Quality of Eggs, Concentration of Lysozyme in Albumen, and Fatty Acids in Yolk in Relation to Blue Lupin-Rich Diet and Production Cycle

SIMPLE SUMMARY: Eggs are an integral part of many people’s diets. Laying hens are commonly fed on soybean meal, which is often genetically modified. It is possible to replace soybean in feed with other high-protein plants. Legumes, including lupins and peas, have the potential to be used in poultry nutrition. The quality of eggs for consumption depends on nutrition and the age of the laying hens. In our research, the goal was to assess the quality of eggs, including the content and activity of lysozyme and the content of fatty acids in egg yolk, depending on the provision of feed with 10%, 15%, 20% or 25% narrow-leafed (blue) lupin (cultivar Boruta) and 10% pea (cultivar Muza) during the laying period. The results show that feeding with lupin had a positive effect on egg yolk saturation, which is important to consumers. A beneficial effect of the proposed feed on the profile of omega-6 and -3 fatty acids and hypocholesterolemic acids was also found. In almost all proposed diets, there was no negative impact of the use of lupins on the weight and physical characteristics of eggs or the characteristics of lysozyme. Changes in egg quality during the laying period are associated with natural changes in the laying physiology of hens. The use of narrow-leafed lupins and pea seeds could be proposed as an alternative to soybean meal for laying hens in countries where the environmental conditions are not good for soybean production. This would offer a wider range of choices in the consumer market since, nowadays, products from animals raised on GMO feeds are not preferred. ABSTRACT: In recent years, the interest in lupin seeds as a source of protein in poultry nutrition has increased. The aim of this study was to assess the quality of table eggs produced by hens that were fed diets containing pea seeds and various levels of narrow-leafed lupin as a substitute for soybean meal. The share of lupin seeds in the treatment groups was 10%, 15%, 20% and 25%. Egg morphology, the fatty acid profile in egg yolk and the amount and activity of lysozyme in egg white were analysed. Results show that using 10–20% lupin seeds in feed in the diet of laying hens in intensive farming does not result in a change in weight or egg structure, their physical properties or their morphological composition. Increasing the share of lupin seeds in feed for laying hens increases the saturation of the colour of egg yolks, which is a desirable feature among consumers. The use of lupin seeds in feed for laying hens does not adversely affect the chemical properties of egg proteins, as expressed by the amount and activity of lysozyme. In feed for laying hens, replacing soybean meal with lupin seeds has a positive effect on the fatty acid profile in egg yolk (omega-3 and -6 polyunsaturated acids and hypocholesterolemic acids).