The Effects of Dietary Chicory and Reduced Nutrient Diets on Composition and Odor of Stored Swine Manure1

By Hanni, S M DeRouchey, J M; Tokach, M D; Goodband, R D; Et al

ABSTRACT Two experiments were conducted to examine the impact of dietary chicory on growth performance and odor of stored swine manure. In Exp. 1, 180 nursery pigs (10.6 +-2 kg BW) were used in a 21-d experiment to evaluate the effects of replacing corn with chicory (0.5 to 10.0%) on pig performance. Overall, ADG increased (linear; P < 0.02) and ADFI tended to increase (P <0.10) as the level of chicory increased in the diet. This effect was primarily due to numerically reduced performance when pigs were fed 0.5 or 1.0% chicory, with growth similar for pigs fed 0, 5, or 10%. In Exp. 2, 12 barrows (initially 59 +- 3 kg BW) were fed each of 4 experimental diets during four 10-d periods in a replicated 4 x 4 Latin square design to compare nutrient excretion and odor analysis of pigs fed 1) conventional corn-soybean meal diet; 2) diet formulated to minimize nutrient excretion; 3) diet 1 with 10% chicory; and 4) diet 2 with 10% chicory. Feces and urine were collected and measured for N, S, and P excretion and retention, as well as for odor and gas analyses. Pigs fed diets formulated to reduce nutrient excretion had less (P < 0.001) total N and P excretion and had simulated slurry with reduced (P < 0.001) pH and less (P < 0.001) S, N, and ammonia. The addition of chicory to the diet also reduced (P < 0.03) N and P excretion. In conclusion, chicory can be fed to pigs to reduce nutrient excretion while maintaining growth performance.

Key words: chicory, environment, manure, nutrient excretion, odor, swine

INTRODUCTION

Nutrients containing N, P, and S that are commonly found in swine diets are not completely digested by the pig, resulting in their excretion in manure. These are precursors to several compounds associated with the odor of swine manure, including ammonia, amines, S-containing compounds, VFA, indole, skatole, phenols, alcohols, and carbonyls (Curtis, L993).

Compounds associated with the odor and nutrient concentrations in swine manure can be altered through dietary or microbial manipulation. Farnsworth et al. (1995) showed that adding 3 or 6% Jerusalem artichoke to a swine diet resulted in manure that had a sweeter, less sharp, and less pungent odor, and had a lesser skatole odor than did manure from pigs eating the control diet. The tuber of the Jerusalem artichoke is rich in inulin, a fructose polymer. Like Jerusalem artichoke, chicory (Cichorium intybus) is also rich in inulin. These fructose polymers (fructooligosaccharides) cause altered VFA patterns by increasing the population of bifidobacteria in the hindgut, thereby reducing odor in feces (Hidaka et al., 1986). Rideout et al. (2004) reported that adding 5% chicory inulin extract to the diet significantly reduced skatole in manure of pigs fed a corn-soybean meal diet, but had no impact on N-related odor.

Therefore, our objectives were to determine 1) the effect of dietary chicory addition on growth performance of swine; and 2) the effects of dietary chicory addition on nutrient excretion and the odor characteristics in stored swine manure. Within the second objective, several other dietary strategies (low protein, non-S- containing trace mineral premixes, and phytase) were evaluated as models to test the effectiveness of chicory addition on nutrient excretion and odor emission.

MATERIALS AND METHODS

The Kansas State University Institutional Animal Care and Use Committee approved all protocols used in the experiments.

Experiment 1

A total of 180 weanling pigs (Line 327 x C22; Pig Improvement Co., Franklin, KY), were blocked by initial BW (10 +- 6 kg) and allotted randomly to 1 of 5 dietary treatments. Each treatment had 6 replications (pens) and 6 pigs per pen.

Pigs were fed treatments for 21 d from d 20 to 41 postweaning. The treatments included a control diet with no added chicory and 4 diets with increasing percentages of chicory (0.5, 1.0, 5.0, and 10.0%). Each treatment had 6 replications (pens) with 6 pigs per pen. Analyzed values of chicory for amino acids, Ca, and P were used in diet formulation (Table 1), with NRC (1998) values used for all other ingredients. All diets were fed in meal form and formulated to be isolysinic and isocaloric (Table 2). The pigs were housed in an environmentally controlled nursery at the Kansas State University Swine Teaching and Research Center. Each pen (1.2 ? 1.5 m) had woven wire flooring and contained a stainless steel self-feeder and one nipple waterer to allow ad libitum consumption of feed and water. Pigs were weighed and feed disappearance was determined weekly to calculate ADG, ADFI, and G:F.

