By Joseph Halbur, Robert Thaler, Ryan Samuel and Eric Weaver, South Dakota State University

The swine industry is no stranger to the use of soybean meal and soy hulls in swine diets. In fact, SBM is a staple, high-value protein source used in swine diet formulations. However, increasing availability of lower cost alternatives such as distillers dried grains with solubles and synthetic amino acids has reduced the use of SBM over time. As we look to the future of a higher soybean crush, SBM and SH at lower relative prices have the potential to return to higher levels of use in common swine diets.

The increasing demand for renewable fuels has driven expansions of current soy processing and renewable bio-diesel facilities. A rapidly expanding United States soybean crush market, stemming from facility renovations and new construction, will change the global supply and economics of soybeans and soybean processing co-products. At the same time China proclaimed a policy for reducing SBM in their swine diets. This proclamation is likely due to the uncertainty around global supply of whole beans from an increase in United States crush capacity. If projections hold true, there will be as much as 8.5 MMT of additional SBM for domestic use. This increased availability of U.S. SBM might justify a greater use in swine diets locally and globally. In fact, several scenarios could lead to the increased need to use more SBM and SH in swine diets.

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Swine diets containing DDGS and synthetic AA are often less expensive than current diets with SBM in the Midwest. Therefore, a holistic assessment of the impact of increased soybean product supply and utilization in swine diets has become an important objective of our research efforts. In particular, we want to focus on how SBM and SH could be used as an economical replacement for DDGS and its effects on growth performance and feeding efficiency in pigs at various stages of growth.

A research trial on wean-to-market pigs was conducted to evaluate the replacement of DDGS with SBM and SH at various inclusion rates and its effects on performance. A total of 566 PIC and Terminal Duroc cross pigs born at South Dakota State University were used in this study. The trial began three weeks post weaning with an average body weight of 17.4 pounds. The pigs were assigned to treatments over two rooms of partially slatted floor, environmentally controlled rooms at SDSU facilities. Individual pig BW was measured along with average daily feed intake every two weeks for the first 12 weeks and every three weeks for the last six weeks.

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The four dietary treatments consisted of formulations designed to value SBM and SH in place of DDGS. Two diets were formulated with DDGS, and two diets were formulated with SBM and SH to replace DDGS levels of 20% and 40% of the diet at comparable levels. DDGS levels were reduced in the final phase to 12 and 6% for high and low, respectively, to reduce carcass iodine values at harvest. All diets were formulated to meet or exceed National Research Council levels. Standardized ileal digestible lysine levels were kept consistent across the four diet regimens. Net energy levels were allowed to decrease in High DDGS or High SBM/SH diets with each phase. Significantly more synthetic AA were added to the DDGS diets to reach required SID AA levels and to lower crude protein in the diet. NE estimates for SBM in formulations were 1134 kcal/lb (94% of corn) and for DDGS were 1062 kcal/lb (88% of corn; NRC, 6-8% oil). The four dietary regimens were allotted to 40 pens (20 pens/room, 5 pens/diet/room) with 14 pigs per pen in a randomized complete block design.

The outcomes of this trial were separated into four timeframes; weeks 0 through 6 (nursery phase), weeks 6 through 15 (grower phase), weeks 15 through 18 (finisher phase) and wean-to-market (overall data). From week 0 to week 6, feed conversion improved in pigs fed high SBM diets relative to high DDGS diets (P < 0.05). In the grower phase, the high DDGS diet significantly increased feed-to-gain compared to the SBM diets (P < 0.05). During the finisher phase, both high and low DDGS diets significantly increased ADFI when compared to SBM diets (P < 0.05). Average daily gain and final body weights were unaffected by treatment for all phases of growth (P > 0.10). For wean-to-market, F:G was significantly higher for the high and low DDGS diets compared to the high and low SBM diets (P < 0.05). ADFI was significantly higher in the High DDGS diet than in the high and low SBM diets (P < 0.05) and tended to be greater than the low DDGS diet (P < 0.10).

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Diets containing SBM and SH improved feed conversion by 6% when compared to diets with DDGS from wean-to-market. The significant difference in feed conversion could be due in part to the need for a higher NE level in both SBM and SH. The inclusion of SH to increase fiber levels, similar to the level associated with DDGS inclusion, did not reduce performance. The higher quality protein and the utilization of intact SBM protein compared to DDGS with higher synthetic AA supplementation improves performance at similar dietary crude protein levels.

ab: Differences denoted if P<0.05

Implications:

The use of SBM and SH in swine diets improved feed efficiency compared to diets containing equivalent levels of DDGS. SBM and SH have a higher relative feeding value compared to DDGS in swine diets probably due to higher NE values and improve protein utilization. For SBM and SH to be used as a viable option for replacement of DDGS, economic predictions for a lower cost of SBM and SH must hold true to offset differences in the total diet cost of DDGS with synthetic AA. Current ingredient profiles and the significant difference in performance of SBM and hulls relative to DDGS with synthetic AA supplementation need to be accounted for when formulating swine diets for highest returns.

Appreciation is expressed to Minnesota Soybean Research and Promotion Council for financial support.