Effect of incubation humidity and flock age on hatchability traits and posthatch growth in Pekin ducks

This study was conducted to determine the effect of incubation relative humidity (RH) from 14 to 24 d of incubation during 3 parental ages on hatchability and posthatching growth of Pekin ducklings. Egg production was divided into 3 age groups (25-35, 36-55, and 56-65 wk). A total of 21,600 hatching eggs was subjected to 55, 60, 65, and 70% RH from 14 to 24 d, whereas standard conditions were used from 0 to 14 d and 24 to 28 d of incubation. All eggs were individually weighed before setting in the incubator and again at 14 and 24 d of incubation to determine egg weight loss. A sample of 20 eggs from unhatched and hatched eggs from each group were randomly taken on the hatching day and used to determine eggshell thickness and pore number. Duckling weight at hatching was recorded and BW gain, feed consumption, feed conversion, and viability were then recorded to 21 d of age. Egg weight increased with hen age but did not differ by incubation treatment. Increasing RH from 55% to 60, 65, and 70% decreased percentage egg weight loss in a stepwise manner irrespective of parental age. Shell thickness was less for hatched eggs compared with nonhatched eggs within each parental age. Shell thickness decreased while pore density increased with increased parental age for both nonhatched and hatched eggs. The lowest embryonic mortality among the incubation periods (14-24 and 0-24 d) and best hatchability of fertile eggs was recorded with 60% RH during the first parental age (25-35 wk), 65% RH during 36-55 wk of age, and 70% RH during 56-65 wk of age. The best incubation results were directly associated with the greatest duckling BW at hatching and at 21 d of age, BW gain, feed conversion, and viability during each parental age period. It was concluded that duck eggs produced within a specific parental age period require a specific incubation RH to attain the best hatchability and posthatching duckling performance.