Protein and energy evaluation of soybean meals processed from genetically modified high-protein soybeans

Identity preserved plant molecular farming offers value-added opportunity for farmers

Bulk commodity row crop production in the United States is frequently subject to narrow profit margins, often complicated by weather, supply chains, trade, and other factors. Farmers seeking to increase profits and hedge against market volatility often seek to diversify their operations, including producing more lucrative or productive crop varieties. Recombinant plants producing animal or other non-native proteins (commonly referred to as plant molecular farming) present a value-added opportunity for row crop farmers. However, these crops must be produced under robust identity preserved systems to prevent comingling with bulk commodities to maintain the value for farmers, mitigate against market disruptions, and minimize any potential food, feed, or environmental risks.

QTL for seed protein and amino acids in the Benning × Danbaekkong soybean population

KEY MESSAGE

We identified QTL associated with protein and amino acids in a soybean mapping population that was grown in five environments. These QTL could be used in MAS to improve these traits. Soybean, rather than nitrogen-containing forages, is the primary source of quality protein in feed formulations for domestic swine, poultry, and dairy industries. As a sole dietary source of protein, soybean is deficient in the amino acids lysine (Lys), threonine (Thr), methionine (Met), and cysteine (Cys). Increasing these amino acids would benefit the feed industry. The objective of the present study was to identify quantitative trait loci (QTL) associated with crude protein (cp) and amino acids in the 'Benning' × 'Danbaekkong' population. The population was grown in five southern USA environments. Amino acid concentrations as a fraction of cp (Lys/cp, Thr/cp, Met/cp, Cys/cp, and Met + Cys/cp) were determined by near-infrared reflectance spectroscopy. Four QTL associated with the variation in crude protein were detected on chromosomes (Chr) 14, 15, 17, and 20, of which, a QTL on Chr 20 explained 55 % of the phenotypic variation. In the same chromosomal region, QTL for Lys/cp, Thr/cp, Met/cp, Cys/cp and Met + Cys/cp were detected. At these QTL, the Danbaekkong allele resulted in reduced levels of these amino acids and increased protein concentration. Two additional QTL for Lys/cp were detected on Chr 08 and 20, and three QTL for Thr/cp on Chr 01, 09, and 17. Three QTL were identified on Chr 06, 09 and 10 for Met/cp, and one QTL was found for Cys/cp on Chr 10. The study provides information concerning the relationship between crude protein and levels of essential amino acids and may allow for the improvement of these traits in soybean using marker-assisted selection.

Nutritional value of soybean meal produced from conventional, high-protein, or low-oligosaccharide varieties of soybeans and fed to broiler chicks

Three experiments were conducted to determine the feeding value to broiler chicks of soybean meal (SBM) produced from high-protein (SBM-HP), low-oligosaccharide (SBM-LO), or conventional (SBM-CV) varieties of soybeans. The 3 SBM contained 54.9, 53.6, and 47.5% CP, respectively. The standardized digestibility (SDD) of amino acids (AA) in the 3 ingredients was measured using a precision-fed rooster assay with cecectomized Single Comb White Leghorn roosters. Results indicated that the SDD of AA was not different among the 3 sources of SBM, with the exception that the SDD of Lys in SBM-HP tended to be greater (P = 0.07) than that in SBM-CV. In the second experiment, a precision-fed rooster assay was used to measure the concentration of TME(n) in each source of SBM. Results indicated that the TME(n) in SBM-HP was greater (P < 0.001) than those in SBM-LO and SBM-CV (3,104 vs. 2,984 and 2,963 kcal/kg of DM). A 14-d growth performance experiment was also conducted using 120 Ross 308 male commercial broiler chicks (mean initial BW = 102.6 g) that were allotted to a completely randomized design. There were 5 chicks/pen and 8 replicate pens/diet. Three corn- and SBM-based diets were formulated based on the data for digestible AA and TME(n) that were measured in the previous experiments. Each source of SBM was used in 1 diet, but because of the greater concentrations of digestible AA in SBM-HP and SBM-LO than in SBM-CV, the inclusion of SBM-HP and SBM-LO were 31.21 and 32.60%, respectively, whereas an inclusion of 38.21% SBM-CV was used. There were no differences among the 3 diets for BW gain or feed efficiency, which indicated that the reduced inclusion rates of SBM-HP and SBM-LO compared with SBM-CV were not detrimental to broiler chick growth performance. It was concluded that, compared with SBM-CV, SBM-HP and SBM-LO are needed in lower concentrations in diets fed to broiler chicks because these 2 sources of SBM have a greater nutritional value than does SBM-CV.

