Immediate and long-term effects of post-hatch feed deprivation on performance, intestinal morphology and nutrient metabolism in on-farm hatched broilers

ABSTRACT As a consequence of the inevitable hatch window and the processing and transporting steps in conventional hatchery practices, broiler chicks may spend up to 20 - 60h without access to feed and water post-hatch. To assess the immediate and long-term effects of post-hatch feed deprivation, 960 Ross308 broilers were allocated to a randomized complete block design with time of hatch during the hatch window as the blocking factor. Within each block, chicks were randomly assigned to one of three treatments: immediate feed access post-hatch (T0), feed access at 24h (T1), or 48h biological age (BA) (T2). Performance parameters were measured at the end of each feeding phase, while relative organ weights, duodenal morphological parameters and fasted nutrient metabolite concentrations were assessed as repeated measures at 24h, 48h, 72h, 96h, days 7 and 10 BA, and at days 14, 28 and 42. Between hatch and day 11, T2 chicks had a higher average daily feed intake compared with T0 and had the highest feed conversion ratio (FCR). Overall, between hatch and day 42, T2 chicks had the least efficient FCR and tended to have the lowest body weight at the end of each feeding phase. Significant effects of post-hatch feed deprivation on the physiological measurements were limited to the relative bursa (RBW) and liver (RLW) weights and were limited to the first two weeks post-hatch, with T2 chicks having a lower RBW compared with T1 between hatch and day 11. Concurrently T1 chicks had a lower RLW compared with T0, which reversed by day 14 as T1 had higher RLW than T0. No effects of post-hatch feed deprivation were present on duodenal morphology and fasted nutrient metabolites, however the effect of sex was present in several of these and relative organ weight parameters. Due to the frequent sampling schedule, insights were gained into the development of post-hatch nutrient metabolism, which may help to further optimize nutritional composition of starter feeds for on-farm hatched broilers.