bacteria introduced during insemination. The resulting inflammation needs to be eliminated from the uterus to assure an optimal environment for the embryos.

Although researchers don't know exactly how sows clear inflammation from the uterus, it is known that the ability to do so decreases dramatically in late estrus. Because of this, the UM researchers wanted to see if performing the last of multiple AI services during late estrus or metestrus would impact farrowing rate and litter size.

The experiment was conducted at four UM experiment station farms using 360 Yorkshire x Landrace sows and gilts. Females were monitored each morning for signs of estrus (standing heat reflex). Estrus was detected by applying back pressure to females while in the presence of a mature boar.

Semen was collected from boars housed at each location. The extended semen was used within 48 hours of collection.

Sows and gilts were inseminated at 24-hour intervals immediately after estrus detection. After receiving a first insemination, females were paired according to parity and estrus status on day 2 of estrus.

Each pair set was inseminated with extended semen from the same collection(s). Control females were inseminated only once (on day 1) if they were not in estrus on day 2 (total of 31 females) or on both days if they were in estrus on day 2 ( total of 149 females).

Late inseminated females in each pair were managed and inseminated in the same manner as control females and then inseminated again 24 hours later regardless of estrus status. Because the average length of estrus for study females was 63 hours, it was likely the third insemination (performed on treatment females still exhibiting signs of estrus) occurred during late estrus.

Females were divided into four groups based on parity at the time of breeding: P0 (gilts), P1 (parity 1), P2 (parity 2), and P3 (all sows of parity 3 and older).

Farrowing rate and estrus duration were similar among herds (Table 1), and significant differences in litter size by parity were only detected between gilts and P3 females.

A second or third insemination performed during late estrus or early metestrus decreased average litter size (Figure 1). Control females had an average of 1.1 more total pigs born and 1.4 more pigs born live per litter compared with late-inseminated females.

P1 and P2 females showed the most marked difference in farrowing rate between control and treatment females. P0 and P3 control females showed a 19% and 2% advantage over late-inseminated females. Farrowing rate and litter size of late-inseminated females were similar regardless of estrus status at the time of their last insemination.

The researchers explain the results demonstrate fertility and litter size decline when the last of multiple inseminations during one estrous cycle is performed during late estrus or metestrus. This observation was independent of whether the females were in estrus or not.

The overall reproductive performance of the herds in this study was typical of well-managed commercial herds. Farrowing rate and litter size in this study rank in the 70th percentile of the 1996 PigChamp data summary. Researchers say the results should be applicable under most on-farm AI conditions.

The present study clearly indicates an insemination late in estrus may counteract previous inseminations. UM researchers emphasize the results of this study do not imply that three inseminations or 24-hour insemination intervals should be avoided, only that the last insemination should not be performed during late estrus or metestrus.

Recent studies have shown the optimal insemination time for achieving high fertilization results is within 24 hours before ovulation. Females observed in estrus for only one day are less receptive to the benefits of increased mating frequency because ovulation likely occurs sometime within this 24-hour period.

Females with longer estrus periods benefit from increased mating frequency because there is a greater chance that a sufficient population of sperm is present in the oviducts before ovulation.

The results presented here emphasize timing of the final insemination(s) is important so the benefits of multiple inseminations are not voided.

Researchers: Kevin J. Rozeboom, M. H. T. Troedsson, Jerry Shurson, Jerry Hawton, and Bo Crabo, University of Minnesota. Phone Rozeboom at (612) 624-3789.

Boar Exposure Impacts Onset Of Puberty University of Nebraska researchers continue to evaluate how boar exposure stimulates earlier puberty in gilts. Physical boar exposure, especially when provided twice daily, brought a more rapid and more synchronous first estrous response than fenceline boar exposure.

This experiment included twice daily versus once daily boar exposure. The interaction of physical boar exposure versus fenceline boar exposure, or continuous fenceline contact was also tested. Treatments started when gilts reached 160 days of age. Gilts were assigned randomly within litters to treatment groups of eight gilts per pen (120 gilts total).

Two sets of three, whiteline boars (10 months of age at start) stimulated the gilts. Gilts were moved from their home room (rooms housing gilts on once and twice-daily boar exposure treatments) into contact with boars housed in the continuous, fenceline boar exposure room for 10-min. sessions.

