Peterson A L, Qureshi M A, Ferket P R, Fuller J C
Department of Poultry Science, North Carolina State University, Raleigh 27695-7608, USA.
Immunopharmacol Immunotoxicol. 1999 May;21(2):307-30. doi: 10.3109/08923979909052765.
As a dietary supplement, beta-Hydroxy-beta-Methylbutyrate (HMB), a catabolite of leucine, has been shown to reduce broiler mortality. In a series of experiments, male broilers (Experiments 1 and 2, n = 576) were grown for 21 days on diets that contained HMB at 0, 0.01. 0.05, and 0.10% of diet. In Experiment 3 (n = 240), chicks were fed diets containing 0, 0.05, 0.075, and 0.10% HMB. HMB dietary supplementation did not significantly affect broiler weight gain in any experiment. However, a trend toward increased mean broiler weight gain per bird was observed in Experiments 1 and 3 when HMB was consumed at 0.10% of the diet. Mean feed to gain ratio was not affected by the inclusion of HMB in broiler diets. In Experiment 3, HMB supplemented diets did not affect bursa of Fabricius, thymus, and spleen weights at 21 days of age. Cutaneous basophilic hypersensitivity response against pokeweek mitogen was higher (P < or = 0.05) at 48 and 72 hours post-injection in chicks on 0.05% dietary HMB (Experiment 1). In Experiment 2, this increase occurred 24 hours post-injection in chicks fed HMB at 0.01% of the diet. On the contrary, the T-cell mediated response against PHA-P mitogen was comparable between all dietary treatments in multiple experiments. Macrophage function profiles were determined at 21 days of age. All chicks in experiments 1 and 2 on HMB supplemented diets showed an increase in the recruitment of Sephadex-G50-elicited abdominal exudate cells (AEC). A 2-fold increase in AEC numbers occurred at the 0.10% HMB level (Experiment 1, P < or = 0.05). Although HMB supplementation did not significantly affect the phagocytic potential of the abdominal macrophages, nitrite levels in the macrophage culture supernatants were higher in 0.01% and 0.05% treatment groups as compared to the controls (Experiment 2, P < or = 0.04; Experiment 3, P < or = 0.05). HMB supplementation did not alter the bird's ability to clear Escherichiacoli or Salmonella arizona from the bloodstream. Beginning 7 days post-hatch, chicks were injected i.v. with a 7% sheep red blood cells suspension. Serum samples were collected to determine the primary and secondary antibody response. Chicks receiving the 0.1% HMB diet in Experiments 1 and 2 exhibited increased IgG and total anti-sheep red blood cell (SRBC) antibody levels during the primary response. During the secondary response, birds consuming the 0.10% HMB diet had elevated IgM levels as well as increased total anti-SRBC levels over the controls in Experiments 1 and 3. These studies show that HMB supplementation improves several immunological functions in young broilers, and such improvement may result in decreased mortality.
作为一种膳食补充剂，β-羟基-β-甲基丁酸酯（HMB）是亮氨酸的一种分解代谢产物，已被证明可降低肉鸡死亡率。在一系列实验中，雄性肉鸡（实验1和2，n = 576）在含有0、0.01%、0.05%和0.10% HMB的日粮中饲养21天。在实验3（n = 240）中，雏鸡饲喂含有0、0.05%、0.075%和0.10% HMB的日粮。在任何实验中，日粮添加HMB均未显著影响肉鸡体重增加。然而，在实验1和3中，当日粮中HMB含量为0.10%时，观察到每只肉鸡平均体重增加有增加的趋势。日粮中添加HMB对肉鸡的料重比没有影响。在实验3中，添加HMB的日粮在21日龄时对法氏囊、胸腺和脾脏重量没有影响。在实验1中，日粮中HMB含量为0.05%的雏鸡在注射商陆有丝分裂原后48小时和72小时，皮肤嗜碱性超敏反应更高（P≤0.05）。在实验2中，日粮中HMB含量为0.01%的雏鸡在注射后24小时出现这种增加。相反，在多个实验中，所有日粮处理组对PHA-P有丝分裂原的T细胞介导反应相当。在21日龄时测定巨噬细胞功能概况。实验1和2中所有添加HMB日粮的雏鸡，葡聚糖凝胶G-50诱导的腹腔渗出细胞（AEC）募集增加。在HMB含量为0.10%时，AEC数量增加了2倍（实验1，P≤0.05）。虽然添加HMB对腹腔巨噬细胞的吞噬潜力没有显著影响，但与对照组相比，0.01%和0.05%处理组巨噬细胞培养上清液中的亚硝酸盐水平更高（实验2，P≤0.04；实验3，P≤0.约等于0.05）。添加HMB并未改变鸡从血液中清除大肠杆菌或亚利桑那沙门氏菌的能力。从孵化后7天开始，雏鸡静脉注射7%的绵羊红细胞悬液。收集血清样本以测定初次和二次抗体反应。在实验1和2中，接受0.1% HMB日粮的雏鸡在初次反应期间IgG和总抗绵羊红细胞（SRBC）抗体水平升高。在二次反应期间，在实验1和3中，采食0.10% HMB日粮的鸡的IgM水平以及总抗SRBC水平均高于对照组。这些研究表明，添加HMB可改善幼龄肉鸡的多种免疫功能，这种改善可能导致死亡率降低。