Experiment 2

Twelve nonlittermate barrows (Line 327 x C22; Pig Improvement Co.), initially weighing 59 +- 3 kg, were used in a 4 x 4 replicated Latin square design. The Latin square consisted of 4 consecutive 10-d periods. At the beginning of period 1, pigs were weighed and assigned to a dietary treatment. Dietary treatments were changed for every 10-d period so that each pig was fed all 4 of the experimental diets.

Table 1. Analyzed nutrient composition of chicory1

Analyzed values of chicory for amino acids, Ca, and P were used in diet formulation (Table 1). All diets (Table 3) were formulated to provide 0.85% true digestible Lys and were fed in meal form. A conventional, 18% CP corn-soybean meal diet was formulated with no crystalline i.-Lys HCl or phytase (0.51% available P). This diet also used a trace mineral premix with the S-containing forms of trace minerals to maximize nutrient excretion and potential for odor production. A second treatment diet was formulated to reduce nutrient excretion through the use of crystalline amino acids, added phytase, and replacement of S-containing trace mineral premix with other forms. The conventional or reduced nutrient diets were fed with none or 10% added chicory, completing the 4 experimental treatments. Pigs were fed at 3% of their BW (start of each period), with feed divided equally between 2 feedings, and pigs had ad libitum access to water. Feed refusals were collected and weighed to determine actual feed intake.

The S-containing and non-S-containing trace mineral premixes used in Exp. 2 were formulated to the same trace mineral concentrations. The S-containing trace mineral premix used in the conventional diet contained zinc sulfate, ferrous sulfate, manganese sulfate, cupric sulfate, calcium iodate, and sodium selenite, whereas the non-S- containing trace mineral premix used in the diets formulated to reduce nutrient excretion and odor contained zinc oxide, ferric chloride, manganese oxide, cupric chloride, calcium iodate, and sodium selenite. Wheat middlings were used as a earner in both the S- and non-Scontaining trace mineral premixes.

Pigs were housed in individual stainless steel metabolism crates (1.5 x 0.6 m) designed for separate collection of feces and urine. Each pig was allowed 3 d to adapt to the dietary treatment. Chromic oxide (0.25% of diet) was used as the indigestible marker to identify the beginning of each fecal collection period and was added to the seventh meal (d 4) of each period. Fecal collection began with the appearance of marked feces followed by approximately 3 d of feces and urine collection. Ferric oxide (0.25% of diet) was then added in the 11th meal (d 6), and fecal collection stopped with the appearance of marked feces. Feces were collected twice daily and pooled for each pig within each period. Urine was collected in plastic bottles containing 25 mL of 6 N HCl. Ten percent of each day’s output (volume basis) was pooled for each pig within each period. Feces and urine were stored in a freezer at -4[degrees]C until further analyses of composition were completed.

Table 2. Diet composition for Exp. 1 (as-fed basis)

Fecal samples were dried for 96 h at 500C and then ground with a Wiley Mill (CW. Brabender Instruments, Inc., South Hackensack, NJ) using a 1-ram screen. The ground samples were used for DM determination and chemical analysis. Urine samples were thawed and centrifuged (2000 x g) to remove trace amounts of particulate matter before analysis. Feces and urine were analyzed for N using a Leco nitrogen analyzer (Leco Corporation, St. Joseph, MI) and for GE by adiabatic bomb calorimetry (Parr Instruments Co., Moline, IL). The DE values of the diet were calculated by subtracting GE excreted from GE intake, and this value was expressed as a percentage and multiplied by the GE value for the feed. The ME was calculated by subtracting the calculated DE by the GE of the urine. Fecal and urine collection and analyses for this study followed the procedures outlined by Woodworth et al. (2001).

