Sayed M A M, Downing J
The Faculty of Veterinary Science, University of Sydney, Camden, New South Wales 2570, Australia.
Poult Sci. 2011 Jan;90(1):157-67. doi: 10.3382/ps.2009-00594.
Exposing broilers to a high temperature increases water and electrolyte K(+) and Na(+) excretion, which negatively affects the heat dissipation capacity and acid-base homeostasis, resulting in losses in growth performance. In this experiment, the efficacy of providing oral rehydration therapy and betaine on growth performance, acid-base balance, and water and electrolyte retention was evaluated. A total of 432 one-day-old broiler chicks (Cobb) were allocated to 72 metabolic cages and reared to 31 d of age under standard conditions. From 32 to 41 d of age, chicks were exposed to heat stress (ambient temperature, 32°C) and high RH (80 to 100% RH) for 9 h daily. The ameliorative effects of a 3 × 3 factorial array of treatments administered via drinking water were evaluated in 8 replicates of 6 chicks per cage for each treatment. Two oral rehydration therapy (ORT) fluids, based on either citrate or bicarbonate salts, were added to tap water. In addition, betaine was added to tap water at an inclusion rate of 0, 500, or 1,000 mg/L to complete the array of 9 liquid-based treatments. Growth performance was assessed at 32, 35, and 41 d of age. From 32 to 35 d of age, chicks receiving ORT fluids exhibited improved growth performance, water balance, and electrolyte (K(+), Na(+)) retention. In addition, the physiological response to stress was attenuated, as indicated by lower heterophil-to-lymphocyte ratios and blood glucose concentrations relative to the negative controls. The addition of betaine at an inclusion rate of 500 mg/L improved BW gain. From d 36 to 41, treatments did not significantly influence growth performance, which suggests that chicks receiving tap water were able to compensate and adapt to the heat-stress conditions. The results demonstrate that the beneficial effects of providing ORT fluids and 500 mg of betaine/L were observed only during the first 4 d of heat exposure. After this period, adaptation to the heat appears to occur, and none of the treatments was successful in improving growth performance.
将肉鸡暴露于高温环境会增加水和电解质钾（K⁺）及钠（Na⁺）的排泄，这对散热能力和酸碱平衡产生负面影响，进而导致生长性能下降。在本实验中，评估了提供口服补液疗法和甜菜碱对生长性能、酸碱平衡以及水和电解质潴留的效果。总共432只1日龄的肉鸡雏鸡（科宝品种）被分配到72个代谢笼中，并在标准条件下饲养至31日龄。从32至41日龄，雏鸡每天暴露于热应激（环境温度32°C）和高湿度（相对湿度80%至100%）环境9小时。通过饮水给予的3×3析因处理阵列的改善效果，在每个处理每组6只雏鸡的8个重复中进行评估。将两种基于柠檬酸盐或碳酸氢盐的口服补液疗法（ORT）液体添加到自来水中。此外，以0、500或1000毫克/升的添加比例将甜菜碱添加到自来水中，以完成9种基于液体处理的阵列。在32、35和41日龄时评估生长性能。从32至35日龄，接受ORT液体的雏鸡生长性能、水平衡和电解质（K⁺ , Na⁺）潴留得到改善。此外，应激的生理反应减弱，相对于阴性对照，异嗜性粒细胞与淋巴细胞比率和血糖浓度较低表明了这一点。添加500毫克/升的甜菜碱提高了体重增加。从36至41日龄，处理对生长性能没有显著影响，这表明饮用自来水的雏鸡能够补偿并适应热应激条件。结果表明，仅在热暴露的前4天观察到提供ORT液体和500毫克/升甜菜碱的有益效果。在此之后，似乎发生了对热的适应，并且没有一种处理能够成功改善生长性能。