Evaluation of the nutritional equivalency of soybean meal with the genetically modified trait DP-3O5423-1 when fed to laying hens

An experiment using 336 Hy-Line W-36 Single Comb White Leghorn hens was conducted to evaluate transgenic soybeans containing the gm-fad2-1 gene fragment and the gm-hra gene. Transcription of the gm-fad2-1 gene fragment results in an increased level of oleic acid (18:1) in the seed, and expression of the soybean acetolactate synthase protein (GM-HRA) encoded by the modified gm-hra gene, is used as a selectable marker during transformation. Pullets (20 wk of age) were placed in cage lots (7 hens/cage, 2 cages/lot) and were randomly assigned to 1 of 4 corn-soybean meal dietary treatments (6 lots/treatment) formulated with the following soybean meals: nontransgenic near-isoline control (control), nontransgenic commercial reference soybean meal A (92M72), nontransgenic commercial reference soybean meal B (93B15), or transgenic soybean meal produced from soybeans containing event DP-3Ø5423-1 (305423). Weeks 20 to 24 were a preconditioning period, and the 4 experimental diets were then fed from 25 to 36 wk of age. Differences between the 305423 and control group means were evaluated, with statistical significance at P < 0.05. Body weight, hen-day egg production, egg mass, feed consumption, and feed efficiency for hens fed the 305423 soybean meal were not significantly different from the respective values for hens fed diets formulated with the near-isoline soybean meal. Likewise, egg component weights, Haugh unit measures, and egg weights were similar regardless of the soybean meal source. This research indicates that performance of hens fed diets containing 305423 soybean meal, as measured by egg production and egg quality, was similar to that of hens fed diets formulated with the near-isoline control and commercial soybean meals.

Effect of dietary soybean oil and soybean protein concentration on the concentration of digestible amino acids in soybean products fed to growing pigs

An experiment was conducted to measure the effect of adding soybean oil to soybean meal (SBM) and soy protein concentrate (SPC) on apparent (AID) and standardized (SID) ileal digestibility of CP and AA by growing pigs. A second objective was to compare AID and SID of AA in a new high-protein variety of full fat soybeans (FFSB) to values obtained in other soybean products. Commercial sources of FFSB (FFSB-CV), SBM, and SPC, and of a new high-protein variety of FFSB (FFSB-HP) were used in the experiment. Four diets were prepared using each soybean product as the sole source of CP and AA in 1 diet. Two additional diets were formulated by adding soybean oil (7.55 and 7.35%, respectively) to the diets containing SBM and SPC. A nitrogen-free diet was also used to measure basal endogenous losses of CP and AA. The 2 sources of FFSB were extruded at 150 degrees C before being used in the experiment. Seven growing barrows (initial BW = 26.2 kg) were prepared with a T-cannula in the distal ileum and allotted to a 7 x 7 Latin square design. Ileal digesta were collected from the pigs on d 6 and 7 of each period. All digesta samples were lyophilized and analyzed for DM, CP, AA, and chromium, and values for AID and SID of CP and AA were calculated. The addition of oil improved (P < 0.05) the SID of most indispensable AA in SBM and SPC. The SID for 6 of the indispensable AA in FFSB-HP were greater (P < 0.05) than in FFSB-CV, and the SID for all indispensable AA except Met was greater (P < 0.05) in FFSB-HP than in SBM. However, the SID for most AA in FFSB-HP was similar to SBM with oil and SPC, but these values were lower (P < 0.05) than in SPC with oil. In conclusion, the addition of oil improved the SID of most AA in SBM and SPC fed to growing pigs, and the SID of AA in FFSB-HP were greater than in SBM and similar to the SID of AA in SBM with oil and in SPC.

