Wang W, Wideman R F, Chapman M E, Bersi T K, Erf G F
Department of Poultry Science, University of Arkansas, Fayetteville, Arkansas 72701, USA.
Poult Sci. 2003 Dec;82(12):1886-97. doi: 10.1093/ps/82.12.1886.
Commercial broilers are constantly exposed to airborne microorganisms and endotoxin (lipopolysaccharide, LPS). It has been shown that microbial contamination of the air was higher in broiler houses using floor litter than in broiler houses using netting-type floors. The current study evaluated the effect of housing conditions on blood leukocyte profiles and tested the hypothesis that, when compared to broilers reared in clean stainless steel cages (Cage group), broilers raised on floor litter (Floor group) should experience a higher environmental challenge and have a desensitized immune system that may exhibit better tolerance/resistance to subsequent intravenous LPS challenge. Hematological parameters were evaluated prior to and following i.v. administration of 1 mg/kg BW Salmonella typhimurium LPS (dissolved at 1 mg/0.25 mL in PBS) or i.v. injection of 0.25 mL/kg BW PBS alone. The results showed that prior to LPS/PBS injection, broilers in the cage group had higher heterophil and monocyte concentrations, a higher B cell percentage within the lymphocyte population, and a higher heterophil to lymphocyte (H:L) ratio in the blood. The i.v. LPS injection resulted in 25% mortality in the cage group and 42% mortality in the floor group within 8 h post-injection. LPS reduced the concentrations of total white blood cells (WBC) and all differential WBC except eosinophils and increased thrombocyte concentrations within 1 h post-injection in both groups. All of these values returned to their respective pre-injection levels within 48 h post-injection in the surviving birds. The two groups exhibited similar overall hematological changes after LPS injection except that the cage group showed a higher H:L ratio at 8 h post-injection and a lower B-cell percentage within the lymphocyte population at 48 h post-injection when compared with the floor group. We concluded that the immune systems of broilers reared on floor litter were desensitized and exhibited less pronounced leukocyte responses to i.v. LPS when compared with those of broilers reared in clean stainless steel cages. However, such desensitization of the immune system did not help broilers survive subsequent i.v. LPS challenge.
商品肉鸡经常暴露于空气中的微生物和内毒素（脂多糖，LPS）中。研究表明，使用垫料地面的肉鸡舍空气中的微生物污染程度高于使用网床式地面的肉鸡舍。本研究评估了饲养条件对血液白细胞谱的影响，并验证了以下假设：与饲养在清洁不锈钢笼中的肉鸡（笼养组）相比，饲养在垫料地面上的肉鸡（地面组）应面临更高的环境挑战，且免疫系统脱敏，可能对随后的静脉注射LPS挑战表现出更好的耐受性/抵抗力。在静脉注射1mg/kg体重的鼠伤寒沙门氏菌LPS（以1mg/0.25mL溶解于PBS中）或仅静脉注射0.25mL/kg体重的PBS之前和之后评估血液学参数。结果表明，在注射LPS/PBS之前，笼养组肉鸡血液中的嗜异性粒细胞和单核细胞浓度更高，淋巴细胞群体中的B细胞百分比更高，嗜异性粒细胞与淋巴细胞（H:L）比值更高。静脉注射LPS后，笼养组在注射后8小时内死亡率为25%，地面组为42%。两组在注射后1小时内，LPS均降低了总白细胞（WBC）和除嗜酸性粒细胞外的所有分类白细胞的浓度，并增加了血小板浓度。在存活的鸡中，所有这些值在注射后48小时内恢复到各自的注射前水平。注射LPS后，两组总体血液学变化相似，但与地面组相比，笼养组在注射后8小时的H:L比值更高，在注射后48小时淋巴细胞群体中的B细胞百分比更低。我们得出结论，与饲养在清洁不锈钢笼中的肉鸡相比，饲养在垫料地面上的肉鸡免疫系统脱敏，对静脉注射LPS的白细胞反应不那么明显。然而，这种免疫系统的脱敏并没有帮助肉鸡在随后的静脉注射LPS挑战中存活下来。