On the final 2 d of each period (d 9 and 10), all feces and urine (nonacidified) were collected for the simulated anaerobic pit system. Simulated anaerobic pit systems are designed to mimic an anaerobic manure system, in which the manure can be analyzed for nutrient content and odor production. Feces and urine were collected twice daily and refrigerated until the end of the 2-d collection period. After all feces and urine were collected, feces from the 3 pigs fed the same diet within each period were combined, and DM content was determined for the combined feces. Urine from pigs fed the same diet was also combined. The feces and urine were then blended together to form a 7.5% DM slurry for each treatment. From this slurry, 19 subsamples were collected – one 2-L sample and eighteen 50-mL aliquots. The samples were stored in separate plastic containers and frozen (-4[degrees]C) until the completion of the 4 feeding and collection periods. The samples were then transported to the Air Quality Laboratory, Department of Biosystems and Agricultural Engineering, University of Minnesota, St. Paul, for odor and nutrient content analyses. Each 2-L sample served as the initial pit slurry and was thawed and placed in a 4-L Erlenmeyer flask to simulate an anaerobic pit. The simulated anaerobic pits were then stored in an environmentally controlled chamber at 22[degrees]C. Then, a single 50mL aliquot was thawed and added to each simulated pit 2 times per week. Nutrient and odor analysis was conducted on d 28 and 56.

On each day of the odor and nutrient analysis, each simulated pit was agitated, and a 100-mL slurry sample was removed. Air samples were taken by placing the 100-mL samples into glass flasks and covering the flask with a mbber stopper that had an inlet and an outlet. Charcoal-filtered N gas was moved over the headspace of the flask at a rate of 1.5 L/min for 50 min to purge existing gases. Then, a 10-mL Tediar bag was attached to the outlet and filled by using a vacuum box. Air sample collection for the study followed the procedures outlined by Schmidt et al. (1999, 2000).

Air samples were analyzed for odor intensity (ASTM, 2004), hedonic tone (WEF, 1995), odor detection threshold, based on European Standards (CEN, 2003) using a triangular forcedchoice dynamic olfactometry (ACSCENT BETA-I, St. Croix Sensory, Inc., Stillwater, MN), and total reduced S concentration with a Jerome meter (Model 631 – X; Arizona Instruments Corp.; Phoenix Ariz.). Each 100-mL slurry sample was then analyzed for pH, total solids, total volatile solids, total N, NH4-N, total minerals, and total sulfide according to standardized methods (APHA, 1992).

Table 3. Composition of 0 and 10% chicory diets for Exp. 2 (as- fed basis)

Statistical Analysis

Data for Exp. 1 were analyzed according to the mixed models procedure of SAS (SAS Inst. Inc., Cary, NC) as a randomized complete- block design, with pen as the experimental unit. Linear and quadratic polynomial contrasts were used to determine the effects of percent chicory added to the diet on pig growth performance. The IML (SAS) procedure was used to calculate coefficients for unevenly spaced treatments. Data from Exp. 2 were analyzed as a replicated 4 x 4 Latin square design according to the PROC MIXED of SAS; the model included the fixed effects of diet formulation, addition of chicory, and 2way interactions between diet formulation and chicory addition. Data from slurry odor and nutrient analyses were analyzed as a randomized complete block design using the mixed models procedure of SAS. Slurry samples were analyzed for odor and slurry makeup on 2 separate days, with the days of slurry analysis representing the blocks in the design. The pooled sample from pigs on a common diet was the experimental unit for the slurry analysis. The model statement included the fixed effects of day of slurry analysis, nutrient content, addition of chicory, and 2-way interactions between nutrient content and chicory addition and random effect of day of slurry analysis.

RESULTS AND DISCUSSION

Experiment 1

Overall, ADG increased (linear; P < 0.02) and ADFI tended to increase (P < 0.10) as the level of chicory increased in the diet (Table 4). This effect was primarily due to numerically reduced performance when pigs were fed chicory at 0.5 or 1.0%, with growth similar for pigs fed 0, 5, or 10%. Feed efficiency was not (P > 0.16) influenced by dietary chicory. Previous research (He et al., 2002) reported a tendency for improved ADG and feed efficiency in nursery pigs with the inclusion of chicory inulin extract in the diet or supplied through the water.

Table 4. Effects of dietary chicory on growth performance1

Experiment 2

There were no (P > 0.19) differences in fecal wet or dry weight among pigs fed any of the 4 dietary treatments (Table 5). There was a nutrient excretion rate x chicory interaction (P < 0.03) for fecal DM percentage, with pigs fed chicory having a lesser fecal DM percentage, regardless of nutrient formulation. Pigs fed the reduced nutrient diet excreted less (P < 0.03) urine than did pigs fed the conventional diet, and the addition of chicory also reduced (P < 0.001) urine excretion, regardless of dietary nutrients.

