Poultry production is one of the most intensive sectors of animal production providing a significant source of animal protein through meat and eggs. However, increasing production intensity has brought challenges related to animal health, welfare, and product quality. In chickens (Gallus gallus domesticus), the sterno-pectoral region represents a key anatomical and functional unit that supports the birds’ body and is essential for locomotion and respiration. This region is particularly susceptible to the adverse effects of intensive selection and production in both broilers, i.e., meat production, and laying hens, i.e., egg production. Skeletal disorders of the sternum, predominantly observed in laying hens, and breast muscle myopathies, primarily affecting broilers, are typically investigated as separate conditions. However, their anatomical co-localization, shared developmental background, and common risk factors suggest they should be considered within a unified framework. The aim of this review is to integrate the current knowledge on skeletal and muscular disorders of the sterno-pectoral region, with emphasis on their interrelationships, underlying mechanisms, and implications for production efficiency and animal welfare. By identifying this region as a critical hotspot for production-related pathology, this review offers a more comprehensive perspective on the biological limits of intensive poultry production and highlights the importance of an integrated approach as the foundation for developing future breeding and production strategies.

The production and reproductive capacity of geese depend on a number of non-genetic factors in addition to genetic factors. The production and reproductive performance of a flock often depends on the influence of non-genetic factors present in the rearing of the flock, such as: applied breeding technology, period of exploitation, age of the flock, body weight of the birds, nutrition, fertility of the males, weight and quality of hatching eggs, and technological procedures during the incubation of the eggs. Productive and reproductive characteristics of geese can be significantly improved by appropriate application of egg production and incubation technology. The application of appropriate breeding technology should be in accordance with the genotype being bred and specific regional growth conditions that allow maximum expression of genetic potential.

The main purpose of the study was to determine the effect of egg mass and egg weight groups (group I eggs under 160 g, group II eggs160 g to 180 g and group III eggs over 180 g) on incubation results, loss of egg weight (moist) during incubation, gosling hatchability, and the relative share of the gosling in the egg mass. A well fertilized egg is an embryo "package" with all the necessary nutrients that facilitate its development until it is hatched and for a few days after hatching. The results of poultry offspring production, i.e., poultry embryo development, depend during its embryonic development, – apart from its genetic basis, – on several non-genetic factors. Eggs with mass between 160 g and 180 g (group II) demonstrated the highest fertilization rate (91.28%) and the highest hatchability out of the number of incubated eggs (83.14%), while the eggs from the group I (lighter than 160 g) showed the highest number of gosling hatchability out of the number of fertilized eggs (91.08%). The lowest embryo mortality was that of group I (5.17% and 6.06%), while the highest is reported for group III (14.29% and 16.67%). The lowest relative loss of egg mass (moist) by day 25 of the incubation period was established for the group I eggs (10.98%), and the highest for the group III (11.71%), with a statistically significant (P<0.01) difference of -0.73 %. Other differences were not statistically significant (P>0.05). The gosling percentage in the egg mass was significantly higher (P<0.001) in the group III of incubated eggs (67.81%) than in group II (66.61%) and group I (65.24%). The relative gosling percentage according to the egg mass grew with the increase of the egg mass, which to a certain extent agreed with our findings, except that these authors reported a considerably lower gosling percentage.

The aim of the study was to examine the influence of the rearing system and age on the phenotypic correlation of the physical properties of the eggs of the Banat naked neck layers. In both examined systems (extensive and semi-intensive system) there were 50 Banat naked neck layers each. The egg properties were examined at three evenly distributed time intervals (40, 45 and 50 weeks of age) in the period from May to July. In order to determine the external properties of egg quality, three basic measures were observed: egg weight, egg length and egg width. Based on the measured length and width of the eggs, the egg shape index was calculated, and subsequently the volume and surface area of the eggs were determined. For each examined factor, the correlation between the mentioned characteristics was determined. The obtained results showed a significant effect of the rearing system on all examined egg properties (R < 0.05), while the influence of age as well as the interaction of the two examined factors had no significant effect. The highest correlation among all investigated factors was found between surface area and egg volume.

