Study on some biologcal performance of mule ducks with discontinued probiotic treatment

Aim: To establish the effect of the new for Bulgaria probiotic ProMixAn Forte® in discontinued treatment of mule ducks for the first 28 days, when reared up to 72 days of age. Material and Methods: A research study was carried out with two groups of 50 female ducks each. The ducks were reared under a three-phase feeding regime, given the same feed, the forage of the experimental group being supplemented with the probiotic from 1 to 28 days of age (starter), after which the probiotic was stopped. Results: After 14 days, the experimental ducks showed significantly higher weight gain (5% – 9% in average for the separate periods), the tendency continuing for 15 days after stopping the probiotic (43 days of age), after which the weight gain decreased by more than 4 times compared to the control group. After 56-th day of age, the experimental ducks had a higher growth rate than the control, but they could not compensate for the lag. At the end of the period, the experimental fowl showed 17% lower final live weight compared to the untreated. The results of the feed conversion ratio (FCR) to produce a kg of live weight were analogous, but opposite in value. FCR was 8 to 13% lower in the experimental birds from 14 to 43 days of age, over 4.5 times higher from 43 to 57 days and 40% lower from 57 to 72 days, thus the negative results in the previous period were compensated. The differences in the separate periods were statistically significant. Conducted microbiological examination of caecum and fresh droppings showed that on the day of discontinuing the probiotic treatment, the ratio of lactic acid to coli bacteria in the experimental group was in favour of the genus Lactobacillus, while 4 weeks later it changed in favour of the coli bacteria.