Updated December 7, 2021:
Soybean meal has played an important role in the livestock industry for many years, with more than 70% of the soybean meal produced in the US being used to feed livestock. Today, the market for soybean meal is expanding. There is a growing interest in the soybean protein in new food systems which include plant-based protein. There has also been a growing interest in soybean meal with >50% meal protein, which could potentially add more value to the soybean crop. While the price of soybean oil is higher than soybean meal, the amount of meal produced is over four times as much as oil. This translates to soybean meal contributing the bulk of the crushing value of soybean on a per bushel basis. So, just a one cent per pound change in soybean meal prices could have 2.5 times the impact on soybean prices when compared to one percent change in soybean oil. Based on the results of the Soybean Quality Report in 2020, by Seth Naeve, the protein concentration was down and the oil content was up in soybeans produced in the US. Oil was up 1.6 points and protein was down 1.2 points. Maintaining soybean protein concentrations in soybean is extremely important in keeping soybean competitive on the world market. Unfortunately, many high protein, low oil lines were discarded in earlier breeding cycles because of an emphasis on high protein, while maintaining at least 18% oil. The goal of this project is to not only increase the protein content beyond the 48% meal protein, but to improve the quality of the protein. We are very encouraged by the data we have been able to collect so far. We have been able to identify numerous breeding lines with high protein >40% and extremely high meal protein (>55%), with yields at or above check cultivars. We have also started to evaluate lines for amino acid composition as well as for protein and oil content. Since amino acids are the key component for the growth and development of animals, soybeans are considered one of the best sources of protein because they contain key amino acids. Key amino acids in soybean meal used for animal feed include arginine, lysine, threonine, methionine and tryptophan. Preliminary results reveal that arginine levels increase as protein levels increase, whereas there are small decreases in cysteine, lysine, methionine, threonine and tryptophan. However, these trends are not absolute. Some lines with a meal protein content of only 46% had amino acid concentrations similar to lines with >50% meal protein. Our research does suggest that, similar to amino acid concentrations in soybean lines containing 46-50% meal protein, there is also variation among lines containing >50% meal protein. It does appear that fewer lines are able to maintain the desired amino acid concentrations when meal protein is >50%. More research is needed to fully understand what amino acid concentrations are preferred by the animal feed industry compared to crude protein content and the stability of the amino acid profile across multiple testing environments. In addition, over 100 lines were requested from the Germplasm Information Network (GRIN). Lines were selected with a protein concentration of at least 47.4% and an oil concentration in the range of 14.1 to 16.1%. All of the GRIN lines were divided up and sent to the collaborator with the most representative environment suited for the maturity group (MG). MG 00-I were grown in MN, II-IV were grown in IL and MG V-IX were grown in NC. Seeds were harvested from each accession so that their oil and protein compositions in two very different growing seasons could be analyzed to confirm the stability of their low oil and/or high protein contents. Data for agronomically important traits like lodging, shattering and pod set were also collected on the PIs. The PIs that had desirable morphological and agronomically important traits were crossed with high-yielding breeding lines in 2020 and 2021. These PIs were crossed with elite lines that performed well in multi-state regional yield tests. In addition, some elite lines have Glycine soja accessions in their pedigrees and some have pedigrees with more than 50% exotic ancestry, mostly from East Asian germplasm accessions. Many of the F1 plants from these crosses were either backcrossed once to their elite parent or were crossed to a different elite parent in a three-way cross to produce progeny that would inherit an average of 75% of their genes from their high-yielding adapted parents. Populations derived from these crosses can potentially be used for mapping novel QTLs associated with lower oil and/or higher protein in seeds, as well as for developing new lines with higher seed protein content. A high percentage of the elite lines used for crossing in this project already have exotic progenitors in their pedigrees, so the breeding lines developed in this project represent truly unique germplasm that is different from virtually anything else available in the United States.