Influence of varying sources of dietary electrolytes on the performance of broilers reared in a high temperature environment

Experiment using 297 broiler chicks, kept from 1 to 42 days under cyclic heat stress (minimum 29.3 degrees C and maximum 38 degrees C), was conducted to investigate the relative efficacies of three sodium (NaHCO3, Na2CO3, Na2SO4), and potassium (KHCO3, K2CO3, K2SO4) supplements at an identical dietary electrolyte balance (DEB) 250 mEq/kg and two chloride supplements (CaCl2 and NH4Cl) at DEB 50 mEq/kg. The desired levels of DEB were achieved by substitution of individual mineral supplement at the expense to builder's sand in the basal starter (DEB 185.6 mEq/kg) and finisher (DEB 174 mEq/kg) diet containing only salt as a source of Na and Cl. Each diet (one basal and eight experimental) was fed to three experimental units having 11 chicks each. The growth performances in K supplements, except KHCO3, were poorer than those of Na supplements. The NaHCO3, Na2CO3, Na2SO4 and NH4Cl increased body weight gain, feed intake and improved feed to gain ratio than those of K2CO3 and K2SO4 after 42 days of age. These supplements also increased the water intake and resulted in lowered body temperature as well as reduced mortality. Very poor performance in CaCl2 supplement was associated with disturbed calcium: phosphorus and very low blood pH (7.19). Better performance was noted with bicarbonate than that with carbonate and sulfate sources. The KHCO3 accentuate the respiratory alkalosis by increasing blood HCO3 contents (26.09 mmol/l) and gave poorer performance than NaHCO3. Blood lymphocytes, hemoglobin, hematocrit and electrolyte balance in heat stressed broilers were better improved by NH4Cl, NaHCO3, NaCO3, Na2SO4 and KHCO3 than those of CaCl2, K2CO3 and K2SO4 Supplements. Present findings emphasized the importance of considering metabolisable anions supplemented in association with cations while balancing the dietary electrolyte equations. That is why DEB equation cannot be used to predict the relative benefits of different mineral supplements. (c) 2005 Elsevier B.V. All rights reserved.