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Abstract. The trial involved 684 Cobb 500 broiler chicks in order to investigate the effects of probiotics and phytogenic additives on performance, gut morphology and cecal microbial concentrations. Birds were assigned to three treatments: control feed, treatment with addition of probiotics in feed and water and treatment with addition of phytogenic blend in feed. The results showed a significant improvement (P<0.01) in body weight gain and a numerical, but non significant (P>0.05) improvement in feed conversion ratio by adding both probiotics and phytogenics in feed. There were no statistically significant differences among treatments regarding total aerobes, anaerobes, lactic acid bacteria, bifidobacteria, enterococci, and Escherichia coli populations (P>0.05) in cecum of broilers. The gut morphology examination showed that probiotics had beneficial effect on jejunum morphology causing a significant (P<0.005) increase in villus height and villus surface area compared to other two groups. On the other hand, phytogenic additive had no effect (P>0.05) on villus height or villus surface area, but reduced the villus/crypt ratio (P<0.05), which may indicate that the improved production results in the group with added phytogenics are not directly connected with changes in gut integrity, but with other physiological mechanisms.

Abstract:In this work quantity of abdominal fat (weight and portion) was examined in broilers of two genotypes in the fifth, sixth and seventh week of their growth. The examination was carried out in production conditions, in the facility for commercial fattening of broilers chickens, so all technical recommendations related to intensive rearing of chickens were provided. Broilers Cobb 500 and Hubbard Classic which were housed in separate boxes (8 boxes for each genotype) were used as a material. Forty male chickens and forty female chickens at the 5, 6 and 7 weeks of age were selected for slaughtering by random selection, so 240 all together sacrificed chickens were prepared for further treatment. By cutting of the carcasses, abdominal fat was removed and measured, and it was put in proportion to the body mass before slaughtering and in this way the share of abdominal fat was obtained. All data was statistically processed by the subprogram Basic Statistic and Anova. The chickens of the genotype Hubbard had significantly higher share (0,96%) and insignificantly higher weight (19,47g) of abdominal fat than Cobb 500 (0,83% and 17,16g). Female chickens of both genotypes in the examination had significantly higher weight (19,84g) and share (0,96%) of abdominal fat in carcass then male broilers. Chickens at the age of 49 days had statistically significantlly higher abdominal fat than the chick at the age of 42 and 35 days in absolute (25,35g) and relative values (1,06%). This confirms the importance of the examined factors on the amount of abdominal fat in carcass of broiler chickens.

Microorganisms could play an important role in adaptation strategies and increase of tolerance to abiotic stresses in agricultural plants. Plant-growth-promoting rhizobacteria (PGPR) mitigate most effectively the impact of abiotic stresses (drought, low temperature, salinity, metal toxicity, and high temperatures) on plants through the production of exopolysaccharates and biofilm formation. PGPR mitigate the impact of drought on plants through a process so-called induced systemic tolerance (IST), which includes: a) bacterial production of cytokinins, b) production of antioxidants and c) degradation of the ethylene precursor ACC by bacterial ACC deaminase. Symbiotic fungi (arbuscular mycorrhizal fungi) and dual symbiotic systems (endophytic rhizospheric bacteria and symbiotic fungi) also tend to mitigate the abiotic stress in plants

In broiler production, stocking density, i.e. floor surface per chicken, is very important welfare factor which directly and indirectly influences and determines the level of growth of chicken body weight, but it is also related to other welfare indicators. Objective of the paper was to define the broiler welfare in different stocking densities by evaluation of their walking ability (gait score), feathering, incidence and degree of hock burns, foot pad lesions, and by determination of the biochemical blood parameters (glucose concentration, total cholesterol concentration), as indicators of condition of stress. One day old chickens of Hubbard genotype were housed in boxes in floor rearing system, in 3 stocking densities and 5 repetitions of each treatment. Treatment A scored stocking density of 10 birds/m 2 ; treatment B, 13 birds/m 2 and treatment C, 16 birds/m 2 . Results of the trial indicate absence of significance of differences between trial groups of broilers in regard to their walking ability, condition of skin and legs, and stress indicators. In general, broiler welfare in all trial groups was satisfactory. However, determined tendencies of worsening of the condition of litter, increase of the frequency of lower scores for walking ability (gait score), hock burns and foot pad lesions which occur with increase of stocking density, indicate the importance of this rearing factor and need to define limiting stocking densities from the aspect of broiler welfare but also economical efficiency of production.