ABSTRACT This study investigated the effects of different levels (0.05, 0.1, and 0.2%) of yeast culture supplementation on body weight, feed intake, feed conversion ratio, egg production, egg weight, egg quality traits, egg yolk fatty acid composition, and microbiological flora in feces. A total of 240 laying hens at 18-19 weeks of age were divided into four groups and fed a basal diet containing 2750 kcal/kg metabolizable energy and 16% crude protein for 16 weeks. The basal diet was supplemented with 0.05, 0.1, and 0.2% commercial yeast culture product obtained from Saccharomyces cerevisiae. The different levels of yeast culture supplementation to the diets did not statistically affect body weight change among the treatments. However, feed intake was lowest in the group fed 0.2% of yeast culture. The highest egg weights were obtained from the groups fed 0.1 and 0.2% yeast culture, when compared with control group. Regarding fatty acid composition, linolenic acid (C18:2 n6) was lowest in the group fed 0.2% yeast culture. However, yeast culture supplementation to the diet did not alter the microbial flora. Yeast culture (S. cerevisiae) supplementation to the diet of laying hens is beneficial for increasing feed intake and egg weight of laying hens without affecting the microbial flora in their digestive system.

ABSTRACT The purpose of this study was to determine live weight and body measurements of male and female native ducks raised in different raising systems. One hundred and twenty native ducks (60 males, 60 females) were used in the study. The ducks were raised in deep litter floor and cage systems. Live weight and body values were measured every two weeks, until they were 56 days old. Three-parameter logistic regression and Gompertz model were used to determine growth model of male and female ducks. Interactions of time-raising system and time-sex were statistically significant in terms of live weight. At the end of eight weeks, live weights of ducks raised in deep litter floor were higher than ducks raised in cage system. In addition, live weights of male ducks were higher than female ducks. Consequently, deep litter floor is more appropriate for live weight in native ducks. Accuracy rate of Three-parameter Logistic and Gompertz models for estimation of growth in ducks was between 0.91-0.95 and similar results were obtained from both models. The Gompertz model is appropriate for the data structure of this study because it contains fewer iterations than the Three-Parameter Logistic model.