Gilts assigned to the continuous, fenceline boar exposure room were relocated to another room away from boars before each session of the once-daily or twice-daily frequency groups' sessions.

Two sets of three boars maintained fenceline contact with pens of continuous fenceline contact gilts (CFBE).

Fenceline boar exposure gilts were placed in a pen adjacent to a pen of boars and received contact with boars through a 16-in. pen divider equipped with vertical bars spaced 4 in. apart.

Boars from each set were distributed individually to pens on alternate days before physical boar exposure gilts (PBE) were brought to the boar room.

Each pen of PBE gilts was placed in a pen with an individual boar for 10 min. Gilts were observed closely for symptoms of estrus during the first five minutes and estrous gilts were removed from the pen to prevent unwanted matings and to keep boars actively working other gilts in the pen.

Each set of boars was rotated daily between the two boar pens so all gilts received exposure to different boars on alternate days. CFBE gilts returned to their home pens heat checking once daily. This typically occurred after a 1- to 2-hour period away from boars.

During the first 10 days of boar exposure, 54% of physical boar exposure twice daily gilts (PBE2x) expressed pubertal estrus as compared to lower numbers for the other groups.

Gilts receiving PBE once daily (PBE1x) showed the greatest first estrous response during the second, 10-day period (45.4%). This same group had achieved a comparable estrous response to PBE2x gilts by 20 days after initiation of boar exposure. PBE gilts maintained a substantial advantage in first estrous percentage over FBE gilts during the first 30 days of boar exposure.

The average interval to first estrus after initial boar exposure was shorter for PBE gilts than FBE gilts (20.2 vs. 29.7 days) and tended to be shorter for gilts exposed to boars twice daily vs. once daily (21.5 vs. 28.4 days). FBE2x gilts expressed first estrus faster on average than FBE1x gilts (23.4 vs. 36.0 days).

CFBE gilts responded similarly to FBE1x gilts (average interval, 31.9 days).

Physical boar exposure, as previously demonstrated in Nebraska studies and elsewhere, clearly worked better than fenceline boar exposure for stimulating earlier puberty in gilts. Frequency of boar exposure had a less consistent effect, but twice daily boar exposure tended to be more effective than once daily exposure. Although the interactions between type and frequency of boar exposure were not significant, the data suggests that frequency of boar exposure may be less of a concern with physical boar exposure than it is with fenceline boar exposure.

Future research will determine whether gilt age or maturation stage influences the response to type and frequency of boar exposure.

Researchers: Dwane R. Zimmerman, Tom McGargill and Norm Rohdal, University of Nebraska. Phone Zimmerman at (402) 472-6424.

More Lean, Less Feed With Transgenic Pigs Research on genetic engineering of pigs to enhance pork production is a continuing priority of Agricultural Research Service (ARS) scientists at the USDA's Beltsville Agricultural Research Center in Maryland. Methods of inserting modified individual genes (transgenes) into pigs and other farm animals to create "transgenic" animals were developed more than a decade ago through a collaborative effort of Beltsville ARS scientists and Ralph Brinster at the University of Pennsylvania.

The original transgenic animals were controversial because the growth hormone (GH) transgene exposed the animals to high concentrations of GH that resulted in severe health problems.

Better methods of regulating the level of GH secretion mean use of a GH transgene still has great potential for helping pork producers reduce feed bills by 20% while producing leaner market hogs at the same time.

Most recently ARS scientists have been investigating another growth-related hormone known as insulin-like growth factor-I (IGF-I). For several years, scientists have known that IGF-I is responsible for providing some of the growth-stimulating effects of elevated growth hormone.

The approach used in creation of the IGF-I transgenic pigs was to direct synthesis of IGF-I specifically in skeletal muscle so a small amount would be able to leak out to bind to the plasma membrane of the muscle fibers and stimulate their growth. This strategy provides IGF-I for local stimulation of muscle fibers without causing a marked increase in the general circulation, which might have a detrimental affect on the general physiology.

Scientists at the Baylor College of Medicine, Houston, TX, and GeneMedicine Inc., The Woodlands, TX, conducted preliminary research showing this strategy was effective in stimulating muscle growth in transgenic mice.

