Abstract
Two hundred ducklings represent two different genotypes White Pekin and Mule ducks (a sterile hybrid from the interspecific cross of a Pekin duck and Muscovy drake) were used in this study to determine influence of breed of ducks (White Pekin vs. Mule), feeding regime (early feed restriction regime by Skip-a-day program vs. free feeding) on Behaviors, Productive performance, Immune response, corticosterone, fear response and economic parameters of the Mule and Pekin ducks. The obtained results showed that Rearing Mule ducks under skip-a-day program for 7 days led to increase of wall exploratory behavior and decrease of aggressive behavior. Moreover, it had a higher body weight from 3rd to 7th weeks of age in addition a higher weight gain from 4th to 6th weeks of age compared to White Pekin ducks. Induction of feed restriction regime improved walking behavior, wing and leg stretch, wall and floor explorations. Moreover, it motivated occurrence of catch-up growth and improved immunity, but it increased aggressive behavior of ducks. The economic analysis showed that total costs of the ducks fed ad-libitum were greater than those fed on restriction regime. In addition, total veterinary management costs were not statistically significant among Mule and Pekin breed and either ad-libitum or restricted feed regime ducks. With reference to the profitability measures, the results obtained showed that the Pekin ducks achieved higher net return than the Mule ducks. Furthermore, the benefit-cost analysis revealed that the restricted regime ducks data were lower than the ad-libitum duck groups.

Key words: Ducks; Welfare, Performance; Feeding regime; Economic efficiency