The objective of this study was to determine the effect of diet composition and the length of storing eggs on the fatty acid (FA) composition of egg yolks. The study was conducted on eggs from Messa 45 hens. The experimental groups were fed diets D1 and D2 containing rape, linseed and evening primrose seeds. The D2 diet contained vitamin E 200 mg/kg, added as an antioxidant to the feed. The FA content and TBA level in fresh yolks and in yolks from eggs that had been stored for 3 or 6 months at -25°C were determined. It was found that both the diet and duration of storage significantly affected the MUFA and PUFA contents in total fatty acids. The observed changes in the PUFA content indicate that vitamin E slowed down the process of oxidation of egg yolk fat. During storage, the extinction of TBA increased in all of the groups.
The study was conducted on 90 thirty-week-old Messa H-43 layers divided into 3 groups. The control group was fed a diet without oil seeds, while the RLP and RLP+E groups were given a diet containing a mixture of 00 rapeseed, linseed, and evening primrose seed. Vitamin E, 200 mg/kg, was added to the RLP+E diet. After 4 weeks, egg quality, fatty acid content, and the lipid oxidation level were determined. Half of the collected eggs were examined the next day and the second half, after 20 days of storage at 12°C. No effect of feeding was found on egg quality. Eggs from groups RLP and RLP+E had less saturated fatty acids and more polyunsaturated fatty acids. Egg weight and albumen quality decreased and yolk content increased during storage, irrespective of the diet. Changes in fatty acid content in yolk during storage were found. Diet and the storage had insignificant effect on oxidation of yolk lipids.KEY WORDS: rape seed, linseed, evening primrose seed, egg quality, TBA, fatty acids
INTRODUCTIONThe subject of many current studies is improving the nutritional value of hen's eggs. One of the methods is increasing egg-yolk polyunsaturated fatty acids (PUFA) content, which can be done by feeding hens diets with oil seeds. Rape 00, linseed and evening primrose seeds can be used for this purpose in Poland. Many authors (Aymond and Van Elswyk, 1995;Brettschneider et al., 1995;Roth-Maier and Kirchgessner, 1995;Niemiec et al, 1997) confirmed the favourable effect of these seeds in diet for layers on PUFA content in egg-yolk. The aim of the presented study was to determine the effect of storage on the quality and fatty acid content of PUFAenriched eggs.
Background. Rearing larval fish under laboratory conditions requires the use of appropriate artificial diets that fully replace natural food. Up till now, no starter has been developed for cyprinid rheophilic fish larvae, and these fish are therefore fed diets developed for other fish species. The present study was undertaken to evaluate the effects of diets of different protein-, lipid-, and fatty acid compositions on growth, survival, and changes in the digestive system during larval development of sneep (nase), Chondrostoma nasus (L.), from hatching until the juvenile stage. Material and methods. From day 4 until day 21 post-hatch, sneep larvae were fed, Artemia nauplii and three starters: Nutra AB 3.0 (NU), Perla plus (PP), and Perla larva proactive (PL). Each experimental treatment was run in triplicate. On day 21 of the experiment, samples of fish were taken for size measurement, histological and morphometrical examination, and fatty acid analyses. Results. The fish fed Artemia exhibited the highest growth rate and survival. Among the groups fed artificial diets, the highest survival and growth were observed in NU group, while PL group showed the worst results (P < 0.05). Comparison of the fatty acid composition in the diets and fish bodies revealed that the levels of n-3 PUFA were considerably higher in the bodies of fish fed starters than in the diets themselves, while concentrations of n-6 PUFA in the PP and PL groups were lower in fish than in diets. The NU diet showed the highest n-3 : n-6 ratio (5.54), while PP had the lowest. The highest MUFA : PUFA ratio occurred in Artemia nauplii and the lowest in the PP diet. Histological observations revealed the presence of supranuclear lipid vacuoles in the enterocytes of the middle intestine section of Artemia-fed larvae. No such vacuoles were found in fish fed artificial diets. Morphological changes in the livers of fish fed various diets involved hepatocyte size and cytoplasm area containing glycogen and lipids. Conclusions. Among the artificial diets, Nutra was the most appropriate for rearing sneep larvae. The results revealed that sneep larvae are capable of elongating and desaturating linolenic-and linoleic acids into longerchain fatty acids.
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