Vpliv različnih sistemov uhlevitve kokoši nesnic na njihovo počutje, prirejo in kakovost jajc ; Effect of different housing systems on welfare, performance and egg qualities of laying hens

V zadnjih desetletjih je EU in z njo tudi Slovenija sprejela več predpisov, ki dokaj natančno predpisujejo posamezne sisteme uhlevitve kokoši nesnic, predvsem v cilju izboljšanja dobrobiti te kategorije kokoši. Na nobenega od predpisanih sistemov ni mogoče gledati črno belo, vsak ima svoje prednosti in slabosti. V primerjavi z rejo v obogatenih kletkah, imajo v alternativnih (nebaterijskih) sistemih uhlevitve kokoši večjo svobodo gibanja, lahko izvajajo prašnate kopeli in ob dostopnosti izpusta zauživajo svežo travo. S povečanim gibanjem in zagotovitvijo gredi se okrepi skeletni sistem živali. Zauživanje trave prispeva k večji vsebnosti vitaminov A in E ter n-3 večkrat nenasičenih maščobnih kislin (VNMK) v jajcih. Izpostavljanje kokoši sončnim žarkom (UV svetlobi) in zauživanje drobnega peska, zagotavljata jajcem iz izpustov trdnejšo jajčno lupino. Največje slabosti reje kokoši v izpustih (prosta reja, ekološka reja) so povečan pogin živali, slabše izkoriščanje krme in pogosto problematičen mikrobiološki status jajc. Večje je tveganje za pojav agresivnega kljuvanja perja in kanibalizma, medtem ko je zaradi stika s prostoživečimi pticami in njihovimi iztrebki večja tudi bolezenska ogroženost. Zelo veliko k poginu v sistemih z izpusti prispevajo napadi plenilcev. Jajca, ki prihajajo iz obogatenih kletk ne pridejo v stik z iztrebki kokoši, nastilom ali blatom, zato je praviloma na njihovi lupini prisotno manjše število mikroorganizmov. Ekonomika prireje jajc je nedvomno na strani obogatenih kletk. Ko analiziramo vpliv sistema uhlevitve nesnic na njihovo dobrobit, prirejo in kakovost jajc je treba poudariti, da ne gre za vpliv sistema kot takega, temveč kumulativni vpliv posameznih dejavnikov (npr. genotipa in starosti kokoši, prehrane, okoljskih dejavnikov, itn.), ki se navezujejo na ta sistem. ; In recent decades, several regulations have been enacted in the EU, and thus also in Slovenia which set out the housing systems for laying hens in fairly precise manner. Their aim was mainly, to improve the welfare of this type of chicken. None of the prescribed systems canbe judged as the best or the worst, each of them has its own strengths and weaknesses. Compared to enriched cages, the alternative (non-battery) housing systems provide hens with greater freedom of movement and allow them to bathe in dust and consume fresh grass as they have access to outdoor runs. Greater freedom of movement and perches strengthen the hen's skeletal system. Grass consumption contributes to increase levels of vitamins A, E and n-3 PUFAs in eggs. Exposure of hens to sunlight (UV light) and consumption of fine sand make the eggshell stronger. Major weaknesses of free-range and organic rearing include higher mortality rates, poor feed conversion and often problematic microbiological status of eggs. The risk of aggressive feather pecking and cannibalism is higher, as is susceptibility to disease from contact with wild birds and their droppings. Predator attacks also significantly increase mortality rates in free-range systems. Eggs from enriched cages do not come into contact with chicken droppings, litter, or mud, so their eggshells are usually covered with lower numbers of microorganisms. The economics of egg production is definitely on the side of enriched cages. When analysing the impact of the housing system on the welfare of laying hens, it should be emphasised that the impact does not come from the system itself, but is considered as a cumulative effect of individual factors (e.g. hen genotype and age, feed, environmental factors, etc.) related to the system.