Effects of adding potassium bicarbonate to diets with high or low crystalline lysine to influence dietary cation-anion difference on finishing pig growth performance.

Dietary cation-anion difference (DCAD), calculated as Na+ + K+ - Cl- in mEq/kg of the diet, represents the influence that monovalent cations and anions from these minerals have on the acid-base status of the animal. However, the recommended range of DCAD for optimal grow-finish swine performance is variable, which may indicate an interaction between DCAD and other ingredients. The hypothesis for this study was that the addition of potassium bicarbonate (KHCO3) to increase diet DCAD when high levels of l-Lys HCl (>0.35% diet) are used may potentially improve growth performance. A total of 1,944 pigs (PIC L337 × 1050, initially 35.2 ± 0.85 kg) were used in a 120-d study. Pens of pigs were blocked by BW and randomly allotted to 1 of 4 dietary treatments in a randomized complete block design. Treatments were arranged in a 2 × 2 factorial with main effects of KHCO3 (0% or 0.4%), and l-Lys HCl level (low or high). l-Lys HCl was included between 0.13% and 0.21% in low diets, and between 0.36% and 0.43% in high diets. There were 27 pigs per pen and 18 replicates per treatment. Treatment diets were corn-soybean meal-based and formulated in four dietary phases (35-60 kg, 60-85 kg, 85-105 kg, and 105-130 kg). Dietary treatments were formulated such that in each phase the diet containing a low level of l-Lys HCl without KHCO3 and the diet containing a high level of l-Lys HCl with KHCO3 had similar calculated DCAD values (169-232 mEq/kg). Additionally, the diet with a low level of l-Lys HCl with KHCO3 was formulated to have the highest DCAD in each phase (220-281 mEq/kg), while the diet with a high level of l-Lys HCl without KHCO3 was formulated to have the lowest DCAD (118-182 mEq/kg). Overall, there was no evidence (P > 0.10) for a KHCO3 × l-Lys HCl interaction or main effect for final BW or any observed growth response or carcass characteristics. The results of this study suggest that supplementing KHCO3 to finishing pig diets with either high or low levels of l-Lys HCl and the corresponding changes in DCAD values did not impact growth performance or carcass characteristics. Published by Oxford University Press for the American Society of Animal Science 2022.