Hous­ing for lay­ers

The Poultry Bulletin - - CONTENTS -

Al­though the ini­tial fi­nan­cial out­lay in­volved in im­ple­ment­ing new hous­ing sys­tems for com­mer­cial lay­ers was costly in the short term, there are ap­pre­cia­ble ben­e­fits in terms of eggs per hen, feed con­ver­sion ra­tios and mor­tal­ity rates. Yet the big­gest ben­e­fit of en­riched cage sys­tems, cer­tainly in mar­kets where con­sumers have a height­ened sense of con­cern for an­i­mal wel­fare, lies in sat­is­fy­ing this aware­ness.

Aware­ness of the wel­fare of an­i­mals, in­clud­ing that of lay­ing hens, be­gan in the 1960’s and led to an aver­sion to eggs pro­duced by hens housed in con­ven­tional bat­tery cages. The Euro­pean Union banned the use of bat­tery cages be­gin­ning in Jan­uary 2012, al­though this is yet to be fully com­plied with by all mem­ber states. This move re­sulted in the de­vel­op­ment of al­ter­na­tive hous­ing sys­tems for lay­ing hens, and a re­newed ef­fort to de­velop al­ter­na­tive hous­ing sys­tems to meet all the re­quire­ments of good hen wel­fare. Each of the sys­tems used have ad­van­tages and dis­ad­van­tages that vary based on lo­ca­tion, man­age­ment, and ge­netic strain of the hens.

Con­ven­tional cages

Con­ven­tional bat­tery cages for lay­ing hens were first de­vel­oped in the US dur­ing the 1920’s to 1930’s. The sys­tem was de­vel­oped to re­duce the in­ci­dence of dis­ease and par­a­sites and also to re­duce can­ni­bal­is­tic peck­ing. Cages makes man­age­ment of the birds eas­ier and re­quires less space than the other sys­tems.

No bed­ding ma­te­rial is used in this sys­tem as the cages are sus­pended above the floor al­low­ing the bird drop­pings to fall through the mesh floors and col­lect be­low the cages. As there is no lit­ter to deal with this al­lows easy col­lec­tion or clean-up of bird fae­ces. The sys­tem is the most eco­nom­i­cal of all cur­rently used sys­tems, with the best pro­duc­tion, qual­ity and ef­fi­ciency. These cages are typ­i­cally wire en­clo­sures with sloped floors to allow the eggs to gen­tly roll to the front of the cages mak­ing it easy to col­lect them.

Apart from the ob­vi­ous ad­van­tage of pro­tec­tion from preda­tors, cages also re­duce the in­ci­dence of ex­po­sure to ma­nure which can re­sult in ex­po­sure to round­worm in­fes­ta­tion and coc­cidia. When hens are reared in cages, there is a re­duc­tion in in­ju­ri­ous peck­ing and mor­tal­i­ties be­cause of smaller so­cial group sizes in each cage. Due to the cage de­sign there is lower in­ci­dence of dirty eggs. It is eas­ier to mon­i­tor the health and well­be­ing of each bird. There is a lower risk of con­tract­ing in­fec­tious dis­eases in caged hous­ing sys­tems com­pared to hens housed on lit­ter, and the ab­sence of lit­ter means lower levels of am­mo­nia, dust and bac­te­ria.

The most ob­vi­ous dis­ad­van­tage is the re­stric­tion

of the nat­u­ral be­hav­iour of hens. They can­not dust-bathe or for­age, there is rel­a­tively lit­tle or no space for them to walk around, they can­not flap or stretch their wings. Hens can­not wag their tails and nest­ing and roost­ing be­hav­iour are not an op­tion in these cages. It is pos­si­ble for hens to get trapped be­tween wires that can at times re­sult in in­juries. They can also dam­age toes from the break­ing of over­grown claws in the wires of the cage floors. Feather peck­ing can also take place in the con­ven­tional cages, which of­ten ne­ces­si­tates beak trim­ming.

