Cage-free housing of laying hens may provide opportunities for widespread environmental distribution of Salmonella contamination and horizontal transmission of infection within flocks. Salmonella Enteritidis in commercial laying flocks presents an ongoing public health concern because reproductive organ colonization in hens leads to deposition inside eggs. Many S. Enteritidis control programs include vaccination to induce protective immunity against infection. Salmonella Kentucky is common in egg production environments but has not been associated with egg contamination. This study compared the invasion of internal organs and horizontal spread of infection during the first 2 wk after experimental S. Enteritidis and S. Kentucky infection of previously vaccinated laying hens in indoor cage-free housing. Two groups of 72 hens each were housed in isolation rooms simulating commercial cage-free barns and 1/3 of the hens were orally inoculated with either S. Enteritidis (1 room) or S. Kentucky (1 room). At 6 and 12 d after inoculation, half of the hens in each room were euthanized and samples of the liver, spleen, ovary, oviduct, and intestinal tract were removed for bacteriologic culturing. Among hens inoculated with S. Enteritidis, 66.7% of the intestinal, liver, and spleen samples were positive for the pathogen at 6 d after infection, as well as 41.7% of intestines and 16.7% of livers from contact-exposed hens. Significantly (P < 0.05) fewer hens were colonized by S. Kentucky. These results demonstrate that vaccines may not always provide complete exclusion of Salmonella. In cage-free housing systems, vaccination should be supplemented with a comprehensive risk reduction effort to prevent extensive horizontal dissemination of Salmonella.

无笼的蛋鸡舍可能会为沙门氏菌污染的广泛环境分布和鸡群内感染的水平传播提供机会。沙门氏菌肠炎在商业鸡群产蛋呈现一个持续的公众健康问题，因为母鸡导致沉积内鸡蛋生殖器官定植。许多小号。肠炎控制计划包括接种疫苗以诱导针对感染的保护性免疫。肯塔基州沙门氏菌在产蛋环境中很常见，但与蛋污染无关。这项研究比较了实验性S感染后前2周内脏器的侵袭和感染水平扩散。肠炎和S.肯塔基感染在室内无保持架壳体先前接种的蛋鸡。两组，每组72只母鸡圈养在隔离的房间模拟商业自由笼谷仓和母鸡的1/3经口要么接种小号。肠炎（1个室）或小号。肯塔基（1个房间）。接种后第6天和第12天，对每个房间的一半母鸡实施安乐死，并取下肝脏，脾脏，卵巢，输卵管和肠道的样本进行细菌培养。在接种S的母鸡中。肠炎，感染后6 d肠，肝和脾样品中66.7％的病原体呈阳性，接触母鸡的肠中有41.7％，肝脏为16.7％。显着地（P  <0.05）较少的母鸡被S所定殖。肯塔基州。这些结果表明，疫苗不一定总能完全排除沙门氏菌。在无笼住房系统中，应补充疫苗接种，并采取全面的降低风险措施，以防止沙门氏菌大量水平传播。