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首页> 外文期刊>Journal of dairy science >High Growth Rate Fails to Enhance Adaptive Immune Responses of Neonatal Calves and Is Associated with Reduced Lymphocyte Viability
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High Growth Rate Fails to Enhance Adaptive Immune Responses of Neonatal Calves and Is Associated with Reduced Lymphocyte Viability

机译：高生长速率未能增强新生儿犊牛的适应性免疫反应，并与淋巴细胞活力降低相关。

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The objective of the study was to evaluate the effects of 3 targeted growth rates on adaptive (i.e., antigen-specific) immune responses of preruminant, milk re-placer-fed calves. Calves (9.1 ± 2.4 d of age) were assigned randomly to one of 3 dietary treatments to achieve 3 targeted daily rates of gain [no growth (maintenance) = 0.0 kg/d, low growth = 0.55 kg/d, or high growth =1.2 kg/d] over an 8-wk period. The NRC Nutrient Requirements of Dairy Cattle calf model computer program was used to estimate the milk replacer intakes needed to achieve target growth rates. All calves were fed a 30% crude protein, 20% fat, all-milk protein milk replacer reconstituted to 14% dry matter. Diets were formulated to ensure that protein would not be limiting. All calves were vaccinated 3 wk after initiation of dietary treatments with Mycobacterium bovis, strain bacillus Calmette-Guerin and ovalbumin. Growth rates for no-growth (0.11 kg/d), low-growth (0.58 kg/d), and high-growth (1.16 kg/d) calves differed throughout the experimental period. Blood glucose concentrations in high-growth calves increased with time and were higher than in low- and no-growth calves. Mononuclear and polymorphonuclear leukocyte percentages in peripheral blood were unaffected by growth rate but did change with advancing age. Percentages of CD4~+ T cells increased with age in no-growth and low-growth calves, a characteristic of maturation, but failed to increase in high-growth calves. Growth rate did not affect the percentages of CD45RO~+ (memory) CD4~+ and CD8~+ T cells, antigen (i.e., ovalbumin)-specific serum IgG concentrations, or antigen (i.e., purified protein deriva- tive)-induced IFN-γ and nitric oxide secretion by mono-nuclear cell cultures. Antigen-elicited cutaneous de-layed-type hypersensitivity responses of no-growth calves exceeded responses of low-growth, but not high-growth, calves. In resting- and antigen-stimulated cell cultures, viabilities of CD4~+, CD8~+, and γδTCR~+ T cells from high-growth calves were lower than those of the same T cell subsets from no-growth and low-growth calves. Alternatively, resting cultures of mononuclear leukocytes from high-growth calves produced more nitric oxide than those from no-growth and low-growth calves. In conclusion, adaptive immune responses were affected minimally by growth rate. The results suggest that protein-energy malnutrition in the absence of weight loss is not detrimental to antigen-specific responses of neonatal vaccinated calves and that a high growth rate does not enhance these responses. The negative effect of a high growth rate on the viability of circulating T cell populations may influence infectious disease resistance of the calf.
机译：这项研究的目的是评估3种目标生长速率对反刍动物，代乳粉喂养小牛的适应性（即抗原特异性）免疫反应的影响。将小牛（年龄为9.1±2.4 d）随机分配到3种饮食疗法中的一种，以达到3种目标每日增重率[无生长（维持）= 0.0 kg / d，低生长= 0.55 kg / d，或高生长=在8周内达到1.2公斤/天]。 NRC奶牛犊牛模型计算机程序的营养需求量用于估算实现目标增长率所需的代乳品摄入量。给所有犊牛饲喂30％的粗蛋白，20％的脂肪，重构为14％干物质的全牛奶蛋白代乳品。制定饮食以确保蛋白质不受限制。在开始用牛分枝杆菌，卡介苗-瓜林芽孢杆菌和卵清蛋白菌株进行饮食治疗后3周，给所有小牛接种疫苗。在整个实验期间，无生长（0.11 kg / d），低生长（0.58 kg / d）和高生长（1.16 kg / d）犊牛的生长速率有所不同。高生长犊牛的血糖浓度随时间增加，高于低生长犊牛和无生长犊牛。外周血中单核和多形核白细胞的百分比不受生长速度的影响，但随着年龄的增长而变化。在无生长和低生长犊牛中，CD4〜+ T细胞的百分比随年龄增加而增加，这是成熟的特征，但在高生长犊牛中却没有增加。生长速率不影响CD45RO〜+（记忆）CD4〜+和CD8〜+ T细胞的百分比，抗原（即卵清蛋白）特异性血清IgG浓度或抗原（即纯化的蛋白衍生性）诱导的IFN的百分比。 -γ和一氧化氮通过单核细胞培养物分泌。抗原引起的无生长犊牛的皮肤迟发型超敏反应超过了低生长犊牛的反应，但没有高生长犊牛的反应。在静息和抗原刺激的细胞培养物中，高生长犊牛的CD4〜+，CD8〜+和γδTCR〜+ T细胞的活力低于无生长犊牛和低生长犊牛的相同T细胞亚群的活力。另外，来自高生长犊牛的单核白细胞的静息培养物比无生长和低生长犊牛的单核白细胞产生更多的一氧化氮。总之，生长速度对适应性免疫反应的影响最小。结果表明，在没有体重减轻的情况下，蛋白质能量营养不良对新生儿接种牛犊的抗原特异性反应无害，并且高生长速度不会增强这些反应。高生长速率对循环中T细胞种群活力的负面影响可能会影响小牛的传染性疾病。

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