The studies investigated the effect of soya oil and various doses of a fermented water-soluble lipid complex in a standard compound feed, which included maize, soya meal, sunflower meal, wheat bran and wheat middlings, limestone, monocalcium phosphate, table salt, baking soda, L-lysine, choline chloride, DL-methionine, L-threonine, an adsorbent, and a vitamin-mineral mixture. Throughout the experimental period, egg production and feed consumption were recorded, and the live weight, physiological condition and survival rate of the flock were monitored. The eggs obtained were weighed and their morphometric parameters determined: egg weight, weight of the white, yolk and shell, shell thickness and strength, shape index, viscosity coefficient, pH of the white and yolk, and refractive index. The total lipid content and the levels of vitamins A and E were determined in the egg yolks. Research findings indicate that egg-laying in hens from all experimental groups began at 115 days of age, and by 140 days of age, the laying rate stood at 39,50–42,35 %. Egg production peaked at 200 days of age, reaching 95,30–96,80 %, and remained at a high level until 320 days of age (94,50–95,75 %). On average, over the entire experimental period, which lasted until the hen reached 450 days of age, the laying rate was 84,23–85,79 %. The highest productivity was observed in hens of experimental group III, which received 1,0–1,3 % of a fermented water-soluble lipid complex. The morphometric parameters of eggs in all experimental groups were approximately at the same level and in accordance with physiological norms. During the period of peak egg-laying intensity, egg weight ranged from 60,15 61,85 g. The highest egg weight was recorded in experimental groups III and IV, where 1,0–1,6 % of a fermented water-soluble lipid complex was added to the diet. During the study period, 15,97–17,09 kg of egg mass per hen was obtained from the laying hens. In the egg yolks of hens in experimental group III, the content of total lipids, vitamin A and vitamin E was higher than in the control group by 8,10 %, 5,81 % and 10,71 % respectively. The live weight of the laying hens throughout the experiment corresponded to the standard values for the Loman LSL-Classic cross. Consequently, replacing soya oil in the diet of laying hens with a fermented water-soluble lipid complex is both practical and cost-effective. The use of this feed additive ensures high levels of productivity and egg quality, while its cost is 24 % lower than soya oil.

Keywords: laying hens, productivity, morpho metric parameters, soya oil, water-soluble lipid com plex, egg yolk, total lipids, vitamins A and E.