Pigs fed the reduced nutrient diet had greater (P < 0.001) ADFI than did pigs fed conventional diets. The difference in ADFI was a result of feeding pigs at 3% of BW instead of feeding a constant rate during each stage. A nutrient content x chicory interaction for DE and ME was observed (P < 0.02), which was the result of the additional chicory increasing the available energy of the reduced nutrient diet, but decreasing the available energy of the conventional diet. This interaction can not be logically explained by the authors in altering the available energy based on diet nutrient level.

There was a nutrient excretion rate x chicory interaction (P < 0.001) for N intake. As expected, pigs fed the reduced nutrient diet had decreased N intake compared with pigs fed the conventional diet. The reduction of N intake between the 2 diets was due to a 22% reduction in dietary CP with the use of synthetic amino acids. The interaction occurred because the addition of chicory to the reduced nutrient diet decreased N intake 16%, whereas there was no change in N intake when adding chicory to the conventional diet. The reason for the difference is 2-fold. First, pigs fed the reduced nutrient diet without chicory had greater total feed intake, as discussed earlier. Second, the reduced nutrient diet without chicory had greater analyzed CP composition than expected, leading to greater calculated N intake.

Total N excretion was reduced (P < 0.001) by approximately 30% when pigs were fed the reduced nutrient diet compared with pigs fed the conventional diet. These results are similar to research conducted by Schutte et al. (1990), where a 20% reduction in N excretion was observed with a 2% decrease in CP. Adding chicory to the diet reduced (P < 0.03) total N excretion by approximately 13 and 8% for pigs fed the diets formulated for reduced nutrient content and conventional diets, respectively. Similar to total N excretion, urinary N excretion was decreased (P < 0.001) by approximately 36% for pigs fed the diet formulated for reduced nutrient content compared with that of pigs fed the conventional diet. DeCamp et al. (2001) reported that a reduction in the dietary CP from 16.1 to 13.8% caused a 24.5% reduction in urinary N excretion. The addition of chicory reduced (P < 0.01) urinary N excretion by approximately 17 and 13% in pigs fed the reduced nutrient diet and the conventional diet, respectively. Fecal N excretion tended to be greater (P < 0.09) with the addition of chicory. Similar results were seen by Rideout et al. (2004), who reported a 1 7% increase in fecal N excretion with the addition of chicory. Additionally, research has shown that when a fermentable carbohydrate (such as chicory) is added, an increase in fecal N excretion and a decrease in urinary N excretion will occur due to a shift of N excretion from urea in urine to bacterial N excretion in feces (Canh et al., 1997; Sutton et al., 1999). There was a nutrient excretion rate x chicory interaction (P < 0.008) for N retention (g/d). Adding chicory reduced N retention for pigs fed reduced nutrient diets, but increased N retention in pigs fed the conventional diets. Because the diets were formulated to amino acid requirements with the use of synthetic amino acids, there was a 15% improvement (P < 0.001) in N retention percentage for pigs fed the diets formulated for reduced nutrient excretion and reduced odor. This result was similar to research conducted by DeCamp et al. (2001), in which N retention was improved by 8% when formulating diets with reduced CP.

Phosphorus intake was approximately 26% less (P < 0.001) for pigs fed the reduced nutrient diet than pigs fed the conventional diets. The addition of chicory to the diet decreased (P < 0.001) P intake by ap- proximately 12 and 10% for pigs fed the reduced nutrient and conventional diets, respectively. Urinary P excretion was not affected by dietary nutrient formulation (P = 0.20) or the addition of chicory (P = 0.53). There was a nutrient excretion rate x chicory interaction (P < 0.005) observed for total and fecal P excreted. This was the result of a smaller amount of P excreted when pigs were fed the reduced nutrient diet, as well as a reduction when chicory was added to this diet. But the effect of lesser total and fecal excretion of P for pigs fed chicory was more pronounced when fed the reduced nutrient diet. There was an interaction (P < 0.002) for P retention both on a gram per day basis and as a percentage. This can be explained by pigs on the reduced nutrient diet retaining a larger amount of P when fed chicory; when fed the conventional diet, pigs retained more P when not fed chicory. Although an explanation of P retention differences in the diet is not available, studies have shown that supplemental phytase in swine diets can result in an increase in the digestibility and retention of P (Jongbloed et al., 1993; Lei et al., 1994), while reducing P excretion by as much as 33% (Lei et al., 1994; Kornegay and Qian, 1996; Liu et al., 1998).

