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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Bedding material, which is a significant part of rodent housing, affects the health and well-being of laboratory animals. The aim of this study was to evaluate perlite as a bedding material for rodents and to compare it with wood shavings, expanded perlite and corncobs. The animals used in this experiment were 48 male and 48 female Sprague-Dawley rats. The bedding materials collected from experimental groups were analysed microbiologically. Blood samples from rats were subjected to biochemical analysis for catalase, glutathione, glutathione peroxidase, malondialdehyde, superoxide and dismutase, and foot pad skins of rats were subjected to histopathological examination. Body weight was determined at the end of the 30-day period. Perlite as the only bedding material had no effect on body weight, and it resulted in less microbial activity compared with the wood shavings, expanded perlite and corncobs. However, using perlite alone had negative effects on the skin, the moisture percentage of bedding and stress parameters. A wood shavings-perlite combination gave better results than perlite alone and appropriate perlite and other bedding material mixtures may result in bedding materials conducive to animal health and welfare. The frequency of changing the bedding material should be limited to once weekly.

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It is known that inflammatory organ damages due to various agents, such as microorganisms including mycoplasmas, lead to oxidative stress. Nitric oxide (NO) functions as an antimicrobial agent, and arginase decreases proinflammatory cytokine release. There are very few studies on arginase activity, NO level and oxidative stress status in mycoplasmal infections. Therefore, the aim of this study was to evaluate erythrocyte arginase activity, plasma NO level and oxidative stress status in sheep with contagious agalactia. The study material consisted of 10 healthy sheep and 14 sheep with contagious agalactia characterised by mastitis, arthritis and keratoconjunctivitis. Erythrocyte arginase activity, plasma NO, malondialdehyde (MDA), total oxidant capacity (TOC) and total antioxidant capacity (TAC) levels were measured. Significant decreases in erythrocyte arginase activity and plasma TAC level (P < 0.001), and significant increases in plasma NO, MDA and TOC levels (P < 0.001) were found in the diseased sheep as compared with the healthy animals. This study suggests that contagious agalactia may cause oxidative stress due to increased plasma MDA and TOC levels and decreased plasma TAC levels, and that the decrease in erythrocyte arginase activity and increase in plasma NO level may contribute to the elimination of mycoplasmal agents causing contagious agalactia.