Social and Environmental Factors Affect Behaviour and Welfare of Turkeys17 July 2013
Studies have demonstrated that turkeys may show large behavioural adjustments in response to sub-optimal environmental conditions, according to a new review paper from Spain and Italy.
Feed presentation and lighting affect bird activity. Catching, crating and transportation are highlighted as the management factors most likely to impact turkey welfare negatively, while the authors highlight the need for more research to be carried out into welfare under commercial conditions.
In modern rearing systems, turkey producers often face economic losses due to increased aggression, feather pecking, cannibalism, leg disorders, or injuries among birds, which are also significant welfare issues, according to J. Marchewka from Neiker-Tecnalia in Vitoria-Gasteiz, Spain and co-authors there and at Italy's University of Milan.
In a review paper in Poultry Science, they report that the main underlying causes appear to relate to rapid growth, flock size, density, poor environmental complexity, or lighting, which may be deficient in providing the birds with an adequate physical or social environment.
To date, they say, there is little information regarding the effect of these factors on turkey welfare. This knowledge is, however, essential to ensure the welfare of turkeys and to improve their quality of life, but may also be beneficial to industry, allowing better bird performance, improved carcass quality and reduced mortality and condemnations.
Their paper reviews the available scientific literature related to the behaviour of turkeys as influenced by the physical and social environment that may be relevant to advances toward turkey production systems that take welfare into consideration.
They address the effects that factors such as density, group size, space availability, maturation, lightning, feeding and transport may have over parameters that may be relevant to ensure welfare of turkeys.
Available scientific studies were based in experimental environments and identified individual factors corresponding to particular welfare problems. Most of the studies aimed at finding optimal levels of rearing conditions that allow avoiding or decreasing most severe welfare issues.
Marchewka and co-authors discuss the importance of these factors for development of production environments that would be better suited from a welfare and economic point of view.
Scientific studies on the effects of the characteristics of the physical and social environment of turkeys’ behaviour and their implications from a welfare standpoint are still scarce, according to Marchewka and co-authors. However, they say, studies have demonstrated that turkeys may show large behavioural adjustments as a response to inadequate environmental conditions. For example, studies focused on the effects of density, group size or both have shown that high densities led to gait deterioration and decreased activity, insufficient space availability related to a higher frequency of injuries, especially wing breakages, as well as increased aggression levels, whereas large group size led to feather pecking occurrences.
Similar to other poultry, a general decline in activity was found with increasing age, with first signs of decreased locomotion becoming apparent generally from four weeks of age onwards, whereas the injurious pecking may occur already after the third week of life.
Feed presentation has also the potential to alter turkey activity, according to the authors. The provision of feed in pellets compared with crumbles has been associated with longer feeding bouts, which could be beneficial to divert the birds from other undesirable activities such as feather pecking. However, these results contrast with the increased feeding time when provided with crumble feed in turkey studies conducted in 1962. The addition of feed enrichments in the form of whole wheat was found to increase eating time but it did not influence birds after six weeks of age. Similar to broiler breeders, feed restriction of turkeys increased oral activity paralleled with increments in standing, walking and preening behaviour, which is typically interpreted as a sign of hunger and frustration. However, as for broiler breeders, it is required to maintain a bodyweight balance to avoid other health and welfare problems associated with overweight.
The issue that has perhaps received the most attention in turkeys is lighting, according to Marchewka and co-authors. Turkeys preferred fluorescent over incandescent lighting, probably because is perceived by them as less intense, and they showed better walking ability when provided with dark periods. Young birds showed clear preferences for brighter environments to perform all activities, whereas adults rested and perched preferably under dim light but conducted all active behaviours in brightness. Some studies have also shown that birds may benefit from UV-A light-enriched environments by reducing visually mediated aberrant behaviours.
However, the authors highlight that, of all the factors that may influence turkey health and welfare, catching and crating, as well as transportation to slaughter, have been shown to be some of the most detrimental procedures for welfare, with the potential of causing not only major carcass damage and lost profitability, but also the death of the birds if procedures are conducted in an inadequate manner.
Current studies have shown that changes in activity, such as locomotion, and time budget schemes, and exhibition of aggression, feather pecking or cannibalism are behavioural indicators that can be largely influenced by the conditions of the physical and social environment, they authors found in their review. However, they stress that it is essential to consider that the results presented in the review were mostly based on studies conducted under strict experimental conditions, and therefore, it is difficult to extrapolate the conclusions to what would happen under commercial systems in which several thousand birds are reared simultaneously.
Additionally, variability between flocks, farms, and even countries caused by different management systems and environmental conditions can determine to a great extent the variability in behavioural and welfare outcomes.
Marchewka and co-authors stress that, in some experimental studies, the effects of density, group size and pen size were often confounded because of the difficulties of separating those effects, and furthermore, biological events often do not follow a linear pattern.
In broilers, they say, differences between experimental and commercial situations were found to cause uncertainty in welfare risk estimation and hazard consequences. This uncertainty could be reduced by further studies, expert opinions and their judgments, and obviously by studies conducted under commercial scenarios.
The review paper's authors conclude that the use of mathematical models for complex analysis may also be relevant to find the optimal balance between flock productivity and welfare.
Marchewka J., T.T.N. Watanabe, V. Ferrante and I. Estevez. 2013. Review of the social and environmental factors affecting the behavior and welfare of turkeys (Meleagris gallopavo).Poult. Sci. 92(6):1467-1473. doi: 10.3382/ps.2012-02943
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