Influence of the length of the post-hatch holding time on growth performance and the development of the proximal part of the gastrointestinal tract of broilers from 1 to 21 d of age

Abstract

We studied the influence of the length of the post-hatch holding time (HT) on the development of the organs of the proximal part of the gastro-intestinal tract and growth performance of broilers from 1 to 21 d of age .In experiment 1, 120 birds were pulled from the hatchery 24 or 48 h after the first egg hatched, vaccinated against major diseases, and prepared for shipping (3 h). Then, chicks were transported (6 h) to the experimental farm. The final length of the HT was 33 and 57 h, respectively. Neither water nor feed were supplied during this period . Each treatment was replicated 6 times and the experimental unit was a cage with 10 birds . The broilers were fed a common low-density diet (EMAn = 2,820 kcal/kg; digestible Lys = 0.92%) in mash form throughout the experiment. Feed consumption, BW, and FCR were determined by replicate at 0, 7, 14, and 21 d of age . At 7 and 21 d of age, 2 birds per cage chosen at random were weighed individually and used to measure the weight (full and empty) and the pH of the crop and the gizzard. In addition, the DM content of the crop digesta was determined . The experimental design was completely randomized . The effects of HT on growth performance and organ traits and its interaction with age were analyzed using the MIXED procedure of SAS. An increase in HT length from 33 to 57 h reduced the BW of the broilers at the arrival to the experimental farm (40.5 vs. 35.6 g; P < 0.001) and at 21 d of age (P < 0.001). From 1 to 21 d of age, bird mortality increased (P < 0.05) as the length of the HT period increased . From 1 to 7 d of age, the longer HT period impaired (P < 0.05) FCR but the effect disappeared after this age. In experiment 2, chick management and experimental design were similar to those described for experiment 1 but a high-density diet (EMAn = 2,970 205Poult . Sci . 98(E-Suppl . 1)kcal/kg; digestible Lys = 1.31%) was used. An increase in the length of the HT period reduced the BW of the broilers at the arrival to the experimental farm (40.7 vs. 36.3 g; P < 0.001) and at 21 d of age (P < 0.05). Also, the longer HT period impaired FCR from 1 to 7 d of age (P< 0.05) but not thereafter. Length of the fasting period after hatch did not affect any of the organ traits studied in any of the 2 experiments at any age . Regardless of the energy and amino acid density of the diet, long fasting periods after hatch reduced growth performance and reduced the feed efficiency of the birds during the first week after hatch. The data indicate that food and water deprivation after hatch delays the start of the growth of the chicks without affecting the development of the proximal part of the gastrointestinal tract.