Prolonged training and physical effort in endurance horses can influence the performance of the endurance horses negatively. The negative impact of the event is especially noticeable if venues are demanding, i.e. bad weather conditions or demanding grounds, high altitude and especially in cases of insufficiently fit horses. One of the most important factors that influence equine performance is abundance of oxygen in the blood, which is directly related to the air oxygen content and changes with atmospheric pressure, so that high altitude and low air pressure demand additional work from horses and accelerate fatigue. The authors goal was to investigate the influence of workload in endurance racing on sport horse organism. A total of 18 trained and competing endurance horses enrolled in a 60 km long endurance race organized on Zlatibor Mountain were included in our survey. Due to the difficult track 8 horses were disqualified due to lameness, and high heart rate and respiration. Only 10 horses completed the race and these animals were submitted to basic physical, clinical and laboratory examinations, in order to evaluate fatigue and stress reaction in endurance horses in Serbia. Results of the clinical and laboratory testing obtained show significant changes in all parameters evaluated which we attributed to physical effort in all 10 horses that finished the race in comparison with the values obtained before the race. In conclusion, 10 horses finished the race and were tested, and they indicated significant alterations in physiological parameters showing stress reaction. The evaluated parameters decreased into physiological interval values during the 5 days following the race.

Meat is a product formed from skeletal muscles of animals through different biochemical processes following rigor mortis. Therefore, characteristics of muscle tissue, its structure, number, diameter and percentage of different muscle fiber types would greatly determine the quantity and the quality of meat. Having in mind that selection and nutrition led to nearly a maximum in meat production, and consumers are having higher and higher demands for „organic“ products, products from more natural production, their concern for animal welfare is rising, the implementation of physical activity in animal rearing could be of more importance in the future. Physical activity could imply outdoor systems, or semi-confinement systems with enriched environment. Also, the impact of this factor could be of higher importance in pigs and chicken, where intensive selection towards lean meat content increased the number of glycolytic fibers in muscles, leading to more pronounced problems with meat quality (PSE meat).

Abstract The aim of this paper was to examine the biochemical and haemological parameters of blood as well as the quality of breast meat of 45 pheasants. The pheasants were divided into three groups and fed by mixtures with the organic selenium supplementation in concentrations of 0.2 mg/kg (I group) and 0.3 mg/kg (II group)and with mixture without selenium in a control group (K). After 60 days of the experiment duration it was determined that the average values of selenium content in the breast meat in blood serum of II group pheasants which were fed with 0.3 mg/kg of organic selenium were significantly higher (p>0.05) in comparison to the same parameters of pheasants of the control K group. The pheasants of II group also had better sensory traits of meat and they achieved the highest difference of the sum of the ranks of the meat acceptability. The difference was by 15 points higher than in the control K group and 7 points higher than in meat of the pheasants I group fed with 0.2 mg/kg of selenium. Adding of organic selenium in the food of II group pheasants (0.3 mg/kg) had a positive effect on increasing the water retention capacity in breast meat by 0.75% compared to the control group, namely by 0.58% in comparison to I group. Average values of chemical parameters of meat (pH, water, fat, proteins and ash content), haematological parameters of pheasants blood (number of erythrocytes, leucocytes and platelets, haemoglobin and haematocrit values) and biochemical parameters of blood serum ( glucose, enzymes AST and ALT), total protein concentration, total cholesterol albumin, triglycerides, Ca, K and Na) were within the limits of reference values for pheasants and very uniform values without significant differences among examined groups.

The purpose of this study was to determine the effects of age and sex of the foal on the gestation length of thoroughbred mares. The study covered six stallions (of average age of 10.25 years) and 34 mares (of average age of 10.51 years) with descent records (pedigree), English Thoroughbred horses raised and actively used for breeding at a study farm called Ljubičevo, located in Serbia. The following average morphological body measures were established: body weight (473.10 kg), withers height (159.55 cm), body length (160.54 cm), chest circumference (188.00 cm), and tibia circumference (19.21 cm) were found to be within the scope of standard measures for this breed and particular ages e.g. 9 to 15. The average gestation length, regardless of the sex of the foal, was 336.57 days. The gestation of mares carrying male foals was somewhat longer (337.70 days) than of mares carrying female foals (335.80 days). The difference (1.90 days) in gestation length was not statistically significant (P>0.05). A weak positive correlation (rp=0.321) was observed between the age of the mare and the gestation length (regardless of foal sex). Additionally, a medium correlation (rp=0.444) was observed between the mare's age and the gestation length in the case of male foals, and a very weak correlation (rp=0.210) in the case of female foals.

