Lessard M, Gagnon N, Petit H V
Dairy and Swine Research and Development Centre, Agriculture and Agri-Food Canada, Lennoxville, QC, Canada J1M 1Z3.
J Dairy Sci. 2003 Aug;86(8):2647-57. doi: 10.3168/jds.S0022-0302(03)73860-0.
Thirty Holstein cows were allotted at calving to 10 groups of three cows blocked for similar calving dates to determine the effects of dietary fatty acids on functional properties of immunocompetent cells in early lactation and at breeding. Cows were assigned at calving to one of three isonitrogenous, isoenergetic, and isolipidic supplements based on either calcium salts of palm oil, Megalac, micronized soybeans, or whole flaxseed. On the day of AI and 20 d later, cows were injected with ovalbumin to measure the antibody response. Blood samples were taken at different times after calving (d 5, 21, 42, and 105) and after AI (d 0, 10, 20, and 40) for quantification of serum progesterone, fatty acids, and prostaglandin E2 concentrations. Isolated peripheral blood mononuclear cells were cultured to evaluate the proliferative response to concanavalin A and in vitro productions of interferon-gamma and prostaglandin E2. In general, feeding flaxseed increased serum omega-3 fatty acids concentration compared with feeding Megalac or soybeans, which decreased the omega-6 to omega-3 fatty acids ratio. There was a significant diet x day interaction for the proliferative response of mononuclear cells after calving and AI, indicating that cell responses from cows fed flaxseed were transiently reduced compared with those fed Megalac and soybeans. Moreover, during the breeding period, serum progesterone concentration was significantly greater in cows fed flaxseed compared with those fed Megalac, whereas serum concentration of prostaglandin E2 was significantly lower in cows fed flaxseed than in those fed Megalac or soybeans. Dietary treatments had no effect on the antibody response to ovalbumin and on in vitro productions of interferon-gamma and prostaglandin E2. However, interferon-gamma and prostaglandin E2 were impaired in the first 3 wk after parturition regardless of dietary treatment. These results suggest that changes in fatty acids, progesterone, and prostaglandins E2 concentrations in serum due to dietary treatment and physiological status influenced systemic immunity as shown by reduced proliferative response. However, other mechanisms must be considered and are discussed to explain dietary effect on lymphocyte proliferative response to mitogenic stimulation and other immune functions.
30头荷斯坦奶牛在产犊时被分为10组，每组3头，按相似产犊日期进行分组，以确定日粮脂肪酸对泌乳早期和配种时免疫活性细胞功能特性的影响。产犊时，根据棕榈油钙盐、美加力（Megalac）、微粉化大豆或全亚麻籽，将奶牛分配到三种等氮、等能量和等脂的补充料之一。在人工授精当天和20天后，给奶牛注射卵清蛋白以测量抗体反应。在产犊后不同时间（第5、21、42和105天）以及人工授精后（第0、10、20和40天）采集血样，用于定量血清孕酮、脂肪酸和前列腺素E2浓度。分离外周血单个核细胞进行培养，以评估对刀豆球蛋白A的增殖反应以及干扰素-γ和前列腺素E2的体外产生。总体而言，与饲喂美加力或大豆相比，饲喂亚麻籽可提高血清ω-3脂肪酸浓度，降低ω-6与ω-3脂肪酸比值。产犊和人工授精后，单核细胞的增殖反应存在显著的日粮×天数交互作用，表明与饲喂美加力和大豆的奶牛相比，饲喂亚麻籽的奶牛细胞反应暂时降低。此外，在配种期，饲喂亚麻籽的奶牛血清孕酮浓度显著高于饲喂美加力的奶牛，而饲喂亚麻籽的奶牛血清前列腺素E2浓度显著低于饲喂美加力或大豆的奶牛。日粮处理对卵清蛋白抗体反应以及干扰素-γ和前列腺素E2的体外产生没有影响。然而，无论日粮处理如何，产后前3周干扰素-γ和前列腺素E2均受损。这些结果表明，日粮处理和生理状态导致血清中脂肪酸、孕酮和前列腺素E2浓度的变化影响了全身免疫，表现为增殖反应降低。然而，必须考虑并讨论其他机制来解释日粮对淋巴细胞对有丝分裂原刺激的增殖反应和其他免疫功能的影响。
