Eggs

what are the four types of egg production systems?

• barn

• free range

• organic

• enriched colony cages

what are features of barn production systems?

• hens housed in buildings with one or more levels

• free to move around

• litter for dust-bathing and scratching

• nest boxes and perches - 15cm of perch per hen

• EU Welfare of Laying Hens Directive - max stocking density of 9 hens per square metre of usable area

• electrical lighting to mimic optimal day length

• British Lion Barn Eggs - 16.5 birds per metre square of usable floor area (more space per bird than EU welfare laying hens directive)

what are features of free range systems?

• hens have continuous daytime access to runs which are mainly covered with vegetation

• EU - max stocking density of 2,500 birds per hectare (2,000 birds per hectare in UK)

• hen house conditions must comply to regulations for birds kept in barns

• outdoor shading in absence of a veranda

• One pop-hole per 600 birds open for 8 hours daily to allow access to the outside

what are features of organic systems?

• Hens producing organic eggs are always free range

• hens must be fed an organically produced diet and range on organic land

• maximum stocking density of 6 hens per square metre of useable area and a maximum flock size of 3,000 birds

• must have nest boxes, adequate perches - 18cm of perch per hen

• litter provided

what are features of enriched colony cage systems?

• battery cages banned - replaced by enriched colony cages

• contain between 40-80 birds, enabling better use of the space and giving them more room to move around the colony

• 750cm² per bird

• nest box for the birds to lay their eggs in, perching space for the birds to sleep on and a scratching area to perform natural behaviours

what do stamps on eggs show?

• method of production:

  • 0 = organic

  • 1 = free-range

  • 2 = barn

  • 3 = caged

• country of origin

• farm ID

• additional marking for Lion Quality eggs

what sizes of eggs do we see?

• <53g = small

• 53-63g = medium

• 63-73g = large

• >73g = very large

what are the egg quality grades?

• grade A - naturally clean, fresh eggs, internally perfect with shells intact and the air sac not exceeding 6mm in depth, yolk doesn’t move away from the centre of the egg on rotation

• grade B - eggs are broken out and pasteurised

• eggs worse than grade B are for non-food use only and are used in products such as shampoo and soap —> industrial eggs

what eggs would fall under grade A in terms of appearance?

• pink shell

• brown shell

• brown speckled shell

  

what are the 3 main parts of the anatomy of an egg?

• the shell or cuticle

• the white or albumen

• the yolk

  

what does the yolk contain?

fats, vitamins and minerals, and about half of the egg’s total protein

what affects the colour of the yolk?

the hen’s diet - no connection with food value

what does the albumen (white) contain?

rich in protein and vitamins

what are common eggshell faults?

• rough shelled eggs - due to two eggs in the shell gland at the same time

• pale shelled eggs - cosmetic change

• soft and weak shelled eggs - commonly from older birds, especially if nearing the end of laying period

• cracked eggs

• dirty and glazed shells - contaminants e.g. faecal material, dust, mud and litter, blood

what are common internal faults?

• double yolked eggs - young, highly productive laying hens

• blood spots in eggs - tiny blood vessel in ovary breaking when yolk is released, more likely at ovulation

• meat spots in eggs (brown in colour) - consist of small pieces of body tissue e.g. internal wall of oviduct

• watery whites - more in older birds, can be due to viral disease e.g. infectious bronchitis

• abnormal yolk colour - e.g. green yolk due to birds consuming green herbage in excess

• mobile and bubbly airspaces - usually due to ruptured inner membrane within albumen

• bacterial and fungal contamination - produce black, red or green dots

• misshaped eggs - when albumen quality if very poor

what types of cracks do we see in eggs?

• hairline cracks - difficult to identify

• star cracks - visible under normal light, more easily sen during candling

• pinhole and toehole cracks - caused by hen or any sharp protrusion coming into contact with egg

how did the Lion Quality Mark Scheme 1998 change number of eggs with salmonella?

requires hens to be vaccinated against salmonella

how did the National Control Programme 2009 change the number of eggs with salmonella?

farms with more than 350 laying hens have to test their flocks for salmonella