This study presents research results of quality and incubation values for Isa Brown hybrid eggs.Eggs were produced in the 33rd week of age at the production peak.Research was conducted on the sample of 252 incubation eggs (240 fertilized eggs).Chick hatchability compared to the number of inserted eggs was 86.51%, and compared to the number of fertilized eggs 90.83%.Average values for quality parameters of brooding eggs and incubation results were as follows: egg weight before insertion 58.41 g, egg length 5.49 cm, egg width 4.29 cm, egg shape index 78.16%and egg volume 53.14 cm 3 , one day old chick weight was 39.15 g, absolute egg weight loss was 6.60 g, relative egg weight loss was 11.31% and relative chick share in the egg weight was 67,03%.Statistically justified (P<0.001;P<0.01; P<0.05) correlation (complete one) was determined between egg weight and egg width (0.908), egg weight and egg volume (0.923) and egg weight and chick weight (0.918), very strong correlation was determined between egg weight and egg length (0.870), strong correlation was determined between egg weight and absolute egg weight loss (0.690), weak correlation was determined between egg shape index and egg width (0.395), and very weak correlation was determined between egg weight and egg shape index (0.188), egg weight and relative egg weight loss (-0.166), egg shape index and egg length (-0.147) and egg shape index and chick weight (0.189).Between egg weight and relative chick share in the egg weight, egg shape index and absolute egg weight loss, egg shape index and relative chick share in the egg weight no statistically justified (P>0.05)correlation was determined.

The main purpose of the study was to determine the effect of egg mass and egg weight groups (group I eggs under 160 g, group II egg mass 160 g to 180 g and group III eggs over 180 g) on incubation results, loss of egg weight (moist) during incubation, gosling hatchability and the relative share of the gosling in the egg mass. Eggs with mass between 160 g and 180 g (group II) demonstrated the highest fertilisation rate (91.28 %) and the highest hatchability out of the number of incubated eggs (83.14 %), while the eggs from the group I (lighter than 160 g) showed the highest number of gosling hatchability out of the number of fertilised eggs (91.08 %). The lowest embryo mortality was that of the group I (5.17 % and 6.06 %), while the highest is reported for the group III (14.29 % and 16.67 %). The lowest relative loss of egg mass (moist) by day 25 of the incubation period was established for the group I eggs (10.98 %), and the highest for the group III (11.71 %), with a statistically significant (P Lass Than 0.01) difference of -0.73 %. Other differences were not statistically significant (P>0.05). Gosling percentage in the egg mass was significantly higher (P Lass Than 0.001) in the group III of incubated eggs (67.81 %) than in the group II (66.61 %) and the group I (65.24 %).

Research was conducted on two broiler parent flocks of Ross 308 and Cobb 500 hybrids.At the beginning of productive cycle (24 weeks of age) for Ross 308 hybrid average body weight of laying hens was 2680.40g, while for Cobb 500 hybrid it was 2697.80g.In the middle of the productive cycle (42 nd week) body weight was 3565.10 g (Ross 308) and 3599.05g (Cobb 500), while at the end of productive cycle (61 st week) body weight for Ross 308 hybrid was 3841.50 g, and for Cobb 500 3850.00g.Determined differences in body weights of laying hens in specific periods of productive cycle (17.40g, 33.95 g and 8.50 g), as well as difference in weight for entire productive period (23.26 g) were not statistically significant (P>0.05).More thorough research of broiler laying hen body weight influence on productive performances was done by determining phenotype correlation coefficient between researched parameters.Therefore between hen body weight and most of productive parameters statistically significant (P<0.001;P<0.01; P<0.05) phenotype correlation coefficients were determined, while between body weight of laying hens and laying intensity of breeding and fertilized eggs determined correlation coefficients were not statistically significant (P>0.05).