The first generation of transgenic pigs were produced by microinjection of the IGF-I gene into the pronucleus of pig eggs just after fertilization in a collaborative study conducted by ARS and GeneMedicine scientists.

When these transgenic pigs reached sexual maturity they were mated to non-transgenic pigs to produce the second generation in which about half would inherit the IGF-I transgene and half would not. The pigs that did not inherit the IGF-I gene served as the controls. These full brothers and sisters were then used to conduct controlled experiments to determine the effects of the IGF-I transgene on growth rate, feed efficiency, carcass composition and general health.

The performance characteristics of the IGF-I transgenic pigs compared to their sibling control pigs are summarized in Table 2, along with similar data collected earlier in Beltsville for GH transgenic pigs and their sibling controls. In contrast to studies with the GH transgene, the IGF-I transgene had definitive effects only on carcass composition. The reduction in carcass fat and increase in lean body mass in the IGF-I transgenic pigs enhanced the carcass value by an estimated $6/market hog in comparison to littermate controls.

While the GH transgenic pigs grew faster, had depressed appetites, and were more efficient than littermate controls, these same parameters were unchanged in the IGF-I transgenic pigs. Most importantly, the overall health status of the IGF-I transgenic pigs did not differ from that of their sibling control pigs. This finding is markedly different from the adverse effects on general health observed earlier with the GH transgenic pigs.

The next phase of the research with the IGF-I transgenic pigs will involve crossing the IGF-I female-line transgenic pigs, with hybrid pigs from several sire-line backgrounds. This will provide a good test of whether muscle development is enhanced by IGF-I in the lean, heavy-muscled, crossbred market hogs.

Such information is essential before any conclusion can be reached on the potential value of the IGF-I transgenic pigs to the swine industry.

Researchers: Vernon G. Pursel, Robert J. Wall, Alva D. Mitchell and Morse B. Solomon, Beltsville Agricultural Research Center, and Robert Schwartz and Mike Coleman, GeneMedicine, Inc. For more information, phone Pursel at (301) 504-8342.

$500 Biofilter Cuts Odors A biofilter was designed, constructed and studied by researchers at the University of Minnesota for less than $500. The biofilter was added to a Minnesota farrowing building with 36 crates over deep pits. The barn had four pit fans. One fan was attached to the biofilter and ran continuously to provide minimum ventilation.

The biofilter was constructed by laying 6-in.-diameter, round wooden fence post on the ground to form a distribution plenum (Figure 1). Perforated plastic slats 6 in. wide were placed on top of the posts to form a porous base for the biofilter bed.

The researchers used a 50:50 combination of Minnesota compost (solid waste from dairy and poultry research) and dark red kidney bean straw for the biofilter bed. The kidney bean straw, available locally, is stiff and does not decompose as readily as other straw. The compost and straw were mixed in a feed mixer and placed 12 in. deep on the plastic slats.

The hood from the exhaust fan was extended and connected to the air plenum below the biofilter bed.

The researchers added a water sprinkler system to the biofilter because the bed began to dry out in the spring and summer. The biofilter was sprayed for 20 min. every day in the summer that it did not rain.

The researchers tested odor samples from above the biofilter and compared it with samples beneath the bed and in the barn. In addition, air samples were tested for hydrogen sulfide and ammonia.

In all three cases, the biofilter reduced odors, hydrogen sulfide and ammonia. Trained odor panels at the University of Minnesota determined that the biofilter cut odor levels an average of 78%.

Tests on air above the biofilter showed an average 86% drop in hydrogen sulfide levels from those in the barn. Tests also showed an average 50% reduction in ammonia levels above the biofilter compared to in the barn.

Researchers: Richard Nicolai and K.A. Janni, University of Minnesota. Phone Nicolai at (612) 625-3701.

Computer Program Predicts Lagoon Levels Producers can use a new computer program to predict lagoon levels based on weather and hog numbers. The predictions will help farmers plan irrigation schedules far into the future. Researchers at Oklahoma State University (OSU) developed the program.

The computer program balances manure and rain water flowing in and out of a single-cell lagoon. It also predicts salt content of lagoons. The ability to do this is important to keep lagoons from overflowing or to plan for enough liquid if irrigation is the goal.

