Poult. Sci.
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Poult Sci 2007. 86:2608-2614. doi:10.3382/ps.2007-00139
© 2007 Poultry Science Association
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METABOLISM AND NUTRITION

Comparison of Broiler Performance and Carcass Parameters When Fed Diets Containing Soybean Meal Produced from Glyphosate-Tolerant (MON 89788), Control, or Conventional Reference Soybeans

M. Taylor*,1, G. Hartnell*, D. Lucas*, S. Davis{dagger} and M. Nemeth*

* Monsanto Company, Product Safety Center, 800 N. Lindbergh Blvd., Mail Stop O3D, Creve Couer, MO 63167; and {dagger} Colorado Quality Research, 400 E County Road 72, Wellington, CO 80549

1 Corresponding author: mary.l.taylor{at}monsanto.com


   ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
A 42-d floor pen study was conducted to compare broiler (Ross x Ross 308) performance and carcass measurements when fed diets containing meal produced from glyphosate-tolerant soybeans (MON 89788) with those of broilers fed diets containing meal produced from control soybean (A3244) that has similar genetic background to MON 89788. Soybean meal produced from 6 conventional soybean varieties was included in the study to provide comparison measurements for broilers fed meal derived from conventional soybeans. It has been found that MON 89788 produces the 5-enolpyruvylshikimate-3-phosphate synthase protein from Agrobacterium sp. strain CP4 (cp4 epsps), which confers tolerance to glyphosate, the active ingredient in Roundup agricultural herbicides. Broilers were fed starter diets (approximately 33% wt/wt dehulled soybean meal) from d 0 to 21 and grower-finisher diets (approximately 30% wt/wt dehulled soybean meal) from d 21 to 42. The study utilized a randomized complete block design with 8 dietary treatments assigned randomly within 5 blocks of 16 pens each (8 male and 8 female) with 10 birds per pen. There were 10 pens per treatment group (5 male and 5 female). No treatment differences (P > 0.05) were detected among dietary treatments for feed intake, weight gain, adjusted feed conversion, or any measured carcass and meat quality parameters. Comparison of all performance, carcass, and meat quality parameters measured showed no differences (P > 0.05) between birds fed the MON 89788 soybean meal diet and the population of birds fed the control and 6 conventional reference soybean meal diets. It is concluded that the diets containing soybean meal produced from MON 89788 were nutritionally equivalent to diets containing soybean meal produced from the control and conventional reference soybean varieties when fed to broilers.

Key Words: broiler performance • genetically modified soybean • carcass yield • 5-enolpyruvylshikimate-3-phosphate synthase from Agrobacterium sp. strain CP4


   INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
A second-generation glyphosate-tolerant soybean that confers tolerance to glyphosate, the active ingredient in Roundup agricultural herbicides, is MON 89788. It has been found that MON 89788 expresses the same protein, 5-enolpyruvylshikimate-3-phosphate synthase from Agrobacterium sp. strain CP4, as that in the first-generation glyphosate-tolerant soybean (40-3-2) but has a molecular expression cassette distinct from that in 40-3-2. In the future, MON 89788 will continue to provide growers flexibility, simplicity, and cost-effective weed-control options; in addition, MON 89788 and varieties containing the trait have the potential to enhance yield and thereby further benefit farmers and the soybean industry. It has been noted that MON 89788 was developed by introduction of the cp4 epsps gene cassette containing a promoter that has been used in other crops such as Roundup Ready Flex cotton (Fincher et al., 2003). In addition, the transformation was based on a new technique of Agrobacterium-mediated gene delivery to soybean meristem, where cells were induced directly to form shoots and cause transgenic plants (Martinell et al., 2002). This new technique allowed direct transformation of the gene cassette into elite soybean germplasm such as the Asgrow soybean variety A3244 (Paschal, 1997), which is known for its superior agronomic characteristics and high-yielding property (Tylka and Marett, 1999). Using elite germplasm as the base genetics, the superior agronomic characteristic of A3244 can be introgressed to other soybean varieties through crosses with MON 89788 containing the cp4 epsps cassette. In general, MON 89788 has been found to have a 4 to 7% yield advantage compared with Roundup Ready soybeans in the same elite genetic background (A3244) while maintaining the weed control and crop safety benefits of the Roundup Ready soybean system. As a result, MON 89788 will be an excellent agronomic base trait for future breeding improvements and multitrait products. This study was conducted to compare nutritional performance (feed intake, BW, and feed:gain), carcass yield, and meat quality of the birds fed diets containing soybean meal produced from the glyphosate-tolerant (MON 89788), the control (A3244) with similar genetic background to MON 89788, and conventional reference soybeans to evaluate the nutritional equivalence of these soybean varieties.


