Abstract This project aimed to develop nutritional strategies to reduce pig growth > 50% for 2 to 6 weeks during crisis management. Previously growth was attenuated by 2.0% NH4Cl additions to hold growth (HG) diets. Compensatory growth was evident after withdrawal of NH4Cl. However, tissue composition was not quantified. The HG diets were formulated to reduce lysine, P, and K and increase Cl. Assumptions were that excess Cl interacts with limited K to create an “apparent” K deficiency, which limits protein accretion. The current experiment assessed body composition responses during recovery from HG diets with 2.0% NH4Cl (HGCL) by feeding control (Ctl) diets or Ctl diets fortified with 150% of lysine, P, and K requirements (+Lys+P+K). At 10 kg, 34 barrows were individually housed and randomly assigned to 1 of 4 dietary treatments with free access to assigned diets and water throughout the trial. During the HG phase pigs were fed either Ctl or HGCL diets until 25 kg; 6 weeks for pigs fed HGCl diets. An additional diet was included to validate K and Cl interactions (0.29:1 K:Cl ratio) in growth attenuation. Potassium bicarbonate was added to the HGCl diet (HGCl+K) to restore a 1.26:1 K:Cl ratio. At 25 kg BW, pigs were fed either Ctl or +Lys+P+K diets until 45 kg body weight (BW). Pig, feed weights, and body composition derived from whole-body DXA scans during the hold (HG, 10 to 25 kg) and recovery (Rec, 25 to 45 kg) phases allowed calculations of BW gain, nutrient intake, and measurements of whole-body bone mineral, fat, and lean gain. Growth of pigs fed HGCl diets was reduced (P < 0.01) by approximately 50% compared with Ctl pigs during the HG phase (Table 1). Pigs fed HGCl diets required 23 more days to grow from 10 to 25 kg. Similar reductions (P < 0.01) in bone mineral and lean gain, but not fat gain, were detected in pigs fed HGCl diets during the HG phase. Addition of K to the HGCl diet partially restored gain, bone, and lean gain (P < 0.01). Compensatory responses in weight, bone, fat, and lean gain were evident in HG pigs fed Ctl diets during Rec. Pigs previously fed HGCl diets compensated and only required 14 extra days to reach 45 kg compared with Ctl. Additions of lysine, P, and K allowed greater (P < 0.01) compensation in BW, bone, and lean, but not fat gain over a 20 kg recovery phase. These results confirm a successful strategy to hold pigs during crisis management with potential benefits of compensatory growth and improved body composition during recovery. Whether the improved lean gain was attributed to the additional lysine, P, or K was not determined in this experiment.
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