PSV-1 - Addition of Ammonium Chloride to Feed Is an Effective Strategy to Attenuate Growth in 25-kg Pigs

Abstract: In response to production challenges, after slaughter plant closures in 2020, growing pigs were fed standard diets plus 2% ammonium chloride (NH₄Cl) to attenuate growth and reduce housing issues. Initially, no growth suppression was observed, however after diet modifications to reduce nutrient concentrations (HG diets), growth of 65 kg pigs was suppressed 90% over the first week. Pigs became refractory after the first week and averaged 50% growth reduction over 3 weeks. The current experiment objective was to evaluate use of NH4Cl as a nutritional strategy to maintain pigs (3 to 6 weeks) at essentially no growth during crisis management. Nine F₂ barrows (24.2 kg), were fed standard diets for a 9-d pre-trial phase to establish baseline traits. Afterwards, HG diets with 1.25, 2.00, or 2.75% NH₄Cl were fed for a 21-d treatment phase then fed control diets for an 11-d recovery phase. Pig weights and feed consumption were measured at various intervals. Additionally, whole-body bone mineral content (BMC), bone mineral density (BMD), and urine cation-anion profiles were determined to assess bone mineralization and physiological adaptation to NH₄Cl. Compared with gain during the pre-trial phase, gain was reduced by 0, 39, and 98% for pigs fed 1.25, 2.0 and 2.75% NH₄Cl. During an 11-d recovery, pigs gained 73.4, 118.5 and 154.1% more than baseline responses. Feed intake reflected similar responses as gain. Likewise, urine concentrations of Cl, NH₄, K, and H responded to dietary treatments, however recovery to baseline values were not complete until day 3 of recovery. Based on limited observations for DXA scans, BMC appeared to be reduced by dietary treatment, but differences were not evident in BMD, likely a reflection of reduced growth. These results are consistent with the effectiveness of NH₄Cl as a strategy to attenuate pig growth during a crisis, “stop-shipment” event.