HOUSING ▶▶▶
Welfare implications of cage-free egg production
Cage-free housing provides laying hens with more space, enabling increased mobility and greater expression of the bird’s natural behaviour. However, even cage-free farming can be associated with some welfare concerns which need to be addressed by egg producers.
BY JOEL ESTEVINHO, ALLTECH I
t is safe to say that the transition from cages to cage- free systems is the most important global trend for the egg sector since the removal of conventional cages. Having started in Europe, the cage-free movement has
since gained momentum in many countries throughout the world, as well as in the United States where it is expected that the share of cage-free eggs will increase to about two thirds of the market by 2026. Indeed, numerous major egg producers, retailers, food service companies and hotel chains have already committed to switch entirely to cage-free eggs by 2025.
Dust and ammonia exposure Chickens housed in cage-free systems have contact with the floor. Increased bird activity will also increase the amount of dust in the air. Consequently, dust levels in cage-free buildings can be 5-15 times greater than in houses equipped with cages. Ammonia (NH3
) is generated from manure. The complete
removal of manure is frequent in cage systems, especially in automated houses, but the full removal of manure in cage- free systems can only be done after the premises have been vacated. Not surprisingly, therefore, ammonia levels are usually greater in cage-free than in cage houses. Litter-based systems are also associated with a greater frequency of intes- tinal disorders which, in turn, lead to higher ammonia levels due to the lower absorption of nutrients and the increased moisture content of manure. The higher aerial pollution in cage-free buildings can de- press the immune system and increase the load of infectious agents. Indeed, it has been reported that total bacteria concentrations in the indoor air of cage-free houses can be 5-9 times greater than in sheds equipped with cages, especially in winter. High levels of ammonia damage the
16 ▶ POULTRY WORLD | No. 10, 2021
epithelium of the respiratory tract, thereby favouring the colonization of air sacs and lungs with airborne E. coli and predisposing the flock to higher mortality. E. coli also attaches to dust particles which then serve as pathogen disseminators inside the poultry shed. De-Odorase is formulated from proprietary extracts of Yucca schidigera, a desert plant that is sustainably grown and har- vested by Alltech. Supplementing the feed with De-Odorase can help to maintain a consistently lower air ammonia level in poultry houses with no detrimental effects on flock pro- ductivity. Wet litter and high ammonia content can lead to footpad dermatitis and bumblefoot, a painful footpad infec- tion. While uncommon in furnished cages, the frequency of bumblefoot can be 3-4 times greater in litter-based houses.
Mortality On average, the hen mortality rate is greater in cage-free sys- tems, especially free-range, compared to furnished cages. A thorough study conducted in the United Kingdom reviewed the on-farm mortality of nearly 1,500 flocks, comprising over 13 million layers. It provided striking evidence for this gen- eral trend. Despite a considerable variation between flocks, under all systems, the average cumulative mortality rate was clearly lower in cage (5.39%) than in cage-free production (8.55%, 8.68% and 9.52%, respectively, for barn, organic and free-range flocks). The greater prevalence of cannibalism, various bacterial in- fections and internal parasites, plus the occasional occurrence of smothering, can help to explain the higher average mortal- ity rate associated with cage-free farms. Free-range chickens are also at risk of predation and can become infected with se- rious diseases, such as avian influenza and Newcastle disease, through contact with wild birds. Chickens have no contact with soil, litter and manure in cages, but this is not so in cage-free housing. Therefore, the natural (faecal-oral) transmission route of several intestinal parasites, such as coccidia and worms, is interrupted in cages but not in litter-based systems. Not surprisingly, these para- sites are much more common in cage-free farms, and the resulting increase in mortality rate can be significant, thereby negatively affecting bird welfare. Histomoniasis (also known as blackhead), a disease that affects the caeca and liver of chickens and turkeys, provides a good example of the re-emergence of parasitic diseases in
PHOTO: JACK CAFFREY
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52
