Different responses of broilers at low, high, or cyclic moderate-high temperatures to dietary sodium bicarbonate supplementation due to differences in dietary formulation

An experiment was carried out to study the interaction of dietary sodium bicarbonate (NaHCO3) supplementation with two different practical dietary formulations on the performance of 3-6-week-old broilers maintained in constant low (20 degreesC), constant high (31 degreesC), or diurnal cyclic moderate-high (25 degrees -35 degreesC) temperature regimens. Dietary formulations using typical Australian feed ingredients and varying in protein sources were used with one diet containing only animal-source protein ingredients (Diet 1) and the other diet containing predominantly plant-source protein ingredients (Diet 2). Feed intake and bodyweight gain (BWG) of broilers exposed to constant high or diurnal cyclic temperature regimens were similar and significantly poorer than those of broilers exposed to low temperatures. Dietary supplementation with NaHCO3 had no significant overall effect on production parameters but significant NaHCO3 x temperature and NaHCO3 x diet interactions were observed for BWG. Sodium bicarbonate improved BWG at constant 31 degreesC, but not at constant 20 degreesC, or in the diurnal cyclic temperature regimen. Sodium bicarbonate significantly improved BWG with Diet 2 (plant-source proteins), which contained an arginine : lysine ratio of 1.31 but not with Diet 1 (animal-source proteins), which contained an arginine : lysine ratio of 1.01.