A high dietary electrolyte balance reduces growth performance and CP and Zn total tract apparent digestibility in weanling piglets

Abstract Text: It is generally accepted that dietary electrolyte balance (dEB, Na + K – Cl, in mEq/kg diet) influences feed intake and growth performance of pigs. However, there is a not clear optimal recommendation for piglets. The objective of this study was to assess the effect of diets differing in the mineral source and dEB on feed intake, total tract apparent digestibility and growth of weanling pigs. A total of 240 piglets (21 days after weaning, initial BW 13.4 ± 1.17 kg) were blocked by BW into 3 blocks (heavy, middle and light), and then distributed into 8 pens per block (10 pigs/pen) and randomly assigned to one of four experimental diets differing in the dEB level: 16 and 133 mEq/kg diets (VL, L), based on the incorporation of calcium chloride (3.6 g/kg); and 152 and 269 mEq/kg diets (H, VH), based on the addition of calcium carbonate (10.6 g/kg), without or with sodium bicarbonate (10 g/kg), respectively. Titanium dioxide (3 g/kg) was used as indigestible marker. The diets were offered for 16 days when performance was evaluated. One fecal sample was collected per pen on day 7 to measure whole-tract digestibility, and five venous blood samples per treatment were collected on day 12 to measure acid-base status of animals. Piglets fed VL and L diets reached higher BW on day 16 (19.01 kg and 19.46 kg, respectively) than did piglets fed VH diet (17.05 kg, P < 0.05). Diet L also promoted a lower (P < 0.05) feed:gain ratio (2.10) and a higher (P < 0.05) digestibility of the CP (74.6%) and Zn (13.0%) than did diet VH (3.23, 68.2% and 1.1%, respectively). The VL diet reduced blood TCO2, bicarbonate and base excess values, as compared with L, H and VH diets (P< 0.01), reflecting the acidogenic nature of that diet. In conclusion, the results show that a high dEB diet (269 mEq/kg) may reduce piglets’ performance and the total tract digestibility of nutrients, possibly associated to its higher acid-binding capacity (427 mEq/kg).

Keywords: dietary electrolyte balance, digestibility, growth performance