Evaluation of fermented corn protein and its effects in either high or low branch chain amino acid to leucine ratio diets on nursery pig performance and feed intake preference.

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 ( < 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,  < 0.001) as FCP increased. High Ile + Val:Leu improved ( < 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 ( < 0.001) the control diet by consuming 82.5% of their intake compared with a diet containing FCP. There was no difference ( > 0.05) in feed consumption of diets containing whole stillage solids compared to FCP. Pigs preferred ( = 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.