A study in poultry farm located near the village of Krepost, region Haskovo on growth performance, feed conversion and mortality of mule ducks from one-day-old to 74-day-old during the different seasons was carried out. In the experiment were used birds originating from the Grimaud frères sèlection company (only male ducks) and from the Breheret company (male and female ducks reared separately). Control measurements were taken on a random sample of 20 ducklings from each group. At the end of the growing period (74-days-old) the male ducks of Breheret company had 3.98% and 1.68% more body weight during the summer and autumn than the ones from Grimaud frères sèlection company, and in the winter and in the spring 3.42% and 0.73% less body weight, but the differences were not significants (ns). This showed that both genotypes had leveled growth ability. Female ducks grown in the spring have shown a higher body weight than the ones grown in summer (P<0.01) and in the winter (P<0.05). The body weight of the male and female ducks at the end of the growing period was lowest in the summer compared to the other three seasons. The feed conversion and the mortality were highest in winter.
Growth performance of mule ducklings during the different seasons