Location: Soybean and Nitrogen Fixation Research2012 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. Low Phytate (LP) soybean meal with or without the addition of coarse corn (CC) was evaluated in broiler diets. Broiler body weight (BW) gain, feed intake (FI), feed conversion ratio (FCR), and gizzard and pro-ventriculus weights were measured at 8, 15, and 21 days of age. From 9-15 days of age, BW gain (360 versus 355 g) and FCR (1.28 versus 1.30 g:g) were improved by the 0%CC diet while from 16-21 days of age the 50%CC diet improved BW gain (773 versus 765 g) with numerically better FCR (1.26 versus 1.29 g:g). Upon necropsy at 8, 15, and 21 days of age, the 50%CC diets produced a larger gizzard and smaller pro-ventriculus compared to 0%CC diets. There was no main effect of Soybean meal (SBM) on either gizzard or pro-ventriculus weight at 15 days of age, but gizzard weight was reduced by the LP diets at 21 days of age and there was an interaction of SBM and CC for gizzard weight at 21 days of age due to normal phytate (NP) SBM resulting in a larger gizzard than LP SBM in the presence of 0%CC. There was an interaction as well for pro-ventriculus weight at 15 days of age due to a larger pro-ventriculus in the NP SBM diet only in the presence of 0%CC.