Davis M E, Brown D C, Maxwell C V, Johnson Z B, Kegley E B, Dvorak R A
Department of Animal Science, University of Arkansas, Fayetteville 72701, USA.
J Anim Sci. 2004 Feb;82(2):581-7. doi: 10.2527/2004.822581x.
Three experiments were conducted to evaluate the efficacy of phosphorylated mannans (MAN) and pharmacological levels of ZnO on performance and immunity when added to nursery pig diets. Pigs (216 in each experiment), averaging 19 d of age and 6.2, 4.6, and 5.6 kg of BW in Exp. 1, 2, and 3, respectively, were blocked by BW in each experiment, and penned in groups of six. A lymphocyte blastogenesis assay was performed in each experiment to measure in vitro lymphocyte proliferation response. In Exp. 1, diets were arranged as a 2 x 2 factorial with two levels of Zn (200 and 2,500 ppm) and two levels of MAN (0 and 0.3% from d 0 to 10, and 0 and 0.2% from d 10 to 38). Zinc oxide increased (P < 0.05) ADG, ADFI, and G:F from d 0 to 10, and ADG and ADFI from d 10 to 24. In Exp. 2, diets were arranged as a 2 x 3 factorial with two levels of Zn (200 and 2,500 ppm) and three levels of MAN (0, 0.2, and 0.3%). Pigs fed 2,500 ppm Zn from d 0 to 10 had greater (P < 0.05) ADG, ADFI, and G:F than pigs fed 200 ppm Zn. From d 10 to 24, ADG was similar when pigs were fed 200 ppm Zn, regardless of MAN supplementation; however, ADG increased (P < 0.05) when 0.2% MAN was added to dietscontaining 2,500 ppm Zn (MAN x Zn interaction, P < 0.05). In Exp. 3, diets were arranged as a 2 x 3 factorial with two levels of MAN (0 and 0.3%) and three levels of Zn (200, 500, and 2,500 ppm). Zinc was maintained at 200 ppm from d 21 to 35, so only two dietary treatments (0 and 0.3% MAN) were fed during this period. Average daily gain was greater (P < 0.05) from d 7 to 21 when pigs were fed 2,500 ppm Zn compared with pigs fed 200 or 500 ppm Zn. The addition of MAN improved (P < 0.05) G:F from d 7 to 21 and d 0 to 35. Lymphocyte proliferation of unstimulated cells and phytohemagglutinin-stimulated cells was decreased (P < 0.05) in cells isolated from pigs fed MAN compared with cells isolated from pigs fed diets without MAN. Lymphocyte proliferation of pokeweed mitogen-stimulated cells isolated from pigs fed MAN was less (P < 0.05) than for pigs fed diets devoid of MAN when diets contained 200 ppm Zn; however, MAN had no effect on lymphocyte proliferation when the diet contained 500 or 2,500 ppm Zn (MAN x Zn interaction, P < 0.05). Although the magnitude of response to MAN was not equivalent to that of pharmacological concentrations of Zn, MAN mayimprove growth response when pharmacological Zn levels are restricted.
进行了三项试验，以评估在保育猪日粮中添加磷酸化甘露聚糖（MAN）和药理学水平的氧化锌对生产性能和免疫力的影响。在每项试验中，猪（每项试验216头）平均日龄为19天，试验1、2和3中猪的初始体重分别为6.2、4.6和5.6千克，在每项试验中按体重进行分组，每组6头猪饲养在一个栏中。在每项试验中都进行了淋巴细胞增殖试验，以测定体外淋巴细胞增殖反应。在试验1中，日粮采用2×2析因设计，有两个锌水平（200和2500 ppm）和两个MAN水平（0至10日龄为0和0.3%，10至38日龄为0和0.2%）。氧化锌使0至10日龄的平均日增重（ADG）、平均日采食量（ADFI）和料重比（G:F）增加（P<0.05），使10至24日龄的ADG和ADFI增加。在试验2中，日粮采用2×3析因设计，有两个锌水平（200和2500 ppm）和三个MAN水平（0、0.2和0.3%）。0至10日龄饲喂2500 ppm锌的猪比饲喂200 ppm锌的猪具有更高（P<0.05）的ADG、ADFI和G:F。在10至24日龄时，无论是否添加MAN，饲喂200 ppm锌的猪的ADG相似；然而，当在含2500 ppm锌的日粮中添加0.2% MAN时，ADG增加（P<0.05）（MAN×锌互作，P<0.05）。在试验3中，日粮采用2×3析因设计，有两个MAN水平（0和0.3%）和三个锌水平（200、500和2500 ppm）。从21至35日龄锌维持在200 ppm，因此在此期间只饲喂两种日粮处理（0和0.3% MAN）。与饲喂200或500 ppm锌的猪相比，饲喂2500 ppm锌的猪在7至21日龄时ADG更高（P<0.05）。添加MAN使7至21日龄以及0至35日龄的G:F得到改善（P<0.05）。与从不添加MAN的日粮的猪分离的细胞相比，从添加MAN的日粮的猪分离的细胞中，未刺激细胞和植物血凝素刺激细胞的淋巴细胞增殖降低（P<0.05）。当日粮含200 ppm锌时，从添加MAN的日粮的猪分离的商陆促有丝分裂原刺激细胞的淋巴细胞增殖低于从不添加MAN的日粮的猪（P<0.05）；然而，当日粮含500或2500 ppm锌时，MAN对淋巴细胞增殖无影响（MAN×锌互作，P<0.05）。尽管对MAN的反应程度与药理学浓度的锌不同，但当药理学水平的锌受到限制时，MAN可能改善生长反应。