En­riched cages

Sim­i­lar to caged hous­ing sys­tem, these pro­vide ad­di­tional fea­tures in each house. These cages of­ten in­clude perches, a nest box and lit­ter or an area where the hens can scratch. They also of­fer more space per hens al­low­ing them room to walk around. The size and con­struc­tion of the cages may vary with some cages hav­ing the ca­pac­ity of hold­ing up to sixty hens.

The ma­jor ad­van­tage of the en­riched or fur­nished sys­tem is the en­vi­ron­men­tal fea­tures it pro­vides for the hens. The birds are able to en­gage in nat­u­ral be­hav­iours such as perch­ing and nest­ing.

Sub­strate ma­te­ri­als can be pro­vided for birds to en­gage in dust bathing be­hav­iour which im­proves feather con­di­tion. The pres­ence of lit­ter can re­duce the in­ci­dence of feather peck­ing as hens can spend time for­ag­ing in the lit­ter rather than peck­ing at their cage mate. When a nest box is avail­able most hens will make an ef­fort to lay in it and the num­ber of dam­aged eggs is sim­i­lar to that of the cage sys­tem. As with the con­ven­tional cages the en­riched/fur­nished cages also of­fer pro­tec­tion from preda­tors.

Dis­ad­van­tages in­clude the pre­dis­po­si­tion of lay­ing hens to bone weak­ness re­sults in more in­ci­dences of bone break­age and frac­ture due to in­creased ac­tiv­ity in these cages. Also, the ad­di­tional fea­tures in the cages have the po­ten­tial to in­crease in­ci­dence of in­jury. Poorly de­signed perches can cause keel bone de­for­ma­tion and bum­ble foot. There is the po­ten­tial for a neg­a­tive im­pact on food safety be­cause a por­tion of the eggs are laid out­side of the nest boxes mak­ing them more likely to be­come soiled or cracked. Cracked eggs may pro­mote egg-eat­ing be­hav­iour and eggs laid out­side the boxes will re­quire ex­tra ef­fort to col­lect.

Barns or aviary hous­ing

These sys­tems are quite sim­i­lar as they are both sheds where hens are housed on an open floor. Hens have ac­cess to lit­ter and nest boxes, while aviary houses have ad­di­tional plat­forms or perches.

The ma­jor ad­van­tages of these sys­tems are im­proved bone strength and plumage and lower levels of hy­per­k­er­ato­sis in birds that do not have ac­cess to perches. Hy­per­k­er­ato­sis is the thick­en­ing of the outer layer of the foot­pad caused by in­creased pres­sure load on the foot while perch­ing or stand­ing on wire floors. Hens in this sys­tem spend a lot of time walk­ing and there are also in­creased nat­u­ral be­hav­iours such as for­ag­ing, dust bathing and com­fort be­hav­iours such as stretch­ing wings and wag­ging tail. Hens are pro­tected from preda­tors

Dis­ad­van­tages in­clude an in­creased pos­si­bil­ity of re­duced health as birds raised on open floor are more likely to come into con­tact with pathogens in fae­ces. This may re­quire han­dling of hens to ad­min­is­ter treat­ment or vac­ci­na­tions. As with the en­riched/fur­nished cage sys­tem, hens that have ac­cess to perches are more prone to in­juries. There is also more in­ci­dence of peck­ing which can re­sult in in­creased mor­tal­ity. This could be a re­sult of in­creased num­bers of so­cial groups in the house. There is re­duced air qual­ity in lit­ter based sys­tems. In­creased am­mo­nia can re­sult in eye prob­lems such as ker­a­con­junc­tivi­tis and can also have a neg­a­tive ef­fect on the res­pi­ra­tory tract.

Free range sys­tems

Birds housed in this type of sys­tem have ac­cess to an out­door area dur­ing the day. This area may be cov­ered or un­cov­ered. They are pro­vided with an in­door area where they come in at nights and are able to roost.

Hens which are free ranged have the great­est range of nat­u­ral be­hav­iour and hence have bet­ter feather con­di­tion when com­pared to the other hous­ing sys­tems.

The main dis­ad­van­tage of free range is that hens are ex­posed to tox­ins, wild bird dis­eases, preda­tors and ex­treme cli­matic con­di­tions.¡

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