The program uses historic Mesonet (a weather network maintained by OSU and the University of Oklahoma) data to determine rainfall entering the lagoon and the evaporation leaving the lagoon. Producers supply data on the number and type of hogs as well as the type of manure handling system in the buildings. Producers also indicate if misters and drippers are used along with the frequency and volume of irrigation.

The computer program then models the daily water level in the lagoon. It also balances salt entering and leaving the lagoon to calculate effluent salinity on a daily basis.

Researchers report the program has successfully predicted daily water levels within 0.1 ft. for lagoons in eastern and central Oklahoma. More tests on lagoons in Oklahoma's Panhandle are underway.

Researchers now are upgrading the graphics to look like a video game. They also want to convert it to use statistical weather generation programs so producers from all over the U.S. may use the program.

The program will cover all types of lagoon-based waste handling systems.

Researcher: Doug Hamilton, Oklahoma State University. Phone (405)744-7089.

Swine Effluent Increases Plant Nitrogen Uptake A hog farm's natural fertilizer has helped many farms lower their fertilizer bills and their reliance on commercial fertilizers. Mahdi Al-Kaisi, regional water quality specialist for Colorado State University Extension, is in the third year of research to finetune the use of swine effluent as a fertilizer and establish best management practices (BMPs), as guidelines for its use.

The research shows corn treated with swine effluent has had better plant nitrogen uptake and higher yields than corn treated with commercial fertilizer. Al-Kaisi believes swine effluent has the potential to be a beneficial fertilizer supplement for many growers.

The research is conducted on the Kenneth Goeglein farm near Yuma, CO. A 36-acre, center-pivot irrigated plot is devoted to this research. Swine effluent is applied to the site through the irrigation system, pumped directly from a nearby swine effluent lagoon.

The main objective of the project is to evaluate the impact of swine effluent as a nutrient source on irrigated crop production under different application rates. In establishing BMPs, Al-Kaisi will also estimate the economic value of using swine effluent as a supplement to commercial fertilization.

When the study began in March 1995, the site was divided into three areas based on soil analysis of the field. Each area receives three different rates of effluent or commercial fertilizers, with a control area in each.

According to analysis of the effluent used on the site, one-acre-inch of the applied effluent is equivalent to 72 lb. of nitrogen/acre. Since 98% of the total nitrogen in swine effluent is made up of ammonium, it is split-applied at different growth stages of the crop, instead of one heavier application to avoid nitrogen loss through volatilization. The main nutrients in effluent are nitrogen and phosphorus, but the effluent also contains a number of micronutrients that commercial fertilizers do not have.

"Effluent needs to be treated like a fertilizer," Al-Kaisi stresses. "You should analyze both the effluent and soil, and apply it according to your crop yield goals, not just the random dumping of manure."

In the 1996 tests, swine effluent was applied to the corn at the 3-, 8- and 12-leaf stages and at tasseling. Commercial nitrogen fertilizer was also applied at similar rates at the same times. Nitrogen uptake by the plants was estimated at silking and at harvest. Mid-season nitrogen uptake under both fertilizer treatments showed a similar response, but total nitrogen uptake at harvest was greater under effluent treatments.

In the 1995 and 1996 grain yields, the effluent-treated corn had better yield response than the corn treated with commercial fertilizer - an average of about a 10 bu./acre increase. The higher yield with the effluent-treated corn may be due in part to the mode and timing of application and the additional macro and micronutrients the swine effluent contains.

In addition to the research plot, Goeglein has two other 128-acre circles where he pumps swine effluent for fertilizer. "I estimate I save $8,000 to $10,000 a year on fertilizer costs for these two circles by supplementing with the effluent," reports Geoglein.

The 3,800-head hog facility on Goeglein's farm utilizes a flush system that releases water at intervals, to clean the pens. The flush water and waste is stored in the nearby lagoon until it is pumped on the fields. Goeglein pumps 90 to 135 lb. of nitrogen from the effluent onto his fields and uses commercial fertilizer for the balance of his fertilizer needs.

Al-Kaisi's research concludes this year and the field work progresses through this season. He will analyze this year's yield and soil data along with the total site data from the past two years before establishing his best management practices for effluent fertilizer use.

Researcher Mahdi Al-Kaisi, Colorado State University Extension Service. Phone (970) 345-2259.