Certain investigations have been conducted in two broiler breeder flocks of Ross 308 and Cobb 500 hybrids. At the beginning of the production cycle (24 weeks of age), an average laying hens? body weight of 2680.40 g was found in the case of Ross 308 hybrid, and 2697.80 g in the case of Cobb 500 hybrid. During 42nd week of age (the middle of the production cycle), the body weight of laying hens was 3565.10 g (Ross 308) and 3599.05 g (Cobb 500), while at the end of the production cycle (61 weeks of age) the body weight of laying hens of Ross 308 hybrid was 3841.50 g, and 3850.00 g of Cobb 500. Identified differences in body weight of laying hens (17.40 g, 33.95 g, 8.50 g) in certain periods of the production cycle, as well as the difference in body weight of laying hens for the entire production cycle (23.26 g) were not statistically significant (P>0.05). More specific observation of the effect of body weight of laying hens on productive capacity of broiler breeders was determined by calculating the coefficients of phenotype correlation between the indicators studied. Thus, statistically significant (P<0.001, P<0.01, P<0.05) coefficients of phenotype correlation between the body weight of laying hens and the majority of production indicators have been determined, while statistically significant (P<0.001, P<0.01, P<0.05) correlation coefficients between the body weight of laying hens and the intensity of laying capacity for hatching and fertilized eggs have been determined, but for a shorter period of the production cycle.

Examinations were conducted in two flocks of broiler parents' hybrids Ross 308 and Cobb 500. At the beginning of the production cycle (24th weeks of age) was determined that the average hens body weight of hybrid Ross 308 was 2680.40 g, and to hybrid Cobb 500 was 2697.80 g. At 42nd weeks of age (middle of the production cycle) hens body weight was 3565.10 g (Ross 308) and 3599.05 g (Cobb 500), while at the end of the production cycle (61st weeks of age) hens body weight of hybrid Ross 308 was 3841.50 g, and to the Cobb 500 was 3850.00 g. Determined differences of hens body weight (17.40 g, 33.95 g and 8.50 g) in specific periods of the production cycle, and the difference in hens body weight for the entire cycle (23.26 g) weren't statistically significant (P>0.05). Specific consideration of the impact of hens' body weight on reproductive performances of broiler parents was determined by calculating the coefficients of phenotypic correlation among the tested indicators. Thus, between hens body weight and most reproductive indicators of broiler parents were determined statistically very significant (P<0.001) coefficients of phenotypic correlation, while between hens body weight and the percentages of chickens feasibility from fertilized eggs were determined significant (P<0.001; P<0.01; P<0.05) correlation coefficients for a slightly shorter period than anticipated production cycle.

This study was to determine how to investigate the effect of using triticale on growth performance, production and slaughter characteristics of broiler chicks.The research was carried out on 400 for feeding chickens, hybrid Ross 308.The first diet was the standard starter, grower I, grower II and finisher and served as control.The other rations contained 7.5%, 12%, 15% and 18% triticale as graded replacement for maize and wheat.The experiment lasted eating chicken 49nd days.Based on recorded productive traits of examined chicken groups in this investigation conclusion can be drawn that the best results is achieved C-group of chicken for mortality, feed conversion, production index, average body weight of chicken before butchery, handled and cooled carcass weight after 49 days of age.

Balkan donkey is native breed of donkeys evolutively adapted to modest breeding conditions and different climatic systems including harsh and severe climate of Serbian mountains. Unfortunately, the purposes for breeding small donkeys have been lost during the 20th century so the population is regressing. There has been no selective breeding of the autochthonous donkeys in Serbia therefore the data on breed characteristics are recent and few. The monitoring of morphological characteristics of autochthonous Balkan donkey population in Serbia have been performed in aim to characterize the population and to define the importance of autochthonous donkeys as national genetic resource . The morphometric parameters evaluated i.e. height at withers (HWi) body length (BLe), thorax girth (TGi), cannon perimeter (CPe) and body weight (BW) in young Balkan donkeys bred in traditional conditions were used for establishment of the following body indexes: Index of Body Frame (IBF), Index of Body Compactness (BCI), Index of Conformation (CoI) and Dactyl-costal Index (DCI) reflecting body development and conformational relations in Balkan donkey population in Serbia.

