The aim of this study was to establish incubation values of eggs (egg fertilization, absolute and relative embryo mortality, and hatchability of male and female chicks), morphometric indicators (preincubation egg mass; length, width, and egg shape index; hatched female and male chicken mass and their relative share in the egg mass before incubation), and the phenotype correlation between some traits in the younger parent flock (YF33—33 weeks) and the older flock (OF49—49 weeks) of the light Institut de Sélection Animale (ISA) Brown hybrid. With regard to incubation values, the younger flock (YF33) demonstrated better incubation results than the older flock (OF49). The egg fertilization rate was 95.24 and 94.22%, respectively, chick hatchability as the percentage of the total of incubated eggs was 86.51 and 84.89%, respectively, and chick hatchability as the percentage of the total of fertilized eggs was 90.83 and 90.09%, respectively. Embryo mortality rate was 8.73 and 9.17% (YF33), and 9.33 and 9.91% (OF49). Regardless of the parent flock age, eggs that hatched female chicks had lower values of observed morphometric traits than those that hatched male chicks, except for the egg shape index (77.49–77.47%, respectively) which was higher by 0.02% in eggs which hatched female chicks, but this difference was not statistically significant (P > 0.05). Contrary to effects of the chick sex, the parent flock age had considerably larger effect on observed morphometric traits, as all morphometric indicators of eggs and hatched chicks of both sexes in the older flock (OF59) had statistically significantly higher values (P < 0.001) than in the younger flock (YF33). The only exception is the relative share of the chicken in the egg mass where the measured difference (−0.03%) was not statistically significant (P > 0.05). The phenotype correlation coefficients determined (rp) between the egg mass before the incubation period and the egg shape index were statistically significant (P < 0.01; P < 0001), except between the egg mass of eggs which hatched female chicks and the egg shape index in the young flock (YF33), whereby the calculated coefficient (rxy = 0.107) was not statistically confirmed (P > 0.05). Furthermore, the egg mass and hatched chicken mass of both sexes increased with the age of the parent flock, and statistically significant absolute phenotype correlation (P < 0.001) was determined between these two indicators.

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.

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 %).

The purpose of this review is to review the current state and achievements in poultry production in Serbia and worldwide, primarily the EU. Particular emphasis is placed on impacts of different rearing system, i.e. housing and fattening, on the production and the quality of the poultry meat and eggs and, simultaneously, on the welfare of poultry and environmental protection according to EU standards. According to the latest available data, total number of poultry produced in Serbia in 2015 was 17,450,000 units and production of meat amounted to around 86,000 t, while consumption was 12.12 kg per person. Egg production in 2015 was approximately 1.7 billion eggs, which is around 202 eggs per hen. A total of 13.1 million tons of poultry meat was produced in EU in 2015. It is evident from the literature that the poultry production in EU and worldwide has undergone significant changes, and clear criteria have been established to improve the quality of the products (meat and eggs), to guarantee the safety of the food, to protect the environment, and to ensure animal welfare in line with the relevant ethic norms. For these reasons, many countries within EU and worldwide, including Serbia, attach importance to housing systems for laying hens, with particular concern for animal welfare. Alternative housing systems (floor, aviary, free range and organic production) are increasingly used in the production of poultry meat and eggs instead of conventional systems. This is because it is considered that alternative housing systems may have positive effect on the productive traits of the poultry and, consequently, on the production of the quality organic meat. Furthermore, it is evident from research that pure (indigenous) breeds and strains are given growing importance in the production of organic meat and eggs in semi-intensive, semi-extensive and even in extensive rearing systems.