Additional information on the variation in U.S. soybean crop

Additional information on the variation in U.S. soybean crop can be found on the following website http://www.unitedsoybean.org/programs/soy_measurements.aspx. This website provides information on the 2008 soybean crop from samples collected by the participants in USDA's National Agricultural Statistics Service's Objective Yield Survey program. This NASS program develops data used to determine USDA's official estimate of crop yield and production. The program provides for NASS personnel to collect physical field measurements and monitor crop progress throughout the growing season. Soybean samples obtained from these fields were ground using a Perten LM 3600 grinder and then scanned on a FOSS 6500 NIR Instrument at the University of Minnesota.

They reported average protein levels of 35.6±1.4% with a range of 33.1 to 37.5% and average oil levels of 17.9±0.9 with a range of 16.6 to 19.2% for the samples NASS personnel collected from the 2008 crop. Not only do they show average protein and oil values by region, they also chart the negative correlation between protein and oil levels and the weak correlation between total lysine to protein ratios (average 6.9±0.16; range 0.9-1.13) in the soybean samples.

What does all of this analytical data on soybeans mean to the nutritionist interested in formulating high performance rations? These soybean composition values indicate that the levels of protein and oil in the soybean are influenced by both the micro-environment where the soybeans are grown and the genetics of the plant. There are regional differences, state differences, county differences and probably field to field differences in the ability for the plant to achieve its genetic potential to accumulate protein and oil in the soybean seed. However, these relatively small differences in composition values are minimized when combined with other samples from other areas. The bottom line is that over the past twenty-five years, averages have become averages. Soybeans will contain, on the average about 35-36% crude protein and 18½ -19½% oil (on a 13% moisture basis). These values have not changed even though soybean yields have steadily increased.

The nutritionist can plan on the soybean processor producing a soybean meal that is consistent and meets specified minimum meal specifications. Meeting soybean meal specifications is possible since processors purchase soybeans from various regions with significantly different micro-environments; the soybeans are blended in storage and processing; and the processing steps are carefully regulated to produce a soybean meal that is the standard protein ingredient for the feed industry. No other feed ingredient can match the compositional consistency of soybean meal.

This is not to say that soybean researchers can not improve the compositional characteristics of the soybean. With time and research funding, it should be possible to improve the composition of the soybean. Research groups are actively conducting efforts to significantly increase seed protein levels; modifying the oil profile; improving the levels and balance of amino acids; reducing the levels of the oligosaccharides; improving the availability of minerals; and investigating other traits that will further increase the competitiveness of soybean meal in providing needed nutrients to high-performance feeds. http://www.unitedsoybean.org/programs/soy_measurements.aspx.

Genetic Improvement of Soybeans Researchers at the Institute of Crop Science and Nuclear Technology Utilization, Zhejiang Academy of Agricultural Sciences in Hangzhou, China reported on the effect of two new low phytic acid (LPA) mutations on seed quality and nutritional traits. Studies conducted at different locations and different seasons showed that the two mutations did not affect the concentration of crude protein, any of the individual amino acids, crude oil, and individual saturated fatty acids. One mutant (Gm-lpa-TW75-1) had consistently higher sucrose contents (+47.4 to +86.1%) and lower raffinose contents (-74.2 to -84.3%) than those of wild type parent (Taiwan 75). The other mutant (Gm-lpa-ZC-2) had higher total isoflavone contents (3038.8 to 4305.4 microg/g) than its parent (1583.6 to 2644.9 microg/g) in all environments. Tests of homozygous F(3) progenies of the cross Gm-lpa-ZC-2 x Wuxing # 4 (WT variety) showed that LPA lines had a mean content of total isoflavone significantly higher than wild type lines. The research group indicated that this study demonstrated that two LPA mutant genes have no negative effects on seed quality and nutritional traits and the mutant genes may have the potential to improve a few other soybean seed properties. They also postulated that these two mutant genes could be valuable genetic resources for breeding soybean varieties with reduced phytic acid seed levels and may have the potential to improve the nutritional value of soybean meal and lessen phosphorus pollution in large scale animal farming.

Yuan, F.J., and co-workers. 2009. Effects of two low phytic acid mutations on seed quality and nutritional traits in soybean (Glycine max L. Merr). J. Agric. Feed Chem. 57(9): 3632-3638.