The experiment was conducted to evaluate the influence of strain and age on some egg quality parameters (egg weight and egg shell strength) of commercial laying hens. Layers of lines ISA Brown and DeKalb White were examined in period of nine months. Both lines were at same age (28 weeks) and were confined in common facility in battery cages. Laying hens were reared and fed according to standard breeding technology. Once a month 25 eggs of each line were taken to be examined for eggshell strength and egg weight, or in other words, total 450 table eggs were tested. Analises were done in Laboratory for testing egg quality by gaudges Egg Multi Tester EMT 5200 and Egg shell Gauge (Robotmation Co. Ltd., Tokyo, Japan) which have computerised equipment to examine quality and physical characteristics of eggs. Statistic analyses on results were done by computer sub-programme ANOVA and Fisher's LSD test to determine the level of statistical significant difference between examined factors. Egg weight was under significant impact of age (P ? 0,05), but not under the influence of strain, although eggs of ISA Brown line were insignificantly heavier than eggs of DeKalb White line. Eggs were heaviest at layers with older age, while they were lightest at younger birds. The results have shown significant differences (P ? 0,05) in eggshell strength compared to line influence (genotype) and months of age. Eggs from ISA Brown laying hens had much better and eggshell strength than those eggs from DeKalb White. Correlations between eggshell strength and egg weight were with significant (R < 0,05) negative value, which indicating that with increasing egg weight decreases of eggshell strength.

The effects of ambient temperatures and hen's age were investigated on poultry farm on the south of R.Macedonia, where annually average temperature was higher then other regions. In nine-month period of testing were included summer, autumn and winter season. Two groups of hens (ISA-BROWN) were used; the first one was younger (to 45-week age) and second was older (above 45-weeks). Once a month, about 100 eggs were examined, so the final number of tested eggs was 877. Average shape index was 75.19% for all eggs. High significance (p<0.01) showed both factors: age and season. Eggs from younger hens had index value of 76.16%, which is pointed on eggs with rounded shape, while older hen's eggs had index 74.20% with elongated shape. In summer and autumn season, most of eggs were with elongated shape, while rounded shape had eggs in winter season.

Significantly higher adiponectin levels were found in AGA neonates compared to SGA neonates. Leptin and adiponectine levels were positively correlated with birth weight. These findings suggest that these adipocytokines may be involved in fetal growth regulation.

This research was conducted with aim to establish genotype influence on eggshell strength of fertilized eggs and its hatchability at parents stock flock of laying type. Eggs from parent's flock of lines ISA Brown and DeKalb White at age of 36-60 weeks were examined. Experiment lasted 6 months, and once a month were examined samples of 30 fertilized eggs. Results have shown significant differences (P ≤ 0.05) in eggshell strength related to genotype influence. Eggs with brown eggshell from line ISA Brown (P ≤ 0.05) had significantly more strength eggshell compared to eggs with white eggshells from line DeKalb White. Results from the analyses of breeding eggs hatchability, examined in the mentioned period have shown that this variable was mainly influenced by age, then by genotype. Eggs of older birds were lower hatchability compared to fertilized eggs produced of younger parent stock flock during the examination period.

The paper presents in short the situation, problems and perspectives of poultry production in the Republic of Macedonia. It has been found that in the last ten years there is a continuous stagnation of poultry breeding, and the reasons for that are: generally very poor economic conditions, the very long period of transition and privatization, and the low living standard. Once a state with high-developed poultry production within the former Yugoslavia when it supplied 30% of the Yugoslav needs for eggs and exported live material (chicks one-day old and pullets), Macedonia today experiences a rapid fall in the production of eggs, while the production of poultry meat as if doesn't exist at all. The needs of the population for chicken meat are satisfied in 94% through import of frozen meat from many countries in the world, which do not meet the required quality standards. A complete revitalization of poultry production is necessary through a series of measures outlined in the paper. Their implementation will contribute to overcoming all the objective and subjective difficulties because the Republic of Macedonia has the necessary resources for the development of poultry breeding which in the future would provide sufficient products for the domestic population, but also for export, especially of products from alternative systems of poultry farming.