Location: Soybean and Nitrogen Fixation Research2013 Annual Report
1a. Objectives (from AD-416):
Improve the overall animal feeding value of U.S. soybean meal from optimum amino acid balance and low phytate phosphorus perspectives. Demonstrate that low phytate soybean meal is a more reliable and economical means to reduce fecal phosphorus output from animals than are fed enzymes such as phytase. Demonstrate the optimum dietary mineral and electrolyte balance required to successfully utilize low phytate soybean meal in animal diets. Demonstrate that feed enzyme efficacy in a diet with low phytate soybean meal differs from when there is a normal phytate soybean meal in the diet of an animal. Demonstrate possible beneficial effects of reduced fecal nitrogen that could lead to reduced ammonia production from animal facilities. Examine the interaction between increased feed particle size to stimulate broiler gizzard and gastrointestinal function and low phytate soybean meal on fecal phosphorus and nitrogen.
1b. Approach (from AD-416):
Grow a significant quantity of low phytate soybeans as well as an equal quantity of commercial soybeans so that both may be harvested, dried, and processed into meal for direct feeding to broilers. Utilize our standardized soybean processing approach developed at TAMU with Dr. Richard Clough to produce low phytate and control meals. Examine the amino acid digestibility of low phytate and commercial meals with and without various feed enzymes in the presence or absence of feed with varying particle size and the fecal output of nitrogen and phosphorus. Develop optimum feed formulation guidelines for various mineral factors that have been found to affect digestion, e.g. calcium: available phosphorous ratio, salt: sodium bicarbonate balance, potassium in a low phytate environment. Continue work towards development of a bioassay to assess the amino acid digestibility on small lots of identity-preserved soybeans using solvent-extracted meal and a modified ileal digestibility test.
3. Progress Report:
This project is related to Objective 2 of this in-house project: To characterize the biological mechanisms that control phytic acid concentration in soybean seed, and determine the impact of genetically lowering phytic acid on seed and seedling vigor, soy protein functionality and soybean meal digestibility. Additional studies were carried out to determine the effect of added phytase to normal and low phytate soybean meal. Results demonstrated that phytase significantly improved live performance in broilers fed diets formulated with normal phytate (NP) soybean meal (SBM) but this was not the case with Low phytate (LP) SBM. Reduced gizzard weight in birds consuming LP SBM with phytase at 22 d could be causally related to the poorer subsequent performance of these broilers and/or there could have been a negative effect of intestinal calcium and phosphorus balance in the LP SBM environment as suggested by our prior results. In prior years we reported that the dietary calcium level was critical to amino acid digestibility when the phytate level of the diet varied. It would appear that this remains true and attention would have to be paid to this detail in commercial practice. However, we have no data to suggest that we cannot find a way to use enzymes in combination with LP SBM or other SBM produced from the various United Soybean Board breeding projects.