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The study of egg-laying patterns and defining ways of increasing egg-laying productivity is a necessary condition for the development and increased efficiency of ostrich breeding. Therefore, some studies deal with egg productivity of ostriches of different age groups (group 1 - age 8-9 years, group 2 - age 4-5 years) for their long-term keeping under a semi-intensive system forest-steppe zone of Ukraine. The sex ratio in the families was 1: 2-3. Behavioral patterns of poultry during the breeding season are close to natural ones. Older individuals are characterized with a longer productive period (January-October) than younger ones (March-September). According to the most extended daylight hours at this time of year, the higher level of egg-laying performance is established in May and summer months. The females’ egg-laying performance analysis shows their significant individual features - 9-42 eggs were obtained from one female. It is worth mentioning that the productivity period’s duration does not continuously regulate the number of eggs. There is a high positive correlation between the duration of the egg-laying process and total egglaying performance in group 1 (r = 0.7981); in group 2  there is no relation between these features (r = -0.0843). The variability of egg-laying cycles of ostrich females has been confirmed, and it requires further studies. According to the intensity of lying during the breeding season, there are differences between younger and older poultry groups. The first two months and the last month of egg-laying are the least productive for all. It was established that the egg weight of older females is higher compared to young ones, with a potential difference between the groups (P&gt; 0.999) and a significant level of individual variability (Cv = 1.78-8.06%). This indicates the necessity of successive work with the herd to optimize egg weight, as a significant variation in egg weight affects the duration of incubation and embryonic development of ostriches. It also leads to the elongation of the “hatch window” that causes heterogeneity of ostrich weight. New data allow characterizing the peculiarities of ostrich physiology, their ability to adapt to industrial conditions of breeding at farms located in the northern part of the forest-steppe zone of Ukrai.

Biological features of egg productivity of black African ostriches under a semi-intensive keeping