High Soybean Meal Diet Could Unlock Extra Energy for Pigs

With new soybean processing facilities in the Midwest, increased production of soybean meal may reduce its market price, making it a more accessible and economically as viable energy and amino acid source. Although soybean meal is the primary protein source used in swine diets in the Midwest, synthetic amino acids often replace much of the soybean meal in diets.

Researchers at South Dakota State University (SDSU) recently completed a study led by Courtney Pohlen to evaluate very high and low levels of soybean meal on pig performance and health. During the 111-day trial, 546 mixed-sex pigs per treatment were evaluated for the effects of diets with 1) low soybean meal inclusion supplemented with synthetic amino acids (5%) versus 2) high soybean meal inclusion (28%). All diets were formulated to meet or exceed NRC requirements and net energy (NE) levels were kept constant across treatments. Pigs fed high soybean meal diets gained weight faster than pigs fed low soybean meal diets.

“Our performance results in the high lean growth pig of today have consistently shown improved gains with soybean meal versus high levels of replacement with synthetic amino acids and/or dried distillers grains with solubles (DDGS). There is a sweet spot for growth rate for soybean meal use and its economics, but the faster growth is a definite indication that growing pigs metabolize SBM more efficiently than modelled in the past,” says Eric Weaver, SDSU assistant professor.

The researchers hypothesized that distinct populations of bacteria that degrade proteins and fiber from complex carbohydrates will be in higher abundance when pigs are fed with high inclusion diets compared to low inclusion diets.

“The proteins, polysaccharides and oligosaccharides of soybean meal can affect gut health and the microbiome through metabolic pathways that are not yet fully understood,” Angel Martinez, SDSU graduate research assistant, shared during the Allen D. Leman Swine Conference. “A better understanding of the effects of higher soybean meal inclusion compared to low inclusion on the swine gut environment and its microbiome is needed.”

Microbiome Composition
To explore the impact on the fecal bacterial composition and identify candidate gut microbial species, the team collected 14 fecal samples per treatment for DNA extraction and 16S rRNA sequencing via PCR amplification of the V1–V3 regions.