The extrusion-expelling process results in a soybean meal with a greater fat content compared to conventionally processed soybean meal. This has the potential to improve growth performance in finishing pigs. With current and future projected soybean meal pricing, producers may have an opportunity to lower feed costs with the use of extruded-expelled soybean meal.

Acidifiers, such as benzoic acid, lower the pH of the gastrointestinal tract. The reduction in pH can potentially lead to improved nutrient digestion and growth performance. There is currently little research to demonstrate and understand the effects of benzoic acid on growth performance in finishing pigs under a commercial setting. Therefore, the objective of this trial was to evaluate the effects of extruded-expelled soybean meal compared to conventional SBM with or without benzoic acid on growth performance, carcass characteristics, and carcass fat iodine value.

Procedures
A total of 2,162 pigs (PIC 1050 × DNA 600; initially 69.2 ± 4.9 lb) were used in a 109-day finishing trial. There were 27 or 28 pigs per pen and 20 pens per treatment. On d 0, pens were blocked by location in the barn and randomly allotted to one of four dietary treatments. A similar number of barrows and gilts were placed in each pen.

Dietary treatments were arranged in a 2 × 2 factorial with main effects of soybean meal source and benzoic acid. Diets contained either conventional soybean meal or extruded-expelled soybean meal (EESBM; 43.2% crude protein and 7.7% crude fat; Lester Feed and Grain, Lester Iowa) with or without the inclusion of VevoVitall (DSM Products; Parsippany, New Jersey), a source of benzoic acid added at 0.25%. Each pen (22.4 × 8.3 ft) contained 1 nipple waterer and a 4-hole dry self-feeder to allow for ad libitum access to feed and water. Pigs were allowed approximately 6.9 ft²/pig.

On d 88 and 96, eight of the heaviest pigs per pen were weighed individually and transported to a commercial packing plant (WholeStone Farms, Fremont, Nebraska) for processing and determination of carcass characteristics. The remaining pigs were marketed at the conclusion of this trial on d 109 and transported to WholeStone Farms for carcass characteristic collection. A fat sample was taken from the belly from one barrow per pen per marketing event and included all three layers of fat. Analysis of iodine value was conducted using near-infrared spectroscopy at WholeStone Farms.

Diet preparation
Experimental diets were fed in six different phases. The metabolizable energy of conventional SBM was assumed at 1,309 kcal/lb and ME value for EESBM was assumed at 1,650 kcal/lb. Lysine hydrochloride was formulated to remain very similar across all treatments within phase to allow the SBM source to be used to help balance the dietary standardized ileal digestible lysine level. All diets were corn-soybean meal-based and were fed in meal form.

Economic analysis
For economic analysis, gain per pig placed, total feed cost per pig, revenue and income over feed cost were calculated using four different low and high revenue and feed cost scenarios. Feed cost per pound of gain was calculated by dividing feed cost per pig by the total weight gained using a low and high feed cost scenario. Revenue per pig placed was determined by total gain times the dressing percentage (0.75) and then multiplied by a carcass price of $0.55 for the low revenue scenario and $0.95 for the high scenario. Income over feed cost was calculated by using the low or high revenue per pig placed minus the low or high feed cost per pig placed.

The following ingredient costs were used for the low cost scenario: corn = $3.36/bu ($120/ton); soybean meal = $280/ton; EESBM = $340/ton; DDGS = $160/ton and benzoic acid = $1.15/lb. For the high cost scenario, the following ingredient costs were used: corn = $6.72/bu ($240/ton); soybean meal = $420/ton; EESBM = $500/ton; DDGS = $260/ton and benzoic acid = $1.15/lb.

Results and discussion
There were no interactions between soybean meal source and benzoic acid for any growth response criteria. Thus, only main effects will be discussed. From d 0 to 51, pigs fed EESBM had greater ADFI and improved F/G compared to pigs fed conventional SBM (Table 1). There was no effect of soybean meal source on ADG. Pigs fed diets without benzoic acid had greater ADG and ADFI compared to pigs fed diets containing benzoic acid. Pigs that were fed diets containing benzoic acid had improved F/G compared to pigs fed diets without benzoic acid.

From d 51 to 109, pigs fed conventional SBM had greater ADFI compared to pigs that were fed EESBM. Pigs fed EESBM had improved F/G compared to pigs fed conventional SBM. There was a tendency for an increase in ADG in pigs fed diets containing benzoic acid compared to pigs fed diets without benzoic acid. There were no main effects for benzoic acid on ADFI or F/G during this period.

Overall (d 0 to 109), pigs fed conventional SBM had greater ADFI compared to pigs fed EESBM without influencing ADG. Therefore, pigs fed EESBM had improved F/G compared to pigs fed conventional SBM. Also, pigs fed diets without benzoic acid had greaterADFI compared to pigs fed diets that contained benzoic acid without influencing ADG. As a result, pigs fed benzoic acid had improved F/G compared to pigs fed diets without benzoic acid.

There were no main effects for soybean meal source or benzoic acid on removals, mortality, or total removals and mortality for the duration of the study (Table 1).

When evaluating caloric efficiency, pigs fed diets containing benzoic acid had improved caloric efficiency compared to pigs fed diets without benzoic acid with no differences between soybean meal sources. This suggests that our initial estimate of ME for the EESBM was accurate. For carcass characteristics, pigs fed EESBM had increased carcass fat iodine value. Benzoic acid did not influence carcass fat iodine value.

For economics, there was a main effect of soybean meal source where pigs fed EESBM had a higher feed cost per pig placed in the low and high feed cost scenarios. There were no differences in revenue per pig placed in the low or high revenue scenarios regardless of soybean meal source or the inclusion of benzoic acid. Pigs fed conventional SBM had a higher IOFC compared to pigs fed EESBM in the high feed cost, high revenue; high feed cost, low revenue; and low feed cost, low revenue scenarios. It is recommended that producers utilize their own current ingredient prices to economically compare these dietary options.

In conclusion, replacing conventional SBM with EESBM improved feed efficiency but due to increased feed cost without influencing gain, it was less economical as measured by IOFC. Also, the addition of benzoic acid improved finishing pig feed efficiency but did not improve IOFC.

Funding, wholly or in part, was provided by the National Pork Board.

Source: Jenna Bromm, Joel DeRouchey, Mike Tokach, Jason Woodworth, Robert Goodband, Jordan Gebhardt, Kiah Berg, Jon De Jong and Courtney Pohlen, who are solely responsible for the information provided, and wholly owns the information. Informa Business Media and all its subsidiaries are not responsible for any of the content contained in this information asset.