Table 5. The effects of dietary nutrient content and chicory on nutrient availability1

Sulfur intake decreased with the addition of chicory to reduced nutrient diets, but increased in the conventional diets (nutrient excretion rate x chicory interaction, P < 0.001). Pigs fed the diets formulated to reduced nutrient concentrations had less S intake (P < 0.001) than did pigs fed the conventional diets. The diets formulated to reduced nutrient content were formulated with non-S-containing trace mineral premixes and DL-Met to minimize S intake. Urinary S excretion was reduced (P < 0.001) by approximately 33% for pigs fed diets formulated to reduced nutrient content. These findings are similar to results of Shurson et al. (1998), in which a reduction in urinary S occurred with the addition of S synthetic amino acids to diets containing low-S trace mineral premixes. Knott and Shurson (2002) associated high protein diets with large amounts of urinary S and N excretion. There was no (P = 0.19) effect of nutrient content, amount of chicory, or chicory x nutrient excretion interaction for total or fecal S excreted. A nutrient content x chicory interaction (P < 0.03) for S retention was seen, as pigs fed chicory had reduced S retention in reduced nutrient diets and increased S retention in conventional diets.

The odor and other response criteria for the 7.5% DM slurry from individual dietary treatments were analyzed on d 28 and 56 of pit storage (Table 6 and 7, respectively). In general, there was a change in the magnitude of results over time (Table 7), but few dietary treatment x day of storage interactions.

The pH of slurry was less (P < 0.01) for pigs fed diets formulated to the reduced nutrient content than that of pigs fed the conventional diets. This is similar to research conducted by Sutton et al. (1996) and Knott and Shurson (2002), who observed a reduction in the slurry pH in diets formulated to reduce CP content. There was also a reduction (P < 0.04) of total solids when chicory was added to diets, which may be due to an increase in the bacteria population. Houdijk (1998) showed that an increase of inulin, similar to that found in chicory, increased bifidobacteria population; the bifidobacteria are involved in the breakdown of organic N-containing compounds (Mackie et al. 1998), which would also account for the reduction of total solids.

Manure slurry NH^sub 4^-N and total Kjeldahl N (TKN) were reduced (P < 0.01) 18 and 15%, respectively, for pigs fed diets formulated to reduced nutrient content. A similar response was found by Sutton et al. (1996) who reported a 28% reduction in NH^sub 4^-N and TKN when they supplemented a corn-soybean meal diet with the first 4 limiting amino acids and, thus, reduced the CP level from 13 to 10%. Furthermore, Hankins et al., (2001) found that reducing CP level of diets with synthetic amino acids reduced the NH^sub 4^-N of the feces by as much as 29%) and further reduced the NH4-N in the urine. The difference in NH^sub 4^-N and TKN concentration between the 2 methods of formulation was due to the reduced N input and enhanced N retention with the use of synthetic amino acids in the diets formulated for reduced nutrient excretion and odor. The addition of chicory, however, did not (P > 0.84) have an affect on the amount of NH^sub 4^-N or TKN in the slurry.

There were no (P > 0.24) differences in total sulfides (H^sub 2^S) in the air or slurry samples measured by the Jerome meter. This is in contrast to Whitney et al. (1999), who showed a 30% reduction in air H^sub 2^S when pigs were fed diets with reduced S contents. Shurson et al. (1998) showed that when the pH is > 8.0, most chemical forms of S compounds exist in solution as ions, and it is not until the pH is < 7.0 that the ions shift to H^sub 2^S. All of the samples stayed at a pH > 8.0 for the study; thus allowing for no significant changes in the H^sub 2^S of the air or slurry samples. The percentage of total S in the slurry was reduced (P < 0.001) by 21% when pigs were fed with the diets formulated to reduced nutrient content. The percentage of total S is the sum of organic and elemental S in the slurry on a DM basis. This is similar to the reductions observed in the nutrient availability part of the study for urinary S excretion and S retention, which were due to the use of synthetic S-containing amino acids and the use of non-S trace mineral premixes. Addition of added chicory tended to increase the (P < 0.08) percentage of S in the slurry on a DM basis.