Atlantic salmon (Salmo salar L.) parr fed genetically modified soybeans and maize: Histological, digestive, metabolic, and immunological investigations

Physiological and health related responses to dietary inclusion of genetically modified (GM) full-fat soybean meal (Roundup Ready; GM-soy) and maize (MON810 Bt-maize; GM-maize), as well as non-parental, untransformed lines (nGM-soy and nGM-maize D2), were evaluated in farmed Atlantic salmon (Salmo salar L.) parr during the first 8 months of feeding. Significant effects of dietary GM presence were only found in intestinal Na+-dependent d-glucose uptake and SGLT1 protein level in the region pyloric caeca in which the highest values were found in the GM-soy, intermediate in the nGM-soy, and lowest in the standard FM fed groups. Data from this study confirm that GM soybeans (RRS) and maize (MON810) at inclusion levels of about 6% appear to be as safe as commercially available nGM soy and maize in diets for Atlantic salmon parr. Results from studies with higher inclusion levels and with non-modified, isogenic or near-isogenic parental lines as control groups are pending.

Effects of extrusion conditions on trypsin inhibitor activity of full fat soybeans and subsequent effects on their nutritional value for young broilers

1. Increasing proportions of soybeans in poultry diets have highlighted the importance of correct processing to inactivate the anti-nutritional factors present whilst maintaining protein quality. 2. Ground full fat soybeans (FFSB) were extruded using a Clextral laboratory model twin-screw extruder with 0.75 l/h of water and end barrel temperatures of 90, 110, 130 and 160 degrees C resulting in trypsin inhibitor activities (TIA) of 14.8, 9.6, 4.5 and 1.9 mg/g sample. 3. The 4 extrudates were used at three different inclusion levels: 200, 400 and 600 g/kg semi-synthetic diet and fed to male Ross broiler chicks from d 19 to d 26. Digesta samples were taken for measurement of coefficient of ileal apparent amino acid digestibility (CIAD) and both pancreas and whole bird weights were measured. 4. Concentration of ileal apparent digestible lysine was increased from 10.53 to 17.63 g/kg FFSB by increasing extrusion temperature from 90 to 160 degrees C. CIAD of lysine was also improved from 0.58 to 0.86. Other amino acids showed similar improvements in both their ileal apparent digestible concentration and CIAD. 5. Mean weight gain over 3 d increased linearly from 42 to 95 g per bird with increasing extrusion temperatures of FFSB. Pancreatic enlargement was evident after 6 d of feeding with FFSB processed at lower temperatures, even when the TIA level was at the recommended threshold of 4 mg/g. 6. The results emphasise the importance of controlled conditions during processing of FFSB for poultry diets and suggest that processing of FFSB in order to reduce TIA levels below 4 mg/g may provide significant benefits for broiler chicks.