   MATERIALS AND METHODS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
 REFERENCES
 
Broilers and Housing

The study was conducted in accordance with the principles and guidelines for the care and use of agricultural animals in research (FASS, 1999), which were consistent with the recent recommendations issued by the International Life Sciences Institute (Cromwell et al., 2003), and, as applicable, were in compliance with FDA (1979) and EPA (1983) good laboratory practice regulations. Ross x Ross 308 broiler chickens were obtained (Welp’s Hatchery, Bancroft, IA) at 1 d of age. Broilers were vaccinated for Marek’s disease at the hatchery and for Newcastle disease and infectious bronchitis at the test site on the study start day. The broilers were randomly assigned by sex to concrete-floored pens (1.5 m x 0.9 m, providing approximately 0.09 m2 per bird), with approximately 13 cm of clean wood shavings in an environmentally controlled building with incandescent lighting. Incandescent lighting was provided for 23 to 24 h/d for approximately the first 4 d of the study and for 10 to 16 h for the remainder of the study. The target room temperature was 34°C at the start of the study and was gradually decreased each day to a target room temperature of 23°C from d 30 through the remainder of the study. Water and feed were available for ad libitum consumption throughout the experiment. Within each pen, water was provided via a hanging automatic bell drinker (36-cm diameter), and feed was provided via a hanging tube feeder (43-cm diameter). A chick feeder tray was placed in each pen for the first 4 d. Environmental conditions (floor space, temperature, lighting, bird density, and feeder and water space) were similar for all treatments.

Experimental Design

A randomized complete block design was used with 8 dietary treatments (test, control, and 6 conventional reference soybean meal diets). For each of the 8 treatment groups, there were 100 broilers in 10 pens (total of 800 broilers): 5 pens of males (10 broilers/pen) and 5 pens of females (10 broilers/pen). Initially, there were an additional 2 broilers in each pen to compensate for early chick mortality during the first few days posthatch. At d 7, the group size was adjusted to 10 broilers/pen. The initial criterion for bird removal on d 7 was unthrifty birds that are smaller and have a health or deformity problem (leg problems, cross beaks, swollen eyes) that would prevent the bird from surviving the length of the study, followed by random selection, the reason for most removal.

Soybean Meal

The MON 89788 and the control soybeans were produced in Jackson County, Arkansas, during the 2005 growing season. The glyphosate-tolerant, MON 89788, soybeans were sprayed with labeled rates of Roundup agricultural herbicides. Conventional reference soybeans (A2824, A2804, A4324, A3469, A3559, and ST3870) produced in 2005 in Jackson County, Arkansas, Clinton County, Iowa, and Jefferson County, Iowa, were representative of commercial soybeans and were used for comparison purposes to provide a range of typical responses. Processing (dehulling, defatting, toasting) of soybeans was conducted at POS Pilot Plant Corporation in Saskatoon, Saskatchewan, Canada.

Pesticide residue (FDA, 1999; Covance Laboratories, Madison, WI: organochlorinates, organophosphates, organonitrogens, and N-methylcarbamates) analyses of the soybeans were conducted to verify that the levels were below the limits of concern for broiler performance. Proximate [CP (methods 955.04 and 979.09), crude fat (methods 960.39 and 948.22), crude fiber (method 962.09), and moisture (methods 926.08 and 925.09)] and amino acid analyses (method 982.30) were performed on the soybean meal at Covance Laboratories according to methods of the AOAC (2005). Carbohydrate values were calculated.