The influence of triticale as feed on the production and carcass traits of chickens is investigated in this paper. The study was conducted on 200 chickens for fattening, hybrid Ross 308. In the experiment, two groups, or treatments, were formed, with 100 chickens in each group. One group was the control group K, with the classical mixture fed to broilers, and the other one was the experimental O-group of chickens fed diets containing triticale genotypes Kg 20. The first diet was the standard starter, grower I, grower II and finisher and served as control. The other rations contained 7.5%, 12%, 15% and 18% triticale as graded replacement for wheat. During the fattening period, health conditions of broilers were periodically monitored, and the following fattening traits as well: weight gain (individual measurements of all the chickens once a week), feed intake and mortality. The feeding trial lasted for 42 days. Feed and water supply for chickens was ad libitum applying floor housing system. Since the yield of carcass as well as the yield and share of some meat categories of cold carcass dressing are very important factors of quality, the influence of feeding treatments on some mentioned traits was monitored. The results showed that the chickens in the control group (K), which were fed a mixture of standard feed, had slightly better productive results compared to chickens in the experimental groups (O), which were fed diets containing triticale. The average body weight of broiler chickens at 42 days of fattening was higher in chickens of K-group - 1896.875 g, and slightly lower in broiler chickens fed triticale - 1846.684 g. By the end of the experimental period (42 days) the highest feed consumption per chicken was recorded in the control group of chickens (4.332 kg). The experimental group of chickens which were fed classical diets had lower mortality throughout the experimental period.

Investigation of the effect of body weight on reproductive performance of hens of broiler breeders was conducted in the hybrid Ross 308 and Cobb 500. At the beginning of the production cycle (24 weeks old) with hybrids Ross 308 determined the average body weight of hens 2680.40 g and 2697.80 g Cobb 500. After 42 weeks of age (mid-production cycle) weight hens was 3565.10 g (Ross 308) and 3599.05 g (Cobb 500), while at the end of the production cycle (61 weeks old) weight layers in the hybrid Ross 308 was 3841.50 g, and Cobb 500 3850.00 g. The differences found in body weight of laying hens (17:40 g, 33.95 g 8:50 g) in certain periods of the production cycle, and the difference in body weight of hens for full production cycle (23:26 g) were not statistically significant (P> 0.05). Specifically assess the influence of body weight on reproductive performance of hens of broiler breeders was determined by calculating the coefficient of phenotypic correlation between the studied parameters. Thus, the association between body weight and most hens reproductive indices of broiler breeders was positive statistically significant (P 0.05), and between the layers of body weight and relative weight loss of eggs, but statistically significant (P <0.001).

In this research influence of the rooster body weight on reproductive performance of broiler parents was examined for Ross 308 and Cobb 500 hybrids. At the beginning of the productive cycle (24 weeks of age) for roosters Ross 308 hybrids average body weight of 3,030.00 g has been determined, while for Cobb 500 rooster average body weight was 3,045.00 g. In the 42nd week of age (middle of productive cycle), body weight of Ross 308 roosters was 4,306.00 g and 4,323.00 g for Cobb 500 roosters, while at the end of productive cycle in the 61st week of age Ross 308 hybrids had average 4.908,00 g and Cobb 500 had 4,918.50 g. Determined differences in body weight of roosters (15.00 g, 17.00 g and 10.50 g) in specific periods of productive cycle, as well as difference in body weight for the entire productive cycle (19.97 g) were not statistically significant (P>0.05). Between rooster body weight and fertilized eggs laying intensity positive statistically significant (P<0.001; P<0.01; P<0.05) correlation coefficients were determined. Between rooster body weight and hatchability percentage of the chicks positive statistically significant (P<0.001; P<0.01; P<0.05) correlation coefficients were determined for both hybrids. However, based on correlation coefficient it has been determined that rooster body weight had positive influence on laying intensity of fertilized eggs till 58th week of age (Ross 308) and 60th week of age (Cobb 500), while on hatchability of chicks it had positive influence till 58th week of age for both hybrids.