Animal nutrition with feeds from genetically modified plants

Plant breeders have made and will continue to make important contributions toward meeting the need for more and better feed and food. The use of new techniques to modify the genetic makeup of plants to improve their properties has led to a new generation of crops, grains and their by-products for feed. The use of ingredients and products from genetically modified plants (GMP) in animal nutrition properly raises many questions and issues, such as the role of a nutritional assessment of the modified feed or feed additive as part of safety assessment, the possible influence of genetically modified (GM) products on animal health and product quality and the persistence of the recombinant DNA and of the 'novel' protein in the digestive tract and tissues of food-producing animals. During the last few years many studies have determined the nutrient value of GM feeds compared to their conventional counterparts and some have additionally followed the fate of DNA and novel protein. The results available to date are reassuring and reveal no significant differences in the safety and nutritional value of feedstuffs containing material derived from the so-called 1st generation of genetically modified plants (those with unchanged gross composition) in comparison with non-GM varieties. In addition, no residues of recombinant DNA or novel proteins have been found in any organ or tissue samples obtained from animals fed with GMP. These results indicate that for compositionally equivalent GMP routine-feeding studies with target species generally add little to nutritional and safety assessment. However, the strategies devised for the nutritional and safety assessment of the 1st generation products will be much more difficult to apply to 2nd generation GMP in which significant changes in constituents have been deliberately introduced (e.g., increased fatty acids or amino acids content or a reduced concentration of undesirable constituents). It is suggested that studies made with animals will play a much more important role in insuring the safety of these 2nd generation constructs.

The use of consumption data to assess exposure to biotechnology-derived foods and the feasibility of identifying effects on human health through post-market monitoring

The pre-market safety assessment of foods derived through biotechnology provides a scientific basis for concluding reasonable certainty of no harm and ensuring safety. At a minimum, the outcome of such an assessment provides sufficient information to estimate the likelihood of adverse effects on consumers, generally precluding the need for post-market monitoring. Post-market monitoring (PMM) may be appropriate under certain conditions where a better estimate of dietary exposure and/or nutritional consequence of a biotechnology-derived food is required, when a potential safety issue, such as allergenicity, cannot be adequately addressed through pre-market studies, or to corroborate dietary intakes of a nutritionally improved food with beneficial effects on human health. Monitoring programs must be hypothesis-driven, and are dependent upon the availability of accurate consumption data. Exposure assessment methods include both deterministic and probabilistic estimates of intakes using food supply data, individual dietary surveys, household surveys, or total diet studies. In the development of a monitoring approach, resource allocation should be dependent upon both the desired level of conservatism and the endpoint of interest. However, the cost of monitoring varies substantially, and the potential to determine causation may be limited.

Ultrastructural analysis of pancreatic acinar cells from mice fed on genetically modified soybean

No direct evidence that genetically modified (GM) food may represent a possible danger for health has been reported so far; however, the scientific literature in this field is quite poor. Therefore, we investigated the possible effects of a diet containing GM soybean on mouse exocrine pancreas by means of ultrastructural, morphometrical and immunocytochemical analyses. Our observations demonstrate that, although no structural modification occurs in pancreatic acinar cells of mice fed on GM soybean, quantitative changes of some cellular constituents take place in comparison to control animals. In particular, a diet containing significant amount of GM food seems to influence the zymogen synthesis and processing.

Ultrastructural morphometrical and immunocytochemical analyses of hepatocyte nuclei from mice fed on genetically modified soybean

No direct evidence that genetically modified (GM) food may represent a possible danger for health has been reported so far; however, the scientific literature in this field is still quite poor. Therefore, we carried out an ultrastructural morphometrical and immunocytochemical study on hepatocytes from mice fed on GM soybean, in order to investigate eventual modifications of nuclear components of these cells involved in multiple metabolic pathways related to food processing. Our observations demonstrate significant modifications of some nuclear features in GM-fed mice. In particular, GM fed-mice show irregularly shaped nuclei, which generally represents an index of high metabolic rate, and a higher number of nuclear pores, suggestive of intense molecular trafficking. Moreover, the roundish nucleoli of control animals change in more irregular nucleoli with numerous small fibrillar centres and abundant dense fibrillar component in GM-fed mice, modifications typical of increased metabolic rate. Accordingly, nucleoplasmic (snRNPs and SC-35) and nucleolar (fibrillarin) splicing factors are more abundant in hepatocyte nuclei of GM-fed than in control mice. In conclusion, our data suggest that GM soybean intake can influence hepatocyte nuclear features in young and adult mice; however, the mechanisms responsible for such alterations remain unknown.