Test to distinguish between battery and free range eggs without visiting the farm

Scientists have developed a method of determining whether eggs labelled as ‘free range’ or ‘barn’ have, in fact, been laid under battery conditions. The procedure, published in Journal of the science of food and agriculture, means eggs can be tested without the need to visit farms.

The give-away is the dust that the eggs pick up from the surface on which they are laid. Because the eggs are wet when freshly laid, the dust attaches to the shell surfaces. The pattern this creates varies accoring to whether the eggs where laid on cage floors, barn nest boxes or outside. These distinctive patterns can easily be distiguished under ultraviolet light because the dust fluorestes.

The authors found that the prevalence of white double parallel lines with 2.0-2.5 cm spacing was a distinguishing feature for eggs laid on wire floors in cages. They concluded that if five or more eggs in a sample of 90 eggs have double fluorescent lines, there is a greater than 999 in 1000 probability that the batch contains some cage-laid eggs.

The method is effective in distinguishing between free range eggs and those laid on a wire floor cage. It does not damage the eggs and can be applied at any stage in the egg marketing chain.

Washing egg can remove or obscure the double lines, so the authors recommend that in countries where egg washing is common, it is best to perform the test before wasing. Distinguishing features in eggshell fluorescence can be used to identify when eggs have been washed, and they can also be used in preliminary screening tests for sun exposure, which in some countries is a cause of runniness of the egg white.

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Enriching chicken with vitamin E

A group of sicentist working in Barcelona, Spain, have found that the vitamin E level in chicken meta can boosted by feeding higher levels of a-tocopheryl acetate to the birds. Furthermore, the content was maintained, even after 7 months of storage at minus 20^oC. The meat could supply about 25% of the recommended dietary allowance.

A factorial design was used for the experiment: three different dietary fat sources (beef tallow, fresh and oxidised sunflower oils and linseed oil), a-tocopheryl acetate (0 or 225mg/kg feed), and ascorbic acid (0 or 110mg/kg/feed).

Raw meat fatty acid composition was affected by dietary fat sources and tocopheryl acetate supplementation. After cooking, it was only affected by dietary fat source. Birds fed linseed oil yielded meat rich in n-3 fatty acids, especially linolenic acid, and the meat would provide about 20% of the recommennded intake for this fatty acid. Birds fed fresh or oxidised sunflower oil produced meat rich in n-6 fatty acids, while those fed beed tallow had meat rich in saturated and monounsaturated fatty acids.

The a-tocopherol content of raw and cooked dark chicken meat was only affected by tocopherol supplement.

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Why is the avian flu virus so dangerous for humans

Scientist have established a theory why the H5N1 strain of avian influenza (AI) virus is so dangerous for himans. The disease so far has been fatal in more than half of the people who have contracted it since 2003.

The explanation lies in the patient’s viral load and the subsequent inflammatory response, say researcher from the Oxford University Clinical Research Unit in an article published in Nature Medicine.

Dr Menno de Jong and colleagues assessed 27 people at the Hospital for Tropical Diseases in Ho Chi Minh City, Vietnam. Eighteen of the patients were infected with H5N1; the other nine had contracted common human influenza viruses.

The investigators learned that those who had H5N1 were carrying substantially higher viral concentrations in their blood and throat than their counterparts who had sub-types of human flu. The H5N1 infected patients who died had much higher viral load than those who survived. The team concluded that the higher the level H5N1, the greater the likehood of death. The severity of lung damage and the increased risk of dying probably were associated with high levels of cytokines, low levels of lymphocytes and the resulting intense inflammatory response in H5N1 patients, the scientists suggested.

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Egg turning angle and prequency impact on embryo position

In a co-operative project between the universities of Ankara, Turkey and North Carolina State, USA, it was concluded that the incidence of malpositioned embryos was increased by a reduced turning angle. However, the effects was ameliorated by increasing the frequency of turning. The work was reported by Drs Elibol and Brake.

Two experiments, each comprising two trials, were carried out to determine if a turning angle of less than 45^o from vertical could be succesful in terms of the number pf malpositioned embryos, i.e. with the head at the narrow end of the egg.

Hatcing egg from commercial broiler breeders flocks aged 55-61 weeks were turned at angles of 35^o, 40^o, or 45^o degrees every hour for 18 days in experiment 1. Turning angle had no effect on fertile hatchability but the incidence of mapositioned embryos was higher in the eggs turned at 35^o degrees than with the other treatments.

In experiment 2, egg were subjected to turning angles of 35^o and a turning frequency of every 60 or 15 minutes, or 45^o every 60 minutes. This time, turning angle and frequency had no effect on fertile hatchability or embryonic mortality. However, the incidence of malpositioned embryos was higher in the group turned with a 35^o angle hourly than with the other treatments.

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Foot pad dermatitis could be eliminated trough breeding

Interesting work by a group of Danish researchers hints that it may in future be possible to select against the susceptibility of broiler to foot pad dermatitis (FPD) without adversely affecting performance.

Scientist at the Danish Institute of Agricultural Science in Tjele found that, at 0.31, the heritability for susceptibility to foot pad dermatitis pad lesions was quite high compared to the heritability for body weight. The hertability of hock burn (HB) susceptibility, however, was only 0.08 and so a solution to this condition trhough selection is unlikely.

A total of more than 2000 birds from 2 strains (fast-growing and slow-growing) were allocated to groups in two time-separated replicates. The development of foot pad dermatitis and hock burn were recorded weekly from day 8 to slaughter on a sample of the live animals. The feet and hocks of all birds were investigated at slaughter (4 or 6 weeks form the fast-growing strain and 8 or 10 weeks for the slow-growing strain).

No foot pad dermatitis lesions and very few low-grade hock burn were found in slow-growing birds. In the fast-growing strain, the first signs oh both lesions were seen in week 2, and the incidence of both type of lesions increased therafter. Bodyweight did not affect foot pad dermatitis but more hock burn was found at higher bodyweight.

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Salmonella infection affected by moulting

Using a tissue culture procedure, scientist at the USDA in Athens, Georgia, USA, have concluded that moulting may affect the invasion of tissues by Salmonella enteris (SE) in laying hens.

They conducted three identical trials in which 80-week-old, active laying hens were divided into two groups of 6 birds each. The moulted group was subjected to a 14-day period of feed withdrawal, and the fully-fed group was offered a standard layer ration. After feed treatment, the crop, ileum, caecum and ovary were collected and subjected to a series of treatment to prepare them for incubation with salmonella enteritis. This was followed by the removal ob bacteria that had not penetrated the tissues, and the counting of salmonella enteritis that remained in the tissues.

Salmonella enteritis invasion of the ovaries was reduced in tissues from moulted hens in trials 1 and 2 compared with full-fed control (>1.2 log reduction) but not in trial 3. Salmonella invasion oh the caeca of moulted hens was numerically increased in trials 1 and 2 and significantly increased in trial 3 compared to the controls (>0.8 log increase). No significant differences in salmonella enteritis invasion were detected for crops and ileum.

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