| Summary: | 碩士 === 東海大學 === 畜產學系 === 87 === Two experiments were conducted to investigate the influence of dietary betaine supplementation on the growth performance, mortality, blood pH value, blood intracellular and extracellular electrolyte concentration of broilers under high ambient temperature.
In experiment 1 and 2, 120 1-day old Arbor Acres male chicks were allotted to a 2 3 factorial design with 4 replicates of chicks each treatment. Chicks were fed in wire-floored breeder cages in two temperature-controlled chambers, and fed a corn-soybean meal diet supplemented with 0, 0.1% or 0.5% of betaine and exposed to constant high ambient temperature (36℃ at the first day, and decreased 0.2℃/day) or constant moderate ambient temperature (33℃ at the first day, and decreased 0.3℃/day), respectively, for 21 days. Blood samples of chicks were taken at day 21 for pH value, intracellular and extracellular electrolyte concentration. The growth performance were measured at day 7, 14 and 21. The results of experiment 1 and 2 showed that broilers exposed to high ambient temperature decreased (P<0.01) weight gain and feed intake, increased (P<0.01) gain/feed and mortality. Dietary betaine supplementation did not (P>0.05) affect weight gain, but increased (P<0.01) gain/feed due to feed intake decreased (P<0.05). There was no influence of broilers exposed to high ambient temperature and dietary betaine supplementation on blood pH value. High ambient temperature increased (P<0.01) extracellular sodium and chloride concentration, and increased (P<0.01) intracellular potassium and decreased (P<0.05) chloride concentration of broilers. Dietary betaine supplementation did not affect intracellular and extracellular electrolyte concentration.
In conclusion, supplementing betaine in diets had no effect on weight gain, but decreased feed intake and improved feed efficiency of broilers under both high and moderate ambient temperatures indicating that betaine supplementation did not affect the heat tolerance of broilers.
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