PSXIV-20 Potassium Carbonate Rescues Growth and Bone Attenuation Responses to Ammonium Chloride in Feed for Growing Pigs, Supporting the Importance of the K:Cl Ratio in Diet Formulations

Abstract

Abstract Addition of 2% NH4Cl to feed effectively attenuated growth of pigs fed a diet specifically formulated with reduced lysine, phosphorus, and potassium (HG). The reduction in K was intended to minimize the amount of NH4Cl required to attenuate growth, as the K:Cl ratio affects growth. The objective was to validate the importance of the K:Cl ratio in HG diets supplemented with 2.0% NH4Cl. The K:Cl ratio hypothesis assumes that excess Cl from NH4Cl supplements interacts with K to create an apparent K deficiency, as renal K excretion must increase to counterbalance excess Cl under restraints imposed by HG diets. Additions of K should rescue growth of pigs fed diets with 2% NH4Cl. After adjustment to individual pens, 18 F2 barrows (12-15 kg) were randomly assigned to 1 of 4 diets: Control standard diet (Ctl, n=4); basal HG, low K diet, no added NH4Cl (HG, n=4); HG+2% NH4Cl for growth-attenuation (2%NH4Cl, n=5); and HG+2%NH4Cl+K2CO3 to counter-balance excess Cl from NH4Cl (2%NH4Cl+K, n=5). Pigs were allowed free access to fresh water and assigned diets for 14 days. Daily pig weights and feed consumption, end of treatment urine electrolytes, and whole-body DXA scans were used to calculate gain, intake, body composition, and efficiency of Ca and P retention. Gain (74%); lean (72%); bone ash (58%); Ca (27%); and P (32%) efficiency traits were reduced (P< 0.05) in pigs fed 2%NH4Cl vs. Ctl. Addition of K to NH4Cl diets partly rescued responses of these traits, restoring responses to that of pigs fed the HG diet. Inferences from urine electrolyte concentrations were consistent with K allowing an increase clearance of excess Cl. In conclusion, NH4Cl attenuation of growth and bone ash responses were mediated by K X Cl interactions. Future experiments will focus on diet modifications to enhance body composition during recovery.