Changes in the colour and the acidity number of egg yolk upon irradiation

Dvořák, Petr; Kunová, J.; Straková, Eva; Suchý, Pavel; Kunová, Veronika

doi:10.1007/s00217-005-1175-7

Cited by 17 publications

(13 citation statements)

References 6 publications

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“…the enhanced colour of egg yolk is probably associated with the increased level of plant pigments in the plant-based diet containing the Juno yellow variety of lupin. Similar findings were also reported by Dvořák et al (2005). one very positive effect of the plant-based diet with regard to the nutritional value of eggs is that it significantly decreased (P ≤ 0.05) the cholesterol level in egg yolk in experimental hens.…”

Section: Discussionsupporting

confidence: 88%

“…This issue including the objective methods of colour determination was addressed by Dvořák et al (2001Dvořák et al ( , 2003Dvořák et al ( , 2004. Dvořák et al (2005) confirmed the improvement of yolk colour after the addition of plant-based components containing natural plant pigments into the feed mixtures. From the consumer health point of view, the level of cholesterol in egg yolk is of a great importance.…”

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confidence: 60%

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Positive Effect of Plant-Based Diet on the Performance and Health of Laying Hens

et al. 2007

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an entirely plant-based feed mixture was prepared to minimize the potential risk of transmitting prion infections through animal feed. It consisted of two protein components (soya extracted meal and lupin seed meal) and was compared with a diet containing animal protein components (fish meal). the objective of the present work was to prepare and verify the effect of the entirely plant-based diet on the performance, selected qualitative indicators of eggs and the hens' state of health. a specially prepared feed mixture containing fish meal was used as a control diet. the tested plant-based diet administered to experimental hens produced no negative effect on egg production variables such as number of eggs per hen or laying performance. the weight of eggs laid by experimental hens was significantly higher (61.66 g, P ≤ 0.01), as compared with the control group (60.03 g). the higher average weight of eggs in the experimental group increased the production of egg mass per layer by 540 g in 252-day experimental period. the beneficial effect of the plant-based diet was demonstrated particularly in the improved egg quality, manifesting itself in a highly significant improvement in yolk colour (P ≤ 0.01) and a significant decrease (P ≤ 0.05) in cholesterol level in egg yolk. Haematological examination did not indicate statistical differences between experimental and control layers in red blood cell indices such as rBC, haemoglobin, hematocrit, MCHC, MCH, and MCv, while white blood cell indices showed a highly significant increase (P ≤ 0.01) in Le in experimental hens. Biochemical tests performed in blood plasma revealed significantly lower molar concentrations of glucose (P ≤ 0.05) and highly significantly lower levels of total lipids, cholesterol, lipoproteins (HDL and LDL) in experimental hens (P ≤ 0.01), as compared with the control group. the results of the study confirm that animal protein in diet for laying hens can be replaced by combination of vegetable protein feeds (soybean and lupin protein) without a negative impact on their performance and health, thereby contributing to solving issues of food safety (a prevention of prion infections). Hens, nutrition, egg production, egg quality, haematological and biochemical examination of bloodIn terms of the safety and quality of raw materials and foodstuffs originating from animals, constant effort in the area of animal nutrition goes into preventing the contamination of feeds with substances that may put human health at risk. the replacement of animal feed with plant-based feed may offer a potentially useful solution to this problem. Due to bovine spongiform encephalopathy in ruminants, a new strategy in the nutrition of animals reared for the production of feed was elaborated. First papers pointing out the option of preparing entirely plant-based diets were published by Suchý et al. (2002) although meat-and-bone meals were an integral part of feed mixtures for poultry (particularly laying hens) at that time. The effect of the diets administered to hens used for prod...

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Section: Discussionsupporting

confidence: 88%

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confidence: 60%

Positive Effect of Plant-Based Diet on the Performance and Health of Laying Hens

et al. 2007

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“…All egg yolk measurements were done automatically three times. The resulting value was the average of the three measured values 8, 9. The results for parameters L *, a *, b * were divided into categories.…”

Section: Methodsmentioning

confidence: 99%

Photocolorimetric determination of yolk colour in relation to selected quality parameters of eggs

2009

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“…Prior to measurement, the instrument was calibrated to the food foil used. All measurements were performed three times and the final value was calculated as the average of the three values measured (Dvořák et al 2005).…”

Section: Methodsmentioning

confidence: 99%

Variation in Egg Yolk Colour in Different Systems of Rearing Laying Hens

Dvořák¹,

Suchý²,

Straková³

et al. 2010

Acta Vet. Brno

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A total of 72 laying hens (ISA BROWN hybrid combination) were divided into two groups. Thirty-six layers in the first group were reared on litter while the second group of layers was reared using the cage rearing system. Samples of eggs were collected from both groups for a period of seven months. Yolk colour was determined using a portable spectrophotometer using a newly developed method, which complied with the CIELAB system. Yolk colour indicator L* decreased for the rearing system on litter, i.e. egg yolk colour became darker in the course of the whole experiment (α = 0.05). Indicator a* showed a distinct increase in the case of the rearing system on litter, with the differences being significant (α = 0.05) over the last three months of the experiment. Differences for the whole experiment were highly conclusive (α = 0.01), as seen from the increasing red colour intensity. Similarly, indicator b* also increased, i.e. egg yolk was of more distinct yellow colour. In the case of the cage-rearing system, egg yolk colour indicators correlated well with egg weight indicators, as compared to the rearing system on litter. The rearing system on litter resulted in significantly increased intensity of orange colour compared to the cage rearing system. CIELAB, spectrophotometer, food colour, litter, cageQuality indicators of eggs depend not only on the nutrition of laying hens and intravital factors but also on the rearing system used.According to Wan Den Brandt et al. (2004), it is more difficult to maintain stable quality of eggs in the outdoor rearing system than in the cage rearing system. He investigated the effect of two rearing systems (outdoor vs. cages) on indicators such as egg weight, egg white, egg yolk, the content of the egg shell, the level and the pH of the white, and dry matter content of the white and the yolk. Characteristics such as egg weight, the content of the shell, the level and the pH of the white, and the levels of dry matter in the white and the yolk correlated with the age of layers and the rearing system. Yolk colour of eggs from layers reared outdoors was significantly darker.The quality of eggs from white (LSLs) and brown layers (LTs) reared in three different housing systems (cages, aviaries, and intensive outdoor rearing) were compared. LSLs gave eggs of better quality as compared to LTs. LSLs showed significantly higher levels of Haugh units (HU) (91.62), egg yolk weight, strength and density of the shell but had significantly lower values for egg yolk colour (12.9) and the occurrence of eggs with meat and blood spots was lower. The comparison of egg quality traits for the rearing systems investigated revealed that none of the systems had superior advantages over the others. The egg yolk weight was increased in the cage system. The highest colour intensity of egg yolk was found in the outdoor rearing system with LSLs and in the cage rearing system with LTs (Leyendecker et al. 2001).Quality indicators of eggs were also monitored in the ISA Brown layers in the cage rearing system,...

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Changes in the colour and the acidity number of egg yolk upon irradiation

Cited by 17 publications

References 6 publications

Positive Effect of Plant-Based Diet on the Performance and Health of Laying Hens

Positive Effect of Plant-Based Diet on the Performance and Health of Laying Hens

Photocolorimetric determination of yolk colour in relation to selected quality parameters of eggs

Variation in Egg Yolk Colour in Different Systems of Rearing Laying Hens

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