ABSTRACT:This study was carried out to investigate the effect of different body weight groups (light (L) = 1 400-1 500; medium (M) = 1 500-1 600 and heavy (H) = 1 600 < g) on performance and egg quality traits of Lohmann hens, 24 weeks of age, in different laying periods. A total of 288 Lohmann White layers were allocated randomly to three groups with respect to live weight, each consisting of 24 replicated cages as subgroups, comprising four hens. The study period lasting for 60 weeks was investigated as four different age periods (first period = 24-40 weeks; second period = 40-54 weeks; third period = 54-68 weeks; fourth period = 68-84 weeks). Differences in the initial live weight at the beginning of experiment among the groups continued to the end of experimental period. Considering the egg production, differences among the groups were not significant (P > 0.05) during the experimental period. Egg weight was determined to be lower in the group with low body weight (64.58 g) than in medium (64.97 g) and heavy hen groups (66.30 g). Differences in feed intake and feed conversion ratio among the groups were found significant, and the mean values were 123.93, 127.48 and 130.67 for feed consumption (g/day); 2.23, 2.28 and 2.27 for feed conversion ratio. Except for the feed conversion ratio, the effect of weight groups by age period interaction on performance parameters was significant (P < 0.01). The effects of body weight on shell strength, shell thickness and yolk index were not significant during the experimental period. However, different body weight groups significantly affected shape index, yolk colour, albumen index and Haugh unit parameters. Shell strength, yolk colour and yolk index values were affected by weight groups by age period interaction. In conclusion, Lohmann White hens in the light group in a uniform flock had higher egg production and lower feed conversion ratio values than those of other weight groups.

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The effect of probiotics in broiler feeding was investigated by evaluating poultry carcass meat quality. Feeds supplemented with different levels of a probiotic (0.0, 0.1 and 0.2%) containing Saccharomyces cerevisiae (115‐Biogallinox) were used in feeding Ross 308 male chicks for 49 days. At the end of the trial period all broilers were sacrificed. After standard dissection of the carcasses, breasts and drumsticks were divided into two groups and vacuum or aerobically packaged than stored at 3 ± 0.5C for 12 days. The breasts and drumsticks were analyzed for pH, thiobarbituric acid reactive substances (TBARS), total mesophilic, total psychrotrophic, lactic acid and Enterobacteriaceae counts every two days during storage. The feeding of probiotic in broiler diets increased pH values of breast and drumstick (P < 0.01) but TBARS, total psychrotrophic bacteria and Enterobacteriaceae counts decreased (P < 0.01). It was determined that pH, TBARS and Enterobacteriaceae counts were lower in breast than drumstick (P < 0.05); but lactic acid bacterial count was higher (P < 0.05) in the drumstick samples. The pH, TBARS and bacterial counts increased during storage (P < 0.01) except for total mesophilic bacteria. The pH, TBARS, total aerobic psychrotrophic bacteria and Enterobacteriacea counts were lower in vacuum than in aerobically packaged samples (P < 0.05).

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