Efficacy of potassium bicarbonate for prevention of fatigue in market pigs

Blotchy skin, labored breathing, vocal distress and muscle tremors are signs of exhaustion in pigs. Severely exhausted pigs may progress to fatigued pigs (downers) that refuse to move and exhibit metabolic acidosis. A 2×2 factorial design was used to evaluate the efficacy of KHCO₃ supplementation for prevention of acidosis. Following a 48 h water restriction, pigs (n=48, ~115 kg, 12 pigs/trial) were allowed 16 h access to either alkaline (ALK, 30.2 g KHCO₃/L) or water (W) treatments. After 16 h, randomly selected pigs were either handled gently (GE, n=4/trial) or aggressively (AG, n=8/trial). AG pigs were moved through a 293 m course including intentional chute restriction 4X and a minimum of 8 shocks from an electrical prod. GE pigs were moved the same distance with a hurdle board, without chute restriction or electrical prod stimulation. Immediately after handling a venous blood sample was collected.

Blood gas values (pH, base excess, HCO₃) were reduced (P < 0.05) in AG vs GE pigs; whereas electrolytes, anion gap (K+Na-Cl- HCO₃), hematocrit, NH4; and lactate concentrations were increased (P < 0.05). Thus, AG induced acidosis. However, ALK treatment of AG pigs was not sufficient to overcome acidosis induced by handling; as these pigs had increased lactate, NH4 and anion gap (P < 0.05) compared to AG handled W pigs. In contrast ALK treatment of GE pigs increased base excess but decreased lactate and anion gap compared to GE handled W pigs. ALK treatment had no detectable effects on carcass quality. However, AG handling increased redness of loin chops (P < 0.05).

In conclusion, KHCO₃ provided at 30.2 g/L did not prevent acidosis induced by aggressive handling of market pigs.