There was a diet nutrient content x chicory interaction for Ca content of the slurry, with less Ca in the slurry from pigs fed the reduced nutrient diet with chicory than the diet without chicory, whereas the slurry from pigs fed the conventional diet with chicory had only a slight decrease in Ca concentration in comparison with the slurry of pigs fed this diet without chicory. The concentration of Mg in slurry was reduced (P < 0.03) for pigs fed diets containing chicory, regardless of dietary nutrient content, whereas pigs fed the reduced nutrient diets had less Na (P < 0.02) and P (P < 0.001) in slurry than did pigs fed the conventional diets. Furthermore, pigs fed chicory, regardless of dietary nutrient content, had lower (P < 0.01) P concentrations in the slurry. The reduction in mineral concentration observed with pigs fed chicory is perhaps due to a fermentation process from chicory digestion liberating bound minerals, making minerals more bioavailable to the pig, thus decreasing mineral excretion in the manure. Compared with research by Spiehs et al. (2000), the concentrations of minerals in this study were greater; in their study the slurry may be have been more diluted because it was taken from pits that would have also included wasted drinking water, whereas slurry samples in the current study were made of only feces and urine. The reduction in the mineral content of the slurry, from both reduced nutrient formulation and the use of chicory, could reduce the mineral concentrations in manure storage systems.

There were no (P > 0.22) differences for odor intensity or odor offensiveness among dietary treatments. This implies that formulation technique, including use of crystalline amino acids, phytase, non-S-containing trace mineral premixes, and the addition of chicory had no effect on reducing the relative offensiveness of swine manure odor as tested by the procedures used in this experiment. Odor intensity and odor offensiveness might have been unaffected due the makeup of the slurries. By increasing or decreasing the amount of urine in slurry due to the fecal DM percentage, elimination any effect of ammonia volatilization and, thus, any effect on odor intensity or offensiveness may have occurred.

Table 6. The effects of dietary nutrient content and chicory on slurry composition and odor quality1

Table 7. The effects of storage time on slurry composition and odor quality

From d 28 to 56, pH of the simulated anaerobic pits was reduced (P < 0.01) by 3%. The addition of the 50-mL aliquots each week to the simulated pits increased both the number of bacteria and the amount of nutrients in the slurry. As the bacteria population increased, the amount of proteins broken down also increased, causing the decrease in slurry pH.

The addition to the simulated pits twice a week was intended to maintain a 7.5% DM slurry; however, from d 28 to 56 there was a reduction (P < 0.01) in the percentage of total solids, which was probably a response to the bacterial population breaking down nutrients. Bastyr and Powers (2001) saw similar declines of total solids when adding manure incrementally over a 10-wk period due to microbial breakdown of solids.

From d 28 to 56, NH^sub 4^-N and TKN in the manure slurry increased (P < 0.001) 23 and 18%, respectively. The difference in NH^sub 4^-N and TKN concentrations between these days was probably due to continued additions of slurry to the simulated anaerobic pits, which increased the amounts of N in the pits.

When the air samples collected from the slurry were tested by the olfactometry panel, odor intensity was scored less (P < 0.001) for d 56 than 28. This reduction was not seen for either the formulation methods or interaction with chicory. Because of the lack of interaction observed between the formulation methods, it was concluded that the reduction in odor intensity was not in response to treatment, but due to scoring of the panel or reduction in other odor compounds over time within the slurry.

IMPLICATIONS

Chicory can be used in nursery pig diets (up to 10%) without compromising growth performance. In addition, pigs fed chicory had reduced mineral excretion, but did not reduce odorous compounds in the manure and by olfactory analysis. Therefore, the use of chicory may be a beneficial ingredient for use in diets to reduce diet costs and manure mineral concentrations.

ACKNOWLEDGMENTS

The authors would like to thank the Kansas Center for Agricultural Resources and the Environment (KCARE) for funding of the experiment, and to Blanca C. Martinez, Scientist, Bioprocessing Laboratory, Department of Biosystems and Agricultural Engineering (University of Minnesota; St. Paul) for performing laboratory analysis.

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S. M. Hanni,* J. M. DeRouchey,*2 M. D. Tokach,* R. D. Goodband,* PAS, J. L. Nelssen,* and S. S. Dritzt

*Department of Animal Sciences and Industry, Kansas State University, Manhattan, 66506-0201; and

[dagger]Food Animal Health and Management Center, College of Veterinary Medicine, Kansas State

University, Manhattan 66506-5601

1Contribution no. 05-285-J of the Kansas Agrie. Exp. Sta., Manhattan 66506.

Corresponding author: jderouch@ksu.edu

Copyright American Registry of Professional Animal Scientists Aug 2007

(c) 2007 Professional Animal Scientist. Provided by ProQuest Information and Learning. All rights Reserved.