Pit Additive Tested Purdue University and Iowa State University released results of a recent field test conducted on a commercial pit additive produced by Monsanto Enviro-Chem Systems.

The field test showed the additive (Alliance) reduced ammonia gas generation and concentrations in a deep-pit hog facility located in Indiana.

The tests were conducted over a 63-day period from Jan. 27-March 30. Air samples in the treated building and a similar building without the additive were analyzed.

The buildings where the tests were conducted included deep pits and no pit ventilation. The buildings' natural ventilation involved an inverted-V chimney roof and curtain sidewalls. Each building is one-room, 40 ft. x 180 ft.

When the testing began, the treated building held 859 pigs weighing an average 141 lb. and the untreated building held 927 pigs of the same weight. When the testing concluded after the majority of the pigs were marketed, pigs remaining in the buildings averaged 242 lb. and included 394 in the treated building and 284 in the untreated building.

The pit additive was sprayed into the top of the pit in the treated building, creating an aerial mist that filled the headspace. One nozzle per 40 pens was used to spray the product. Spraying was controlled by a programmable logic controller. The product was sprayed for 8 min., three times a day. The amount of chemical sprayed was 0.066% of the manure production of 9,920 lb./day.

Air samples were drawn from 6 in. beneath the slotted floor and along the length of the chimney to assess gas emissions.

The researchers checked the levels of ammonia, carbon dioxide and hydrogen sulfide in the treated and untreated buildings.

They found the additive affects ammonia levels the most, creating a 69% reduction in the treated building.

No change in hydrogen sulfide levels were noted by the researchers. They noted, however, that the reduction in ammonia often leads to an increase in hydrogen sulfide. They speculated that the additive kept hydrogen sulfide levels low when, in fact, they should have increased.

The carbon dioxide levels in the treated building were 5% lower than the untreated building.

Contact researcher: Al Heber, Purdue University. Phone (765) 494-1167.

Excess Nutrients Not Related To Farm Size A recent study conducted on swine and beef farms in Nebraska found the farms generally accumulated substantial amounts of excess nitrogen and phosphorus.

The researchers at the University of Nebraska checked the balance of nitrogen and phosphorus in this study on the whole farm. They measured the nutrients going into the farm by way of such things as feed and fertilizer and leaving the farm in manure, crops, etc.

By examining the balance of the nutrients on the whole farm, the researchers hoped to identify characteristics or management practices that minimize the excess accumulations.

Some 33 farms were examined, including 17 swine farms. The research was conducted for one year.

The nitrogen imbalance varied on all the farms, ranging from 4 tons to 2,180 tons/year, representing 14-77% of total nitrogen inputs on the farm. The phosphorus imbalance ranged from -4 to +280 tons/year.

The researchers report the nutrient imbalance cannot be explained strictly by the size of the livestock operation. Substantial variation in both nitrogen and phosphorus balance existed between individual farms. Larger livestock units did tend to have greater nutrient imbalances. However, some of the largest nutrient imbalances were on farms with 100-1,000 animal units, not the 2,500 animal units and larger farms.

Several of the small livestock operations had no imbalance of phosphorus and were actually drawing up soil phosphorus reserves with their crops.

Overall, the researchers found lower nitrogen and phosphorus imbalances for livestock operations with larger relative land bases.

Purchased animal feeds were a significant source of the nitrogen and phosphorus inputs. Nitrogen coming onto the farms as feed varied from 33-77% of total nitrogen on farms with less than 250 animals units and more than 2,500 animal units. Phosphorus coming on the farm as feed ranged from 62-71% of total inputs for the same groups.

Fertilizer represented the most significant source of nitrogen and phosphorus for livestock operations with less than 2,500 animal units.

The researchers concluded that using livestock herd size or livestock-to-cropland density to evaluate environmental risk is not accurate. It oversimplifies a complex issue. Neither smaller-sized livestock operations or operations better integrated with crop production insured that a sustainable nutrient balance results.

They suggested looking at new strategies to reduce nitrogen and phosphorus accumulations on livestock farms. A couple of options are reducing the levels of nitrogen and phosphorus in feed and marketing manure to off-farm customers.

Researchers: Rick Koelsh and Gary Lesoing, University of Nebraska. Phone Koelsh at (402) 472-4051.