The aim of the study was to compare the mineral content between the peel and the pulp of citrus fruits and to determine which citrus fruit, among orange (Citrus sinensis), pomelo (Citrus maxima), mandarin (Citrus reticulata Blanco), lemon (Citrus limon), key lime (Citrus aurantifolia), and red, yellow, or green grapefruit (Citrus paradisi), is the richest in minerals. The research material consisted of fresh citrus fruits belonging to the genus Citrus L in the family Rutaceae. The fruits were purchased at a supermarket at one time. To prepare laboratory samples, each fruit was cut in half, and one half was homogenized, treating the sample as a whole (peel + flesh), while the other half was peeled and the pulp (F) and peel (P) were homogenized separately. To determine the content of minerals (Na⁺, K⁺, Ca⁺², Mg⁺², Fe⁺², Zn⁺², Cu⁺², Mn⁺², and Se⁺²), the samples were mineralized and analyzed using an Analytik Jena PlasmaQuant PQ 9000 inductively coupled plasma optical emission spectrometer. The content of macro- and micronutrients in the peel of most of the fruits far exceeded their quantity in the pulp. Oranges and pomelos are the fruits richest in iron and copper, so they could be recommended in cases such as hemoglobin production disorders resulting from a deficiency of these elements. Oranges can additionally enrich the body with potassium, phosphorus, and manganese, while lime can be a source of calcium, zinc, sodium, and especially potassium. It should also be noted that all citrus fruits are a very valuable source of potassium, which is needed to ensure the water and electrolyte balance.

The use of whole citrus fruits in the food industry means that the valuable peel is used, but this may raise palatability or health concerns among consumers. The content of sugars, dietary fibre, redox compounds, lead, and cadmium was compared in citrus fruits (orange; pomelo; mandarin; lemon; key lime; and red, yellow, and green grapefruit). The pulp of all fruits contained significantly less fibre, tannins, and phenolic compounds than the peel. Whole citrus fruits had significantly lower content of sugars and higher content of dietary fibre and phenolic compounds, including ferulic acid, than their pulps. Whole grapefruits had higher concentrations of ascorbic acid. Whole lemons, limes, and mandarins had higher antioxidant potential than their pulp, due to their higher content of ascorbic acid, tannins, and phenolic compounds. Lead and cadmium content in whole fruits, while higher than in the pulps, was well below the acceptable daily intake.

This study was to assess the effect of fermented rapeseed meal (FRSM) in the diet of sows, taking into account the physiological period (pregnancy or lactation) and reproductive cycle (primiparous or multiparous sows), on production performance, nutrient digestibility, colostrum immunoglobulin content, and microbial flora in sows. The experimental material included 30 primiparous gilts and 30 multiparous sows after their second lactation. The animals in the control groups CG (gilts) and CS (sows) received a standard diet for pregnant or lactating sows, depending on the reproductive period. Experimental groups EG and ES comprised gilts and multiparous sows, respectively, receiving a diet with a 4% share of FRSM in place of soybean meal up to 100 d of gestation. In addition, from 100 d of gestation to 7 d of lactation, the sows in experimental groups received a diet with a 9% share of FRSM, and then again a diet with a 4% share of FRSM until the end of lactation. The addition of 4% to 9% share of a FRSM component in feed significantly improves production parameters, mainly in primiparous gilts, leading to an increase in litter size and in litter weight at 28 d of age. It also helps to improve the digestibility of crude protein, fat, and crude fiber, and positively affects the gut microbiota of sows. Fermentation of rapeseed meal is an effective way to reduce anti-nutrients and to increase the level of lactic acid in the diet. It also stimulates the immune system, which improves piglet health, reducing the severity of diarrhoea and mortality.

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Due to exposure of animals to numerous stress-inducing factors and a high level of cellular metabolism resulting from the conditions and manner in which they are raised, destabilisation of the redox balance towards excessive activity of free radical species is a common phenomenon. Enhancing the antioxidant status of the animal organism by optimising the level and quality of feeding, and especially by supplementation with exogenous antioxidants, may be one essential and highly effective means of improving the health and thus the productivity of animals. Natural plant supplements in diets for poultry can be used to enhance antioxidant defence mechanisms and reduce the intensity of oxidation processes, which negatively affect the quality of poultry products, i.e. meat and eggs. Analysis of the available studies shows that antioxidant processes in the organism of birds can be stimulated via administration of extracted active compounds, among which the highest antioxidant activity is found in resveratrol, hesperidin, genistein, thymol and carvacrol, and herbs, for example from garlic, aloe vera, oregano and rosemary.