Stocking density effects on broiler welfare: Identifying sensitive ranges for different indicators

Abstract

Although stocking density is perceived as a topic of major importance, no consensus has been reached on what density would allow for good welfare. In the present study, the welfare of 4 replicates of birds stocked at 8, 19, 29, 40, 45, 51, 61, and 72 broilers per pen (or 6, 15, 23, 33, 35, 41, 47, and 56 kg actually achieved BW/m(2)) was studied using 6 welfare indicators. Density did not affect bursa weight, mortality, or concentrations of corticosterone metabolites in droppings but did influence leg health (P = 0.015) and footpad and hock dermatitis (P < 0.001) and tended to influence fearfulness (P = 0.078). However, not every increase in density or group size, or both, led to poorer welfare for the affected indicators: leg health and fearfulness showed unexpected peaks at intermediate densities. Furthermore, the indicators were influenced at different densities: leg strength showed a steep decrease from 6 to 23 kg/m(2), hock dermatitis rose from 35 to 56 kg/m(2), and footpad dermatitis and fearfulness were only significantly higher at the highest density of 56 kg/m(2). No threshold stocking density above which all aspects of welfare were suddenly altered was found in this study. Instead, different aspects of welfare were influenced at different densities or group sizes, or both. Thus, evaluating the effects of stocking density on welfare as a whole would require either identification of acceptable levels for each separate indicator or a weighting of the indicators in an integrated welfare score. A tentative attempt to such an integration, made using equal weights for all parameters, showed a decrease in welfare as density increased (P < 0.001). The lowest 2 densities (6 and 15 kg/m(2)) scored better than most middle densities (23, 33, 35, and 47 kg/m(2)), whereas all densities scored better than the highest density (56 kg/m(2)).

Live Performance, Carcass Yield, and Welfare of Broilers of Different Genetic Strains Reared at Different Housing Densities

“…In addition, Oliveira et al (2005) and Buijs et al (2009) did not observe any effect of rearing density on that parameter either. On the other hand, Moreira et al (2004), evaluating three housing densities (10, 13, or 16 broilers/m 2 ), observed significant reduction in weight gain in birds housed at 10 and 16 birds/ m 2 .…”

The effect of level of straw bale provision on the behaviour and leg health of commercial broiler chickens

“…As birds rarely used SBs for perching, possibly owing to difficulty in accessing the top of high bales (Carley Bailie, personal observation), it is possible that increased numbers of SBs may have resulted in decreased floor space available for use by the birds (Kells et al, 2001). Increased bale numbers may therefore have effectively increased stocking density, and this has been shown to have a detrimental effect on latency to lie in broilers (Buijs et al, 2009). However, as bales tended to disintegrate over the course of the rearing cycle, the resultant decrease in floor space associated with the provision of extra SBs may not have been an issue during the latter weeks of the rearing cycle.…”

Vocalisation sound pattern identification in young broiler chickens

“…Chicken health, welfare and growth performance is dependent on human management, environmental management, genetics, nutritional and disease factors (Yahav et al, 2005;Buijs et al, 2009;Kenny et al, 2012). Progress has been made in the last 10 years to develop indices and potential on-farm measures of animal welfare, for example, the AWIN (2015) and Welfare Quality (2009) protocols.…”