This study assessed the effects of breeder age, placement time and the use of a pre-placement feed (PPF) on yolk sac absorption, duodenum villus height and crypt depth and performance of male broiler chicks. A total of 1440 broiler chicks were randomly allocated to eight treatments. The study design was fully randomized in a 2 × 2 × 2 factorial scheme (breeder age × placement time × PPF). The factors were: broiler chicks from breeders of two ages (29 or 55 weeks), two placement times (24 or 48 h after pulling) and PPF or not of 2.5 g/chicks inside transport boxes. Yolk sac relative weight was determined from pulling to four days post-hatch; duodenum villus height and crypt depth were determined at pulling and at three and seven days of age; and performance was determined until 37 days. Six replications of two chicks for each treatment were used for yolk sac absorption, while eight replications of 15 measurements of one chick for each treatment were used for villus height and crypt depth. A total of 1440 broiler chicks were used (180 from each treatment) to determine performance. All experimental treatments were randomly assigned to six pens each with 30 chicks per pen-floor (12 birds/m²). Early access to feed stimulated yolk sac absorption until four days of age (P ≤ 0.05), and this effect was stronger for chicks from 29-week-old broiler breeders (P ≤ 0.05). On the other hand, placement within 48 h negatively impaired the development of duodenum villus and crypt until 7 days of age for chicks from young broiler breeders, but this negative effect could be reduced by the use of PPF (P ≤ 0.05). These results suggest that the use of PPF inside transport boxes is recommended for chicks from young broiler breeders that will be submitted to delayed feed access in order to improve gastrointestinal tract development, mainly that of the duodenum mucosa.

本研究评估了种鸡年龄、放置时间和使用放置前饲料 (PPF) 对卵黄囊吸收、十二指肠绒毛高度和隐窝深度以及雄性肉鸡生产性能的影响。总共 1440 只肉鸡被随机分配到 8 个处理组。研究设计在 2 × 2 × 2 因子方案（种鸡年龄 × 放置时间 × PPF）中完全随机化。这些因素是：来自两个日龄（29 或 55 周）种鸡的肉鸡、两个放置时间（拉动后 24 或 48 小时）以及运输箱内的 PPF 是否为 2.5 克/小鸡。卵黄囊的相对重量是从拉到孵化后四天测定的；十二指肠绒毛高度和隐窝深度在拉动和 3 日龄和 7 日龄时测定；并确定性能直到 37 天。每种处理的两只小鸡的六次重复用于卵黄囊吸收，而每种处理的一只小鸡的 15 次测量值的 8 次重复用于绒毛高度和隐窝深度。总共使用了 1440 只肉鸡（每个处理 180 只）来确定性能。所有试验处理随机分配到六个围栏，每个围栏每层有 30 只雏鸡（12 只鸡/平方米）。早期获得饲料刺激卵黄囊吸收，直到四日龄（P  ≤  0.05），这种影响对来自 29 周龄肉种鸡的雏鸡更强（P  ≤  0.05）。另一方面，在 48 小时内放置对肉鸡雏鸡 7 日龄前十二指肠绒毛和隐窝的发育产生负面影响，但这种负面影响可以通过使用 PPF 来减少（P  ≤  0.05）。这些结果表明，建议将 PPF 装入运输箱内的小鸡，这些小鸡将延迟采食，以改善胃肠道发育，主要是十二指肠粘膜的发育。