Welfare of organic laying hens kept at different indoor stocking densities in a multi-tier aviary system. II: live weight, health measures and perching

Abstract

Multi-tier aviary systems, where conveyor belts below the tiers remove the manure at regular intervals, are becoming more common in organic egg production. The area on the tiers can be included in the net area available to the hens (also referred to as usable area) when calculating maximum indoor stocking densities in organic systems within the EU. In this article, results on live weight, health measures and perching are reported for organic laying hens housed in a multi-tier system with permanent access to a veranda and kept at stocking densities (D) of 6, 9 and 12 hens/m 2 available floor area, with concomitant increases in the number of hens per trough, drinker, perch and nest space. In a fourth treatment, access to the top tier was blocked reducing vertical, trough, and perch access at the lowest stocking density (D6x). In all other aspects than stocking density, the experiment followed the EU regulations on the keeping of organic laying hens. Hen live weight, mortality and foot health were not affected by the stocking densities used in the present study. Other variables (plumage condition, presence of breast redness and blisters, pecked tail feathers, and perch use) were indirectly affected by the increase in stocking density through the simultaneous reduction in access to other resources, mainly perches and troughs. The welfare of the hens was mostly affected by these associated constraints, despite all of them being within the allowed minimum requirements for organic production in the EU. Although the welfare consequences reported here were assessed to be moderate to minor, it is important to take into account concurrent constraints on access to other resources when higher stocking densities are used in organic production.

Welfare of organic laying hens kept at different indoor stocking densities in a multi-tier aviary system. I: egg laying, and use of veranda and outdoor area

“…This increased egg production was not a reflection of hen weight, as the birds in the 2 nd year were heavier throughout the production period (Steenfeldt and Nielsen, 2015), but may have been caused by subtle differences in the feed composition between the two flocks. The finding that across flocks laying percentage was reduced in the largest group size may be a consequence of the concomitant reduction in drinker or nest accessibility.…”

“…Laying percentage was significantly lower at the highest stocking density, most likely due to the concomitant reduction in nest and drinker accessibility, but no systematic effects were found on other laying variables (eggs laid outside nests, aviary side preferences, egg weights). For the measures reported here (laying behaviour, use of veranda and outdoor area), the welfare consequences for the hens of doubling the indoor stocking density were minor; however, a more complete welfare assessment based on additional results are reported in Steenfeldt and Nielsen (2015).…”

“…Except for the stocking density in D12, the experiment followed the EU regulations on the keeping of organic laying hens (EC 889/ 2008(EC 889/ , 2008. Results on egg production, laying behaviour and use of veranda and outdoor area are presented here, whereas most of the welfare related measures, including live weight changes, perching behaviour and health results, are presented in Steenfeldt and Nielsen (2015); this associated article should therefore be consulted for a full evaluation of the welfare consequences of allowing more hens per available floor area in these types of organic egg production systems.…”

“…Hens primarily used the range near the house (within 50 m) and hens kept at the lowest stocking density and the smallest group size appeared to use the outdoor area more extensively, based on an assessment of vegetation cover ( P < 0.05). For the measures reported here, the welfare consequences of increased stocking density were assessed to be minor; additional results are reported in the associated article (Steenfeldt and Nielsen, 2015). …”

Enriquecimento ambiental para gaiolas convencionais de poedeiras em função de diferentes densidades de alojamento

“…Uma das causas desse efeito está relacionada ao espaço limitado e à indisponibilidade de recursos que aumentem o repertório comportamental destas aves, condição comumente observada em sistemas de gaiolas em bateria. Consequentemente, comportamentos anormais podem surgir, como inquietação, arranque de penas e canibalismo, resultando em desgaste da plumagem, em lesões na crista e no coxim plantar, bem como deformações na sua estrutura óssea (PETEK e MCKINSTRY, 2010;HARTCHER et al, 2015;STEENFELDT et al, 2015;BLATCHFORD et al, 2016).…”