Casteel E T, Wilson J L, Buhr R J, Sander J E
Department of Poultry Science, University of Georgia, Athens 30602.
Poult Sci. 1994 Nov;73(11):1679-84. doi: 10.3382/ps.0731679.
Extended posthatch holding (in the hatcher) has been reported to dehydrate chicks, reduce broiler performance, and depress immune response. Nevertheless, some commercial hatcheries are increasing incubation time in an attempt to minimize possible bacterial contamination of incompletely healed navels. The objectives of this study were to determine the effects of posthatch holding on broiler performance and the effects of bird density and additive stress on performance and immune response. Twelve hundred broiler eggs (58 to 70 g) were incubated. Chicks were removed from the hatcher after 528 h of incubation, banded, and weighed. Half of the chicks were returned to the hatcher for an additional 24 h (HELD). Both hatcher treatments were placed at two densities (.07 and .12 m2 per bird). Individual BW were taken at 21 and 43 d of placement and 43 d of age. The HELD chicks weighed significantly less than controls at time of placement. At 21 d postplacement the HELD broilers were significantly heavier than controls, but were similar by 43 d. Total feed conversion was not affected in the HELD treatment, but birds in the .07 m2 per bird density were less efficient in terms of total feed conversion. Chick holding time and density seemed to affect antibody titers at 5 wk. Although holding chicks in the hatcher for 24 h did not clinically dehydrate chicks or affect performance, it decreased immune response. In addition to less efficient growth, birds in the more crowded pens had depressed immune response.
据报道，孵化后延长留存时间（在孵化箱中）会使雏鸡脱水、降低肉鸡生产性能并抑制免疫反应。然而，一些商业孵化场正在延长孵化时间，试图将未完全愈合肚脐可能受到的细菌污染降至最低。本研究的目的是确定孵化后留存对肉鸡生产性能的影响，以及饲养密度和附加应激对生产性能和免疫反应的影响。1200枚（58至70克）肉鸡种蛋进行孵化。孵化528小时后，雏鸡从孵化箱中取出，佩戴脚环并称重。一半雏鸡放回孵化箱再留存24小时（留存组）。两种孵化箱处理方式都设置了两种饲养密度（每只鸡0.07和0.12平方米）。在饲养后第21天和第43天以及43日龄时记录个体体重。留存组雏鸡在饲养时体重显著低于对照组。饲养后第21天，留存组肉鸡体重显著高于对照组，但到43天时二者体重相近。留存组的总饲料转化率未受影响，但每只鸡饲养密度为0.07平方米的鸡群在总饲料转化率方面效率较低。雏鸡留存时间和密度似乎会影响5周龄时的抗体滴度。虽然在孵化箱中留存雏鸡24小时在临床上并未使雏鸡脱水或影响生产性能，但降低了免疫反应。除了生长效率较低外，饲养密度较大栏舍中的鸡免疫反应也受到抑制。