Diets

Diets were formulated based on the individual nutrient analyses of each soybean meal lot (Table 1Go). Dietary protein was provided by the dehulled soybean meal and corn. Diets were formulated to meet or exceed NRC (1994) values for broiler chickens. A coccidiostat, salinomycin (Sacox, Intervet Inc., Millsboro, DE), was included in all diets at a level of 50 g/ton. Broilers were fed a starter diet containing approximately 33% wt/wt soybean meal from d 0 to 21. For the rest of the study (d 21 to 42), broilers were fed a grower-finisher diet containing approximately 30% wt/wt soybean meal (Table 2Go). Proximate [CP (method 990.03), crude fat (method 954.02), and moisture (method 934.01)] amino acid analyses (method 982.30) and mineral analyses (method 985.01) of poultry diets (University of Missouri, Experiment Station Chemical Laboratories, Columbia, MO) were conducted according to AOAC (2000) methods for confirmation of formulated levels of nutrient composition.


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  		Table 1. Proximate (%) and amino acid (% of soybean meal) composition1 of MON 89788, control, and conventional reference soybean meal
 

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  		Table 2. Ingredient composition of diets containing MON 89788, control, and conventional reference soybean meal
 
Measurements

Broilers were observed regularly for general health. All dead birds and those killed due to their unhealthy condition were weighed and necropsied, and the probable cause of death or reason for removal was documented. Broilers were weighed at d 0 and 42 by pen and individually at study termination (d 43 for males and d 44 for females). Average BW (kg) and feed intake (kg) were calculated from pen data. Adjusted feed conversion was calculated by dividing the total feed consumption per pen by the total BW of the surviving broilers and those that died or were removed from the pen. At the end of the study, all broilers were processed for assessment of carcass yield by severing the jugular, scalding, plucking, eviscerating, and then placing the eviscerated bird in an aerated chill tank (ice and water). The fat pad was removed and weighed during the eviscerating process. After the birds were chilled to approximately 7°C for approximately 50 min, the birds were removed and allowed to drain for a minimum of 15 min in a container with ice on the top and bottom. Individual bird chilled weight was obtained, the bird was deboned, and the individual parts were weighed and recorded. Skinless thigh and breast tissues were collected from 1 randomly selected broiler from each pen and analyzed for moisture (method 934.01), protein (method 984.13), and fat (method 954.02) at the Experiment Station Chemical Laboratories (Columbia, MO) according to the 17th edition of the AOAC (2000) methods.

Statistical Analysis

Statistical analysis (ANOVA) was carried out using a linear mixed model procedure of SAS, version 9.1.3 (SAS Institute Inc., Cary, NC). The statistical model included effects of treatments, sex, block, and sex x treatment interactions, with the experimental unit being the pen. The mean values obtained for the broilers fed MON 89788 diets were compared (combined sex) with those fed the control and conventional reference soybean meal diets at the 5% level of significance using a protected Fisher’s least significant difference test (Fisher, 1949). When a significant sex x treatment interaction was noted (P < 0.15), the mean values were also evaluated by sex. An additional statistical analysis compared data from broilers fed the MON 89788 diets to the population of responses from broilers fed the control and conventional reference soybean meal diets to determine whether the values of the test soybeans were within the population of control and reference soybeans used in this study.


   RESULTS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
DISCUSSION
 REFERENCES
 
Pesticide levels in MON 89788, control, and conventional reference soybean meal used in diet preparation were below the limits of concern for broiler performance. All pesticide values were below the assay limits of detection as reported in parentheses: organophosphates (0.050 ppm), organonitrogens (0.500 ppm), organochlorinates (0.200 ppm), and N-methylcarbamates (0.100 ppm). The nutrient assay results for diets are presented in Table 3Go.


