Nutritive values for major feed ingredients vary considerably not only among different feedstuff, but also within the same ingredient produced in different geographical regions and production batches. Rapid screening to assess true nutritive value has been a great challenge in the feed industry. This research study evaluated soybean meal (SBM) samples of four different regions using both near infrared reflectance spectroscopy (NIRS) and broiler experiments.
In the first broiler study, four SBM samples were assigned identical “book values”, so that the four dietary formulations were the same, varying only in the sources of SBM. In the second broiler study, individual NIRS prediction values for each SBM were used in the ration formulation. The level of SBM was varied to ensure diets were iso-energetic and iso-nitrogenous. The broiler studies consisted of eight treatments with six replicates using sixteen male birds each, from day 1 to 40 of age.
The results showed that when using the common values for the four SBM, broiler performance was very different in terms of live weight gain and feed conversion (P<0.05); when the diets were formulated using individual NIRS values for each individual SBM, the birds grew very similarly.
The results demonstrated that the four SBMs used in this study were very different in their nutritive quality, as shown by NIRS analyses and their performances in the broiler diets. The study also confirmed that the quality of a SBM is largely defined by its levels of metabolizable energy and digestible amino acids, rather than crude protein levels as routinely judged in most commercial practice.
Table: Nutrient Values of Four Soybean Meals as Estimated by Near Infrared Reflectance Spectroscopy (%)
The results clearly demonstrated that the nutritive quality of various SBMs is not the same; their values are largely defined by their levels of metabolizable energy and digestible amino acids. This means that knowing the specific composition of any SBM, then the quality and economic value of that meal can be calculated. A lower quality SBM (with lower levels of metabolizable energy and digestible amino acids) may still produce good broiler performance if the diet is formulated with its correct nutrient values. To obtain optimum broiler performance accurate nutrient values are needed for the SBM used in the broiler feed formulations.