Department of Animal Sciences, University of Florida, Gainesville 32611, USA.
J Dairy Sci. 2010 Sep;93(9):4280-91. doi: 10.3168/jds.2010-3314.
Objectives were to determine effects of feeding pomegranate extract (POMx) rich in polyphenols on performance, health, nutrient digestion, and immunocompetence of calves in the first 70 d of age. Holstein calves (n=67), at 2+/-1 d of age (d 0=birth day) were randomly assigned to 0 (control), 5 (POMx5), or 10 g/d (POMx10) of pomegranate extract containing 16.9% gallic acid equivalent (GAE) to result in intakes of 0, 850 and 1,700 mg of GAE/d or an average of approximately 0, 15, and 30 mg of GAE/kg of body weight (BW) per day. All calves received colostrum during the first 24 h, pasteurized milk thereafter until 61 d of age, and grain was fed ad libitum for the first 70 d of age. Calves were housed in individual hutches, and grain intake, attitude and fecal scores, incidence and duration of health disorders, and treatments for health problems were evaluated daily. Body weight was measured on 2 consecutive days at 2, 30, and 70 d of age and averaged for each measurement. Concentrations of glucose and 3-hydroxybutyrate were measured in plasma. Nutrient digestion was measured using total fecal collection during a 3-d period. Neutrophil phagocytic and killing activities and antibody response to immunization with ovalbumin were measured. Peripheral blood mononuclear cells were cultured and cytokine production measured. Feeding POMx had no effect on intake or BW gain in the first 30 d of age, but after 30 d of age, both grain dry matter intake and BW gain decreased with increasing addition of POMx, which resulted in calves that were 1.8 and 4.3 kg lighter at 70 d of age for POMx5 and POMx10, respectively, compared with controls. Feeding POMx did not influence dry matter, organic matter, or starch digestibility, but it reduced crude protein and fat digestion. Plasma concentrations of glucose and 3-hydroxybutyrate were similar among treatments throughout the first 70 d of age. Measures of calf health such as fecal and attitude scores, risk of fever, and rectal temperature were not altered by treatments. Similarly, neutrophil phagocytic and killing activities did not differ among treatments. On the contrary, feeding POMx increased synthesis of interferon-gamma and interleukin-4 by peripheral blood mononuclear cells and improved total immunoglobulin G responses to ovalbumin vaccination. These results suggest that feeding POMx top-dressed onto the grain suppresses intake of grain and digestibility of fat and protein, likely because of the high tannin content. Nevertheless, polyphenols from POMx enhanced mitogen-induced cytokine production and response to vaccination, which might benefit immune competence of calves and potentially health. Additional studies are warranted to minimize the effect of POMx on intake and digestibility and to better understand the mechanisms by which polyphenols improve immune response of calves.
目的在于确定在犊牛生命的前 70 天中，给富含多酚的石榴提取物（POMx）会对其性能、健康、营养消化和免疫能力产生何种影响。选择 67 头荷斯坦小牛，在出生后的 2+/-1 天（出生日为 d0）时，随机分配到 0（对照）、5（POMx5）或 10 g/d（POMx10）的石榴提取物，石榴提取物中含有 16.9%的没食子酸当量（GAE），分别导致摄入 0、850 和 1700mg 的 GAE/d 或每天平均约 0、15 和 30mg 的 GAE/kg 体重。所有的小牛在出生后的头 24 小时内接受初乳，此后接受巴氏杀菌牛奶，直至 61 日龄，70 日龄前自由采食谷物。小牛单独关在畜栏里，每天评估谷物摄入量、态度和粪便评分、健康障碍的发生率和持续时间以及健康问题的治疗情况。在 2、30 和 70 日龄的连续两天测量体重，并对每次测量的体重进行平均。测量血浆中葡萄糖和 3-羟丁酸的浓度。使用 3 天的总粪便收集来测量营养消化。测量对卵清蛋白免疫接种的中性粒细胞吞噬和杀伤活性以及抗体反应。培养外周血单核细胞并测量细胞因子的产生。在生命的前 30 天内，给 POMx 不会影响采食量或体重增加，但在 30 天后，随着 POMx 添加量的增加，谷物干物质采食量和体重增加均减少，结果导致 POMx5 和 POMx10 组的小牛在 70 日龄时分别比对照组轻 1.8 和 4.3 公斤。给 POMx 不会影响干物质、有机物或淀粉消化率，但会降低粗蛋白和脂肪消化率。在生命的前 70 天内，各处理组的血浆葡萄糖和 3-羟丁酸浓度相似。粪便和态度评分、发热风险和直肠温度等小牛健康指标不受处理的影响。同样，中性粒细胞吞噬和杀伤活性在各处理组之间也没有差异。相反，给 POMx 会增加外周血单核细胞产生干扰素-γ和白细胞介素-4，并改善卵清蛋白接种的总免疫球蛋白 G 反应。这些结果表明，将 POMx 撒在谷物上喂养会抑制谷物的采食量和脂肪及蛋白质的消化率，这可能是因为其单宁含量高。然而，POMx 的多酚增强了有丝分裂原诱导的细胞因子产生和对疫苗接种的反应，这可能有益于小牛的免疫能力，并可能有益于健康。需要进一步的研究来最小化 POMx 对采食量和消化率的影响，并更好地了解多酚提高小牛免疫反应的机制。