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  		Table 3. Nutrient composition of diets containing MON 89788, control, and conventional reference soybean meal
 
Chick mortality was low (1%) during the first 7 d, and those observed were due to bacterial infection, dehydration, or refusal of feed (starve-out). Mortality from d 7 to 42 ranged from 1 to 5% across treatments (mortality for the MON 89788 treatment was 4%). The deaths on d 7 to 42 were primarily attributed to sudden death and ascites. Mortality was random across treatments, and remaining broilers in all treatments were in good health.

Performance measurements of BW at d 0 (g/bird) and d 42 (kg/bird), total feed intake (kg/bird and kg/pen), and adjusted feed conversion (kg/kg) were not different (P > 0.05) for birds fed MON 89788, control, and conventional reference soybean meal diets (Table 4Go). Likewise, carcass measurements including processing live weight, chilled weight and fat pad weight (kg and % of live weight), and weights of breast, wing, drum, and thigh parts (each expressed as kg and % of chilled weight) were not different (P > 0.05) between broilers fed diets containing MON 89788 and those fed the control or reference soybean meal diets. No differences (P > 0.05) among any of the diets were observed for the percentage of moisture, protein, or fat in skinless thigh and breast meat samples collected at processing. Comparison of the data from broilers fed soybean meal produced from MON 89788 to that of the population of broilers (combined sex) fed diets containing control and conventional reference soybean meal showed no differences (P > 0.05) in any measured performance, carcass yield, or meat quality parameter (Table 5Go).


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  		Table 4. Performance, carcass yield, and meat quality comparison of broilers fed diets containing MON 89788, control, and conventional reference soybean meal1
 

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  		Table 5. Performance, carcass yield, and meat quality comparison of MON 89788 with population of control and conventional soybean meal references
 

   DISCUSSION
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
REFERENCES
 
Comparative feeding studies with broilers may be used to detect potential unintended (pleiotropic) effects resulting from the transformation event or from the expression of the new trait (or traits) by examining performance characteristics during a rapid growth period of broilers during which they are sensitive to small nutrient or antinutrient changes in the diet (Chesson and Flachowsky, 2003; Flachowsky et al., 2005). Broiler studies have become a standard component of the safety and nutritional assessment of crops developed through bio-technology (Astwood and Fuchs, 2001). Previously, researchers have reported no biologically relevant differences in performance when poultry and livestock were fed diets containing meal produced from first-generation glyphosate-tolerant soybeans (40-3-2) as compared with meal produced from conventional soybeans (Hammond et al., 1996; Cromwell, et al., 2002). This paper describes a broiler study conducted as part of an overall safety assessment of the second-generation glyphosate-tolerant soybean, MON 89788. The nutritional evaluation was based on a direct comparison between the biotechnology-derived crop and the relevant conventional counterparts. The statistical significance of any potential differences in performance and carcass yield and quality between broilers fed diets containing MON 89788 and the parental control was assessed in the context of the range of natural variation by including the conventional reference diets. This inclusion of multiple conventional reference diets also increased the sensitivity and statistical power of the test.

The results of this broiler feeding study support the conclusion that there are no differences in the parameters evaluated among broilers fed soybean meal produced from glyphosate-tolerant (MON 89788), genetically similar control, and conventional reference soybeans. Therefore, soybean meal derived from MON 89788 is nutritionally equivalent to soybean meal derived from varieties currently in the marketplace. This conclusion is consistent with the results of previous feeding studies conducted with the first-generation (40-3-2) glyphosate-tolerant soybeans (Hammond et al., 1996). These results are as expected based on extensive compositional evaluation of the MON 89788 glyphosate-tolerant soybeans, which showed no biologically relevant differences in nutrient and antinutrient content compared with the control soybeans. These data support the conclusion that the soybean meal produced from MON 89788 is as wholesome and nutritious as conventional soybean meal based on its ability to support rapid growth and equivalent carcass yield and composition in broiler chickens.

