Breeder age and post-hatch feed access influence physiology of residual yolk sac, intestinal development and performance of broiler chicks

Abstract

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.