Reduced dietary electrolyte balance affects growth performance and fecal odor compounds in growing pigs

Dietary electrolyte balance (dEB), which influences growth performance, has recently been suggested as a cost-effective acidification strategy for odor mitigation in swine production, yet its effects on fecal volatile fatty acids and volatile organic compounds remain poorly understood. This study was conducted to investigate the effect of dietary electrolyte balance (dEB) on growth performance and fecal odor-related compounds of growing pigs.

A total of 90 crossbred barrows (34.1 ± 2.97 kg) were allocated to three treatments with six replicate pens using a randomized complete block design. The experimental diets were formulated to replace limestone with calcium chloride at 0%, 50%, and 100% to set dEB at 159, 80, and 1 mEq/kg. The pigs were housed for five weeks in an environmentally controlled room and had free access to water and diets. Data were analyzed using the MIXED procedure of SAS, and linear and quadratic effects were evaluated using orthogonal polynomial contrasts (p < 0.05).

At 3 and 5 weeks, body weight decreased linearly as dEB levels decreased (p = 0.017, p = 0.021). Average daily gain tended to decrease linearly as dEB decreased from 0 to 3 weeks (p = 0.077) and 0 to 5 weeks (p = 0.059). Average daily feed intake decreased linearly (p = 0.002) from 3 to 5 weeks and showed a quadratic response (p = 0.029) from 0 to 5 weeks as dEB decreased. Gain-to-feed ratio exhibited a quadratic response to decreasing dEB from 0 to 3 weeks (p = 0.001) and 0 to 5 weeks (p < 0.001). Decreasing dEB tended to reduce fecal p-cresol (p = 0.086) and skatole (p = 0.073) concentrations, whereas volatile fatty acid concentrations were not affected.

Moderate dEB reduction may influence fecal odor-related compounds, but excessive reduction may compromise growth performance.