Received for publication April 2, 2007. Accepted for publication September 3, 2007.


   REFERENCES
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
AOAC. 2000. Official Methods of Analysis of AOAC International. 17th ed. AOAC Int., Gaithersburg, MD.

AOAC. 2005. Official Methods of Analysis of AOAC International. 18th ed. AOAC Int., Gaithersburg, MD.

Astwood, J. D., and R. L. Fuchs. 2001. Status and safety of biotech crops. Pages 152–164 in Agrochemical Discovery–Insect, Weed, and Fungal Control. D. R. Baker and N. K Umetsu, ed. ACS Symposium Series 774. Am. Chem. Soc., Washington, DC.

Chesson, A., and G. Flachowsky. 2003. Transgenic plants in poultry nutrition. World’s Poult. Sci. J. 59:201–208.[CrossRef][Web of Science]

Cromwell, G., G. Dana, and G. Hartnell. 2003. Pages 1–62 in Best Practices for the Conduct of Animal Studies to Evaluate Crops Genetically Modified for Input Traits. Int. Life Sci. Inst., Washington, DC.

Cromwell, G. L., M. D. Lindemann, J. H. Randolph, G. R. Parker, R. D. Coffey, K. M. Laurent, C. L. Armstrong, W. B. Mikel, E. P. Stanisiewski, and G. F. Hartnell. 2002. Soybean meal from Roundup Ready or conventional soybeans in diets for growing-finishing swine. J. Anim. Sci. 80: 708–715.[Abstract/Free Full Text]

EPA. 1983. 40 CFR Part 160. Federal Insecticide, Fungicide and Rodenticide Act (FIFRA): Good Laboratory Practice Standards. Environ. Prot. Agency, Washington, DC.

FASS. 1999. Guidelines for the Care and Use of Agricultural Animals in Research and Teaching, 1st rev. Fed. Anim. Sci. Soc., Savoy, IL.

FDA. 1979. 21 CFR Part 58. Good Laboratory Practice Regulations for Nonclinical Laboratory Studies. Food Drug Adm., Washington, DC.

FDA. 1999. Multiclass multiresidue methods: 304 method for fatty foods. Pages 304-1–304-33 in Pesticide Analytical Manual Volume 1: Multiresidue Methods. 3rd ed. Food Drug Adm., Washington, DC.

Fincher, K. L., S. Flasinski, and J. Q. Wilkinson. 2003. Plant expression constructs. Monsanto Technology LLC, assignee. United States patent 6,660,911.

Fisher, R. A. 1949. The Design of Experiments. Oliver Boyd, Edinburgh, UK.

Flachowsky, G., A. Chesson, and K. Aulrich. 2005. Animal nutrition with feeds from genetically modified plants. Arch. Anim. Nutr. 59:1–40.[CrossRef][Web of Science][Medline]

Hammond, B. G., J. L. Vicini, G. F. Hartnell, M. W. Naylor, C. D. Knight, E. H. Robinson, R. L. Fuchs, and S. R. Padgette. 1996. The feeding value of soybeans fed to rats, chickens, catfish and dairy cattle is not altered by genetic incorporation of glyphosate tolerance. J. Nutr. 126:717–727.[Abstract/Free Full Text]

Martinell, B. J., L. S. Julson, C. A. Emler, Y. Huang, D. E. McCabe, and E. J. Williams. 2002. Soybean Agrobacterium transformation method. Monsanto Technology LLC, assignee. United States patent 6,384,301.

NRC. 1994. Nutritional Requirements of Poultry. 9th ed. Natl. Acad. Sci., Washington, DC.

Paschal, E. H. 1997. Soybean cultivar 88154622393. Asgrow Seed Company, assignee. United States patent 5, 659,114.

Tylka, G. L., and C. C. Marett. 1999. Evaluation of soybean varieties resistant to soybean cyst nematode in Iowa 1999. http://www.extension.iastate.edu/Pages/plantpath/tylka/Frames.html Accessed Feb. 15, 2006.





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