Welfare indicators in laying hens in relation to nest exclusion

Abstract

Consumer concerns about the welfare of laying hens are increasing, leading to increased interest in identifying reliable ways to assess welfare. The present study evaluated invasive and non-invasive welfare indicators in relation to a stressful challenge. The study included 126 Lohmann Selected Leghorn hens housed in furnished cages. Welfare indicators were measured between 61 and 70 wk of age in birds excluded from their nests for 5 consecutive d and control birds that had continuous access to nests. Baseline recordings were carried out in both groups prior to and post exclusion period. The assessed indicators were: corticosterone metabolites in droppings (FCM), corticosterone concentration in yolk, corticosterone concentration in plasma, irregularities of eggshells, heterophil to lymphocyte (H:L) ratio, tonic immobility duration, and feather cover. Behavioral observations showed that the birds had a clear preference for using the secluded nest sites, confirming that they were likely to perceive nest exclusion as an undesirable experience. Further, elevated levels of FCM in droppings, yolk corticosterone concentrations, H:L ratios and irregular eggshells were detected in both nest deprived and control birds during the exclusion. This suggests that these indicators were able to detect an increased stress response arising from nest deprivation, and it is hypothesized that the stress spread to birds in adjacent cages with access to nests. There was a positive and consistent correlation between FCM in droppings and eggshell irregularities, also supporting the use of eggshell irregularities as a potential non-invasive welfare indicator. However, the pattern of the stress response varied between indicators and correlations were generally few and inconsistent, highlighting the complexity of the relationship among welfare indicators.

Climatic Variation: Effects on Stress Levels, Feed Intake, and Bodyweight of Broilers

“…Corticosterone is the main adrenocortical hormone present in the peripheral blood. Elevated blood corticosterone levels and heterophil to lymphocyte (H/L) ratios are well-known physiological indicators of welfare (Rogers et al, 2015;Alm et al, 2016), and are used as a stress indicators in poultry (Delezie et al, 2007;Cirule et al, 2012). Corticosteroids contribute for the reestablishment of homeostasis via negative feedback mechanisms that act on the hypothalamus and/or pituitary structures, decreasing HPA axis activation (Canoine et al, 2002).…”

The use of glucocorticoid hormones or leucocyte profiles to measure stress in vertebrates: What’s the difference?

“…Urinary CORT increased after toe‐clipping in cane toads Rhinella marina , but N/L ratios were unaffected (Narayan & Hero, ). We are aware of only one positive relationship between leucocyte profiles and CORT measured noninvasively, a weak correlation between H/L ratio and faecal CORT metabolites in laying hens (Alm et al., ). The general lack of positive correlations illustrates further that although both metrics are clearly valid for assessing stress responses, the relationship between them is complex and not always detectable.…”

Stress and reactivity in three Italian chicken breeds

“…For that reason these topics have received much attention in the poultry industry in recent years due to the growing concerns for welfare. Heterophil to lymphocyte (H/L) ratio and plasma corticosterone concentration are widely used as stress evaluation criterion in poultry (Debut et al 2005;Franciosini et al 2005;Cirule et al 2012) and are well known as physiological indicators of welfare (Rogers et al 2015;Alm et al 2016). The H/L ratio is a more reliable indicator of mild to moderate stress than plasma corticosterone (Maxwell 1993).…”