(P26-042-25) Soybean Isoflavone Daidzein as a Potential Functional Feed Additive to Enhance Pig Health

Objectives: Soybean isoflavones have been proposed as an alternative to in-feed growth promoting antibiotics used in livestock operations. The current information on the role of isoflavones in improving pig’s growth and health is scarce, and there are conflicting reports. Many of the previous studies use an isoflavone-mix as a diet supplement. Aiming at minimizing putative confounding effects from varying bioactivity of different isoflavones in a mixture, we used a single soybean isoflavone, daidzein, to supplement pigs’ diets and isolate physiological effects of this isoflavone.

Methods: Weaned pigs (twenty-one-days old, N = 36) were fed one of three diets containing different levels of daidzein: a low isoflavone corn-soybean protein concentrate diet (0 ppm), and the same diet supplemented with either 50 ppm or 150 ppm daidzein. Body composition was evaluated using dual-energy x-ray absorptiometry (DXA) before sacrificing the pigs on day 28.

Results: After 28 days, pigs fed the 0 ppm daidzein diet showed higher body weight and fractional body weight compared with pigs fed the daidzein supplemented diets (P < 0.05). Body composition was similar among groups. Feed intake was less for pigs fed the 150 ppm daidzein diet compared with those fed the 0 and 50 ppm (P < 0.0001). However, feed efficiency was greater for pigs fed the 50 ppm daidzein diet compared with pigs fed the 0 and 150 ppm diets (P < 0.001).

Conclusions: In this study, supplementation with an isolated isoflavone, daidzein, showed a negative effect on piglet growth. Daidzein supplementation at 50 ppm increased feed efficiency but had a negative effect on weight gain. Although feed efficiency was not different from the 0 ppm group, the lower weight gain and concomitant reduction in feed intake in the group supplemented with 150 ppm daidzein suggest that there are issues related to palatability or toxicity at this level of supplementation. Our findings indicated a dose-dependent relationship between daidzein, growth and nutrient utilization.

Funding Sources: This work was partially funded by the United Soybean Board. This abstract contains interim findings from the research and has not received formal peer review or been published.