The aim of this work was to study the topography, morphology, vascularisation, histology and innervation of the lungs in the ground squirrel (Spermophilus citellus) and compare these data with those concerning the rat, mole rat, rabbit and mouse. The research was carried out on 15 animals. It was revealed that the right lung has four lobes (cranial, middle, caudal and accessory lobes), while the left lung is not divided into segments. The functional vessels are a. pulmonalis dextra et sinistra and vv. pulmonales (5–6), while the nutritive vessels of the lungs are a. bronchoesophagea dextra and v. bronchoesophagea dextra. Histological tissue sections of the lungs revealed that the wall of terminal bronchioles contains no cartilage and the mucosal epithelium is pseudostratified, cubic and ciliated. Clara cells (club cells, bronchiolar exocrine cells) are present but have no cilia. The lung alveolar diameter is 37 μm on average, and the thickness of the alveolar wall and the interalveolar septa is 1.38 μm. Destruction of the alveolar walls, accumulation of erythrocytes in the capillaries of alveolar septa and destruction of the cytolemma of the capillary endothelium were detected. In addition, connective tissue fibres and peripheral nerves were detected by silver impregnation.

The European Union in 2012 banned conventional battery cages for the welfare reasons. However, transition to new housing systems uncovered some new problems, such as keel bone damage (KBD), which also could endanger welfare of laying hens. Although KBD is a research topic which attracts a growing attention in the EU, in Serbia it is still rather unknown phenomenon, even among the scientific and professional community. This research is the first attempt to determine the prevalence of KBD in laying hens in housing systems currently existing in Serbia. The results of conducted monitoring show presence of KBD on all observed farms, except the organic one. The occurrence of KBD was at an acceptable level (from the standpoint of hen welfare) in the free-range system, enriched cages without equipment and conventional battery cages (4%, 3% and 1%, respectively), while in the fully equipped enriched cages it was high (39%). One could assume that this high prevalence of KBD in this system is a consequence of a long roosting on a metal perches.

SUMMARY Goose is a poultry species modest in terms of breeding conditions that enters breeding relatively late. These birds are characterised by the lowest production of eggs during the season, lower fertility and lower degree of hatchability than any other species of poultry. The productive and reproductive abilities of geese are dependent on genetic and numerous non-genetic factors. The right choice of the genotype, adequate application of breeding technology and incubation of eggs, as well as thoroughly planned selection, can greatly improve the reproductive properties of geese. Selection of genotypes and selection work for their improvement should be in accordance with regional breeding conditions, which allow maximum expression of genetic potential and conservation of animal genetic resources.

Intensive broiler chicken production involves different lighting regimes, which affects a natural cycle of secretion of melatonin, a hormone included in multiple physiological processes in a bird's body. This research aimed to determine the effects of dietary melatonin supplementation during the first two weeks of broiler chickens' life, bred under constant 24 h lighting, on their health and some hematological, biochemical, and production parameters. The study lasted 6 weeks. Three hundred and twenty 1-day chickens were divided into two groups (control - C and experimental - M), with four replications and 40 chickens in each replica. In the first two weeks (the first phase of the study), a continuous lighting mode 24L: 0D was applied. Group M was receiving a diet supplemented with 30 mg/kg synthetic melatonin only during the first phase. Group C had a diet without melatonin supplementation throughout the whole study. Melatonin addition had a statistically significant effect (P<0.01) on the mean values of body weight and daily weight gain at the end of the 1st, 2nd, 3rd, 4th, 5th, and 6th week. The chickens of the experimental group have had a significantly higher value of the European Production Efficiency Factor (EPEF) (P<0.05). The results presented in this paper indicate a direct benefit in stress relief in broilers and a value of the organism's antioxidant system promotion, manifested by improved production performance and fattening efficiency.

The first few weeks after broilers hatch are the period of most intense bone growth and development, and the time when they are most susceptible to the influence of various external and internal factors. Research in the recent decades has focused on the involvement of melatonin in bone development during early life in chickens. Melatonin release from the pineal gland has a circadian rhythm, with the highest levels circulating during the night and decreasing during the light phase of the day. Various types of lighting are used in intensive broiler production. In this study, the effects of melatonin on the tibial structure and growth of broilers were investigated. During the first two weeks of life, two groups of chickens were kept under continuous light and fed the same diet, with the experimental group receiving melatonin in the amount of 0.03 g/kg of feed. The results obtained showed that the addition of melatonin in the diet had positive effects on the development and growth of the tibia, which was expressed in a significantly greater thickness of the diaphysis and cortical bone of the diaphysis, higher breaking force and higher values of alkaline phosphatase activity. The cortical bone mineral density of the tibia did not differ significantly between the groups of chicken.