Research Highlights

Research Highlights
Soybean Meal: These Varieties Are for the Birds

Photo: United Soybean Board

By Laura Temple

Common knowledge says you are what you eat. So, nutritionists recommend eating what the body needs. That’s how they develop diets for food animals like broiler chickens.

Feed formulations provide chickens with the combination of energy, amino acids and other nutrients needed for healthy growth. Soybean meal provides a key source of protein for broilers at all life stages, because it provides a good mix of essential amino acids. Synthetic amino acids supplement the soybean meal and other ingredients to create a complete feed.

Michael Kidd, professor of poultry nutrition at the University of Arkansas, understands feed formulations. But considering what nutrients chickens need led him to collaborate with University of Arkansas soybean breeders to develop better soybeans for broiler feed, with support from the Arkansas Soybean Promotion Board. 

“When thinking about enhancing the nutritional profile of soybeans as a feed source, commercial breeders often focus on synthesized amino acids, in the hopes of reducing additives,” he explains. “We took a different approach. We selected the amino acid traits we wanted by evaluating amino acid profiles for those not commercially available in feed-grade form.”

The team identified seed genomes with profiles containing high levels of amino acids considered less critical today, because they are not the most limiting in current soybean meal and corn diets. They focused on seven amino acids: phenylalanine, tyrosine, arginine, aspartate, glutamate, glycine and proline.

“We believe that poultry nutritionists will be formulating diets to these amino acids within the next 10 years,” Kidd says. “We want to provide a soybean line that contains higher levels of less limiting amino acids.” 

One of Kidd’s doctoral students, Savannah Wells-Crafton, carried out feeding trials to learn how much broilers are what they eat. The trials included soybean meal made from some of the University of Arkansas experimental soybean lines bred to different objectives, thanks to Arkansas Soybean Promotion Board funding.

Feeding Trials

For the first trial, Wells-Crafton compared broilers fed meal from different soybean varieties during the finisher phase, when they were 28 to 42 days old.

“The finisher phase is when broilers eat the most feed,” she explains. “We kept diets and conditions the same prior to that point, and the only difference in the feed was the type of soybean meal used.”

Due to the limited supply of soybeans from experimental lines, Wells-Crafton compared diets including full fat soybean meal from three soybean varieties. One experimental line was bred for higher amino acid content with input from Kidd’s team. Another was bred for higher oil content. The third was a standard commercially available soybean variety. She had the soybeans crushed in small batches that kept each type of meal separate.

“We saw no statistical difference in feed intake, weight gain, feed conversion ratio or processing yield between the types of feed,” she reports. “However, we did see numerical differences in feed conversion ratio with the experimental lines, as both were better than the control. While that difference didn’t register statistically, it was enough that it caught our attention.”

She notes that both experimental soybean lines in the trial had higher-than-average protein and oil content. For that reason, she chose to feed standard defatted soybean meal from the experimental soybean line bred for oil in a second trial. 

That trial compared dry extruded soybean meal from those identity-preserved soybeans with standard commercially available dry extruded soybean meal and solvent-extracted soybean meal. Each type of soybean meal was used in feed for every growth phase: the starter phase from 0 to 14 days, grower for 14 to 28 days, and finisher from 28 to 45 days.

“The feed in this trial was formulated for energy and amino acid profile,” Wells-Crafton says. “While we again saw no difference in broiler performance, we used 2% less soybean meal from the experimental line in feed for all growth stages. That means this soybean meal would be worth more and broiler diet cost would be reduced.”

She adds that they saw no performance difference based on meal processing method.  

The findings from these two trials indicate that feeding meal from identity-preserved soybeans could benefit broilers and provide another value-added opportunity for soybean farmers. The initial findings will inform future research looking at the digestibility of different soybean meals.

Kidd and Wells-Crafton are leveraging this research funded by the Arkansas Soybean Promotion Board into a research proposal for the United Soybean Board. 

“All this work ties into the future for identity preservation at crush facilities,” Kidd says. “As traceability improves, the broiler feed industry will find it worth the money to formulate diets with more precision. I dream of the day when soybean crush facilities, poultry company ingredient buyers and nutritionists work in tandem on optimizing essential nutrients in meal, not just decreasing its anti-nutritional factors.”

Published: Feb 12, 2024