SUMMARY A large amount of existing evidence shows that the micro- and macrostructure of feed has a strong influence on the function, development and health of the gastrointestinal tract (GIT), which, in turn, affects the performance of poultry birds. Notably, the majority of data corresponding to feed structure-induced changes in the productivity of birds has been generated from studies using broiler chickens. However, feed particle size and feed form remain an obscure and undervalued area of study in the feeding of layer chickens, with sparse evidence reported between the 1940s and 2000s. Moreover, feed in the form of crumbles and pellets, which has made a major contribution to broiler production efficiency, has not been the feed of choice for layers, where mash diets have been common practice worldwide for many years. Nonetheless, the role of feed structure in the feeding of layer chickens has recently begun to attract more interest. However, results are divergent and often not as satisfactory as expected, except in the case of gizzard weight, which typically decreases by 8% and 16% on average with finely ground and pelleted feed, respectively. The results for most performance parameters, however, are typically insignificant. In some cases where the effect of the feed form was significant, pelleting increased feed consumption by 6%, whereas a clear 9% reduction was observed in another example. The incongruities in the results are likely due to confounding factors, such as management conditions and ingredient composition of the diets. Nevertheless, the effect of feed form on the investigated parameters was more evident than the effect of feed particle size. The following review provides an overview of data from seven decades regarding the implications of feed structure on the physiology, histology, metabolism and development of the gut and the performance of egg-laying chickens.

中文翻译：

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饲料结构对蛋鸡胃肠道性状和生产性能的影响：70 年经验概述

总结 大量现有证据表明，饲料的微观和宏观结构对胃肠道 (GIT) 的功能、发育和健康有很大影响，进而影响家禽的生产性能。值得注意的是，大部分与饲料结构引起的鸟类生产力变化相对应的数据是从使用肉鸡的研究中产生的。然而，饲料粒度和饲料形式在蛋鸡饲养方面仍然是一个模糊和被低估的研究领域，在 1940 年代和 2000 年代之间报告的证据很少。此外，碎料和颗粒形式的饲料对肉鸡的生产效率做出了重大贡献，但一直不是蛋鸡的首选饲料，多年来，饲料饲料在全球范围内已成为普遍做法。尽管如此，饲料结构在蛋鸡饲养中的作用最近开始引起更多的兴趣。然而，结果各不相同，而且通常不如预期的那样令人满意，除了在使用细磨饲料和颗粒饲料时，通常会分别减少 8% 和 16% 的平均重量。然而，大多数性能参数的结果通常是微不足道的。在某些饲料形式影响显着的情况下，制粒使饲料消耗量增加了 6%，而在另一个例子中观察到明显减少了 9%。结果的不一致可能是由于混杂因素造成的，例如管理条件和饮食的成分组成。然而，饲料形式对研究参数的影响比饲料粒度的影响更明显。