Wednesday, January 25, 2017

Variation of Soybean Meal Quality Across Countries

Quite often we are asked that why soybean meal of different origin requires a distinct feed specification matrix record. In other words, why soybean meal from the U.S. needs to be a different ingredient from soybean meal from India, or Argentina, or Brazil. After all, they all start with very similar raw material, which is raw soybeans from a handful of seed genetic suppliers. And, although growing conditions are not exactly similar across the world, they still are not significantly disparate to warrant such a wide difference in soybean meal nutrient specifications. To explain this issue, we must focus on three issues that cause soybean meals from different sources to have different nutrient values:
1. Soybean hulls

Quite often, a part of the outer shell of the beans (the hull) is added back to the soybean meal. Thus, by adding more hulls back, we get from 48 percent down to 44 percent crude protein, with a corresponding increase in total fiber concentration.
2. Residual oil

The amount of oil extracted from soybeans differs according to the processing method followed, which is not exactly similar across the world. It appears the factories within a region or country tend to follow similar methods, which results in similar end product specifications.
3. Thermal processing

The solvent extraction method used for oil removal from soybeans involves a certain degree of thermal processing. This cooking can be mild or severe, depending on the processing method and quality of machinery. Exposure to high temperatures denatures the protein and renders it less digestible/available to animals. This is a major issue that greatly diminishes the value of the primary source of animal feed protein worldwide.
In brief, the resulting end nutritive value of soybean meal has nothing to do with country of origin, but rather with processing methods that tend to be similar within a country. This is why soybean meal purchases are often characterized by country of origin.
"Soybean meal is not the same ingredient everywhere as its nutritive value depends on country of origin"
Crude protein concentration has been and remains the most important aspect in quality control for soybean meal. But, soybean meal is an international commodity, and despite being used throughout the world, it is exported by a handful of countries. It pays then to focus on such major exporters to investigate whether their processing conditions affect not only protein concentration, but also protein quality, which is equally important.
In a recent study published in Poultry Science, the nutrient composition, ileal amino acid (AA) digestibility, and apparent metabolizable energy for poultry (AME) of 55 soybean meal (SBM) samples were evaluated from the United States (US; n = 16), Argentina (ARG; n = 16), Brazil (BRA; n = 10), and India (IND; n = 13). Samples were collected from commercial mills in Southeast Asia, and they were compared using laboratory analyses and animal studies.
There were significant (P < 0.05 to 0.001) differences due to origin in crude protein (CP), fat, ash, fiber and non-starch polysaccharide (NSP) contents of SBM. The average CP content of US, ARG, BRA, and IND samples was determined to be 47.3, 46.9, 48.2 and 46.4 percent (as-fed basis), respectively. Compared with SBM from other origins, crude fiber and NSP contents were lower (P < 0.05) and sucrose content was higher (P < 0.05) in the US samples. The IND samples had the highest (P < 0.05) contents of fiber, ash and NSP, and lowest (P < 0.05) contents of fat and sucrose. Differences (P < 0.0001) were also observed due to country of origin for in vitro protein quality measures (urease index, KOH protein solubility, and trypsin inhibitor activity). Significant (P < 0.001) effects due to origin were ob-served for all minerals. Soybean meal from the US and IND had higher (P < 0.05) calcium contents (0.45 percent) compared with those from ARG and BRA (0.28–0.31%). Phosphorus and potassium contents were lowest (P < 0.05) in SBM from IND, and no differences (P > 0.05) were observed in SBM from other origins. Iron content was markedly high (928 mg/kg) in SBM from IND compared with those from other origins (103–134 mg/kg).
Major origin-related differences (P < 0.0001) were observed in the AME of SBM. The average AME content of US, ARG, BRA and IND samples was 2,375, 2,227, 2,317 and 2,000 kcal/kg (as-fed basis), respectively. Total AA contents of US, ARG, BRA, and IND samples were similar (P > 0.05) for 9 of the 17 amino acids. Major differences (P < 0.05 to P < 0.001) due to origin were determined for the digestibility of all AA. The IND samples had the lowest (P < 0.05) digestibility and no differences (P > 0.05) between samples from other 3 origins. However, the digestible CP content of US SBM was higher (P < 0.05) than those of ARG and IND, but similar (P > 0.05) to that from BRA. The digestible CP contents of SBM from the US, ARG, BRA, and IND were 40.0, 38.6, 39.8, and 36.7 percent, respectively. Digestible contents of indispensable AA, in general, followed the same trend as that of digestible CP.
In conclusion, the present evaluation showed that major differences in nutritive value do exist between SBM from different origins in terms of nutrient contents, AME, and digestible AA.