Some ingredients bind more acid in the stomach than others which can increase gastric pH in weaned pigs causing decreased protein digestion and allow pathogenic micro-organisms to proliferate. Our objective was to measure acid-binding capacity at a pH of 4 (ABC-4) of common nursery ingredients and determine additivity in diets. Ingredient categories included: cereal grains, vegetable proteins, animal proteins and milk, vitamin premixes and minerals, amino acids, and fiber sources. A 0.5 g sample of each ingredient was suspended in 50 mL of distilled deionized water and titrated with 0.1 N hydrochloric acid. Sample ABC-4 was calculated as the amount of acid in milliequivalents (meq) required to lower 1 kg to a pH of 4. Cereal grains were found to have lower ABC-4 compared to other ingredients. Vegetable proteins had higher ABC-4 with more variation than cereal grains. Soybean meal (SBM) had an ABC-4 of 602 ± 28.2 meq. Soy protein concentrate and enzymatically treated soybean meal (ESBM) had higher ABC-4 compared to SBM while fermented soybean meal (FSBM) was lower. Zinc oxide (ZnO) and calcium carbonate (CaCO3) had the highest ABC-4 among all ingredients with values of 21,863 ± 598.7 and 18,384 ± 769.7 meq, respectively. Following ingredient analysis, a series of diets were analyzed to determine additivity by comparing the differences between calculated and analyzed ABC-4 value. All diets analyzed had lower ABC-4 than calculated values; however, analyzed ABC-4 increased along with calculated values across diets. The first series of diets were arranged in a 2 × 5 factorial consisting of increasing CaCO3 with or without ZnO. There was a ZnO × CaCO3 interaction (P = 0.020) for difference between calculated and analyzed ABC-4. Within the interaction, differences between calculated and analyzed ABC-4 increased (linear, P < 0.001) as CaCO3 increased in diets without ZnO, but not in diets with ZnO. The second series of diets analyzed consisted of different levels of SBM with either FSBM or ESBM included at 5% of the diet. Differences between calculated and analyzed values were not different between treatments (P = 0.640). In conclusion, perfect ABC-4 additivity in diets was not found due to lower analyzed than calculated values; however, analyzed ABC-4 still increased as calculated values increased. This data suggests diet ABC-4 can be adjusted through selection of ingredients but more feeding trials are needed to determine its impact on pig performance.

Three experiments were conducted to evaluate fermented corn protein (FCP) in nursery pig diets. The removal of non-fermentable components before fermentation of DDGS results in high protein dried distillers grains (HPDDGs). Fermented corn protein is produced when protein and yeast fraction syrup from ethanol production is added back to HPDDGs resulting in a product with up to 50% CP and 2% Lys. In Exp. 1, 350 barrows, initially 6.0 kg, were used to evaluate FCP as a replacement to enzymatically treated soybean meal. Treatments were arranged in a 2 × 2 + 1 factorial with main effects of specialty protein source (FCP or enzymatically treated soybean meal) and level (5 or 10%) or a control diet without any specialty protein source. There were 5 pigs per pen and 14 replications per treatment. From d 0 to 31, pigs fed enzymatically treated soybean meal had improved (P < 0.05) ADG and feed efficiency (G:F) compared to pigs fed FCP. In Exp. 2, 350 pigs, initially 12.1 kg, were used to determine the effects of FCP with high or low Ile and Val (Ile+Val):Leu ratio on growth performance. Treatments were arranged in a 2 × 2 + 1 factorial with main effects of FCP level (10 or 20%) and Ile+Val:Leu ratio (low or high) in addition to a corn-soybean meal control diet with 5 pigs per pen and 14 replications per treatment. From d 0 to 21, ADG, ADFI, and G:F worsened (linear, P < 0.001) as FCP increased. High Ile+Val:Leu improved (P < 0.05) G:F compared to low Ile+Val:Leu. In Exp. 3, 180 pigs, initially 7.7 kg, were used in a feed intake preference trial evaluating various FCP fractions. A total of 6 diet comparisons with 5 pigs per pen and 6 replications per comparison were used. Corn protein sources and fractions used included: FCP, HPDDGs, whole stillage solids (approximately 2/3 of FCP), and thin stillage solids (approximately 1/3 of FCP), and a control diet. Pigs preferred (P < 0.001) the control diet by consuming 82.5% of their intake compared with a diet containing FCP. There was no difference (P > 0.05) in feed consumption of diets containing whole stillage solids compared to FCP. Pigs preferred (P = 0.001) the diet containing thin stillage solids by consuming 75.8% of their intake with this diet compared to the diet containing FCP. In conclusion, feeding FCP decreased growth performance in nursery pigs, but increasing Ile+Val:Leu improved G:F. Diet preference comparisons suggest that whole stillage solids are the component of FCP that leads to reduced feed intake.

A total of 360 pigs (initially 5.7±0.2 kg) were used to determine the effect of pharmacological levels of Zn and dietary Na concentration on nursey pig growth performance. The experiment compared NRC (2012) and European CVB (2020) Na estimates for this weight range (0.35% and 0.24%, respectively), with or without added Zn from ZnO. At weaning, pigs were randomly allotted to pens (6 pigs/pen) and fed a common diet for 7 d. On d-7 after weaning (d-0 of trial), pigs were assigned to 6 dietary treatments with 10 replications/treatment. Dietary treatments were arranged in a 2×3 factorial with main effects of Zn (0 or 2,000 ppm from ZnO) and Na (0.13, 0.24, or 0.35% from salt). All diets contained 110 ppm of Zn from the trace mineral premix. Following a 14-d experimental period, pigs were fed a common phase 3 diet for 21-d. There were no Zn×Na interactions for ADG or ADFI (P >0.05). From d 0-14, adding dietary ZnO or increasing Na increased (linear, P < 0.05) ADG and ADFI. An interaction for G:F (linear, P = 0.019) was observed where increasing Na up to 0.35% improved G:F when pharmacological levels of Zn were fed, but pigs fed diets without ZnO had a quadratic response (P =0.024) with maximum G:F at 0.24% dietary Na. From d 14-35 and overall, an interaction was observed (linear, P < 0.05) for G:F. Within the interaction, pigs previously fed diets without ZnO observed a linear decrease in G:F as Na level increased (linear, P =0.001), but pigs previously fed diets with ZnO observed no difference in G:F with increasing Na. In summary, increasing dietary Na and the addition of 2,000 ppm Zn from ZnO independently improved daily gain and feed intake in nursery pigs, but an improvement in G:F from increasing Na up to 0.35% was only observed when pharmacological ZnO was present.

Two experiments were conducted to determine if fermented corn protein (FCP) can serve as a replacement to enzymatically treated soybean meal (ESBM) in 6.0 to 15.8 kg or as a replacement for soybean meal in 12.1 to 24.7 kg pig nursery diets. In Exp. 1, 350 barrows (initially 6.0 kg) were randomly allotted to 5 treatments with 5 pigs/pen and 14 replications/treatment. Dietary treatments were arranged in a 2×2 + 1 factorial with a control diet or diets with 5 or 10% FCP or ESBM. Newly weaned pigs were fed phase 1 diets for 10-d followed by phase 2 diets for 21-d. There were no interactions throughout the experiment. Overall (d 0-31), pigs fed increasing FCP had decreased (linear, P ≤ 0.026) ADG and ADFI with no differences in G:F, whereas increasing ESBM had no effect on growth performance (Table). Pigs fed ESBM had increased (P ≤ 0.034) ADG and G:F compared with pigs fed FCP with no effect on ADFI. In Exp 2, 350 pigs (initially 12.1 kg) were randomly assigned to pens with 5 pigs/pen and 14 replications/treatment. On d 24 after weaning (d 0 of trial), pens of pigs were weighed and assigned to 5 dietary treatments. Dietary treatments were arranged in a 2×2 + 1 factorial with a control diet or diets with 10 or 20% FCP with either high or low Val+Ile:Leu ratios. There were no interactions observed throughout the experiment. Overall (d 0-21), ADG, ADFI, and G:F worsened (linear, P < 0.001) as FCP increased. High Val+Ile:Leu ratios improved (P = 0.017) G:F compared with low Val+Ile:Leu ratios with no effect on ADG and ADFI. In summary, using FCP to replace ESBM for nursery pigs weighing 6.0 to 15.8 kg had decreased growth performance. Increasing concentrations of FCP in diets for pigs weighting 12.1 to 24.7 kg worsened growth and increasing Val+Ile:Leu ratios only improved G:F.